Commercial Potential of Giant Reed for Pulp, Paper and Biofuel Production RIRDC Publication No. 10/215
RIRDC
Innovation for rural Australia
Commercial Potential of Giant Reed for Pulp, Paper and Biofuel Production by Dr Chris Williams and Dr Tapas Biswas With the Support of FibreCell Australia Pty Ltd
December 2010 RIRDC Publication No. 10/215 RIRDC Project No. PRJ-000070
© 2010 Rural Industries Research and Development Corporation. All rights reserved. ISBN 978-1-74254-180-8 ISSN 1440-6845 Commercial Potential of Giant Reed for Pulp, Paper and Biofuel Production Publication No. 10/215 Project No. PRJ-000070 The information contained in this publication is intended for general use to assist public knowledge and discussion and to help improve the development of sustainable regions. You must not rely on any information contained in this publication without taking specialist advice relevant to your particular circumstances. While reasonable care has been taken in preparing this publication to ensure that information is true and correct, the Commonwealth of Australia gives no assurance as to the accuracy of any information in this publication. The Commonwealth of Australia, the Rural Industries Research and Development Corporation (RIRDC), the authors or contributors expressly disclaim, to the maximum extent permitted by law, all responsibility and liability to any person, arising directly or indirectly from any act or omission, or for any consequences of any such act or omission, made in reliance on the contents of this publication, whether or not caused by any negligence on the part of the Commonwealth of Australia, RIRDC, the authors or contributors. The Commonwealth of Australia does not necessarily endorse the views in this publication. This publication is copyright. Apart from any use as permitted under the Copyright Act 1968, all other rights are reserved. However, wide dissemination is encouraged. Requests and inquiries concerning reproduction and rights should be addressed to the RIRDC Publications Manager on phone 02 6271 4165. Researcher Contact Details Dr Chris M. J. Williams South Australian Research and Development Institute Sustainable Systems, Water Resources and Irrigated Crops GPO Box 397 Adelaide SA 5001.
Associate Professor Jim Cox, South Australian Research and Development Institute Sustainable Systems Water Resources and Irrigated Crops GPO Box 397 Adelaide SA 5001.
Phone: 08 8303 9567 Fax: 08 8303 9473 Email: retired 2009
Phone: 08 8303 9334 Fax: 08 8303 9473 Email:
[email protected]
In submitting this report, the researcher has agreed to RIRDC publishing this material in its edited form. RIRDC Contact Details Rural Industries Research and Development Corporation Level 2, 15 National Circuit BARTON ACT 2600 PO Box 4776 KINGSTON ACT 2604 Phone: Fax: Email: Web:
02 6271 4100 02 6271 4199
[email protected]. http://www.rirdc.gov.au
Electronically published by RIRDC in December 2010 Print-on-demand by Union Offset Printing, Canberra at www.rirdc.gov.au or phone 1300 634 313
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Foreword In Australia and many other countries, escalating demands for high quality water resources, arable land, food and fossil fuels is rapidly growing. With an emerging “feed versus fuel debate” there is a pressing need to find options for the use of marginal lands (unsuited for food crops) and wastewaters or saline ground waters to produce second generation biofuel or biopaper crops. Arundo donax (A. donax) was selected as a potential crop for use in this area. Research shows it can produce 45.2 tonnes/hectare/year grown on marginal land using saline winery wastewater for irrigation. In addition A. donax can produce more lignocellulosic biomass using less land than other alternative biomass crops currently grown on marginal lands. Laboratory studies demonstrate that A. donax can produce up to 240 L of bioethanol per oven dry tonne of biomass, with potential of up to 350 L. Weed risk management guidelines have been developed for A. donax in Australia. This project was funded from the industry revenue which is matched by the funds provided by the Australian Government. This report is an addition to RIRDC’s diverse range of over 2,000 research publications and it forms part of our New Rural Industries R&D program, which aims to provide the knowledge for diversification in Australia’s rural industries. Most of RIRDC’s publications are available for viewing, free downloading or purchasing online at www.rirdc.gov.au. Purchases can also be made by phoning 1300 634 313.
Craig Burns Managing Director Rural Industries Research and Development Corporation
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Acknowledgments The project team acknowledges the funding provided by the Rural Industries Research and Development Corporation of Australia and FibreCell Australia Pty Ltd and South Australian Research and Development Institute for financial support. . The authors thank Mr Lyndon Palmer and Mrs Teresa Fowles of Waite Analytical Services of the Plant Science Department, University of Adelaide, Waite Campus for chemical analyses, and the staff of the Analytical Crop Management Laboratory at Loxton for total nitrogen and organic carbon analyses. Thanks go to Mr D. Maschmedt, formerly of Primary Industries and Resources, South Australia for the soil classifications. We thank Dr Lin Lin Low of Constellation Wines, Berri Estates, South Australia for storage and flood irrigation of winery wastewaters to the A. donax crops at Barmera; John Matheson and Paul Harris (University of Adelaide) for provision of wastewaters and application of the drip irrigations on the Roseworthy A. donax crops. Also included in our thanks are Mr Stephen Heading and the dedicated team of casuals who assisted in the experimental work. Special thanks to Louise Chvyl for her indispensable, most capable assistance with tabulation of data, and compilation of this report. We also thank Ms Adrienne Twisk for most capable assistance with formatting and final revisions of this report.
Please note: Dr Williams retired in December, 2009, and Dr Biswas has moved to a new position interstate. Please direct all enquiries, in the first instance, to Associate Professor Jim Cox, Principal Scientist, Water Resources and Irrigated Crops, SARDI, GPO Box 397, Adelaide, South Australia 5001. His email is
[email protected].
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Contents Foreword
......................................................................................................................................... iii
Acknowledgments ................................................................................................................................ iv Executive Summary ............................................................................................................................. xi Introduction .......................................................................................................................................... 1 Objectives
.......................................................................................................................................... 2
Methodology .......................................................................................................................................... 3 Chapter 1: Dry matter yield, carbon accumulation and biochar from Arundo donax grown in South Australia ............................................................................................... 4 Chapter 2: Salt tolerance and nutrient dynamics of Arundo donax ............................................... 20 Chapter 3: Weed risk management guidelines for Arundo donax plantations in Australia ........ 42 Chapter 4: Evaluation of Arundo donax for pulp/paper ................................................................. 70 Chapter 5: Pretreatment and fermentation studies for second generation ethanol production from Arundo donax ................................................................................... 72 Chapter 6: Arundo donax in the upper South East of South Australia ......................................... 82 Implications ........................................................................................................................................ 89 Recommendations ............................................................................................................................... 90 Appendices ........................................................................................................................................ 91 References
...................................................................................................................................... 143
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Tables Table 1.1:
Treatment details for experiments on arable soil at Roseworthy ....................................................... 6
Table 1.2:
Dry matter (DM) biomass yields (t/ha) at Roseworthy at each clearfell for the A. donax old stand (first clear felled 7/06/2005 after 30 years) .............................................................................. 9
Table 1.3:
Organic carbon (t/ha) sequestered at Roseworthy at each clearfell, from the A. donax old stand (first clearfelled 7/06/2005). .............................................................................................................. 9
Table 1.4:
Stem height, diameter, number, dry weight and percent dry matter for 5 June 2006 clearfell harvest at Roseworthy...................................................................................................................... 11
Table 1.5:
Dry matter (DM) biomass yields at Barmera CF at each clearfell* .................................................. 15
Table 1.6:
Organic carbon sequestered at Barmera CF at each clearfell* ......................................................... 15
Table 1.7:
Maximum yield, net energy, fuels/year (mean value from the second to the twelfth year of growth, Italy). .................................................................................................................................. 18
Table 2.1:
Suction tube soil water ECswe (dS/m), at Barmera, from January 2008 to March 2009a................ 25
Table 2.2:
Suction tube soil water extract nitrate-N (mg/L), at Barmera, from January 2008 to March 2009a. ................................................................................................................................... 26
Table 2.3:
Average carbon and macro-nutrient concentrations (% on a dry matter basis) of A. donax at Barmera for 3 annual clearfell harvests. .......................................................................................... 30
Table 2.4:
Average carbon and macro-nutrient uptake by A. donax at Barmera at 3 annual clearfell harvests. ........................................................................................................................................... 31
Table 2.5:
Nutrient concentrations for 23 March 2006 harvest for the established planting at Roseworthy ... 33
Table 2.6:
Nutrient uptake for 23 March 2006 harvest for the established planting at Roseworthy ................. 33
Table 2.7:
Average macro-nutrient concentrations of A. donax at Roseworthy final harvest 2009 .................. 34
Table 2.8:
Average macro-nutrient removals for Roseworthy final harvest 2009 (25/06/2009) ....................... 34
Table 2.9:
Average macro-nutrient concentrations in the rhizomes, string and hair roots for 2 annual harvests of A. donax at Barmera........................................................................................... 35
Table 2.10:
Average meso-nutrient concentrations of the rhizomes, string and hair roots of A. donax for 2 annual harvests at Barmera ........................................................................................................... 36
Table 2.11:
Average micro-nutrient concentrations in the rhizomes, string and hair roots of A. donax for 2 annual harvests at Barmera. .......................................................................................................... 37
Table 2.12:
Comparison of soil organic carbon and nutrients at 29 June 2005 and 28 February 2006 at Roseworthy for the established planting at different soil depths...................................................... 38
Table 2.13:
Soil organic C and macro-nutrients at the final sampling (June 2009) of the A. donax clearfell treatments at the Roseworthy sites. .................................................................................... 38
Table 2.14:
Comparison of soil average organic C and macro-nutrients at the start (May 2006), middle (May 2007) and end (June 2009) under A. donax clearfell treatments at the Barmera site ............. 39
Table 2.15:
Soil average organic C and macro-nutrients at the start (May 2006), middle (May 2007) and end for the control area of the Barmera trial .................................................................................... 40
Table 5.1(a): Inhibitory compounds derived from acid/enzyme hydrolysate (10% w/v) of A. donax. .................. 79 Table 5.1(b): Inhibitory compounds derived from alkali/enzyme hydrolysate (10% w/v) of A. donax. ................ 79 Table 5.2:
Summary of pretreatment and fermentation results for 10% (w/v) A. donax. .................................. 80
Table 6.1:
Preliminary cost assumptions for A. donax plantations ($/ha) ......................................................... 84
Table 6.2:
Preliminary industrial A. donax growing system costs/ha: summary ($) ......................................... 85
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Table 6.3:
Preliminary factory gate “oven dry” tops $/t to achieve 15% IRR and mature A. donax plantation yields (t/ha/year of “oven dry” tops) ............................................................................... 85
Table 6.4:
IRR results for conversion factories using A. donax feedstock sited in the South East of South Australia (central price estimates shown first in each series). ............................................... 87
Appendix Tables Table 1.A.1: Soil profile descriptions for A. donax sites at Barmera, South Australia. ....................................91 Table 1.A.2: Roseworthy Monthly Weather Data ........................................................................................92 Table 1.A.3: Loxton Research Centre Monthly Weather Data ......................................................................93 Table 1.B.1: Summary of batch pyrolysis trial results. ......................................................................................... 99 Table 1.B.2: Mass and energy balance. .............................................................................................................. 104 Table 1.B.3: Proximate and ultimate analysis results from ITA for A. donax feedstock .................................... 105 Table 1.B.4: Proximate and ultimate analysis results from ITA for A. donax biochar ....................................... 106 Table 2.A.1: Irrigation water composition (salinity (EC) and nutrients) in holding lagoon, Barmera, prior to application to Adx ab from June 2006 to July 2007. .................................................................. 107 Table 2.A.2: Irrigation water composition (salinity and nutrients) in holding lagoon, Barmera, at 7 sampling dates from September 2006 to May 2007 a. ................................................................... 108 Table 2.A.3: Irrigation water composition (salinity (EC) and nutrients) in the holding lagoon, Barmera, prior to application to Adx ab. ........................................................................................................ 109 Table 2.A.4: Irrigation water composition (salinity and nutrients) in holding lagoon, Barmera, at 9 sampling dates from January 2008 to April 2009 a. ....................................................................... 110 Table 2.A.5: Irrigation water composition (nutrients and metals in mg/L) applied in 2006 at Roseworthy. ...... 111 Table 2.A.6: Average meso-nutrient concentrations of A. donax organs at Barmera for 3 annual clearfell harvests. ......................................................................................................................................... 112 Table 2.A.7: Average meso-nutrient uptake of Adx organs for 3 annual clearfell harvests at Barmera ............. 113 Table 2.A.8: Average micro-nutrient concentrations for 3 annual clearfell harvests at Barmera ....................... 114 Table 2.A.9: Average micro-nutrient removals concentrations for 3 annual clearfell harvests at Barmera. ..... 115 Table 2.A.10: Average meso-nutrient concentrations at Roseworthy for final harvest 2009 ................................ 116 Table 2.A.11: Average meso-nutrient removals at Roseworthy for final harvest 2009 ........................................ 116 Table 2.A.12: Average micro-nutrient concentrations at final Roseworthy harvest 2009. ................................... 117 Table 2.A.13: Average micro-nutrient removals at Roseworthy for final harvest 2009 (25/06/2009).................. 117 Table 4.A.1: Pulping of A. donax ....................................................................................................................... 119 Table 4.A.2: DEpD bleaching of unbleached pulp ............................................................................................. 120 Table 4.A.3: Physical Strength Properties .......................................................................................................... 121 Table 4.B.1: Summary of types of paper ............................................................................................................ 125 Table 4.B.2: Summary of magnesium bisulphate pulping results. ...................................................................... 126 Table 4.B.3: Summary of the woodmeal and pulp analysis ................................................................................ 130 Table 4.B.4: Summary of the wood/non-wood properties .................................................................................. 133
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Figures Figure 1.1:
Potential pathways to convert cellulosic biomass to biofuels. .................................................. 4
Figure 1.2:
A. donax, old stand, 361 days after first clear fell, left: Dryland and right: Irrigated treatments at Roseworthy............................................................................................................ 9
Figure 1.3 a, b:
Dry matter (DM) and organic carbon (C) yields of A. donax top growth, at Roseworthy old stand, irrigated clearfell (CF) treatment, 2005 to 2009....................................................... 10
Figure 1.4 a, b:
Dry matter and organic carbon yields of A. donax rhizomes, at Roseworthy old stand, irrigated CF sites, 2005-2009 ................................................................................................... 10
Figure 1.5 a, b:
Dry matter and organic carbon yields of A. donax tops, at Roseworthy old stand, dryland CF sites, 2005-2009. .................................................................................................... 11
Figure 1.6 a, b:
Dry matter and organic carbon yields A. donax rhizomes, at Roseworthy old stand, dryland CF sites, 2005-2009. .................................................................................................... 11
Figure 1.7 a, b:
Dry matter and organic carbon yields of A. donax tops, at Roseworthy, new planting, CF sites, 2006-2009. ................................................................................................................. 12
Figure 1.8 a, b:
Dry matter and organic carbon yields of A. donax rhizomes, at Roseworthy new planting, CF sites, 2006-2009. ................................................................................................................. 12
Figure 1.9 a, b:
Dry matter and carbon yields of A. donax tops, at Roseworthy, new planting, uncut sites, 2006-2009........................................................................................................................ 13
Figure 1.10 a, b: Dry matter and carbon yields of A. donax rhizomes, at Roseworthy new planting, uncut sites, 2006-2009........................................................................................................................ 13 Figure 1.11:
Left: Loveday rootstock of A. donax in marginal soil at Barmera, 5 months after planting, October, 2006; Right: same A. donax at first clearfell, June 2007 (yield 45.2 t/ha dry tops). .. 15
Figure 1.12 a, b: Dry Matter (DM) and organic carbon (C) yields of A. donax tops at Barmera for the annual clearfell treatments for the Loveday (▲) and Henley Beach rootstocks (•) over 3 years to 2009. ........................................................................................................................ 16 Figure 1.13 a, b: Dry Matter (DM) and organic carbon (C) yields of A. donax rhizomes at Barmera for the annual clearfell treatments for the Loveday (▲) and Henley Beach rootstocks (•) over 3 years to 2009. ........................................................................................................................... 16 Figure 1.14 a, b: Dry Matter (DM) and organic carbon (C) yields of A. donax tops at Barmera for the annual uncut treatments for the Loveday (▲) and Henley Beach rootstocks(•) over 3 years to 2009. ........................................................................................................................... 17 Figure 1.15 a, b: Dry Matter (DM) and organic carbon (C) yields of A. donax rhizomes at Barmera for the annual uncut treatments for the Loveday (▲) and Henley Beach rootstocks (•) over 3 years to 2009. ........................................................................................................................ 17 Figure 2.1:
ECswe and other variables change with time for first year growth of A. donax at Barmera, SA for (a) Loveday, and (b) Henley Beach rootstocks. Soil solution ECswe results are from suction tubes installed at 30, 60 and 90 cm soil depths................................... 23
Figure 2.2:
Changes in salinity of the influent irrigation, ECw and soil water extracts, ECswe in dS/m, and chloride and nitrate-N concentrations (mg/L) with time for the first year of growth of A. donax at Barmera, SA for Loveday and Henley Beach rootstocks....................................... 24
Figure 2.3:
Relative yield (RY) of dry tops of A. donax in response to the salinity of the saturatedsoil extract (ECe) ...................................................................................................................... 27
Figure 2.4:
Relative yield (RY) of dry tops of A. donax in response to the saturated- soil extract (ECe). ..................................................................................................................................... 27
Figure 2.5:
Schematic representation of possible layout, flows and concentrations of salt in SBC biosystem (modified after Blackwell et al. 2000, from Biswas and Williams 2009). ............... 28
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Figure 3.1:
Predicted distribution of A. donax in Australia (based on temperature only and not refined to areas with riparian ecosystems only) ........................................................................ 48
Figure 3.2:
Scoring for Comparative Weed Risk in the riparian and terrestrial land uses. .......................... 51
Figure 3.3:
Australian herbaria records for A. donax (Australia’s Virtual Herbarium) ............................... 53
Figure 3.4:
Scoring for Feasibility of Containment in the riparian and terrestrial land uses. ....................... 56
Figure 3.5:
Weed risk management action matrix and locations of the two land uses assessed for A. donax.................................................................................................................................... 57
Figure 3.6:
Example of data generated from AFLP analysis. ................................................................... 59
Figure 3.7:
Identical individuals grouped together: the group they are in and number of individuals in that group.............................................................................................................................. 61
Figure 3.8:
Dendrogram redone with only one representative from each group of identical individuals. ... 62
Figure 3.9:
Map of SA sample locations. The 4 individuals from the second genotype (blue) are indicated with blue triangles. .................................................................................................... 63
Figure 3.10:
Map of all samples. Individuals from the second genotype (blue) are indicated with blue triangles. ................................................................................................................................... 64
Figure 5.1:
Sugar extraction using 2% H2SO4 at 121oC, 30 min followed by 2% cellulase and 4% glucosidase (Novozyme) treatment at 60o C, pH 5.0 and 180 rpm for 22 h. ............................. 75
Figure 5.2:
Sugar extraction from A. donax using 2% H2SO4 at 134oC, 60 min followed by 2% cellulase and 4% β-glucosidase (Novozyme) treatment at 60o C, pH 5.0 and 180 rpm for 22 h. ............ 75
Figure 5.3:
Sugar extraction of A. donax using 2% H2SO4 at 134o C, 60 min followed by 2 % cellulase and 4 % β-glucosidase (Novozyme) treatment at 50o C, pH 5.0 and 180 rpm for 22 h. .......... 76
Figure 5.4:
Sugar extraction using 2% H2SO4 at 134o C, 30min followed by 0.2% cellulase and 0.4% β-glucosidase (Novozyme) treatment at 50o C, pH 5.0 and 180 rpm for 22 h. ......................... 76
Figure 5 5:
Sugar extraction of 10 % (w/v) A. donax using 2% NaOH at 134o C, 60 min followed by 2 % cellulase, 2% xylanase and 4 % β-glucosidase (Novozyme) treatment at 50o C, pH 5.0 and 180 rpm for 22 h. ......................................................................................................... 77
Figure 5.6:
Fermentation profile of ZM4 (pZB5) using A. donax acid/enzyme hydrolysate derived from 10% (w/v) substrate loading using 2% H2SO4 at 134o C for 60 min followed enzyme hydrolysis at 50o C for 22 h using 2% cellulase and 4% β-glucosidase. ................................... 78
Figure 5.7:
Fermentation profile of ZM4 (pZB5) using A. donax alkali/enzyme hydrolysate derived from 10% (w/v) substrate loading using 2% NaOH at 134o C for 60 min followed enzyme hydrolysis at 50o C, pH 5.0 for 22 h using 2% xylanase, 2% cellulase and 4% β-glucosidase. 78
Figure 5.8:
Schematic diagram of 2nd generation ethanol production process using acid/enzyme hydrolysis used in this study. .................................................................................................... 81
Figure 5.9:
Schematic diagram of 2nd generation ethanol production process using alkali/enzyme hydrolysis used in this study. .................................................................................................... 81
Figure 1.B.1:
Batch pyrolysis test rig. .......................................................................................................... 97
Figure 1.B.2:
Recorded process data from batch pyrolysis run. ................................................................... 98
Figure 1.B.3:
Proximate analysis results. ................................................................................................... 100
Figure 1.B.4:
Gross calorific value results. ................................................................................................ 101
Figure 1.B.5:
Ultimate analysis results. ...................................................................................................... 102
Figure 1.B.6:
Feedstock ash constituent results.......................................................................................... 103
Figure 4.B.1:
Relationship between total pulp yield and kappa number (100% P. radiata) ...................... 127
Figure 4.B.2:
Comparison of pulp strength properties (100% P. radiata used as control). ........................ 128
Figure 4.B.3:
Samples of subdivided P. radiata (right) and Adx (left) ...................................................... 129
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Figure 4.B.4:
Sample of Adx as received (left) and after cutting with a band saw (right).......................... 132
Figure 4.B.5:
Preparation of bisulphite pulping liquor (left) and analysis of the prepared liquor (right) ... 134
Figure 4.B.6:
Picture of digester (left) and liquor extraction point (right) ................................................. 134
Figure 4.B.7:
Collection of photographs from process steps and testing equipment .................................. 141
Figure 4.B.8:
Digital photos of selected handsheets................................................................................... 142
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Executive Summary What the report is about In Australia and most countries, increasing demands for high quality water resources, arable land, food and fossil fuels are greater than the sustainable, economic supply. This report presents research on the perennial, rhizomatous grass, giant reed (Arundo donax) to assess its use: 1. On marginal lands and wastewaters or saline ground waters, to produce lignocellulosic feedstocks (together with other biomass crops) 2. For new second generation biofuels and/or pulp/paper industries for Australia. Who is the report targeted at? This report is targeted at all sectors of the Australian and overseas biomass, second generation biofuels and the pulp/paper industries. The report is also intended to inform landcare agencies, policy makers, rural industries, local, state and federal governments, research funding bodies and researchers, investment bodies, communities, environment groups, media and the general public. Background Australia has large reserves of saline ground water (over 5,000 mg/L of total soluble salts) with 3,434 GL/year of sustainable groundwater unsuitable for drinking or irrigation of traditional crops. In addition, urban and peri urban sewage wastewater produced annually is 1,824 GL, of which only 156 GL is reused. Saline soils in Australia and South Australia (SA) are estimated to cover 2.6 and 1.4 million ha, respectively. In many situations large areas of saline, marginal soils exist adjacent to the saline water resources. Research was needed to use such wastewaters to grow salt tolerant, non-food biofuel crops, such as A. donax, on nearby saline, marginal lands, develop sustainable production systems and define biomass yields, carbon accumulation and processing qualities of the biomass for biofuels or pulp/paper. A concern, however, was whether weed risk management guidelines can be developed for A. donax plantations in Australia. Also, baseline data for industry are required on the potential yield of biofuels (eg. ethanol) per dry tonne of A. donax biomass and an evaluation of A. donax for pulp/paper or biochar products and the potential economic returns. Aims/objectives •
Produce baseline data to describe the biomass growth curves, carbon accumulation and nutrient uptake by the perennial grass, A. donax (giant reed) grown on saline, marginal land and arable land.
•
Assess the yield and quality of A. donax biomass feedstocks and their conversion efficiencies to biofuels or pulp/paper.
•
Conduct, for the Australian context, a formal weed risk assessment of A. donax and compile weed risk management guidelines.
•
Estimate indicative factory gate prices for A. donax, on different classes of land and internal rates of return for enterprises producing bioenergy and other products or pulp/paper.
Results/key findings We report for the first time in Australia, growth curves for giant reed (A. donax) for dry matter biomass yields and carbon accumulation over 3 years when grown on a marginal and an arable soil.
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A. donax produced more cellulosic biomass and sequestered more carbon per annum, using less land and pesticides than any other alternative crop reported in the literature, for warm temperate to sub tropical environments and for marginal lands under similar water input regimes (either irrigated with wastewaters or grown dryland with over 450 mm of annual precipitation). A.donax was grown with no pesticides and minimal energy inputs in South Australia (SA). A. donax produced a high biomass yield of 45.2 t/ha of dry tops in the first year, when grown on saline, marginal land at Barmera in SA with winery wastewater. On arable soil in South Australia at Roseworthy Campus (near Gawler), A. donax produced 45.4, 58.4, 55.6 and 59.3 t/ha/year of dry tops each clearfell year, when irrigated with reclaimed sewage. The non-irrigated A. donax treatment at Roseworthy produced 12.6 and 12.9 t/ha of dry tops with 5.3 and 3.8 ML/ha, respectively of precipitation in the period between clearfells. We suggest A. donax has potential as a biomass crop on dryland, marginal soils in areas which receive over 450 mm of annual precipitation. If groundwater is available (even moderately saline) within 3 metres of the surface, A. donax roots are likely to access such subsoil waters to enhance yields. From the results of this project we classed A. donax in the premium group of crops for biomass yields, and carbon accumulation (high yields of harvested above ground carbon/ha/year). A. donax grown with wastewater irrigation, sequestered over 20 t/ha/clearfell year of carbon in the plant tops and maintained a similar amount in dynamic equilibrium in rhizomes (underground stems). If each tonne of sequestered carbon is valued at A$30, then this can generate A$600/ha for carbon stored in rhizomes in a dynamic equilibrium. Work undertaken by a commercial company (Pacific Pyrolysis) found that A. donax is a suitable material for commercial pyrolysis and biochar production and recommended further larger scale pilot tests be undertaken to obtain baseline data to design an efficient factory. Our results have shown that A. donax is a highly salt tolerant plant (halophyte) and can act as an interceptor crop to remove certain potential pollutants such as nitrogen and potassium from wastewaters and produce high yields under low or high nutrient regimes. Work with weed ecology experts indicated that A. donax had a negligible weed risk to terrestrial natural ecosystems (non riparian areas) of Australia, provided ongoing protocols (eg. site selection, buffer zones, basic crop hygiene and other practices) are put in place to prevent any spread to riparian areas. Conversely, A. donax was assessed as not suitable to be grown in riparian areas (less than 1 in 50 year flood risk), nor should it be allowed to spread to such areas in Australia. A. donax has the potential to produce up to 5 times more air dry pulp/ha/year (15.2 t) compared to Eucalyptus hardwoods (3.1t) when grown in southern Australia and irrigated with similar quantities of wastewater. A. donax appears suitable for making lower brightness and lower quality grades of tissues and with further optimisation, using the common kraft pulping process, it appears possible to make generic photocopier papers from A. donax. The kraft test results indicate that there is an opportunity to replace some of the imported eucalypt pulp with kraft pulped A. donax, as both are similar, short fibre pulps. Laboratory-scale studies with 10% (weight/volume) A. donax have demonstrated that up to 240 L of ethanol per oven dry tonne of A. donax can be produced with acid/enzyme hydrolysis and 224 L/dry tonne with alkali/enzyme pre-treatment. Future studies are needed for larger scale research, with optimised pre-treatment and fermentations, as well as conditioned micro-organisms. These techniques are likely to result in significant improvements in ethanol yields and productivities from A. donax of up to a total of 300-350 L/oven dry tonne of biomass (to match the best ethanol yields recorded per dry tonne, from cellulosic feedstocks to date). The cost of growing A. donax in the upper South East of SA, in the Meningie Downs area was assessed (allowing a 15% internal rate of return to the grower). At A$60/oven dry tonne at the factory gate and 500,000 oven dry tonnes supplied per year to a conversion factory, A. donax shows potential as a new industry for SA to produce either bioethanol and lignin, or pulp/paper, provided 3 years of near-market agronomy research and development and upscaling is funded and conducted. Preliminary estimates indicate an internal rate of return on funds employed of 22% per annum for the bioethanol
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and lignin enterprise and 18% per annum for the pulp/paper enterprise, based on central price estimates. It is expected that the commercial potential of non food, lignocellulosic crop feedstocks grown on marginal lands for conversion to biofuels will increase in future if the price of fossil fuels rises significantly, as is expected. Implications for relevant stakeholders The implications for industry are most encouraging. Internationally, there is major funding for developmental research into second generation biofuels, a limited number of new, commercial scale factories and growing interest in developing new second generation biofuel factories in Australia. They could provide breakthrough conversion technologies to lower the cost of lignocellulose conversion to biofuels. Australia has large areas of underutilised, cheap marginal lands and saline ground waters or low quality wastewaters. Australia has a modern, technologically-driven agricultural sector that could benefit from development of new regional industries based on non-food biofuel or pulp/paper crops. A. donax has good potential to be a major lignocellulosic feedstock, when grown in non riparian zones provided ongoing protocols are put in place to prevent any spread to riparian zones. A. donax, together with other lignocellulose feedstocks could form the basis of new biofuel and/or pulp/paper industries for Australia. Mining and food processing industries can also consider growing salt tolerant A. donax for disposal of moderately saline wastewaters on marginal lands in non riparian zones (using an integrated biosystem such as ‘serial biological concentration’) and producing lignocellulosic feedstock for biofuels or pulp/paper. Rural communities can explore the options for growing A. donax, a non-food, energy crop on underutilised land and using moderately saline water resources and benefit from job creation from new industries. Policy makers can use the information provided in this report to make informed decisions on biofuels and carbon credit policies (including emerging industry incentive schemes) to benefit Australia’s communities and industries in future. Recommendations This report forms the basis for obtaining baseline data, guidelines for agronomic systems, salt tolerance, weed risk management and potential biomass yields and carbon accumulation of A. donax grown for lignocellulosic feedstocks for biofuels or pulp/paper, on marginal or arable lands in dryland or irrigated biosystems. The report also provides preliminary estimates of indicative factory gate prices for A. donax, grown on different classes of land, and internal rates of return for enterprises producing bioenergy and other products or pulp/paper in SA. Further work needs to be undertaken on the following: 1. Verify the quality characteristics of A. donax biomass for ethanol or pulp/paper by conducting larger scale factory tests on the A. donax. 2. Assess overseas technology to convert A. donax biomass to bioethanol (within 16 hour time from factory gate to ethanol). Develop partnerships to progress options to develop bioethanol factories in Australia using A. donax and other plant lignocellulosic feedstocks for biofuels. 3. Determine the use of the waste ferment biomass mulch (up to 2,000 tonnes per day) from the bioethanol factory. This may have potential as a soil amendment in A. donax plantations. A number of research and development gaps have been identified.
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•
Further work is needed to validate findings in small scale commercial plantations of A.donax of 5 hectare by 3 industrial biosystems, to upscale and demonstrate production systems developed in this report. The three proposed production systems are: dryland, roots self irrigated by the shallow water table and a saline, flood irrigation/drainage biosystem).
•
Develop pilot commercial systems of whole stem and/or rhizome plantings (based on the findings of Christou et al. 2000), with modifications to sugar cane planting and harvesting equipment to handle A. donax for large scale plantations, in non riparian zones of Australia.
•
Definition of the minimum nutrient and irrigation requirements of A. donax for target biomass yields for a range of environments. This should include assessment of wastewaters of different qualities on the survival and productivity of A. donax.
•
Plant species in Australia posing significant weed risks can be regulated through the various noxious weed Acts of the States and Territories. These are policy decisions for each government. As such it is not appropriate for this report to mandate a particular management approach. Rather, it is a guide for each State or territory to consider in determining their policy on A. donax. Each State interested in the potential cultivation of A. donax needs to develop a sound weed risk management policy (in the early stages of industry development).
•
It is desirable to obtain funds and conduct an international forum on: ‘Potential and barriers to develop A. donax and other lignocellulosic crops for biofuels or pulp/paper’. This would greatly facilitate the compilation of best practices and technologies to help establish new second generation biofuels industries.
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Introduction In Australia and most countries, increasing demands for high quality water resources, arable land, food and fossil fuels are greater than the sustainable, economic supply. This report presents research on the perennial, rhizomatous grass, giant reed (A. donax) for use on marginal lands (unsuited for food crops) with wastewaters or saline ground waters (or non-irrigated in areas with over 450mm annual precipitation) to produce lignocellulosic feedstocks (together with other biomass crops) to form the basis of new second generation biofuels and/or pulp/paper industries for Australia. The primary advantages of having a lignocellulosic biofuels industry are that the source materials are relatively cheap, domestically available, may not divert resources from food production, and they can be used to add value to existing rural industry processes (Warden and Haritos 2008). Globally, there is a growing need for cost effective, plentiful and low carbon dioxide emission transport fuels for industry and second generation biofuels could supply a portion of the global need (Warden and Haritos 2008). The biomass yields, carbon accumulation and biochar from A. donax are reported in Chapter 1, its salt tolerance and nutrient dynamics in Chapter 2, and weed risk management guidelines in Chapter 3, all to develop sustainable production systems. To provide new baseline data for industry, feedstock quality tests on A. donax are presented for pulp/paper in Chapter 4, for ethanol in Chapter 5 and potential economic returns in Chapter 6.
1
Objectives 1.
Overall, this project aims to produce baseline data to describe the biomass growth curves and nutrient uptake by the perennial grass, A. donax (giant reed) grown on saline, marginal land and arable land.
2.
Assess and report the yield and quality of A. donax biomass products from different production systems and their conversion efficiencies to biofuels or fibre. Compare such results for A. donax with that for other major crop options as reported in the literature, as feedstocks for biofuels (in Chapters 1, 5 and 6), for bioremediation (in Chapters 2 and 6) or for fibre/pulp/paper (in Chapters 4 and 6).
3.
Work with weed ecology experts (including Dr John Virtue, Department of Water, Land and Biodiversity Conservation and Dr Chris Preston, University of Adelaide) to conduct, for the Australian context, a formal weed risk assessment of A. donax and compile a weed risk management guidelines report (in Chapter 3).
4.
Assess via research conducted with Professor Peter Rogers (University of New South Wales) the pre treatment and fermentation for second generation ethanol production from A. donax (in Chapter 5).
5.
Conduct economic analyses, with Dr Ian Black, Principal Economist, SARDI, to estimate indicative factory gate prices for production of A. donax, on different classes of land and internal rates of return for enterprises producing bioenergy and other products or pulp/paper (in Chapter 6).
2
Methodology This report presents research on the potential and obstacles of growing A. donax (giant reed), on marginal lands and using wastewaters or moderately saline ground waters, to produce lignocellulosic feedstocks for biofuels and/or pulp/paper production. The methodologies utilised for each of the components of this project are detailed in the Materials and Methods sections of respective Chapters, and are summarised as follows: •
Plant yield and nutrient content data were used to calculate biomass yields, carbon accumulation and biochar from A. donax grown on marginal land and on arable soil, with varying irrigation regimes, (Chapter 1).
•
Data on salinity (ECswe) and nutrient concentration of soil water, together with crop evapotranspiration and plant and soil nutrient data were used to determine the salt tolerance and nutrient dynamics of A. donax (Chapter 2).
•
Weed ecology experts conducted a weed risk assessment using the South Australian Weed Management System (Virtue 2008) for future A. donax plantations in Australia (Chapter 3).
•
Two studies were commissioned to assess the feedstock quality of A. donax for pulp/paper, using two different methods. Central Pulp and Paper Research Institute, Saharanpur, India, assessed A. donax using the kraft pulping method and CSIRO Material Science and Engineering utilised the bisulphite pulping process (Chapter 4 and Appendices 4.A and 4.B respectively).
•
Laboratory-scale fermentation studies using both acid/enzyme and alkali/enzyme pre-treatments were undertaken to assess the potential for ethanol production (Chapter 5).
•
A preliminary economic analysis of production of A. donax on different classes of land and internal rates of return for conversion enterprises was undertaken. Details of the figures and assumptions used are documented (Chapter 6).
The results determined in Chapters 1, 2, and 3 are necessary to develop sustainable production systems for A. donax. The analyses and assessments reported in Chapters 4, 5 and 6 provide basic information the use of A. donax within the biofuels and pulp/paper industries.
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Chapter 1: Dry matter yield, carbon accumulation and biochar from Arundo donax grown in South Australia by Chris Williams1, Tapas Biswas1, 2, Louise Chvyl1, Paul Harris3 and Chris Dyson1 1 SARDI, GPO Box 397, Adelaide, SA 5001, Australia, 2 Murray-Darling Basin Authority, GPO Box 1801, Canberra, ACT 2601 3 University of Adelaide, Waite Campus, PMB 1, Glen Osmond, SA 5064
Introduction More than 50 % of the cropped land in Australia is affected by soil acidity, sodicity and salinity problems with an estimated annual impact to the agriculture of over A$2,500 million (National Land and Water Resources Audit, 2002). Sustainable systems to use marginal land and waste waters for second generation biofuel or pulp/paper crops are urgently needed (Williams et al. 2007). The introduction of high-yielding, non-food biomass crops to support the change to renewable energy policy is inevitable. A. donax, commonly known as giant reed, has many relevant potential uses as feedstock for biofuels, pulp/paper or fodder production (Spafford 1941; Lewandowski et al. 2003; Paul and Williams 2006; Williams et al. 2006; 2008a). It is a perennial rhizomatous grass that has been present for over 150 years in Australia (Jessop et al. 2006). Williams et al. (2006; 2008b) reported A.donax produced exceptionally high biomass yields, of 51 t/ha of total dry matter yield of tops when harvested 43 weeks after clearfell (of a 30 year old stand) grown on arable land, irrigated with sewage effluent at Roseworthy, South Australia, and grown with no pesticides. Pathways for producing biofuels from A. donax are shown in Figure 1.1.
Potential pathways for biochar, biofuels Pyrolysis+ Use saline soils and saline wastewaters on
Bio- oil
pressure
Thermal treatment SALT TOLERANT GRASSES (eg Arundo donax ) , TREES
“Syngas ”
Organic wastes
Biochar: soil carbon store / C credit
Microbes or catalysts
Consolidated process (microbes Or enzymes)
Feedstock development SUNLIGHT
BIOMASS (smart breeding, genetic engineering)
MONOMERS
Biomass deploymerisation (microbes or enzymes)
FUELS
Biofuel production (microbes, enzymes or catalysts)
Algae Source: modified from The Economist, 2008
Figure 1.1: Potential pathways to convert cellulosic biomass to biofuels.
4
Giant reed, to put A. donax in its environmental context, is invasive in riparian systems of many regions of the world. The lack of fertile seed production limits spread of the reed via various seed dispersal mechanisms. Where stem and rhizome fragments are broken and dispersed by floodwaters, the species provides a significant weed threat. Based on the assumption that the appropriate planting sites are selected (eg. no plantations in riparian zones subject to flooding) and appropriate rigorous crop hygiene is employed (eg. use of buffer areas, covered transport), A. donax could be grown with a manageable level of risk (see Chapter 3; also Williams et al. 2006; 2008a; Pollock, Czako and Marton, unpublished data). This chapter describes the biomass production and carbon accumulation, pyrolysis and biochar characters of A. donax grown without pesticides on both arable and on marginal lands and examines potential roles for A. donax in Australian agriculture.
Materials and methods Field studies were conducted at the Roseworthy Campus (34˚ 52' S, 138˚ 69' E, altitude 68 m) of the University of Adelaide, South Australia. The climate of the region is typical of the southern Mediterranean-type environment, which consists of hot, dry summers and cool, wet winters. The experimental designs were blocks without replication, and subsamples were taken from each treatment to calculate means and indications of standard errors. An established, mainly dryland planting in a 90 m by 6 m block of A. donax of over 30 years in age, (‘old stand’) was divided into two blocks. The area was clear-felled to 10 cm on 7 June 2005 and 150 kg N/ha was surface applied. An irrigation regime using drippers was imposed from 16 January 2006 on a 60 metre portion of the block, (‘irrigated stand’) which had previously received some informal rainwater run-off, with the remainder never irrigated and termed ‘dryland stand’ (Table 1.1). For a supplementary study, rhizome sections of A. donax were planted at 5 rhizomes/m2 in a 40 m by 20 m block on 15 December 2005 (termed the ‘new planting’) and irrigation begun on 20 December 2005 (Table 1.1). Nitrogen was surface applied at 150 kg N/ha, 7 days before planting. The soil textures of the topsoils were loamy sand and medium clay at the old and new stands, respectively. The arable soils for the old stand and new plantings were a Calcareous, Regolithic, Red-Orthic Tenosol and a Sodic, Hypercalcic, Red Dermosol, respectively (Isbell 2002). Class 3 treated sewage effluent from the Campus residential area (reclaimed water) and pond treated dairy and pig effluent (recycled water) were used to irrigate the irrigated old stand and new planting, respectively (Table 1.1). Rates applied are given in the results section. At every clearfell A. donax plants were cut to 10 cm above soil level, per treatment. Plant yield, carbon and nutrient content and uptake were assessed from 3 to 5 quadrats of 0.5 or 1 m2 cut to 10 cm at each harvest. A total of 1 to 4 harvests of plant tops and rhizomes from the regrowth A. donax were conducted each year. Fresh weights of leaf and stem fractions were recorded and subsamples oven dried at 70˚C to determine dry matter content, yields, nutrient content and uptake. Plant and soil samples were analysed using procedures as described by Williams et al. (2004) and water by APHA (1998) methods. No pesticides were applied to A. donax during the conduct of these field experiments.
5
Table 1.1: Treatment details for experiments on arable soil at Roseworthy Treatment
Initiated
Method
Begin irrigation
Water source
Dripper spacing
Dryland old stand
7 June 2005
Clearfelled every 12-15 months
na
na
na
Irrigated old stand
7 June 2005
Clearfelled every 12-15 months
16 January 2006
Sewage effluent
75 * 50 cm#
New planting cut
15 December 2005
Rhizomes planted; then clearfelled every 12-15 months
20 December 2005
Pond-treated Dairy
100 * 50 cm#
New planting uncut
15 December 2005
Rhizomes planted; then left uncut
20 December 2005
Pond-treated Dairy
100 * 50 cm#
na=Not applicable #
Distance between polypipe lines of drippers then spacing between drippers in the line
The field site for studies on marginal land was a former salt evaporation basin near Barmera, SA (34° 14' S, 140° 35' E). The soil at the site was loamy sand overlying a sandy clay loam (pedology details in Appendix Table 1.A.1). The 1:5 soil:water Electrical Conductivity (EC) in the top 90 cm of soil ranged from 0.62 to 1.53 dS/m (saline soils). A. donax plantings were established by planting rhizomes from a nearby wild A. donax stand at Loveday, SA (Loveday rootstock) and a second rootstock from sandhills, approximately 100 metres from seawater at an Adelaide beach, Henley Beach, (Henley Beach rootstock). Rhizomes of both rootstocks were planted at 2-4 per linear metre in furrows 1 m apart (Williams et al. 2008b), (approximately 4 t/ha of rhizomes on an oven dry matter basis). The area was flood irrigated periodically with pond treated winery wastewater. The rates applied for each period of A. donax regrowth between clearfells are presented in the results section. Three to four harvests of plant tops and rhizomes were conducted each year to measure dry matter production and carbon accumulation, nutrient uptake and major salt elements, eg. sodium (Na) and potassium (K), with portions of both plantings remaining uncut. Plant, soil and water samples were analysed as per Williams et al. (2004) and APHA (1998). Climate data for both sites are presented in Appendix Tables 1.A.2 and 1.A.3. A sample of A. donax Loveday rootstock (stems with leaves) was sent to Pacific Pyrolysis, for batch pyrolysis tests to assess its suitability as a feedstock for commercial pyrolysis for heat, power and biochar production.
Results and discussion Plant and rhizome yield and carbon accumulation by A. donax at Roseworthy (a)
Clearfell old stand irrigated and dryland Total yield of A. donax plant top growth (leaf + stem) in the Roseworthy 30-year old stand, one year after the initial clearfell (CF), for the irrigated old stand was 45.4 t/ha of dry matter (DM), (Table 1.2). Thereafter this irrigated old stand at Roseworthy produced very high and consistent dry matter yields of plant tops of 58.4, 55.6, and 59.3 t/ha, respectively, each
6
clearfell year for the next 3 years (Table 1.2, Figures 1.2-1.5). For each of these 4 regrowth periods between clearfells (Table 1.2), irrigation rates applied were 17.9, 20.6, 13.5 and 14.7 ML/ha, respectively (plus precipitation of 5.3, 2.9, 3.8 and 2.3 ML/ha, respectively). The dry matter yields (Table 1.2) are higher than the range reported by Christou et al. (2001) and slightly greater than the highest yield sites reported in Angelini et al. (2005) and Lewandowski et al. (2003) in Europe. Christou et al. (2001) reported that the highest irrigated treatment (up to 14 ML/ha of irrigation plus approximately 5.6 ML/ha of precipitation/year) produced the densest stands and the highest yields, every year, of 24 to 30 t of dry matter/ha/year over 8 years of an annual clearfell regime. The ranges of A. donax yield results between countries are likely to be related to differences in genotypes, climate, soils, years, age of plantings, crop management and irrigation regimes. The relative quantity of carbon (C) sequestered in A. donax top growth and rhizomes (t C/ha/year) was closely related in relative terms to the A. donax top growth total dry matter yields (t/ha/year), (Tables 1.2, 1.3 and Figures 1.3 and 1.4). This was due to the carbon content of the plant organs being relatively constant: leaf, stem and rhizome C ranged from 41-47%, 38-47% and 43-49%, respectively on a dry matter basis (Chapter 2). Williams and Biswas (2009a) reported similar findings for the carbon content of A. donax organs in a series of pot trials conducted in a greenhouse. It is important to note that when the stand at Roseworthy, over 30 years old, was first clearfelled on 7 June 2005, to initiate the annual clearfell regime, 82.1 t/ha of oven dry green live stems plus 60.3 t/ha of dry dead stems were removed (Table 1.2). Moisture content of dead stems was less than 15% whereas green, live stems were over 40% moisture at all harvests. In our current work, after the initial clearfell harvest, for the 4 clearfell years to 2009, green live stems always made up over 95% of the biomass harvested. Therefore, regular annual clearfell harvest of A. donax irrigated plantations is likely to be an excellent strategy to reduce fire risk in dry seasons. If plantations of A. donax are left unharvested, significant quantities of accumulated very dry, dead stems could pose a far greater fire risk compared to annual clearfelled irrigated plantations. Experience in Texas confirms that significant amounts of dead stems of A. donax pose a high fire risk in dry seasons (Dr R Pollock, USA, pers. comm.). The dryland stand produced a total dry matter yield of A. donax tops of 12.6 t/ha one year after the first clearfell (Table 1.2). In subsequent clearfell years, the A. donax dryland stand produced dry matter yields of plant tops of 6.0, 12.9 and 6.7 t/ha, respectively (Table 1.2 and Figure 1.5). These yields were likely most dependent on precipitation which varied from 2.3 to 5.3 ML/period between clearfells, over the 4 years (Appendix Table 1.A.2). The long-term mean annual rainfall at Roseworthy is 440 mm. In similar rainfall periods, non-irrigated A. donax yields of 12.6 and 12.9 t/ha of dry matter tops (Table 1.2) surpassed total yields of 8 t/ha recorded for dense Wimmera ryegrass (Lolium rigidum) stands grown nearby on similar soils near Clare, SA (Williams and Allden 1976). Furthermore, carbon sequestered by the dryland A. donax old stand tops, 5.0 and 5.1 t/ha for 3.8 and 5.3 ML of precipitation in the clearfell periods 1 and 3 (Table 1.3), was far greater than the 2.83 and 2.98 t/ha/year for Eucalyptus cladocalyx (sugar gum) and Corymbia maculata (spotted gum), respectively, as reported by Paul et al. (2008) for whole tree biomass (tops plus roots) when mean annual rainfall was 5.1 ML for regions of southern Australia. Furthermore, for the same clearfell periods as above, the A. donax dryland stand had 6.2 to 7.5 t/ha of carbon sequestered in dynamic equilibrium, in rhizomes. Similarly, the harvested above ground carbon, for the dryland old stand, of 5.0 and 5.1 t/ha, for the clearfell periods 1 and 3, as above, were double the 2.5 t/ha/year of carbon in switchgrass tops grown on the fertile soils of the Great Plains, USA, which received the mean annual precipitation of 4.3 to 7.8 ML/ha (Liebig et al. (2008).
7
It is stressed that when the dryland portion of the 30 year old stand was first clearfelled, 18.6 t/ha of dead dry stems were removed (a potential fire risk) along with the 10.1 t/ha of green, live stems (Table 1.2). This portion of the 30 year old stand had no previous irrigation. Once the clearfell regime was imposed, on the dryland old stand, negligible numbers of very dry, dead stems were harvested, only green live stems with over 40% moisture content. The stems in the irrigated old stand were higher, greater in girth, more numerous and with greater dry weight per stem than the stems in the dryland stand but had similar % dry matter (Table 1.4). Stems produced in the new planting (irrigated), after 6 months were similar in the above characteristics to those in the non-irrigated treatment of the established stand after 1 year regrowth from clear fell. Christou et al. (2001) recorded that the stems of highly irrigated plants were significantly longer and thicker than the stems of the non-irrigated plants in most years. A rhizome of A. donax is a creeping stem, usually horizontally, at or under the surface of the soil and differing from a root in having scale leaves, or shoots near its tips, and producing roots from its under surface (McClure 1993). Rhizomes may also be referred to as rootstocks. For the old stand, we discovered that once the clearfell regime was imposed, the rhizome dry matter yields/ha/clearfell period came into dynamic equilibrium. This varied from 46.6-69.3 and 16.5-25.2 t/ha/clearfell, respectively, for the irrigated and dryland old stands, respectively (Table 1.2, Figures 1.4 and 1.6). We suggest that the water supply to the A. donax plants was the most likely major determinant of the rhizome yield equilibrium levels achieved in a given environment and crop clearfell regime. Organic carbon in rhizomes only ranged from 43-49% (Chapter 2). The rhizomes contained organic carbon between 20.5-30.5 and 6.2-10.8 t/ha/clearfell period, for the irrigated and dryland old stands, respectively (Table 1.3 and Figure 1.6). . (b)
Irrigated new planting, clearfell and uncut The total yields of dry matter (DM) of top growth of A. donax from the new planting at Roseworthy at each clearfell (CF) were, 31.1, 40.2, 9.2 and 23.0 t/ha, respectively (Figure 1.7). For each of these 4 regrowth periods between clearfells, wastewaters applied by irrigation were 15.9, 9.5, 4.4 and 6.3 ML/ha, respectively, (plus precipitation of 2.8, 1.9, 3.8 and 2.3 ML/ha, respectively). The variations in top yields (Figures 1.7-1.10) were most likely due to variable irrigation rates due to reduced supplies of wastewaters, the onset of drought conditions and the unplanned grazing by cattle. Top growth standing yields from the uncut, new planting at Roseworthy (Table 1.1) varied from 31.1 to 23.8 t/ha of dry matter at each sampling. Rhizome dry matter yields were in the range of 17.5 to 47.7 t/ha, during the same period (Table 1.10). The carbon content of A. donax organs was relatively constant, with leaf, stem and rhizome contents ranging from: 4148, 41-48 and 44-49%, respectively, on a dry matter basis (Chapter 2). The quantities of carbon sequestered by each organ were closely related in relative terms to the dry matter yields of that organ (Figures 1.7-1.10).
8
Table 1.2: Dry matter (DM) biomass yields (t/ha) at Roseworthy at each clearfell for the A. donax old stand (first clear felled 7/06/2005 after 30 years). Standard error of the mean is shown in parentheses.
Days Leaf Green Stem Tops# Rhizome from CF Irrigated CF 7/06/2005# 0 7.2 (1.4) 82.1#(19.1) 89.3#(31.8) 74.6 (17.2) Dryland CF 7/06/2005# 0 1.0 (0.2) 10.1 (2.5) 11.1 (4.2) 51.8 (8.4) Irrigated CF 5/06/2006 356 7.7 (1.1) 37.7 (5.6) 45.4 (6.6) 69.3 (26.3) Dryland CF 5/06/2006 356 2.3 (0.6) 10.3 (2.6) 12.6 (3.2) 23.3 (4.6) Irrigated CF 5/06/2007 365 9.7(4.4) 48.7 (18.7) 58.4 (23.1) 46.6 (20.4) Dryland CF 5/06/2007 365 1.8 (0.3) 4.2 (0.7) 6.0 (1.0) 16.5 (2.7) Irrigated CF 3/09/2008 456 4.1 (0.2) 51.5 (25.5) 55.6 (25.7) 50.9 (2.2) Dryland CF 3/09/2008 456 2.2 (0.6) 10.7 (4.3) 12.9 17.4 (3.2) Irrigated CF 26/06/2009 296 4.6 (1.3) 54.7 (16.4) 59.3 (17.7) 58.8 (6.9) Dryland CF 26/06/2009 296 2.7 (0.4) 4.0 (0.7) 6.7 (0.5) 25.2 (6.5) # At the initial clearfell after over 30 years growth, 7/06/2005, 60.3 t/ha of dead stems were removed but not included in the green, live tops total yield. Treatment/ Date
Table 1.3: Organic carbon (t/ha) sequestered at Roseworthy at each clearfell, from the A. donax old stand (first clearfelled 7/06/2005).
Treatment/ Date Irrigated CF Dryland CF Irrigated CF Dryland CF Irrigated CF Dryland CF Irrigated CF Dryland CF Irrigated CF Dryland CF
7/06/2005 7/06/2005 5/06/2006 5/06/2006 5/06/2007 5/06/2007 3/09/2008 3/09/2008 26/06/2009 26/06/2009
Days from CF 0 0 356 356 365 365 456 456 296 296
Leaf 3.5 0.4 3.2 1.1 4.7 0.8 1.9 1.0 2.2 1.2
Green Stem 38.8 (13.2) 4.5 (2.2) 17.5 3.9 21.9 1.6 23.2 4.1 24.6 1.5
Tops 42.3 4.9 20.7 5.0 26.6 2.4 25.2 5.1 26.8 2.8
Rhizome 35.6 (16.0) 26.7 (4.2) 30.5 6.2 20.5 7.1 22.4 7.5 25.9 10.8
Figure 1.2: A. donax, old stand, 361 days after first clear fell, left: Dryland and right: Irrigated treatments at Roseworthy.
9
b)
100
60
80
50 C (t/ha)
DM (t/ha)
a)
60 40 20
40 30 20 10
0
0
0
1
2
3
4
0
Years from initiation
1
2
3
4
Years from initiation
Figure 1.3 a, b: Dry matter (DM) and organic carbon (C) yields of A. donax top growth, at Roseworthy old stand, irrigated clearfell (CF) treatment, 2005 to 2009.
b)
80 70 60 50 40 30 20 10 0
C (t/ha)
DM (t/ha)
a)
0
1
2
3
4
40 35 30 25 20 15 10 5 0 0
1
2
3
Years from initiation
Years from initiation
Figure 1.4 a, b: Dry matter and organic carbon yields of A. donax rhizomes, at Roseworthy old stand, irrigated CF sites, 2005-2009
10
4
a)
b) 10
C (t/ha)
DM (t/ha)
20
10
0
5
0
0
1
2
3
4
0
Years from initiation
1
2
3
4
Years from initiation
Figure 1.5 a, b: Dry matter and organic carbon yields of A. donax tops, at Roseworthy old stand, dryland CF sites, 2005-2009.
b)
60
30
50
25
40
20
C (t/ha)
DM (t/ha)
a)
30 20
15 10
10
5
0
0
0
1
2
3
4
0
Years from initiation
1
2
3
4
Years from initiation
Figure 1.6 a, b: Dry matter and organic carbon yields A. donax rhizomes, at Roseworthy old stand, dryland CF sites, 2005-2009. Table 1.4: Stem height, diameter, number, dry weight and percent dry matter for 5 June 2006 clearfell harvest at Roseworthy. Standard error of the mean is shown in parentheses.
Treatment Old stand Dryland Irrigated New planting Irrigated
Height (cm)
Diameter (mm)
Number of stems (per m2)
Stem dry weight (g/stem)
Dry matter (%)
224 (41) 422 (38)
16.2 (2.9) 22.0 (2.9)
17.3 (1.6) 22.0 (3.8)
36.9 (5.2) 61.7 (5.5)
43.4 (0.7) 44.1 (1.1)
233 (115)
14.3 (6.4)
26.4 (5.0)
46.1 (10.3)
41.2 (0.2)
11
b)
45 40 35 30 25 20 15 10 5 0
25 20 C (t/ha)
DM (t/ha)
a)
15 10 5 0
0
0.5
1
1.5
2
2.5
3
0
3.5
0.5
1
1.5
2
2.5
3
3.5
Years from planting
Years from planting
Figure 1.7 a, b: Dry matter and organic carbon yields of A. donax tops, at Roseworthy, new planting, CF sites, 2006-2009.
b)
20
35 30 25 20 15 10 5 0
15 C (t/ha)
DM (t/ha)
a)
10 5 0
0
0.5
1
1.5
2
2.5
3
3.5
Years from planting
0
0.5
1
1.5
2
2.5
3
3.5
Years from planting
Figure 1.8 a, b: Dry matter and organic carbon yields of A. donax rhizomes, at Roseworthy new planting, CF sites, 2006-2009.
12
b) 60
30
50
25
40
20
C (t/ha)
DM (t/ha)
a)
30 20
15 10
10
5
0
0 0
0.5
1
1.5
2
2.5
3
0
3.5
0.5
1
1.5
2
2.5
3
3.5
Years from planting
Years from planting
Figure 1.9 a, b: Dry matter and carbon yields of A. donax tops, at Roseworthy, new planting, uncut sites, 2006-2009.
b)
60
25
50
20
40
C (t/ha)
DM (t/ha)
a)
30 20
15 10
10
5
0
0 0
0.5
1
1.5
2
2.5
3
3.5
0
0.5
1
1.5
2
2.5
3
3.5
Years from initiation
Years from planting
Figure 1.10 a, b: Dry matter and carbon yields of A. donax rhizomes, at Roseworthy new planting, uncut sites, 2006-2009.
Plant and rhizome yield and carbon accumulation by Adx at Barmera (marginal land) One year after planting at Barmera, the flood irrigated Loveday rootstock of A. donax produced 45.2 t/ha of total above ground biomass (including 20.6 t/ha of carbon sequestered) at the first clearfell (Tables 1.5 and 1.6, Figure 1.12). In comparison, the Henley Beach rootstock produced 29 t/ha of dry tops (including 13.7 t/ha of carbon), (Figure 1.12, Tables 1.5 and 1.6).
13
Carbon sequestration is the uptake and storage of atmospheric carbon in, for example, soils and vegetation. Photosynthesis by A. donax during the first year was the likely main mechanism for the large amounts of organic carbon accumulated, namely 20.6 and 12.0 t/ha in the dry tops and rhizomes, respectively, for the Loveday rootstock (Table 1.6). The Loveday rootstock at Barmera, under the clearfell regime produced high dry matter yields of plant tops of 45.2, 35.0 and 28.8 t/ha, respectively, at each clearfell harvest over 3 years (Table 1.5, Figures 1.11 and 1.12). In comparison, the Henley Beach rootstock produced yields of dry tops of 29, 12.8, and 10.8 t/ha over the same periods. The differences from year to year within a rootstock could be due to reduced irrigation rates due to reduced supplies of wastewaters. For each of these 3 regrowth periods between clearfells, wastewaters applied by irrigation were, 21, 16.7 and 12.6 ML/ha, respectively, (in addition there was a recorded precipitation of 2.2, 2.5 and 1.1 ML/ha, respectively). Carbon accumulation by the 2 rootstocks reflected, in relative terms, the differences in dry matter yields (Table 1.6, Figure 1.12). Differences between these two rootstocks were likely due to genetic and/or genotype by environment interactions. For example, yields of dry rhizomes for the Loveday and Henley Beach Adx rootstocks were 26.6, 40.8 and 44.9 and 16.3, 10.0 and 8.7 t/ha, over the three year period (Table 1.5 and Figure 1.13). These variations in top growth and rhizome yields were likely due to the onset of drought conditions and restricted irrigation rates in years 2 and 3 (16.7 and 12.6 ML/ha of wastewaters applied) compared to 21 ML/ha in the first year. The Loveday rootstock produced higher rhizome yields of dry matter in years 2 and 3, compared to the Henley Beach rootstock. This correlated with the higher top growth yields of the Loveday rootstock at all harvests (Tables 1.5, 1.6 and Figures 1.12 and 1.13). The sections of the A. donax rootstocks left uncut for three years at Barmera, reached top growth yields of 32.8 to 48.6 for the Loveday rootstock and 6.0 to 29 t/ha for the Henley Beach rootstocks (Figure 1.14). Each rootstock in the uncut treatment, also reached a maximum yield for rhizome dry yields and carbon sequestered in top growth and rhizomes (Figures 1.14 and 1.15). Total yields for A. donax will vary with differences in irrigation inputs, harvest regimes, climate and management conditions. Dead, dry stem yields for the Loveday rootstock, at the final harvest at Barmera were 8.4 and 9.8 t/ha, respectively for the uncut and clearfell stands, respectively. This may be due to to the cumulative effects of the high Biological Oxygen Demand (BOD) of the applied wastewaters (over 4000 mg/L), having an impact on stem growth and survival (refer to Chapter 2). Growth cycle of A. donax in South Australia Each year for all field experiments reported in this project, new shoots of A. donax emerged August to September (early spring at the Southern Hemisphere latitude of 350S), the stems and leaves then grew rapidly to reach maximum growth rates during December and January (mid summer at these sites), (growth curves in Figures 1.3-1.15). Crop growth rates declined in autumn (March to May, in the Southern Hemisphere), with nil to very limited growth in the mid winter months (June, July). In the Northern Hemisphere, at a higher latitude of 430N, Angelini et al. (2009) reported that in winter time A. donax plants stop their growth because of low temperatures and regrowth occurs the following spring. However, we found that only when severe frosts occurred, as observed at the Barmera site in 2008, did plant growth stop and significant leaf mortality occur.
14
*
Table 1.5: Dry matter (DM) biomass yields at Barmera CF at each clearfell . Standard # error of the mean is shown in parentheses
Adx rootstock Loveday Henley Beach Loveday Henley Beach Loveday Henley Beach #
Date 16/05/2007 16/05/2007 20/08/2008 20/08/2008 22/04/2009 22/04/2009
Biomass yield (t/ha/year) Days Leaf Stem Tops from CF * 365 9.3 (2.1) 35.9 (3.4) 45.2 (3.5) 356* 11.3 (4.9) 17.7 (6.6) 29 .0 (10.7) 462 0.8 (0.3) 34.3 (12.9) 35.0 (13.2) 462 0.3 (0.2) 12.6 (1.8) 12.8 (1.7) 245 5.9 (0.5) 22.9 (4.6) 28.8 (5.1) 245 3.3 (0.5) 7.52 (0.7) 10.84 (0.3)
Rhizome 26.6 (5.4) 16.3 (7.8) 40.78 (6.8) 10.04 (1.0) 44.9 (10.0) 8.73 (0.1)
Trials planted 16 May 2006 at Barmera, South Australia *
Table 1.6: Organic carbon sequestered at Barmera CF at each clearfell . Standard error # of the mean is shown in parenthesis .
Organic carbon yield (t/ha/year) Adx rootstock Loveday Henley Beach Loveday Henley Beach Loveday Henley Beach #
Date 16/05/2007 16/05/2007 20/08/2008 20/08/2008 22/04/2009 22/04/2009
Days from CF 365* 365* 462 462 245 245
Leaf 4.1 (0.9) 5.3 (2.4) 0.4 (0.1) 0.2 (0.1) 2.8 (0.3) 1.4 (0.2)
Stem 16.5 (1.4) 8.4 (3.2) 17.6 (7.1) 6.2 (1.0) 9.2 (1.8) 3.4(0.3)
Tops 20.6 (1.4) 13.7 (5.0) 17.8 (7.2) 6.4 (1.0) 11.9 (2.0) 4.8 (0.1)
Rhizome 12.0 (2.5) 7.3 (3.5) 20.4 (4.1) 4.8 (0.6) 19.8 (3.0) 3.8 (0.1)
Trials planted 16 May 2006 at Barmera, South Australia
Figure 1.11: Left: Loveday rootstock of A. donax in marginal soil at Barmera, 5 months after planting, October, 2006; Right: same A. donax at first clearfell, June 2007 (yield 45.2 t/ha dry tops).
15
b)
50
25
40
20 C (t/ha)
DM (t/ha)
a)
30 20
15 10
10
5
0
0
0
1
2
3
0
0.5
Years from planting
1
1.5
2
2.5
3
Years from planting
Figure 1.12 a, b: Dry Matter (DM) and organic carbon (C) yields of A. donax tops at Barmera for the annual clearfell treatments for the Loveday (▲) and Henley Beach rootstocks (•) over 3 years to 2009.
b)
50
25
40
20 C (t/ha)
DM (t/ha)
a)
30 20
15 10
10
5
0
0
0
1
2
3
Years from planting
0
1
2
3
Years from planting
Figure 1.13 a, b: Dry Matter (DM) and organic carbon (C) yields of A. donax rhizomes at Barmera for the annual clearfell treatments for the Loveday (▲) and Henley Beach rootstocks (•) over 3 years to 2009.
16
b) 50
25
40
20
30
15 C (t/ha)
DM (t/ha)
a)
10
20 10
5
0
0
0
1
2
0
3
1
2
3
Years from planting
Years from planting
Figure 1.14 a, b: Dry Matter (DM) and organic carbon (C) yields of A. donax tops at Barmera for the annual uncut treatments for the Loveday (▲) and Henley Beach rootstocks(•) over 3 years to 2009.
b)
50
25
40
20
30
C (t/ha)
DM (t/ha)
a)
20 10
15 10 5
0
0
0
1
2
3
Years from planting
0
1
2
3
Years from planting
Figure 1.15 a, b: Dry Matter (DM) and organic carbon (C) yields of A. donax rhizomes at Barmera for the annual uncut treatments for the Loveday (▲) and Henley Beach rootstocks (•) over 3 years to 2009.
17
Pyrolysis and biochar from A. donax Results for pyrolysis tests conducted and reported by Pacific Biochar, including biochar yields from A. donax, are presented verbatim in Appendix 1.B. They concluded that A. donax is a suitable material for commercial pyrolysis and biochar production and it is recommended that further larger, pilot scale tests be undertaken to allow more detailed information to be gathered to meet future needs to design an efficient, full scale factory for combined heat and power and biochar (Appendix 1.B). Comparison of biomass species as pulp or energy crops and potential of A. donax Using results from year one of trials reported in this project, Paul and Williams (2006) estimated that A. donax irrigated with wastewaters has potential to produce up to 5 times the air dry pulp yield per hectare per year compared to Blue gum (Eucalyptus globulus) hardwood trees, when grown in South Australia (based on 40 t/ha of oven dry stems produced by Adx per annum). In subsequent years at Roseworthy, 2007-2009, irrigated A. donax produced from 48.7-54.7 t/ha/clearfell period of oven dry stems (Table 1.2). These results indicate that A. donax is a promising alternative to conventional non wood pulp/fibre options. Other fibre crops, such as kenaf (Hibiscus cannabinus) which produced a peak dry matter yield of 25.6 t/ha with irrigation in the Ord Irrigation Area, Western Australia, (Wood 1978), required from 5 to 29 sprays of insecticide per growing season, to prevent plants being defoliated by insects. Perennial grasses have many beneficial traits as energy crops (Lewandowski et al. 2003). A. donax with the C3 photosynthetic pathway was found to produce 34.8% higher dry matter yields compared to Miscanthus x giganteus (hybrid), a C4 grass (Table 1.7), in field trials in Italy over 11 years (Angelini et al. (2009). Low winter temperatures and shorter growing seasons are major limits to the growth of C4 grasses in southern Australia (Williams et al. 2009) and northern Europe (Lewandowski et al. 2003). Switchgrass (Panicum virgatum), favoured in some regions, a native to north America, usually produces lower biomass yields/ha/year, when compared to the above 2 grasses under the same conditions (Lewandowski et al. 2003, Dr R. Pollock, USA, pers. comm.). Table 1.7: Maximum yield, net energy, fuels/year (mean value from the second to the twelfth year of growth, Italy).
Treatment
Yield (t/ha)
Net Energy (GJ/ha)
Petrol Equiv. (t/ha)
Coal Equiv. (t/ha)
A. donax 37.7 637 14 20 (Adx) Miscanthus x 28.7 467 10 15 giganteus (hybrid) Advantage of 34.8 36.4 40 33.3 Adx (%) Source: Angelini et al. (2009), Central Italy, 857mm rainfall and water table at 120cm deep during the driest periods. To evaluate the performance of A. donax and Miscanthus x giganteus in agricultural production systems as bioenergy crops, Angelini et al. (2009) calculated the net energy yield (energy output minus energy inputs/ha) and energy production efficiency (the ratio between energy output and input/ha). Their results showed that 1 ha of A. donax produced net energy of 637 GJ/ha and could substitute for 14 t/ha and 20 t/ha of petroleum and coal, respectively (Table 1.7). Such yields surpassed those from M. giganteus by over 25% per annum (Table 1.7) grown under the same conditions. They also calculated annual crops require approx. 50% of the total energy produced for production; whereas A. donax requires only 1.9% and Miscanthus 2.6%/year.
18
Efficient production of pulp/paper or bioenergy from such perennial grasses requires selection of the most appropriate grass species for the given growing region/climatic/management conditions (Lewandowski et al. 2003), and selection to meet target yields and quality criteria within the framework of sustainable, profitable production systems. Since research on perennial rhizomatous grasses is recent, there are significant gaps in the knowledge base and further work is needed.
Conclusions Introduction of high yielding, high carbon, non-food biomass crops to support the change to renewable energy policy is desirable. When compared to data presented in the literature in relation to other biomass species, A. donax produces more cellulosic biomass and sequesters more carbon per annum, under SA conditions. It should be noted that the reports in the literature are for biomass grown under warm temperate to sub tropical temperature on marginal lands with similar water input regimes (either irrigated with wastewaters or grown dryland with over 450 mm of annual precipitation). A. donax produced the high biomass yield of 45.2 t/ha of dry tops in the first year, when grown on saline, marginal land at Barmera with winery wastewater. On arable soil at Roseworthy, A. donax produced 45.4, 58.4, 55.6 and 59.3 t/ha/year of dry tops each clearfell year, when irrigated with reclaimed sewage. The non irrigated, clearfell Adx treatment at Roseworthy produced 12.6 and 12.9 t/ha of dry tops with 5.3 and 3.8 ML of precipitation in the periods between clearfells, respectively. These biomass yields consisted of 5.0 and 5.1 t/ha of harvested above ground carbon (carbon sequestered in plant tops), which was double that produced by switchgrass grown on fertile soils of the Great Plains, USA, with annual precipitation of 4.3 to 7.8 ML (Liebig et al. 2008), and greater than that of sugar gums grown in southern Australia (Paul et al. 2008). We suggest A. donax has potential as a biomass crop on dryland, marginal soils in areas which receive over 450 mm (4.5 ML) of annual precipitation. If groundwater is available within a few metres of the surface, A. donax roots are likely to access such subsoil waters to enhance yields (Angelini et al. 2009). From the results of this project we classed A. donax in the premium group of crops for carbon sequestration (including high yields of harvested above ground carbon per ha per annum) and carbon credits, when irrigated with wastewaters, as it sequestered over 20 t/ha/year of carbon in plant tops and maintained a similar amount in dynamic equilibrium in rhizomes (underground stems). If each tonne of sequestered carbon is valued at A$30, then it will generate some A$600/ha for carbon stored in rhizomes in a dynamic equilibrium. Furthermore, carbon stored in the true root system of A. donax, in addition to the rhizomes, needs to be assessed in future. Preliminary calculations by Paul and Williams (2006) indicated that giant reed has the potential to produce up to 500 per cent more air dry pulp per ha per year (15.2 t) compared to Eucalytus hardwoods (3.1 t) when grown in southern Australia. Further research is required to obtain data on the long term productivity of giant reed (assuming a plantation life of 20-35 years) and to define irrigation, wastewater quality, nutrient requirements and other best management practices for sustainable systems. A. donax produced up to 45.2 t/ha per year of dry tops on the saline, marginal soils at Barmera (with wastewater irrigation). This grass, a wetland monocot, could form the basis of a new industry producing biofuels and/or pulp/paper, using saline, marginal soils and moderately saline wastewaters in southern Australia. Further research is needed to upscale and demonstrate/verify production systems and methodologies developed in this report, as well as pilot commercial systems of whole stem and/or rhizome plantings (based on the findings of Christou et al. 2000), and mechanisation of planting and harvesting equipment to handle A. donax. The three proposed production systems are: dryland, saline self- irrigation, flood irrigation/drainage biosystem (further descriptions in Chapters 2 and 6).
19
Chapter 2: Salt tolerance and nutrient dynamics of Arundo donax Chris Williams1, Tapas Biswas1, 2, Louise Chvyl1 and Chris Dyson 1 1 SARDI, GPO Box 397 Adelaide, SA, 5001 2 Murray-Darling Basin Authority, GPO Box 1801 Canberra, ACT 2601
Introduction Salt in irrigation waters and subsoils is often associated with the elevation over time of the salt content of the rootzone, which in turn results in reduced crop biomass yields (Lazarova and Bahri 2005). An aim of research reported in this chapter is to define the salt tolerance and nutrient removal by A. donax and to develop guidelines for the beneficial use of highly saline wastewaters for irrigation (eg. reuse of some Salt Interception Scheme (SIS) wastewaters) on marginal lands. Soil salinity refers to the concentration of dissolved salts in the soil solution. The soluble salts in soils predominantly consist of the cations: sodium (Na), calcium (Ca), magnesium (Mg), potassium (K) and the anions: chloride (Cl), nitrate (NO3), sulphate and bicarbonate. Soil salinity levels are usually determined by measuring the electrical conductivity (EC in deci Siemens/metre, dS/m) of a soil suspension, which estimates the concentration of soluble salts in the soil at a given depth sampled. High EC values, corresponding to high concentrations of soluble salt in soil, are undesirable as they reduce normal growth and yield of most plant species and also restrict land use options and may lead to increased soil erosion. With increased irrigation efficiency comes the greater risk of increased salt, nutrient and other chemical accumulation within the crop root zone. Knowledge of soil water composition in the root zone is crucial for sustainable irrigation, especially when wastewater is used. By using a SARDI soil water extractor (SoluSAMPLERTM , Biswas 2006) and analysing the extracted solution for salinity and nutrients, it is possible to monitor whether salt and/or nutrients are accumulating in the root zone and then to adjust irrigation or fertiliser practices to develop sustainable irrigation and nutrient systems for Adx crops. Lewandowski et al. (2003) in their review of grasses grown for biomass in Europe, state that A. donax is salt tolerant, but provide no evidence for this claim or neither do they discuss the degree of salt tolerance of the plant. Similar statements were made in the paper on A. donax by the former Director of Agriculture in South Australia, (Spafford 1941. The first objective of this study was to define the salt tolerance of A. donax and gain an understanding of nutrient dynamics when A. donax was grown on saline, marginal land with winery wastewater on a former salt evaporation basin near Barmera, SA (34O 14’ S, 140O 35’E). The second aim was to describe the content and uptake of nutrients by A. donax crops grown under saline and non-saline regimes in order to develop sustainable nutrient management strategies for the maintenance of economic yields of biomass to provide a stable feedstock supply.
20
Materials and Methods Design and layouts of the field studies on A. donax conducted on the former salt pan site near Barmera, (saline soil) and on arable land at Roseworthy, SA have been described in Chapter 1 (Materials and Methods). The electrical conductivity (ECswe) of 1:5 soil:water extracts of root zone soils at Barmera ranged from 0.62 to 1.53 dS/m (indicating saline soils). Salinity (as ECswe) and nutrient concentrations of the soil water extracts were assessed at Barmera using especially designed SARDI soil water extractors installed at 30, 60 and 90 cm soil depths in the centre of the ridge of the planting row. The soil water extractor is a porous ceramic suction cup device, which can sample soil water after a suction of 60-70 kPa is applied (Biswas 2006) down an access tube using a simple syringe and Luer lock device. The vacuum draws the moisture from the surrounding (unsaturated) soil into the inert ceramic cup which can then be brought to the soil surface for measuring its salinity and nutrient content (Biswas et al. 2007). Soil water extract samples were collected from the permanently installed soil water extractors (at c. 13 month intervals) from August 2006 to April 2009 at the Barmera site. These samples (volumes of 10–50 ml) were used to measure EC with a Hanna meter and pH with a pH meter, and then frozen. The frozen samples were sent to CSIRO, Land and Water, Analytical Chemistry Lab, Urrbrae, Waite Research Precinct for nutrient, chloride and metal analyses. Methods used for analysing water samples were as described by APHA (1998). Crop evapotranspiration (ETo) was calculated from the modified Penman-Monteith equation as described by Allen et al. (1998). Soil samples from depths of 0-30, 30-60, 60-90cm were collected in June 2005 and June 2009 to measure changes in soil nutrients over time. These data contributed to an assessment of sustainability indicators and of related issues. Plant and soil samples were analysed using procedures as described by Williams et al. (2004).
Results and Discussion Chemical composition of influent wastewater The chemical composition of the winery wastewaters in the holding lagoon used to irrigate the A. donax crops at the Barmera saline soil site are shown in Appendix Tables 2.A.1 to 2.A.4. According to the Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC 1999), irrigation water with a salinity of EC 800 uS/cm (equals 0.8 dS/m) is considered saline, and irrigation water with an EC >2.4 dS/m is highly saline and considered not suitable for irrigation under ordinary conditions for traditional crops (eg. cereals, citrus, vegetables). This is due to the expected induced salinisation of soils and the reduction in yield of most traditional crops under normal conditions of highly saline influent irrigation systems (Peverill et al. 1999; Shaw 1999). The high dry matter yields of top growth produced by the Loveday rootstock stand of A. donax of up to 45.2 t/ha/year under the annual clearfell regime (Chapter 1), over 3 years, under the saline influent irrigation regime, indicated a potential high salt tolerance of Adx under the field conditions of this study at Barmera. Electrical conductivity (ECse) of the soil paste saturated extract of between 2-4 dS/m indicated yields of salt sensitive crops is most likely to be significantly reduced (Biswas and Higginson 1998). The treated winery influent wastewater (hereafter termed recycled water) used to irrigate the A. donax stand at Barmera was usually very low in nitrate ( 20 dS/m as extremely salt tolerant, as this was extremely high salinity at which first signs of yield loss may occur in such crops, whereas it was unsuitable for most crops. Date palm (Phoenix dactylifera) classed as a salt tolerant crop, incurred a 50 % yield reduction when the salinity of the soil, ECse is 18 dS/m, equivalent to salinity of the soil water extract, ECswe of 32 dS/m (Ayers and Westcot 1989; Lazarova and Bahri 2005). The A. donax Loveday sourced rootstock was exposed to salinities in the soil water extracts, ECswe, of 18-50 dS/m and 15-48 dS/m from February to June in both 2007 and 2008, respectively, data from suction tubes installed at 30, 60 and 90 cm soil depths (Figures 2.1, 2.2 and Table 2.1). This period for the flux of high ECswe in the root zone coincided with the time of maximum growth rate and biomass yields of A. donax (as reported in Chapter 1). Further, the total yield of dry tops of A. donax, Loveday rootstock, of 45.2 t/ha in the first year was similar to that reported for one year regrowth from clearfell for a 30 year old stand of A. donax at Roseworthy Campus, SA of 45.4 t/ha (Williams et al. 2008). These results indicated an extremely high salt tolerance by A. donax, even in the first year of growth under the conditions of this field study at Barmera, SA. Changes in concentrations of chloride ions in soil water extracts were similar to those for ECswe; both indicated high levels of salt in the rootzone at Barmera. There was a marked increase in both these salinity indicators from January to May, for both 2007 and 2008 (Figure 2.2 and Table 2.1) associated with the hot summer temperatures and reduced irrigation inputs at times (eg. 5.8 ML/ha of winery wastewater was applied in this period in 2007).
22
Nitrate levels in soil water should be considered when developing sustainable systems for irrigated crops (Williams et al. 1999). Concentrations of nitrate-N in the soil water extracts from suction tubes at 30 and 60 cm deep in the soil (nitrate mainly from the winery wastewater applied, Figure 2.2 and Table 2.2) were likely to be adequate to high for optimal plant growth at all times in year one (Williams and Maier 1990; Reuter and Robinson 1997; Williams et al. 1999). However, nitrate-N concentrations were unlikely to pose an off site pollution threat as soil water extracts from suction tubes at 90 cm soil depths at Barmera were usually negligible (< 1 mg/L) or low (6 mg/L) during the last 18 months of this project (Table 2.2). a)
Irrigation / Rain (mm)
90
Irrig (mm) Rain (mm) ETo (mm) 30cm EC 60cm EC 90cm EC
40
30 80 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0
20
10
Soil Solution EC (dS/m) or ETo (mm)
50
100
0
7 7 7 7 7 7 7 6 6 6 6 6 8/0 /09/0 /10/0 /11/0 /12/0 /01/0 /02/0 /03/0 /04/0 /05/0 /06/0 /07/0 1 1 1 1 1 1 1 1 1 1 1 1/0
b) 20.0
100
17.5 15.0 12.5
80 70 65 60 55 50 45 40 35 30 25 20 15 10 5 0
10.0 7.5 5.0
Soil Solution EC (dS/m) or ETo (mm)
Irrigation / Rain (mm)
90
Irrig (mm) Rain (mm) ETo (mm) 30cm EC 60cm EC 90cm EC
2.5 0.0
7 7 7 7 7 7 7 6 6 6 6 6 8/0 /09/0 /10/0 /11/0 /12/0 /01/0 /02/0 /03/0 /04/0 /05/0 /06/0 /07/0 1 1 1 1 1 1 1 1 1 1 1 1/0
Figure 2.1: ECswe and other variables change with time for first year growth of A. donax at Barmera, SA for (a) Loveday, and (b) Henley Beach rootstocks. Soil solution ECswe results are from suction tubes installed at 30, 60 and 90 cm soil depths.
23
350
300
250
200
150
100
50
Nitrate- N Concentration (mg/L)
1/07/2007
0 0
5000
4000
3000
2000
1000
0
0
Sample time (date)
24 1/04/2007 1/05/2007 1/06/2007 1/07/2007
1/04/2007 1/05/2007 1/06/2007 1/07/2007
1/05/2007
1/06/2007
1/07/2007
0
1/04/2007
50
1/03/2007
100
1/03/2007
150
1/03/2007
200
1/02/2007
250
1/02/2007
300
1/02/2007
350
1/01/2007
400
1/01/2007
0
1/12/2006
1000
1/11/2006
2000
1/12/2006
3000
1/11/2006
4000
1/10/2006
5000
1/10/2006
6000
1/01/2007
1/01/2007
1/12/2006
1/11/2006
1/10/2006
1/09/2006
1/08/2006
30cm
1/12/2006
1/07/2007
1/06/2007
1/05/2007
60cm
90cm
1/07/2007
1/06/2007
1/05/2007
1/04/2007
1/03/2007
1/02/2007
Loveday
1/11/2006
1/04/2007
1/03/2007
1/02/2007
60 50 40 30 20 10 0
1/10/2006
1/09/2006
40
1/09/2006
40
1/09/2006
50
1/08/2006
1/01/2007
1/12/2006
60
1/08/2006
50
E.C.(dS/m)
30
Chloride Concentration (mg/L)
1/07/2007
1/06/2007
1/05/2007
1/04/2007
1/03/2007
1/02/2007
1/01/2007
1/12/2006
1/11/2006
Influent Irrigation
1/08/2006
1/07/2007
1/06/2007
1/05/2007
1/04/2007
10
1/11/2006
1/10/2006
90cm
1/06/2007
1/05/2007
1/04/2007
1/03/2007
1/02/2007
10
1/10/2006
1/09/2006
1/08/2006
60cm
1/03/2007
1/02/2007
1/01/2007
1/12/2006
1/11/2006
1/10/2006
20
1/09/2006
E.C.(dS/m)
30cm
1/01/2007
1/12/2006
1/11/2006
1/10/2006
400 1/09/2006
20
1/08/2006
6000
1/08/2006
Chloride Concentration (mg/L) 60
1/09/2006
1/08/2006
Nitrate- N Concentration (mg/L) 60 50 40 30 20 10 0 Henley Beach
Influent Irrigation
30
Sample time (date)
Figure 2.2: Changes in salinity of the influent irrigation, ECw and soil water extracts, ECswe in dS/m, and chloride and nitrate-N concentrations (mg/L) with time for the first year of growth of A. donax at Barmera, SA for Loveday and Henley Beach rootstocks. ECswe results are from suction tubes at 30, 60 and 90 cm soil depths.
Table 2.1: Suction tube soil water ECswe (dS/m), at Barmera, from January 2008 to March a 2009 . Sampling depth of suction tube Sampling Date
30cm
60cm
90cm
Loveday Rootstock 15/01/2008
15.8 (5.1)
18.5 (3.4)
nsp
14/03/2008
23.4 (2.4)
20.7 (3.5)
25.6*
07/04/2008
19.5 (2.3)
19.3 (2.5)
25.2*
01/05/2008
47.8 (31.5)
14.6 (4.2)
17.5*
09/07/2008
13.5 (0.3)
12.0 (3.2)
nsp
30/09/2008
10.7 (2.5)
8.2 (3.1)
4.6*
13/03/2009
7.4 (0.4)
7.7 (1.8)
4.0*
23/04/2009
7.0 (2.3)
8.2 (3.0)
3.1*
Henley Beach Rootstock 15/01/2008
12*
12*
12*
14/03/2008
10*
12.5 (2.1)
10.9 (0.9)
07/04/2008
10*
7.9 (0.6)
7.1 (0.2)
01/05/2008
18.8 (10.9)
6.8 (0.1)
7.1 (0.2)
09/07/2008
16.9 (6.7)
6.0 (0.9)
5.3 (1.3)
30/09/2008
20.6 (14.5)
7.9 (0.8)
7.9 (2.8)
09/01/2009
12.9 (0.1)
8.6 (1.2)
11.4 (2.0)
13/03/2009
6*
6*
5*
23/04/2009
3*
6.1 (2.6)
3.9 (1.4)
a
CSIRO, Land and Water, Analytical Services, Waite Precinct, (standard procedures). nsp = no solution produced * sample produced from 1 replicate only
25
Table 2.2: Suction tube soil water extract nitrate-N (mg/L), at Barmera, from January 2008 to a March 2009 . Sampling Date 15/01/2008 14/03/2008 7/04/2008 1/05/2008 9/07/2008 30/09/2008 13/03/2009
Sampling depth of suction tube 30cm 60cm Loveday Rootstock 121.4 (114.6) 39.5 (38.6) 71.5 (58.4) 93.3 (91.6) 0.3 (0.1) 0.2 (0.1) 7.2 (7.1) 1.9 (1.8) 0.1 (0.02)
