organic nutrient sources, a controlled-release fertilizer and potting media with no ...... Lab, release in summer (11.73%) was numerically higher than in spring ...
NUTRIENT RELEASE AND AVAILABILITY FROM INDIVIDUAL AND BLENDED NUTRIENT SOURCES FOR ORGANIC TRANSPLANT PRODUCTION
By IDALIA ALEJANDRA SIERRA AUGUSTINUS
A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2007
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© 2007 Idalia Alejandra Sierra Augustinus
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To my son Andreé this is for you
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ACKNOWLEDGMENTS Many people supported me during this life experience. First and foremost I want to thank God for his immense love, help, and fidelity. I give him the honor and glory of this journey. I would l like to thank my supervisory committee members (Dr. Danielle Treadwell, Dr. Eric Simonne, and Dr. Donald Graetz) for giving me the opportunity to work with them, and for their great contributions to my personal and professional development. I am especially grateful to Dr. Danielle Treadwell. Without her guidance, perseverance, and patience this would have not been possible. I will always admire her personally and professionally. I also want express my gratitude to the Fulbright-OAS Ecology Program for enabling me to pursue my graduate studies. I extend my thanks to all the Horticultural Sciences Department staff for their help; and especially Mike Alligood, I extend to him my deepest gratitude. I thank all of my friends (Gina Canales, Pili Paz, Elena and Dilcia Toro, Elena Sierra, Byron Reyes and Aparna Gazula) for their friendship and fun and happy memories. I would like to thank my son, my parents, brothers, family, and friends for all of their love and support from the distance. Finally, I would like to extend my deepest gratitude to Jorge Abastida for all his support and love during this time.
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TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES...........................................................................................................................7 LIST OF FIGURES .........................................................................................................................9 ABSTRACT...................................................................................................................................11 CHAPTER 1
INTRODUCTION ..................................................................................................................13
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LITERATURE REVIEW .......................................................................................................16 Overview of the Organic Industry ..........................................................................................16 US Greenhouse and Vegetable Transplant Production ..........................................................17 Vegetable Greenhouse Production ..................................................................................17 Transplant Production .....................................................................................................18 Environmental Concerns .................................................................................................19 Use of Organic Amendments in Vegetable Production..........................................................20 Organic Transplant Research..................................................................................................21 Factors Affecting Mineralization and Nitrification Process...................................................25 Electrical Conductivity and pH .......................................................................................26 Temperature and Moisture ..............................................................................................27 Conclusions.............................................................................................................................29
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EFFECT OF TEMPERATURE ON NUTRIENT RELEASE RATES FROM ORGANIC NUTRIENT SOURCES APPROVED FOR ORGANIC TRANSPLANT PRODUCTION.......................................................................................................................33 Abstract...................................................................................................................................33 Introduction.............................................................................................................................34 Materials and Methods ...........................................................................................................37 Media Characteristics and Organic Nutrient Sources .....................................................37 Cultural Practices.............................................................................................................38 Leachate Collection and Analysis ...................................................................................39 Calculation of net N mineralization and nitrification......................................................40 Experimental design and statistical analysis ...................................................................41 Results and Discussion ...........................................................................................................41 Media Solution pH ..........................................................................................................41 Media Solution EC ..........................................................................................................42 Ammonium Release Rates ..............................................................................................43 Nitrate Release Rates.......................................................................................................45 Phosphorus and Potassium Release and Availability......................................................46
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Nitrogen Availability.......................................................................................................47 4
EFFECT OF TEMPERATURE ON NUTRIENT RELEASE RATES FROM CUSTOM ORGANIC BLENDS FOR ORGANIC TRANSPLANT PRODUCTION............................58 Abstract...................................................................................................................................58 Introduction.............................................................................................................................59 Materials and Methods ...........................................................................................................63 Media Characteristics and Organic Amendments ...........................................................63 Cultural Practices.............................................................................................................64 Leachate Collection and Analysis ...................................................................................65 Calculation of Net N Mineralization and Nitrification....................................................65 Experimental Design and Statistical Analysis.................................................................66 Results and Discussion ...........................................................................................................66 Media Solution pH ..........................................................................................................66 Media Solution EC ..........................................................................................................68 Ammonium Release Rates ..............................................................................................70 Nitrate Release Rates.......................................................................................................71 Phosphorus and Potassium Release and Availability......................................................73 Nitrogen Availability.......................................................................................................73
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ORGANIC CUSTOM BLENDS AFFECT GROWTH AND NUTRIENT CONTENT OF BASIL (Ocimum basilicam L.) TRANSPLANTS ...........................................................84 Abstract...................................................................................................................................84 Introduction.............................................................................................................................85 Materials and Methods ...........................................................................................................87 Media Characteristics and Organic Blends .....................................................................87 Cultural Practices.............................................................................................................89 Data Collection................................................................................................................90 Statistical Analysis ..........................................................................................................90 Results and Discussion ...........................................................................................................91 Media Solution pH ..........................................................................................................91 Media Solution EC ..........................................................................................................92 Seedling Germination......................................................................................................93 Seedling Growth..............................................................................................................95 Nutritional Status.............................................................................................................97
APPENDIX A
ADDITIONAL RESOURCES .............................................................................................105
B
ANALYSIS OF VARIANCE...............................................................................................108
LIST OF REFERENCES.............................................................................................................112 BIOGRAPHICAL SKETCH .......................................................................................................119
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LIST OF TABLES Table
page
3-1.
Chemical properties of potting media and organic nutrient sources..................................49
3-2.
Values for constituents of the irrigation water used in the greenhouse and laboratory used for irrigation of organic nutrient sources...................................................................49
3-3.
Regression analysis between media solution pH and EC and N mineralization (Nmin) and nitrification (Nnit) of organic nutrient sources for the summer season. ........50
3-4.
Net cumulative release as mineralized (Nmin) and nitrified (Nnit) N from three organic nutrient sources, a controlled-release fertilizer and potting media with no fertilizer, as influenced by temperature regime, season and time of incubation................51
4-1.
Chemical properties of potting media and custom organic blends. ...................................75
4-2.
Values for constituents of the irrigation water used in the greenhouse and laboratory used for irrigation of custom organic blends. ....................................................................75
4-3.
Regression analysis between media solution pH and EC and N mineralization (Nmin) and nitrification (Nnit) of custom organic blends. ..............................................................76
4-4.
Net release as mineralized (Nmin) and nitrified (Nnit) N from four custom organic blends, a controlled-released fertilizer and potting media with no amendment, as influenced by temperature regime, season and time of incubation....................................77
5-1.
Chemical properties of potting media and custom organic blends used for basil transplant production. ........................................................................................................99
5-2.
Values for constituents of the irrigation water used in the greenhouse. ............................99
5-3.
Analysis of variance on the effect of four custom organic blends, a controlledreleased fertilizer and media with no fertilizer on germination and mean days to emergence of basil transplants. ........................................................................................100
5-4.
Analysis of variance on the effect of four custom organic blends, a controlledreleased fertilizer and media with no fertilizer on height and dry weight of basil transplants. .......................................................................................................................101
5-5.
Analysis of variance on the effect of four custom organic blends, a controlledreleased fertilizer and media with no fertilizer on total nitrogen per gram of dry weight of basil transplants. ..............................................................................................102
A-1.
Research on the use of compost and other organic fertilizer for organic vegetable production in greenhouse.................................................................................................105
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A-2.
Research on the use of compost and other organic fertilizer for organic vegetable and transplant production in greenhouse ................................................................................106
A-3.
Volume of custom blends and controlled-release fertilizer added to each pot ................107
B-1.
Analysis of variance of cumulative nitrogen mineralization from five organic nutrient sources, a controlled-released fertilizer and potting media with no fertilizer. ...108
B-2.
Analysis of variance of cumulative nitrogen nitrification from five organic nutrient sources, a controlled-released fertilizer and potting media with no fertilizer..................108
B-3.
Analysis of variance of cumulative nitrogen mineralization from four custom organic blends, a controlled-released fertilizer and potting media with no fertilizer. ..................109
B-4.
Analysis of variance of cumulative nitrogen nitrification from four custom organic blends, a controlled-released fertilizer and potting media with no fertilizer. ..................109
B-5.
Analysis of variance of total nitrogen content in basil transplants grown using four custom organic blends, a controlled-released fertilizer and potting media with no amendment.......................................................................................................................110
B-6.
Analysis of variance of dry weight of basil transplants grown using four custom organic blends, a controlled-released fertilizer and potting media with no amendment.......................................................................................................................110
B-7.
Analysis of variance of height of basil transplants grown using four custom organic blends, a controlled-released fertilizer and potting media with no amendment. .............110
B-8.
Analysis of variance of mean days to emergence of basil transplants grown using four custom organic blends, a controlled-released fertilizer and potting media with no amendment..................................................................................................................111
B-9.
Analysis of variance of emergence (%) of basil transplants grown using four custom organic blends, a controlled-released fertilizer and potting media with no amendment.......................................................................................................................111
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LIST OF FIGURES Figure
page
2-1.
Biochemical equations for mineralization and nitrification...............................................32
3-1.
Average media solution pH measured by pour-through media extraction procedure for summer season from five organic nutrient sources, a controlled-released fertilizer and potting media with no amendment..............................................................................52
3-2.
Average media solution EC measured by pour-through media extraction procedure for summer season from five organic nutrient sources, a controlled-released fertilizer and potting media with no amendment..............................................................................53
3-3.
Regression analysis between net cumulative release of NH4+ - N and NO3- - N from five organic nutrient sources, a controlled-release fertilizer and potting media with no fertilizer as affected by cumulative degree days...........................................................54
3-4.
Net cumulative plant available nitrogen (PAN) from three organic nutrient sources, a controlled-release fertilizer and potting media with no fertilizer under two temperature regimes during two seasons. ..........................................................................55
3-5.
Net cumulative available ammonium (NH4+-N) from three organic nutrient sources, a controlled-release fertilizer and potting media with no fertilizer under two temperature regimes during two seasons. ..........................................................................56
3-6.
Net cumulative available nitrate (NO3--N) from three organic nutrient sources, a controlled-release fertilizer and potting media with no fertilizer under two temperature regimes during two seasons. ..........................................................................57
4-1.
Average media solution pH measured by pour-through media extraction procedure from four custom organic blends, a controlled-released fertilizer and potting media with no amendment, as influenced by temperature regime, season and time of incubation...........................................................................................................................78
4-2.
Average media solution EC measured by pour-through media extraction procedure from four custom organic blends, a controlled-released fertilizer and potting media with no amendment, as influenced by temperature regime, season and time of incubation...........................................................................................................................79
4-3.
Regression analysis between net cumulative release of NH4+ - N and NO3- - N from custom organic blends, a controlled-release fertilizer and potting media with no amendment as affected by cumulative degree days...........................................................80
4-4.
Net cumulative available potassium from four custom organic blends, and controlled-release fertilizer under two temperature regimes during two seasons..............81
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4-5.
Net cumulative plant available nitrogen (PAN) from four custom organic blends, a controlled-release fertilizer and potting media with no amendment under two temperature regimes during two seasons. ..........................................................................82
4-6.
Net cumulative available NH4+-N from four custom organic blends, a controlledrelease fertilizer and potting media with no amendment under two temperature regimes during two seasons. ..............................................................................................83
5-1.
Average media solution pH measured by pour-through media extraction procedure from four custom organic blends, a controlled-released fertilizer and potting media with no amendment used for basil transplant production. ...............................................103
5-2.
Average media solution EC measured by pour-through media extraction procedure from four custom organic blends, a controlled-released fertilizer and potting media with no amendment used for basil transplant production. ...............................................104
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Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Master of Science NUTRIENT RELEASE AND AVAILABILITY FROM INDIVIDUAL AND BLENDED NUTRIENT SOURCES FOR ORGANIC TRANSPLANT PRODUCTION By Idalia Alejandra Sierra Augustinus August 2007 Chair: Danielle Treadwell Major: Horticultural Science Plant available nutrients are released from organic nutrient sources through biological processes that are influenced by temperature, moisture, pH and electrical conductivity (EC) of the plant growing medium. To improve fertility management in organic vegetable systems, this research was conducted to study the effect of temperature on the release rates of ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3--N), phosphorus (P), and potassium (K) from individual and blended organic nutrient sources. The objective of this research was to study the effect of temperature on the release rate of ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3-N), phosphorus (P), and potassium (K) from nutrient sources and blends for five weeks under two temperature regimes during two seasons (spring and summer) and the effect of these blends on growth and nutrient content of basil (Ocimum basilicum) transplants. Five individual nutrient sources approved for use in organic production were used, and included two N sources: 1) blood meal (BLM); 2) feather meal (FM); two P sources: 3) bone meal (BM); 4) rock phosphate (RP); and one K source: 5) potassium magnesium sulfate (KMS). In addition, four custom blends: 1) FM + BM + KMS (FBK); 2) FM + RP +KMS (FRK); 3) BLM + BM + KMS (BBK); and 4) BLM + RP + KMS (BTK) were compared to a controlled-release synthetic fertilizer (CRF) and a control of potting media with no amendment (NA). Media was composed of peat, vermiculite,
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perlite, gypsum and dolomitic limestone. Individual nutrient sources were mixed with media at a 1:5, while blends were applied at a rate to provide 16N-2.6P-9.9K. Media solution pH and EC significantly affected N nitrification from individual amendments. Increasing temperature, as the sum of degree days, enhanced cumulative plant available nitrogen release for all treatments. In both experiments, nitrification was low, and was attributed to high EC; and although not studied in this research, by the volatilization of NH3+, denitrification and scarce presence of nitrifying bacteria in peat. Water extractable P was detected only in CRF (< 5g kg-1). The BRK blend had the highest net cumulative K release rate, 45% equivalent to 44 g kg-1 blend, followed by BBK and FBK (39% and 38%), representing 38 g kg-1 blend of available K. In the basil experiment, the percent of basil germination and mean days to emergence were similar among all treatments except in one case the BBK, where reduction was attributed to high EC levels. Basil transplants grown during spring in blends containing FM (FBK and FRK) were taller and had more dry weight than those in blends containing BLM. During summer, CRF 0.94 g > FRK 0.62 g = FBK 0.53 g = BRK 0.39 g = BBK 0.25 g, and > NA 0.04 g. All fertilized transplants had sufficient tissue N concentration; however transplants produced in NA were deficient in N.
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CHAPTER 1 INTRODUCTION The National Organic Program (NOP) is a marketing program that is housed in the United States Department of Agriculture (USDA) and the Agricultural Marketing Service designed to provide uniform, national standards for agricultural products. After full implementation of NOP in October 2002, US interest in organic products continues to grow in both number of product categories and sales outlets. The increasing consumer demand for healthy and nutritious foods and increasing distribution in conventional grocery channels are the major drivers of market growth. Fresh fruits and vegetables are the largest category of sales of organic food, therefore, research on nutrient management of organic production of vegetables has increased over the past two decades. In organic systems, plant nutrition is based mainly on the transformation of organic materials into plant available forms of nutrients by microorganisms. Nutrients are supplied either by plant and animal-based amendments or mined natural products and are sometimes available as commercial formulations. This has stimulated interest in meeting crop nutrient requirements using manures, compost and other organic materials. According to the new National Organic Standards (NOS), producers are required to use certified organic vegetable transplants for field grown vegetables. Considerable research has been done on the use of organic nutrient sources for transplant production. Research has focused on evaluating compost and vermi-compost as potting media constituents, and the use of animal and plant wastes products, animal by-products and liquid organic fertilizers. Results have not been consistent, and in some cases, the addition of organic materials to potting media has increased both electrical conductivity (EC) and pH to levels not suitable for transplant growth.
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Since plant nutrition in certified organic production is based mainly on the decomposition of organic materials by microorganisms, abiotic factors that affect microbial activity are of vital importance in determining nutrient release. These factors include pH and EC, temperature and moisture. Because both mineralization and nitrification are microbial-mediated processes, conditions that affect microbial activity in the media will directly affect the release patterns of organic fertilizers. Research to improve management of organic fertilizers for organic transplant production has increased over the past years. Studies have focused on optimizing the use of compost and animal and plant-based resources as nutrient suppliers. Although some studies have demonstrated that organic amendments and fertilizers may be used successfully in organic transplant production, it is hard to generalize the results to other crops and potting media, mainly due to the high variability on the composition and nature of these materials and the specific management used in each study. Although more information has recently become available, future research should attempt to understand how environmental factors such as temperature and moisture and chemical factors such as pH and EC affect the availability of nutrients. In turn, this will provide tools to better synchronize release from organic materials with plant nutrient demand and will allow for the development of nutrient management recommendations with organic amendments and similar resources. The purpose of this research was to determine the type and rate of nutrient sources needed to produce certified organic transplants with two temperature regimes. The specifics objectives were to: •
Determine the effect of temperature when the moisture level of potting media is held constant on the nutrient release rates from five different organic amendments approved for organic transplant production (Chapter 3).
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•
Determine the effect of temperature when the moisture level of potting media is held constant on the nutrient release rates from four custom blends made from five different organic amendments (Chapter 4).
•
Determine the effects of application rates of custom blends made from different organic amendments as well as the effect of nutrient form on the growth and nutrient content of basil transplants (Chapter 5).
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CHAPTER 2 LITERATURE REVIEW Overview of the Organic Industry Organic agriculture is practiced in more than 120 countries, with almost 31 million ha of farmland under certified organic management worldwide representing 0.7% of the worlds’ agricultural land. Currently, the countries with the greatest organic areas are Australia (11.8 million hectares), Argentina (3.1 million hectares), China (2.3 million hectares) and the US (1.6 million hectares) (Willer and Yussefi, 2007). Compared to other continents, North America had the highest growth of organic land, cropland, pasture and range land; 500,000 ha more compared to the end of 2004 (Willer and Yussefi, 2007). According to the Economic Research Service of the United States Department of Agriculture (USDA, 2003), organic farming became the fastest growing segment of US agriculture during the 1990's, and has sustained an average growth rate of 20% a year. Total organic farming area increased from 538,623 ha in 1997 to over 1.6 million hectares in 2005, representing 0.5% of the total agricultural land (USDA, 2007a). Global sales of organic food and beverages have increased by 43% from $23 billion in 2002 to $33 billion in 2005. The North American market valued at about $14.9 billion, accounted for 45% of global revenues in 2005 (Sahota, 2007). As reported in Oberholtzer et al. (2005), Natural Food Merchandiser estimated US retail sales of organic foods and beverages was $3.3 billion in 1996. In 2005, sales of organic food and drink were $14.5 billion (Sahota, 2006). Fresh market organic fruits and vegetables were the largest category of sales accounting for 39% ($5.4 billion) of the organic food sales in 2005 (Organic Trade Association, 2006). In 2002, the NOS were officially implemented by the USDA’s National Organic Program (USDA, 2007b). The NOS provide uniform standards for the production, handling, and labeling of organic agricultural products. Four years after full implementation of US NOS, interest in
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organic products continues to grow for the number categories of product offered and venues for selling these products (Haumann, 2007). Consumers belief that organic products are more healthy and nutritious than conventionally grown products combined with increasing distribution in conventional grocery channels are the major drivers of market growth (Haumann, 2007). Meanwhile, producers are turning to organic farming systems as a potential way to decrease reliance on nonrenewable resources, capture high-value markets and premium prices and increase farm income (USDA, 2003). In 2007, Florida had approximately 130 organic operations certified under the NOP (D. Treadwell, personal communication). In 2002, Florida Certified Organic Growers and Consumers Inc. (FOG), conducted a survey of certified organic producers in Florida. With a 33% response rate, certified operators reported cultivation of vegetables, citrus, sprouts, micro-greens, hay, pasture, blueberries, tropical fruits, chestnuts, herbs and edible flowers. Florida’s certified organic growers reported a 21% increase in sales between 2001 ($517, 580) and 2002 ($627, 645) (Austin and Chase, 2004). US Greenhouse and Vegetable Transplant Production Vegetable Greenhouse Production According to the 2002 Census of Agriculture, the greenhouse vegetable area of the US was approximately 590 ha (National Agricultural Statistics Service; USDA, 2004). In Florida, the greenhouse industry increased from 27 ha in 1991 to 39 ha in 2001 (Tyson et al., 2004). In 2001, the four major greenhouse crops were colored peppers (15.5 ha), tomatoes (7.3 ha), herbs (6.8 ha) and European cucumber (4.8 ha) (NFREC, 2001). In 2005, the total US certified organic area in greenhouses, including nursery crops and plant starts, was 1332 ha (USDA, 2007c). Florida’s vegetable transplant industry was last inventoried in 1989 and 1990. During that period, there were 34 operators producing $1.15 billion in sales of vegetable transplants. Tomato,
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pepper, and cabbage transplants represented the greatest volume (> 83%) (Vavrina and Summerhill, 1992). No recent published information is available, but according to the Southwest Florida Research and Education Center (SWFREC), there are over 20 commercial vegetable transplant producers in the state which produce a wide array of herbs and vegetables including: tomato, pepper, celery, squash, eggplant, cabbage, triploid watermelon, muskmelon, broccoli, onion, lettuce, leek and Brussels sprouts (SWFREC, 2007). Transplant Production Transplant production has replaced direct seeding for many vegetable crops because they provide uniformity and consistency compared to direct-seeded crops. Farmers use transplants because they usually want earlier production and greater early yields compared to direct seeding (Dufault, 1998). Transplants are typically started in the greenhouse where environmental factors such as temperature and moisture can be controlled. The goal in transplant production is to provide healthy, sturdy and compact plants with a well-developed root system and the appropriate level of stress tolerance to withstand environmental challenges when transplanted into the field. Therefore, commercial growers require that all phases of transplant production be strictly controlled, especially the growth rate. Nutritional and irrigation regimes are the most effective way of controlling transplant growth. Considerable research on nutrition of vegetable transplants has been conducted over the past 20 years (Dufault, 1998), but there is no generalized fertilizer program, so growers use their own blends and schedule based on experience (Cushman, 2007). Nutrient management in transplant production, conventional or organic, is different from field production because there are only a few weeks (5-7 weeks) from sowing to transplanting. In addition, roots are restricted to a relatively small amount of growth media; therefore efficient methods of nutrient supply are very important.
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Environmental Concerns Nitrate (NO3-) is one of the nutrients that may cause contamination of groundwater because it moves easily through the soil and it can be carried by rain or irrigation water. Geographic analysis has indicated that land use is a major factor in the distribution of total nitrogen (N) and total phosphorus (P) concentrations and yields in streams and rivers (Mueller and Spahr, 2006). Nitrate concentration is greater at agricultural (>50% agriculture and 25% agriculture and >5% urban) than at urban sites (>25% urban and
