Utilization of Municipal Solid Waste Compost in

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Journal of the Indian Society of Soil Science, Vol. 66, No. 1, pp 28-39 (2018) .... argentometric (Mohr's) titration as described by. Jackson (1973). Carbonate ( ...
Journal of the Indian Society of Soil Science, Vol. 66, No. 1, pp 28-39 (2018) DOI: 10.5958/0974-0228.2018.00004.X

Utilization of Municipal Solid Waste Compost in Reclamation of Saline-sodic Soil Irrigated with Poor Quality Water Parul Sundha*, Nirmalendu Basak, Arvind Kumar Rai, Rajender Kumar Yadav and Dinesh Kumar Sharma Division of Soil and Crop Management, ICAR-Central Soil Salinity Research Institute, Karnal, 132 001, Haryana Salinity and sodicity are the major stresses in soils of arid and semi-arid regions. These regions often face rainfall shortage and groundwater contains excess salts with variable sodium adsorption ratio (SAR). Therefore, a laboratory experiment was conducted to investigate the impact of municipal solid waste compost (MSWC) in reclamation of saline-sodic soil with pH, electrical conductivity (EC) and exchangeable sodium per cent of 10.7, 3.09 dS m-1 and 70.3, respectively. Soil with gypsum (25 and 50% of gypsum requirement, GR) and its combination with 10 and 20 t ha-1 of farmyard manure (FYM), MSWC of Karnal (KC) and Delhi (DC) were incubated at 60% field capacity. After 30 days of incubation, a soil columnleaching experiment was carried out with treated and control soil. Columns were sequentially leached up to ten pore volumes using water of SAR 5 and 15 with constant electrolyte concentration (60 me L-1). Nature, amount and independent integration of amendments had positive influence on lowering of soil pH and EC. The GR25DC (20 t ha-1) treated soil showed maximum decrease for both soil pH and EC irrespective of SAR of water. Further, soil reclamation efficiency (based on losses of cation mass) increased with application of organic amendment rates (20 t ha-1) in conjunction with GR25 compared to non amended soil/ GR25 + lower doses of organic amendment. Quality and purity of agricultural grade gypsum is issue, therefore GR25 and 20 t ha-1 MSWC can be advocated for reducing alkalinity and salinity stress of soil under use of poor quality water. Key words: Gypsum, saline-sodic soil, municipal solid waste compost, sodium absorption ratio, reclamation efficiency

Soil salinity and sodicity deleteriously affect soil properties and impose stress on plants and thereby reduce crop yield (Rengasamy 2006). Soil salinity is mainly associated with presence of higher quantity of electrolytes which imbalances the nutrient availability, translocation and plant growth (Muhammad and Khattak 2011); while sodicity badly impedes the soil aggregation (Tejada and Gonzalez 2005). Saline–sodic soils are considered to be highly degraded and least productive as they hinder plant growth because of deterioration of soil physical, chemical and biological properties. Arid and semi-arid areas face the problem of water scarcity with both in terms of quality and quantity (Jalali and Merrikhpour 2008). Continuous use of poor quality water increases soil pH and exchangeable sodium percentage (ESP) which *Corresponding author (Email: [email protected])

adversely effects crop growth and yield (Choudhary et al. 2011) but limitation in water availability force people to use saline, sodic or saline-sodic water for irrigation. Among reclamation technologies, sodic soil reclamation is carried out using chemical amendments such as gypsum, phosphogypsum, calcium chloride, sulphur or acids (e.g. H2SO4) and other acid formers. Amongst organic amendments farmyard manure (FYM) (Dubey and Mondal 1993, 1994), corn stalk (Li and Keren 2009), pig manure (Liang 2003), sheep and poultry manure (Jalali and Ranjbar 2009) are used as amendments. Organic amendment in conjunction with gypsum is an economic, scientific and sustainable way of sodic soil reclamation (Amezketa et al. 2005). Since, they increase solubility of CaCO3 and other calcic minerals because of increased soil pCO2 concentrations and organic acids production (Choudhary et al. 2006; Li and Keren 2009) which

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further accelerates the leaching of Na+, decrease the ESP and electrical conductivity (EC) and increase the water-holding capacity and aggregate stability (Dubey and Mondal 1993, 1994). Under limited availability of manures, environmental waste compost could be a promising alternative for restoring soil productivity and sustaining crop yields in salt-affected soils (Lakhdar et al. 2011). Abundant availability of solid waste in India and other parts of the world may help in reclamation of degraded soils. Saline-sodic soils are deficient in organic matter and other nutrients, therefore, municipal waste compost addition may help in enhanced nutrient availability and structural improvement of these soils (Lakhdar et al. 2008; Walker and Bernal 2008). Irrigation with variable sodium absorption ratio (SAR) water adds or leaches cations and anions in exchange phase and may accelerate or hinder the reclamation. Sodic soil requires calcium (Ca2+) for replacing excess Na+ from the exchange complex. Reclamation of sodic soil makes the root zone congenial for absorbing water and nutrients for crop plants (Qadir et al. 2007) and maintain appropriate soil permeability by providing sufficient electrolyte concentration in soil water system (Li and Keren 2009). Accordingly, we hypothesized that (i) application of MSWC in conjunction with gypsum will help in reclamation of sodic soils and (ii) leaching with variable SAR water will establish the new equilibria in solid and solution phase to affect the reclamation process. Therefore, the present study aimed to evaluate (i) the efficiency of MSWC in conjunction with gypsum (GR25) in reclamation of saline-sodic soil; and ii) the movement of monovalent and bivalent cations mass in outflow water during progress of reclamation under the use of gypsum, FYM and MSWC. Materials and Methods Soil sampling Bulk samples were collected from 0-20 cm soil layer in Saraswati forest range (30°00′04.5′′ N;

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76°25′27.3′′ E), Kaithal, Haryana, India which were air-dried and crushed to pass through a 2-mm sieve, homogenized by thorough mixing and physicochemical properties were analyzed. The soil was saline-sodic with pH of saturation paste (pHs) 10.16 (pH1:2 10.71); EC of saturation extract (ECe) 12.15 dS m-1 and EC1:2 3.09 dS m-1; and of cation exchange capacity (CEC) 27.2 cmol(p+)kg-1 with ESP 70.3. Soil was clayey in texture and contained organic C (OC) of 1.1 g kg-1, CaCO3 of 1.45%, and sand, silt and clay per cent of 59.3, 17.4 and 23.3, respectively. The gypsum requirement for 100 per cent neutralization (GR100) of sodicity was 22.7 t ha-1 as estimated by method of Schoonover (1952). Amendments and soil incubation The compost was collected from Karnal (KC) and Delhi (DC), while FYM from ICAR-CSSRI campus dairy were used after analyzing their physicochemical properties (Table 1). Processed soil was incubated with scheduled doses of the amendments viz., control without amendment, 25% recommended dose of mineral gypsum (GR25); 50% recommended dose of mineral gypsum (GR50); GR25 + 10 t ha-1 FYM (GR25F10); GR25 + 20 t ha-1 FYM (GR25F20); GR25 + 10 t ha-1 of Karnal compost (GR25KC10); GR25 + 20 t ha-1 of Karnal compost (GR25KC20); GR25 + 10 t ha-1 of Delhi compost (GR25DC10); GR25 + 20 t ha-1 of Delhi compost (GR25DC20) at 60% water holding capacity for one month to equilibrate the exchange reaction in soil. The FYM treatment was taken as organic check to test the potential of MSWC in reclamation of saltaffected soils. Soil column leaching and analysis Soil column study was performed with 30 cm long PVC cylinder (10.5 cm internal diameter and a centric drainage hole) arranged in completely randomized factorial design replicated thrice. Around 2.5 cm layer of acid cum deionised water washed sand ( GR25DC > GR50/25. Greater leachate EC in GR25KC treated soils was because of high EC of the KC compared to the DC. Increase in amount of gypsum or higher doses of FYM and compost with GR25 enhanced leaching of electrolytes. Leachate of GR25F amended soil showed

greater EC and lower pH compared to other amendments. Organic amendments improve structural stability of the soil and release of electrolytes because of chelation between humic substances and divalent cations (Li and Keren 2009; Choudhary et al. 2011; Chaganti and Crohn 2015). Leaching behavior of cations on pore volume The Ca2+ content of the effluents drastically declined up to PV-VI with 1.3 and 0.7 me L-1 for SAR 15 and 5 and subsequently increased in an erratic manner for all the treatments leached with different water qualities (Fig. 3). Breakthrough curves (BTC) for Ca 2+ indicated that leachate water never equilibrated for Ca2+ with incoming water quality. The mean Ca2+ concentration for PV-X was very low for SAR 15 (2.4 me L-1) compared to SAR 5 (14.4 me L -1). Differences in the concentration of Ca 2+ in incoming water and effluent were slightly greater for SAR 5 with 32.59 me L-1 compared to 30.93 me L-1 in SAR 15 at PV-X. Results further indicated that soil was never saturated for exchange reaction between Ca2+/Mg+ for Na+. Water quality had no definite trend in leaching of Ca2+ in the effluents. Nearly similar amount of Ca2+ (mean 5.89 and 5.72 me L-1) was leached when low SAR water was applied for two incremented GR treatments viz., 25GR and 50GR.

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EC (dS m-1)

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Value (me L-1)

Fig. 2. Leachate EC (dS m-1) versus the pore volumes when different amended soils were leached with saline SAR water

Fig. 3. Leachate Ca2+ and Mg2+ (me L-1) versus the pore volumes when different amended soils were leached with saline SAR water

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Different SAR water had mixed effect on Na+ leaching for different amendments (Fig. 4). Apparently, a usual increase in Na+ leaching was observed up to PV-II for both the water qualities, however, increment was not comparable to the incoming concentration of Na + for both water qualities. The BTC data indicated high concentration of mean Na+ of 140.3 and 216.4 me L-1 for low sodic water in PV-I and II compared to 130.2 and 201.8 me L-1, respectively for high SAR water. Further, Na+ concentration drastically declined upon leaching with saline SAR water. Mean values of BTC indicated greater Na+ concentration in soil leachates when soil was leached with high SAR water. Increment in quantity of gypsum and FYM enhanced more Na+ concentration in leachates which indicates that inputs of organic matter occupied cation-exchange sites and coated soil particle surfaces, limited Na+ adsorption and enhanced leaching of Na+ (Wright et al. 2008) A considerable amount of K + released upon leaching with saline SAR water. Greater amount of K+ was lost (0.08 me L-1) upon leaching with low SAR 5 compared to SAR 15 of 0.06 me L-1. All soil amendments (gypsum, FYM, KC and DC) released nearly similar amount of K+ in the range of 0.05-0.06 me L -1 on leaching with high SAR saline water. However, increase in the dose of FYM and compost

Na+ (me L-1)

However, the Ca2+ loss increased to 2.02 me L-1 for 50GR compared to 1.34 me L-1 in 25GR for high SAR water. Integration of gypsum and FYM (GR25F20) always maintained higher Ca2+ concentration for both water qualities. The PV-II showed a drastic decline in Mg 2+ content compared to PV-I and this decline continued upto PV-IV with similar values of 0.4 me L-1 for SAR 5 and 15 (Fig. 3). Thereafter a concomitant increment in Mg2+ concentration up to 7.7 me L-1 with low SAR water for PV-X was recorded. However, this increment nearly polynomial for leaching continued with high SAR water. Overall water quality described ~2.2 time higher Mg2+ concentration in mean soil leachates of SAR 5 water compared to SAR 10. The BTCs of Mg2+ showed a similar trend like Ca2+ for respective soil treatments. Further, BTC revealed that overall mean Mg2+ concentration was (1.56 me L-1) quite similar with mean Ca 2+ (1.69 me L -1 ) concentration when high SAR water was used as an incoming solution whereas, under low SAR water, leaching of mean Mg2+ concentration was 3.42 me L-1 compared to 5.66 me L-1 for Ca2+. Jalali and Ranjbar (2009) reported incremental losses of ions on increase of SAR of incoming water. Increment in doses of FYM and DC enhanced the amount of Ca2+ and Mg2+ in soil leachates.

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Fig. 4. Leachate Na+ (me L-1) versus the pore volumes when different amended soils were leached with saline SAR water

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released greater amount of K+ when soil was leached with high saline SAR water. Leaching behavior of anions on pore volume Greater amount of CO32- ranging from 1.25 to 2.75 me L-1 released on increasing the SAR level of water from 5 to 15. Greater release of CO32- of 10.8 and 9.3 me L-1 was detected at PV-II for SAR 15 and 5, respectively. Among soil treatments, control soil released maximum concentration of CO32- of 2.28 and 7.42 me L-1 against the incoming water quality SAR 5 and 15, respectively. Increment in doses of gypsum, FYM and MSWC decreased the concentration of CO32in soil leachates. The HCO 3- concentration of soil leachates increased four-fold under low SAR water compared to high SAR water. The HCO3- released was at peak at PV-II followed by sharp decline when low SAR water was applied. Conversely, HCO3- concentration gradually declined with each pore volume when SAR 15 was used. Increment in the level of gypsum, FYM and composts released excess concentration of HCO3-. However, release of HCO3- was lower in GR25 and GR25F10 compared to leaching with GR50 and GR25F20 for SAR 5 water. Jalali and Ranjbar (2009) and Zarabi and Jalali (2012) reported incremental losses of HCO3- when different amended soils were leached with incremental level of SAR water.

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The CO 32- and SO 42- concentration followed nearly similar pattern. An appreciable quantity of SO42- released at PV-I, raised at PV-II then drastically declined in subsequent pore volumes. The SO42- losses were higher for SAR 5 compared to SAR 15 water. Application of amendments released more SO 42compared to control soil. Further, GR50, and individual elevated doses of FYM, DC with GR25 indicated higher leaching losses of SO42-. As gypsum contains SO42-, its application facilitates greater release of SO42- compared to untreated soil. Break through curve of Cl - indicated overall losses of Cl- from soil as incoming solution contained 60 me Cl- L-1. Among different quality water used, high SAR 15 water released greater concentration of Cl- compared to SAR 5. It was noticed that losses of Cl- were at peak from the initial PV-I and II, thereafter, gradually declined in subsequent pore volumes. Application of soil amendments merely had an influence on loss of Cl-. However, elevated doses of gypsum and DC accelerated Cl- loss as this inherently contained greater quantity of Cl- compared to KC. Changes in SAR of pore volume Water quality, amendments and pore volumes strongly influenced the leachate SAR (Fig. 5). Leachate SAR was never equilibrated with incoming water SAR. As expected, SAR (89.4) was greater

Fig. 5. Leachate SAR (mmol1/2 L-1/2) versus the pore volumes when different amended soils were leached with saline SAR water

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when saline water with high SAR 15 were used for leaching compared to SAR 5 (66.5) water. Presence of soluble Ca2+ and Mg2+ declined leachate SAR in amended soils applied with SAR 5 water compared to SAR 15 water. The SAR level was attained ~42 and 49 compared to incoming water quality of 5 and 15 in PV-I. Further, it was at peak at PV-IV at highest level of 126.5 and 127.3 for SAR 5 and 15, respectively. A decline in the level of SAR to13.7 was detected at PV-X when leaching was performed with SAR 5. However, a gradual decrement in level of SAR was observed but it never reached below 50.0 up to the PV-X for leaching under high SAR water. As the initial soil was saline-sodic in category, a greater amount of soluble and exchangeable Na+ have leached at the earlier pore volume. Further, it declined the SAR due to readily available source of amendment; gypsum, compost and presence of Ca2+ in incoming water (Yazdanpanah and Mahmoodabadi 2013). Similarly, an increment in the doses of gypsum, manure and composts exhibited lower values of SAR in effluent. Soil pH and EC Applying gypsum alone or in combination with different levels of FYM, KC and DC decreased pH1:2 accompanied with increased EC1:2 of soil determined after 30-days incubation (Table 3). The efficiency of different amendments in lowering the pH1:2 was GR50 > GR25KC10/DC10 = GR25KC20/DC20 = GR25F20 = GR25F10 > GR25. Change in EC1:2 and pH1:2 of the soil incubated with gypsum/ gypsum + organic amendments are linked with change in electrolytes concentration of soil solution. It appeared that supply

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of soluble Ca2+ through gypsum replaced Na+ from the exchange complex with the consequent release of Na+ in soil solution. The increased EC1:2 in salinesodic soil have suppressing effect on the alkaline hydrolysis of Na-clay because of common ion effect (Brady and Weil 2014). On mineralization, applied FYM and compost also release large quantity of CO2 and decrease soil pH1:2 and slightly increase soil EC1:2 (Jalali and Ranjbar 2009). Leaching with quality waters had major influence on decrease of both pH1:2 (P< 0.0001) and EC2 (P< 0.01) (Fig. 6a, Table 4). As expected the decrease in pH1:2 was greater for SAR 5 [8.66 (n=81; P GR25 (1.71) > GR25DC10 (1.69) = GR25KC10 (1.66) = GR25KC20 (1.65) = GR25F20 (1.64) = GR25F10 (1.63) = GR50 (1.63), respectively. Contrary to this, a maximum salt leaching occurred for GR25DC10 (3.42) > GR25KC10 (3.33) > GR25F20 (3.30) = GR25KC20 (3.29) > GR25F10 (3.23) > GR50 (3.10) >GR25 (3.01) > GR25DC20 (2.96) > Control (2.75).

Table 3. pH1:2 and EC1:2 (dS m-1) of soil before and after leaching with different treatments Treatments Control GR25 GR50 GR25F10 GR25F20 GR25KC10 GR25KC20 GR25DC10 GR25DC20

After incubation pH1:2 EC1:2 10.71a 10.59b 10.40d 10.53c 10.52c 10.54bc 10.53c 10.53c 10.49c

3.71d 3.93cd 4.11abc 4.19abc 4.30ab 4.30ab 4.26ab 4.36a 4.04bc

After Leaching pH1:2 EC1:2

Δ pH1:2

ΔEC1:2

8.87ab 8.88ab 8.78bc 8.91a 8.87ab 8.89ab 8.89ab 8.84ab 8.66c

1.85a 1.71cb 1.63c 1.63c 1.64c 1.66c 1.65c 1.69c 1.83ab

2.75e 3.01d 3.10cd 3.23bc 3.30ab 3.33ab 3.29ab 3.42a 2.96d

0.97ab 0.92b 1.01ab 0.97ab 1.00ab 0.97ab 0.98ab 0.93b 1.08a

Change

GR25: 25% gypsum requirement; GR50: 25% gypsum requirement; GR25F10: GR25 + farmyard manure @ 10 Mg ha-1; GR25F20: GR25 + farmyard manure @ 20 Mg ha-1of farmyard manure (F); GR25KC10: GR25 + Karnal compost @ 10 Mg ha-1; GR25KC20: GR25 + Karnal compost @ 20 Mg ha-1; GR25DC10: GR25 + Delhi compost @ 10 Mg ha-1; GR25DC20: GR25 + Delhi compost @ 20 Mg ha-1. Numbers followed by different letters are significantly different at P ≤ 0.05 by Tukey’s test

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Soil pH

Fig. 6a

Treatment

Soil EC (dS m-1)

Fig. 6b

Treatment Fig. 6. Influence of water quality on soil pH1:2 (Fig. 6a) and EC1:2 (Fig. 6b)

A significant influence of water quality was apparent on leaching of salt from highly alkaline soil. Decrease in pH1:2 along soil depth were in order of 0-5 cm < 510 cm < 10-15 cm with 8.86, 8.81 and 9.26, respectively. Conversely, decrease in soil EC 1:2 appeared as oppositely with 1.22 > 0.87 > 0.85 dS m-1 for soil depth 0-5, 5-10 and 10-15 cm, respectively. Soil reclamation efficiency The soil reclamation efficiency based on the

cation loss during soil column leaching experiment has been described in table 5. Saline-sodic soil reclamation efficiency increased with application of 20 t ha -1 organic amendment in conjunction with GR25; likewise per cent change of cations mass (CM%) for Ca 2+ was greater in GR25DC20 (50.9) followed by GR25F20 (36.1)/GR25 (29.7)/ GR25KC10 (26.4)/ GR50 (24.7), GR25F10 (24.5), GR25KC210 (14.1)/ GR25DC10 (13.6), when low SAR water used for leaching. Similarly, higher doses

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Table 4. ANOVA table describing the effect and interaction of amendments, water quality and soil depth on soil pH1:2 and EC1:2 (dS m-1) Source/ variables

pH1:2

EC1:2

Mean square

Pr > F

Mean square

Pr > F

0.02 8.72 5.52 0.89 0.11 0.02 0.09 0.02

0.20