Yield and Nutrient Export of Grain Corn Fertilized with Raw and Treated Liquid Swine Manure Martin H. Chantigny,* Denis A. Angers, Gilles Bélanger, Philippe Rochette, Nikita EriksenHamel, Shabtai Bittman, Katherine Buckley, Daniel Massé, and Marc-Olivier Gasser
Treatment of liquid swine manure (LSM) is an option to improve nutrient management. Mineral fertilizer, raw LSM, and LSM treated by anaerobic digestion, flocculation, fi ltration, or natural decantation were sidedressed (100 kg N ha−1) to grain corn (Zea mays L.) on a clay and a loam soil. Over 3 yr, corn grain yield (6 to 11 Mg ha−1), N export (83 to 176 kg ha−1), and P export (19 to 40 kg ha−1) were similar among LSM types and between LSMs and mineral fertilizer. Th is was attributed to the immediate incorporation of LSM to minimize N volatilization. Treated LSMs reduced P input to soil by 3 to 24 kg ha−1, compared with raw LSM. Th is reduced corn P export by 2 to 4 kg ha−1 on the clay soil, but had no effect on the loam soil. Soil NO3 content after harvest was higher with the mineral fertilizer (19–31 kg NO3 –N ha−1) than with LSMs (13–20 kg NO3 –N ha−1) in the clay soil, but was similar for all treatments in the loam soil. We conclude that when sidedressed to corn and immediately incorporated, raw and treated LSMs have a fertilizer value similar to the mineral fertilizer. Moreover, the risk of postharvest NO3 accumulation with the raw and treated LSMs was similar to mineral fertilizer on the loam and lower on the clay.
M
ore than 7 million hogs are produced annually in the province of Québec, Canada, and 75% of this production is concentrated in areas dominated by grain corn production (Bureau d’Audiences Publiques sur l’Environnement, 2003), representing about 350,000 ha. In many soils of those areas, applications of swine manure have long exceeded crop nutrient requirements, resulting in soil P enrichment (Simard et al., 1995) and increasing the transfer of P and NO3 to surface and ground water (Beauchemin et al., 1998). Swine manure is often managed as a slurry due to ease of collection and application. The great availability of nutrients in LSM makes it amenable to applications to standing crops. However, separation of animal manure slurries into dry matter (DM) rich and clarified liquid fractions can provide additional flexibility in manure nutrient management by concentrating P in the DM rich fraction, while most N remains in the liquid fraction (Pain et al., 1978; Møller et al., 2000). Chantigny et al. (2007) compared the effect of several manure treatments on the partition of DM, N, and P in LSM. They reported that anaerobic digestion and chemical flocculation removed 65 to M.H. Chantigny, D.A. Angers, G. Bélanger, P. Rochette, and N. EriksenHamel, Agric. and Agri-Food Canada, Soils and Crops Res. and Dev. Cent., 2560 Hochelaga Blvd, Québec, QC, Canada, G1V 2J3; S. Bittman, Agric. and Agri-Food Canada, Pacific Agric. Res. Cent., Box 1000, Agassiz, BC, Canada, V0M 1A0; K. Buckley, Agric. and Agri-Food Canada, Brandon Res. Cent., 18th St. & Grand Valley Road, Brandon, MB, Canada, R7A 5Y3; D. Massé, Agric. and Agri-Food Canada, Dairy Cattle and Swine Res. Cent., 2000 College St., C.P. 90, Sherbrooke, QC, Canada, J1M 1Z3; and M.-O. Gasser, Inst. de recherche et de dév. en agroenvironnement, 2700 Einstein St., Québec, QC, Canada, G1P 3W8. Received 1 Nov. 2007. *Corresponding author (
[email protected]). Published in Agron. J. 100:1303–1309 (2008). doi:10.2134/agronj2007.0361 Copyright © 2008 by the American Society of Agronomy, 677 South Segoe Road, Madison, WI 53711. All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher.
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70% of the initial DM in LSM, compared with 30 to 40% for natural decantation and fi ltration. In addition, depending on the treatment type, 30 to 80% of initial P could be removed from LSM and concentrated in the DM rich fraction, whereas >85% of initial N remained in the liquid fraction. The DM rich fraction of treated LSMs can thus be used as a P-based organic fertilizer. For farm operations facing a P surplus, the DM rich fraction can be more easily exported to other farms or to composting or fertilizer processing plants. Because it contains >95% water, the liquid fraction of LSM usually remains on farm where it is valued as a N-rich liquid fertilizer. In field trials, LSM was found to be as efficient as mineral fertilizers for the production of grain crops (Balik and Olfs, 1998; McLaughlin et al., 2000; Daudén and Quìlez, 2004; Ball Coelho et al., 2005; Carter and Campbell, 2006; KwawMensah and Al-Kaisi, 2006) due to its high nutrient availability. In the province of Québec, however, only 70% of total N is credited for LSM sidedressed to corn cropped on soils with 30% clay; in contrast, 100% of P is credited for LSM sidedressed to corn on all soil texture classes (Centre de Référence en Agriculture et Agroalimentaire du Québec, 2003). Few field studies have assessed the effect of treated LSMs on crop yield and nutrient uptake. Perennial forage yields were similar to or slightly higher with anaerobically digested (Rubaek et al., 1996), mechanically separated (Mattila et al., 2003), and chemically flocculated LSM (Chantigny et al., 2007) than with raw LSM. For corn, similar yields were reported with anaerobically digested and raw LSM (Loria et al., 2007). Nitrogen uptake by cereals receiving LSM was increased by the mechanical removal of DM (Sørensen and Thomsen, 2005). Chantigny et al. (2007) observed that N uptake by forage fertilized with anaerobically digested and chemically
Abbreviations: LSM, liquid swine manure; DM, dry matter; FUE, fertilizer use efficiency; ANR, apparent N recovery.
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ABSTRACT
flocculated LSM was similar to that obtained with mineral fertilizers, but was lower with raw, decanted, and fi ltered LSMs. Soil NO3 content after harvest was similar or lower with LSM than with mineral fertilizers when both were managed similarly (Beauchamp, 1986; Diez et al., 2001; Daudén and Quìlez, 2004). In agreement, Chantigny et al. (2007) reported similar soil NO3 content after harvest with mineral fertilizer, raw LSM, and treated LSMs applied to perennial forage. We are not aware of studies comparing the effect of mineral fertilizer, raw, and treated LSMs on crop P uptake or NO3 accumulation in soils cropped to corn. The objective of this study was to compare mineral fertilizer, raw LSM, and treated LSMs (anaerobically digested, anaerobically digested/flocculated, fi ltered, and decanted) on two soils of contrasting texture for corn grain yield, N and P exports, and soil NO3 content after harvest. MATERIALS AND METHODS Manure Collection and Analyses Raw LSM was obtained during the winters of 2004, 2005, and 2006 from a commercial farrow-to-finish swine operation. Animals were fed a corn-soybean-based diet and raised in a slatted-floor barn with minimal bedding. The LSM was collected by composite subsampling during the emptying of the transfer tank. The LSM had been accumulating for about 48 h in the transfer tank at time of collection. The collected LSM was thoroughly stirred and part of it was transferred into an anaerobic, psychrophilic batch digestor as described by Massé et al. (1996). The rest of the manure was stored in four 1-m3 plastic containers for 6 wk in the dark at 15°C. After this storage period, the upper half of raw LSM was pumped out of two plastic containers and transferred to an empty 1-m3 container. This manure was labeled Decanted LSM and represented the clarified fraction of LSM after 6 wk of natural settling of solids. Manure from a third plastic container was passed through a rotary vacuum (–66 kPa) fi lter with porosity of 10 μm. The draining liquid was collected in a plastic container and labeled Filtered LSM. Manure in the fourth plastic container was used as is and labeled Raw LSM. After digesting for 1 mo, part of the anaerobically digested LSM was transferred into a 1-m3 plastic container and labeled Digested LSM, whereas another part of the digested material was transferred into a plastic tank and chemically flocculated with the polymer Aquaperl (Les produits environnementaux Atlas Inc., Sherbrooke, QC, Canada) and a copolymer of a quaternary acrylate salt and acrylamide (Chemfloc CTT 8668, CHEMCO Inc., St-Augustin-de-Desmaures, QC, Canada). The flocks were allowed to precipitate at the bottom of the tank for 48 h and 1 m3 of the surface liquid fraction was transferred in a plastic container and labeled Digested/Flocculated LSM. The various LSM types were transported to the experimental sites, subsampled, and analyzed to determine application rates based on total N content. The LSMs were continuously stirred during field application and subsampled for detailed characterization and to calculate actual N application rates. On each application date, a 2-L composite sample was collected from each LSM type. The LSM samples were homogenized with a Polytron (Model PT 3100, Kinematica AG, Littau-Lucerne, 1304
Switzerland) for 2 min and tested for pH by direct reading with a glass electrode. All other analyses were made in triplicate for each LSM type. The DM content was determined as the weight of material remaining after drying 100 mL of LSM at 55°C for 96 h. Total C concentration was measured by injecting 50 μL of homogenized LSM into an automated combustion C analyzer (Model Formacs, Skalar Analytical, De Breda, The Netherlands). Total N and P concentrations of the homogenized LSM samples were determined by acid digestion as described by Chantigny et al. (2007). The concentrations of NH4 and PO4 in the acid digests were measured with an automated continuous-flow injection analyzer (Model QuickChem 8000 FIA+, Lachat Instruments, Loveland, CO). The mineral N content in LSM was determined by shaking 10 mL of LSM with 50 mL of 1 M KCl for 60 min. The extract was fi ltered with prewashed (1 M KCl) fi lter papers (Whatman #42). Blank samples were used to detect any N contaminations. The NH4, NO3, and NO2 concentrations were measured in the extracts with the automated continuous-flow injection analyzer described above. The sum of NO3–N and NO2–N contents always accounted for 85% with digestion/flocculation and fi ltration (Table 1). While the decline in P is explained by the removal of solids during decantation, fi ltration, and digestion/flocculation, the decline that occurred during anaerobic digestion was most likely due to (i) the settling of solids at the bottom of the digester and (ii) the formation of struvite (MgNH4PO4 · 6H2O), which precipitates and
accumulates on the sides of the anaerobic digester (Shu et al., 2006). As the content of the digester was not agitated during transfer of the digestate to the storage container, settled solids, struvite, and associated P were mostly excluded from the digested LSM used in our study. Even though P content was reduced in the digested LSM, the N to P ratio was about the same as raw LSM (Table 1). Greater decrease in P content with decantation, fi ltration, and digestion/flocculation, however, raised the N to P ratio of LSM by two- to sixfold. In agreement with previous studies (Sommer and Husted, 1995; Chantigny et al., 2007), decantation had little effect on the pH of LSM, but anaerobic digestion, with or without flocculation, and fi ltration increased it by up to 1.1 unit (Table 1). The application rates of LSM were based on preliminary analysis of the total N content before field application. The various LSM types were sampled again during field application and analyzed to determine the actual amounts of N and P applied. Based on this second analysis, the actual amounts of N applied were higher than expected for raw LSM in 2005, and lower than expected for raw, digested, digested/flocculated, and decanted LSMs in 2006 (Table 2). When averaged over the 3 yr of the experiment, however, N application rates were reasonably close to 100 kg ha−1 for all LSM types. As all LSMs were applied on a total N basis, P application rates were 3 to 24 kg ha−1 yr−1 lower with the treated LSMs than with the raw LSM.
Table 2. Actual amounts of N and P sidedressed† as mineral fertilizer (MF) or as raw or treated liquid swine manure (LSM) at the 4- to 6-leaf stage of corn. N source MF LSM type Raw Digested Digested/flocculated Decanted Filtered
2004 2005 2006 Mean‡ 2004 2005 2006 Mean‡ kg N ha–1 kg P ha–1 100 100 100 100 0 0 0 0 107 110 97 107 108
124 113 103 105 100
87 88 87 88 101
106 104 96 100 103
21 24 4 10 4
28 25 4 8 4
27 17 3 11 3
25 22 4 10 4
† Values do not include starter fertilizers: 20 kg P ha –1 as triple superphosphate to all plots; 30 kg N ha –1 as NH4NO3 to all plots except the control. ‡ Average values for 2004 to 2006.
Table 3. Analysis of variance (P values) comparing seven treatments over 3 yr for corn grain yield, N and P exports, and postharvest soil NO3 content in a clay soil and a loam soil. Clay Sources of variation
Yield
Loam
N P export export
Treatment (TRT)
