Profitability of Cropping Systems Featuring Tillage and Compost Jeremy W. Singer,* Craig A. Chase, and Keith A. Kohler
ABSTRACT
Cropping Systems
Productivity rather than profitability is often used to compare agronomic systems. The objective of this study was to compare profitability of moldboard plow, chisel plow, and no-tillage with or without composted animal manure in a corn (Zea mays L.)– soybean [Glycine max (L.) Merr.]–wheat (Triticum aestivum L.)/clover (Trifolium spp.) rotation during three rotation cycles. Corn and soybean grain and seed yield exhibited a tillage × compost amendment interaction. Yield in moldboard and chisel plow with or without compost was similar, but yield in no-tillage with compost was 8 and 5% greater than without compost for corn and soybean. Wheat yielded 5% higher in moldboard and chisel plow than no-tillage and 4% higher in compost than nocompost amendment. Wheat returns were similar among tillage and 7% higher when compost was amended. Corn production with or without compost amendment had similar returns in moldboard plow. Corn in chisel plow with compost had 8% greater returns than the no-compost treatment. Corn in no-tillage with compost had 15% greater returns with compost amendment than without. Similar corn returns were generated for all tillage systems if compost was applied. Soybean production using no-tillage had 9% greater returns than without compost and greater returns than moldboard and chisel plow with or without compost. Summing returns across the three-crop rotation indicated cycling nutrients through compost application exhibits a functional synergy in no-tillage and chisel plow but not moldboard plow for these crops, which enhances their profitability.
A
gronomists often perpetuate inefficient production systems by presenting data that supports the goal of maximizing production instead of maximizing profits. Few agronomic studies examine both the productivity and profitability of cropping systems. If production costs continue to increase and profit margins become smaller, crop producers will increasingly scrutinize their crop production costs. Consequently, agronomic research should include some measure of system or treatment profitability. Singer et al. (2003) compared the profitability of grain and forage crop rotations using chisel plow or no-tillage practices. They reported rotations including alfalfa (Medicago sativa L.) increased returns to land and management compared solely to grain or seed crop rotations, mainly by lowering N inputs. In the absence of forage markets, grain and oilseed cropping systems that include organic amendments and green manures can offset fertilizer inputs, among other benefits, by enhancing nutrient cycling. Singer and Cox (1998a) compared corn production in continuous corn, corn–soybean, and a 3-yr rotation of corn– soybean–wheat/red clover (Trifolium pratense L.). Nitrogen fertilizer input was reduced 25% in the 2- and 3-yr rotation
J.W. Singer, USDA-ARS, and K.A. Kohler, 2110 University Blvd., Ames, IA 50011; C.A. Chase, Iowa State Univ., 720 7th Ave. SW, Tripoli, IA 50696.Received 27 Aug. 2009. *Corresponding author (
[email protected]). Published in Agron. J. 102:450–456 (2010) Published online 5 Jan. 2010 doi:10.2134/agronj2009.0327 Copyright © 2010 by the American Society of Agronomy, 5585 Guilford 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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compared with continuous corn and corn yielded 10% higher than continuous corn with greater fertilizer N. The corn– soybean rotation had higher returns than the 3-yr rotation because wheat yields averaged 3696 kg ha–1 and the wheat price averaged $0.14 kg–1 during the period from 1994 to 1996 compared with corn, which averaged 9343 kg ha–1 with a price of $0.13 kg–1 (Singer and Cox, 1998b). The red clover green manure was only credited with 45 kg N ha–1, which was similar to the soybean credit. Meyer-Aurich et al. (2006) reported rotations that included wheat had yearly net returns that were greater than the rotation that only included corn and soybean and the full economic benefit of including wheat in the rotation was only fully realized when wheat was interseeded with red clover. In their economic analysis, production costs were 1% lower for chisel plow compared with moldboard plow in corn, soybean, and wheat (Meyer-Aurich et al., 2006). Archer et al. (2007) compared economic returns for conventional and organic crop rotations using conventional and strip tillage. The conventional system used commercial fertilizer while the organic rotations used manure to supply nutrients. Total production costs for the corn–soybean–wheat/alfalfa– alfalfa rotation in the conventional system using conventional tillage was $454 ha–1 compared with $459 ha–1 in the same rotation and tillage in the organic system (Archer et al., 2007). Seventy-five percent of the higher costs for seed, chemical, and fertilizer in the conventional system compared with the organic system were offset by the costs for manure hauling and loading. In their analysis they assumed no cost for purchasing the manure and a cost of $6.61 Mg–1 for solid manure for mixing, loading, and transporting within 1.6 km of the field. Singer et al. (2004 and 2007) reported a tillage × amendment interaction for no-tillage with and without compost amendment for corn and soybean. Quantifying the economic benefit of reduced tillage and compost amendment will assist
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Table 1. Sequence of corn (C), soybean (S), and wheat/clover (W/Cl) and frequency of compost application for the period from 1996 to 2007 near Ames, IA. The site had been managed in continuous corn (CC) from 1988 to 1996. 1996 CC CC CC
1997 S S S
1998 W/Cl† S C†
1999 C† W/Cl† S
2000 S C† W/Cl†
2001 W/Cl† S C†
2002 C† W/Cl† S
2003 S C† W/Cl†
2004 W/Cl† S C
2005 C W/Cl† S
2006 S C W/Cl†
2007 W/Cl S C
† Fall compost application.
producers in optimizing their production systems. Consequently, the objective of this work was to compare returns to land and management for moldboard plow, chisel plow, and no-tillage with or without composted animal manure in a corn–soybean–wheat/clover rotation during three rotation cycles from 1999 to 2007. MATERIALS AND METHODS Field research was conducted at the Iowa State University Agronomy and Agricultural Engineering Research Farm near Boone, IA (42°01´ N, 93°45´ W, 341 m above sea level) from 1999 through 2007 on Canisteo silty clay loam (fine-loamy, mixed, superactive, calcareous, mesic Typic Endoaquolls) and Clarion loam (fine-loamy, mixed, superactive, mesic Typic Hapludolls) soils. The experimental site had been in continuous corn production from 1987 to 1996, with tillage main plots consisting of moldboard plow, chisel plow, and no-tillage since 1988. In 1997 the entire site was planted to soybean. Soil samples collected from the top 18 cm in 1997 indicated that tillage had not affected soil pH (6.7), OM (63 g kg–1), P (Bray-1, 54 mg kg–1), or K (ammonium acetate extraction, 210 mg kg–1) levels. Organic matter concentrations were determined by dry combustion using a LECO CHN-2000 (LECO Corp., St. Joseph, MI).1 In 1998, a corn–soybean–wheat/clover rotation was initiated with all phases represented each year (Table 1) in each tillage system. The experimental design was a randomized complete block in a split-plot treatment arrangement with four replicates. Tillage main plots, 22.8 m wide by 27.4. m long, were fall moldboard plow, fall chisel plow, and no-tillage before corn and soybean rotational phases. Moldboard plow depth was approximately 20 cm. Chisel plow depth was 25 cm using twisted shanks. Spring secondary tillage operations included an early spring disking and a preplant field cultivation in moldboard and chisel plow systems. After soybean harvest and before wheat seeding, moldboard plow plots had one pass with a tandem disk and one pass with a field cultivator, chisel plow plots had one pass with a field cultivator, and no tillage was performed in the no-tillage plots. A no-till planter with 76 cm wide rows and row cleaners was used to plant all corn plots. The same planter was used to plant soybean plots from 1999 to 2004 and a grain drill with 15 cm wide rows was used from 2004 to 2006. Wheat was drilled in 19 cm wide rows from 1998 to 2003 and in 15 cm wide rows from 2004 to 2006. Subplots, 7.6 m (10 rows with a 76 cm row spacing) wide by 13.1 m long, consisted of the application of compost (amended) or no-compost. Bedded swine manure compost was applied from 1998 to 2003 and beef cattle compost was applied from 1 Mention of trade names or commercial products is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.
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2004 to 2006. Both swine and cattle manure was mixed with corn stalks or grain straw bedding and was approximately 6 to 9 mo old before land application. The compost process was facilitated by using a manure spreader to homogenize the material via repiling. Composition of compost used during the study period is presented in Table 2. The compost application rate during the first crop rotation cycle (1998–2000) was set at 8000 kg C ha–1 per application, reduced to 4000 kg C ha–1 during the second cycle (2001–2003), and changed to a P removal basis from 2004 to 2006 (Table 2). Compost was applied after corn and wheat/clover from 1998 to 2003 and only after wheat/clover from 2004 to 2006. The P removal rate was based on the P removal of corn, soybean, and wheat grain or seed during the 3-yr rotation (35, 22, and 16 kg P ha–1, respectively). In 1998, 1999, 2000, and 2001, the straw residue after wheat harvest was allowed to remain on the compost plots, but was removed from the no-compost plots. In subsequent years, all wheat straw was baled. Straw yields were not determined in this study. For the economic analysis, a harvest index of 0.3 was used to estimate wheat straw yield with the assumption that 90% of the wheat straw was harvestable. Compost was applied mechanically and by hand during the study period. The fall moldboard plow and chisel plow operations were conducted within 3 d after compost application. Compost moisture content was determined by drying at 70°C for 48 h. Compost total C and N were determined after acidification with 0.5N HCl (1:2 sample/solution ratio), air drying, grinding, and dry combustion in a Carlo-Erba NA1500 NCS elemental analyzer (Haake Buchler Instruments, Paterson, NJ). Compost P and K were determined on dried ground samples after digestion with 10 mL DI water, 5 mL HNO3, and 1 mL HCl. Compost samples from 2004 to 2006 were acidified with 0.44 M tartaric acid instead of HCl. Potassium was analyzed using atomic absorption in emission mode, while P was determined colorimetrically using ascorbic acid and ammonium molybdate. Eight soil cores to a depth of 18 cm were collected in the spring in each subplot to monitor changes in P, K, and organic matter concentrations. Potassium was surface applied to all no-compost plots in April of 2004 at a rate of 101 kg ha–1 based on soil test results. All no-compost plots had optimal or higher levels of P throughout the study period and only required one application of K. Consequently, we assume these elements were not limiting in the no amendment treatment and did not confound amendment treatment response. Corn hybrid ‘Pioneer Brand 3563’ was planted from 1999 to 2001, ‘Pioneer Brand 35P12’ was planted from 2002 to 2004, and ‘Dekalb DKC59–08’ was planted from 2005 to 2007 in mid to late April from 1999 to 2006 and on 11 May 2007 at a seeding rate of 81,510 seeds ha–1. Starter fertilizer was not applied. Late spring soil NO3–N concentrations were used to determine sidedress N application rates in compost and no-compost treatments. In 1999, 2001, and 2002, rates were 451
Table 2. Composition and application rate of fall 1998 to 2006 compost amendment. Year 1998 1999 2000 2001 2002 2003 2004 2005 2006
H2O
P
K
340 318 311 415 433 523 374 348 505
– 5.0 7.2 6.2 3.1 9.0 5.7 4.5 6.3
C
N
C:N
114 105 147 227 175 216 218 164 220
10.6 7.6 13.0 13.9 11.0 16.4 16.7 11.0 13.7
10.8 13.8 11.3 16.3 15.9 13.2 13.1 14.9 16.1
g kg–1 – 11.2 16.1 13.7 13.2 15.5 16.6 14.6 12.8
averaged across tillage systems. In 2000, six rates were applied for each tillage × amendment combination. In 1999, 2001, and 2002, 151, 174, and 123 kg N ha–1 was applied to no-compost plots, and 118, 151, and 67 kg N ha–1 was applied to compost plots. In 2000, 162, 106, and 106 kg N ha–1 was applied to the no-compost plots in no-tillage, chisel plow, and moldboard plow systems, respectively, while the compost plots received 146, 84, and 62 kg N ha–1 for the three tillage systems. In 2003, all compost plots received 101 kg N ha–1, while no-compost plots in no-tillage, chisel, and moldboard plow received 162, 157, and 112 kg ha–1. In 2004 and 2005, compost plots received 101 and 67 kg N ha–1, while no-compost plots received 168 and 146 kg N ha–1. In 2006, compost plots received 67 kg N ha–1 and no-compost plots in no-tillage, chisel, and moldboard plow received 134, 95, and 95 kg ha–1. In 2007, compost plots received 101 kg ha–1 while no-compost plots received 168 kg ha–1. Starting in 2002, the compost history was considered similar to a manure history, which significantly lowered N inputs on compost plots. All sidedress N was 32% urea ammonium nitrate applied using a point-injector applicator and was applied between V4 and V5 (Hanway, 1963). Soybean variety ‘Pioneer Brand 9294’ was planted from 1999 to 2001, ‘Pioneer Brand 92B84’ from 2002 to 2004, and ‘Asgrow Brand 2203’ from 2005 to 2007 was planted in early to mid-May all years at a rate of 444,600 seeds ha–1. No fertilizer was applied during the soybean phase of the rotation except for the K application in the spring of 2004. Wheat variety ‘Arapahoe’ was planted from 1998 to 2003 and ‘Karl 92’ was planted from 2004 to 2006 in October at a rate of 3.2 million seeds ha–1. ‘Jerry’ oat was planted in the spring of 2001 because wheat winterkilled. ‘Bigbee’ berseem clover (Trifolium
Compost dry Mg ha–1 61.6 74.7 54.1 22.3 15.7 15.2 13.2 6.9 9.4
N 653 568 703 310 172 241 220 76 129
P kg ha–1 – 374 390 138 49 137 75 31 59
K – 837 871 306 207 236 219 101 120
alexandrinum L.) was frost seeded in March of 1998 and 1999 while ‘Cherokee’ red clover was frost seeded in March of 2000 to 2006 at 20 kg seed ha–1 using a drop spreader. ‘Southern Belle’ red clover replaced ‘Cherokee’ in 2007 using the same seeding rate. Ammonium nitrate fertilizer was topdressed in wheat annually in early April at a rate of 45 kg N ha–1. Clover was chemically killed each fall. Typical management practices were used for corn and soybean weed control. No herbicide was applied to wheat. All crops were harvested with a plot combine. Three interior 76 cm corn and soybean rows were harvested after end-trimming, while the entire subplot was harvested for drilled soybean and wheat. Reported grain yields were adjusted to a moisture content of 155, 130, and 130 g kg–1 for corn, soybean, and wheat, respectively. Machinery costs were determined by applying estimates to the cultural practices for each tillage and amendment treatment using Duff y and Smith (2007 and previous years). The standardization of costs per operation eliminated differences from machinery repairs and depreciation and allowed the focus to be on the field practice. Seed, chemical, and fertilizer expenses were the actual expenses paid by the research project (Table 3). Other crop expense was estimated using Duff y and Smith (2007 and previous years) and included crop insurance, miscellaneous expenses, and interest on preharvest expenses. Miscellaneous expenses could include cost items such as crop enterprise record-keeping fees, magazine subscriptions, organizational member fees and other crop-related expenses that do not fit neatly into one of the other cost categories. The analysis of returns focuses on the returns to land and management using the higher of average crop prices or government support price (Table 4). Prices listed are marketing year
Table 3. Input prices during the study period. Input Seed Corn, 80,000 kernel unit Soybean, 22.6 kg unit Wheat, kg Clover, kg Fertilizer UAN 32%, kg NH4NO3, kg K, kg Herbicide Dual II†, L Roundup‡, L
1999
2000
2001
2002
2003 $
2004
2005
2006
2007
93.90 24.55 0.37 3.46
93.90 24.55 0.37 3.75
93.90 24.55 0.37 3.75
113.96 26.95 0.37 3.75
113.96 26.95 0.37 3.75
113.96 26.95 0.37 3.75
82.25 27.36 1.10 3.75
82.25 27.36 1.10 3.75
82.25 27.36 1.10 3.75
0.37 0.44
0.44 0.62
0.62 0.79
0.46 0.66
0.44 0.64
0.51 0.71 0.26
0.60 0.75
0.84 1.23
0.97 1.26
15.05 8.99
17.01 8.60
21.69 8.47
11.77
21.69 11.85
27.51 11.85
12.40
19.63 3.44
18.61 2.79
† Dual II Magnum was used in 2001, 2003, 2004, 2006, and 2007. ‡ Roundup Ultra, UltraMAX, or WeatherMAX were used from 1999 to 2005 and Roundup original in 2006 and 2007.
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Table 4. Prices received by Iowa farmers, 1999 to 2007.†
average price received by farmers in Iowa (USDA-NASS, 2007). For 1999, 2000, and 2001 (soybean only), the average price received was lower than the estimated average Iowa county loan rate over the study period. After 2001, all average prices received were above the estimated county loan rate. The higher of the average price or county loan rate takes into account the price support offered by loan deficiency payments. The other two payments received by farmers (direct and counter-cyclical) are not considered in this paper. Direct and counter-cyclical payments are not based on actual production and are not affected by what is actually produced on the land. Therefore, they would be the same regardless of tillage and amendment treatment. Wheat straw price was assumed to be $45 Mg–1. Gross revenues were determined by multiplying price by yield. Production costs were subtracted from gross revenues to determine economic returns to land, labor, and management. To calculate economic returns to land and management, labor costs were subtracted. The wage rates used varied by year (Duff y and Smith, 2007 and previous years) and were estimated by the number of hours of fieldwork (Table 5). Estimated hours for fieldwork for the moldboard and chisel plow treatments differed only slightly (0.10–0.12 h ha–1). Land charges are not considered in this study. Consequently, this study assumes debt charges, equity charges, real estate taxes, and other land ownership costs are not affected by tillage and amendment. Analysis of variance was conducted using the PROC MIXED routine of SAS v9.2 to test for main and interaction effects. Block and year and their interactions were considered random effects, while tillage and amendment were considered fi xed effects. Least squares means are presented for main and interaction effects and are compared using the PDIFF routine
Table 6. Corn and soybean grain and seed yield for moldboard plow (MP), chisel plow (CT), and no-tillage (NT) main effect and compost amendment subplot analyzed across years (1999–2007) using year as a random effect. Wheat grain yield is presented from 2000 to 2007. In the spring of 2001, oat was planted because wheat winterkilled. Treatment
2.67 2.77 2.47 2.54 2.12 1.70 2.84 4.69 3.61 2.64 4.62 3.53
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MP no MP yes CT no CT yes NT no NT yes
4457 4511 4391 4624 4200 4389
Corn yield kg ha–1 12648 12456 12131 12504 11266 12216
ANOVA Tillage Amendment Tillage × amendment
