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Quantitative understanding of relationships between NO emission and plant N uptake are needed to select environmentally optimal management systems for corn ( L.) production. Studies were conducted from 2014 to 2016 in Indiana to assess long-term tillage and N source effects on NO emission, and in 2015 and 2016 on relationships between NO losses and N recovery efficiency (NRE) and N use efficiency (NUE), in a continuous corn system. Tillage treatments (mostly in place since 1975) consisted of no till (NT), strip till (ST), chisel plow (CP), and moldboard plow (MP), whereas the N source comparison involved sidedress urea ammonium nitrate applied at 220 kg N ha with and without nitrapyrin. Grain yield averaged 6.5% greater for MP than for CP and NT in the 3-yr period. Nitrapyrin never increased grain yield or NRE but reduced cumulative seasonal NO emission in 1 yr. Tillage affected NO emission in 2 of 3 yr, when emissions decreased in the order MP > CP > ST > NT. Significant negative linear relationships existed between NO emission and NRE under NT and ST, and between NO and NUE under ST, but not for CP and MP. Overall, NO losses under ST and NT decreased by 17 and 13 g N ha, respectively, per unit increase of NRE, and by 63 g N ha per unit increase of NUE under ST. Our results confirmed that selected management systems such as NT or ST that improved NRE and/or NUE can potentially reduce NO emissions during continuous corn production.

Current interest in soil-conserving tillage in China has developed from the concern that Chinese agricultural land loses 73·8 Mg C annually. Previous research has shown that changing from conventional tillage to conservation tillage field management increases soil C sequestration. The aim of this study is to determine if no tillage with stubble retention can reduce soil carbon loss and erosion compared with conventional tillage for a cornfield in northern China. We found that soil organic C storage (kg m−2) under conservation tillage in the form of no post-harvest tillage with stubble retention increased from 28% to 62% in the soil depths of 0–30 cm (p

Annual legume green manure (LGM) cover crops may have potential in dryland wheat (Triticum aestivum L.) production areas where rotation with whole-year summer fallow is practiced. No-till cropland management enhances soil water conservation, possibly enabling cover cropping, but tillage may be necessary to stimulate mineralization of LGM N in time to affect crop yield. A 2-yr LGM-wheat crop sequence study was repeated three times in Montana, with mean annual precipitation of 356 mm. Spring-planted pea (Pisum sativum L.) and lentil (Lens culinaris Medik.) The LGM were terminated at first bloom with tillage or herbicide. Post-termination weed control also was accomplished with either tillage or herbicide in a factorial combination with the termination treatments, resulting in four management regimes. Fallow and non-N-fixing cover crop controls were included and subjected to the same management regimes. Spring wheat was grown the following year in subplots with four levels of N fertilizer. Wheat tiller density increased only when LGM was tilled at least once. Tillage also resulted in reduced soil water storage and wheat kernel weight in 1 yr. Effects on grain yield were usually neutral or positive, with pea more frequently having a positive effect than lentil, and interactions with tillage varying each year. Wheat grain protein was increased by pea LGM regardless of tillage, even when LGM did not affect wheat yield, indicating that LGM N supply is accelerated by tillage. Managing LGM in dryland environments involves a tradeoff of soil water for N supply, and tillage affects this balance.

Management practices are needed to reduce soil C losses from croplands converted from Conservation Reserve Program (CRP) grassland. We evaluated the effects of irrigation, tillage, cropping system, and N fertilization on surface residue and soil organic C (SOC) at the 0- to 85-cm depth in relation to crop yields in a sandy loam soil from 2005 to 2011 in croplands converted from CRP in western North Dakota. Treatments were two irrigation practices (irrigated vs. nonirrigated) as the main plot and six cropping systems [CRP, conventional till malt barley (L.) with N fertilizer (CTBN), conventional till malt barley without N fertilizer (CTBO), no-till malt barley–pea (L.) with N fertilizer (NTB-P), no-till malt barley with N fertilizer (NTBN), and no-till malt barley without N fertilizer (NTBO)] as the split plot arranged in a randomized complete block with three replications. Soil surface residue amount and C content were greater in CRP and NTBN than the other cropping systems. At 0 to 5 cm, SOC was greater in irrigated CRP, but at 0 to 85 cm it was greater in nonirrigated NTBN than most other treatments. At 0 to 20 cm, SOC increased by 0.26 to 1.21 Mg C ha yr in NTB-P and CRP but decreased by 0.02 to 0.68 Mg C ha yr in other cropping systems. Surface residue C and SOC at 0 to 10 cm were related to annualized crop grain yield (= 0.45–0.77, ≤ 0.12, = 10). Because of positive C sequestration rate and favorable crop yields, NTB-P may be used as a superior management option to reduce soil C losses and sustain yields in croplands converted from CRP in the northern Great Plains.

Strip-till can improve soybean (Glycine max (L.) Merr.) yield and increase P and K availability relative to no-till. Our objectives were to evaluate the eff ect of P and K rate and placement in no-till and strip-till on soybean-seed oil and protein content, aboveground growth and P and K accumulation, and soil water. A 3-yr fi eld experiment was conducted near Urbana, IL, with tillage/fertilizer placement treatment as the main plots: no-till/broadcast (NTBC), no-till/deep band (NTDB), and strip-till/deep band (STDB) with banded fertilizer at 15 cm beneath the planted row. Phosphorus (0, 12, 24, and 36 kg ha -1 yr -1 ) was the subplot and K (0, 42, 84, and 168 kg ha -1 yr -1 ) was the sub-subplot. Higher protein and oil yields were produced with STDB than the no-till treatments. Increase protein yield with P fertilization occurred only for the no-till treatments, but STDB maintained higher protein yield than the no-till treatments when no P was applied, indicating that STDB was more eff ective at making P available to the crop. Phosphorus and K placement made no diff erence in protein and oil concentration or yield. Leaf area index (LAI) was greater for STDB than NTBC and NTDB and greater for NTDB than NTBC. Phosphorus and K fertilization increased LAI relative to the check by V2 stage illustrating the importance of fertilization for early growth. Th e advantage for soybean production with STDB over the no-till treatments was the result of greater soil water content in STDB during the reproductive stages.

Fertilizer placement is often designed to improve nutrient availability. Our objective was to determine the effect of P and K rate and placement in no-till and strip-till on grain yield; water, P, and K values in the soil; and the distribution of corn (Zea mays L.) roots. A 4-yr field experiment was setup near Urbana, IL, with a corn–soybean [Glycine max (L.) Merr.] rotation. Tillage/fertilizer placement was the main plot [no-till/broadcast (NTBC), no-till/deep band (NTDB), and strip-till/deep band (STDB)]; deep band was 15-cm beneath the crop row. Phosphorus fertilizer rate (0, 12, 24, and 36 kg P ha⁻¹ yr⁻¹) was the subplot, and K-fertilizer rate (0, 42, 84, and 168 kg K ha⁻¹ yr⁻¹) was the sub-subplot. Measurements included grain yield and yield components, grain and shoot P and K concentrations, root parameters, and soil-water, P, and K values. Strip-till/deep band produced greater kernels row⁻¹ and 9.43 Mg ha⁻¹ yield that was 7.8% greater than NTBC and 7.9% greater than NTDB. Deep banding increased soil P and K test values beneath the crop row and lowered soil surface test values compared with broadcast applications, but had no effect on root distribution. Across treatments, greatest apparent P and K uptake occurred in the surface layer where most roots were present and where precipitation replenished water to a greater extent than deeper layers. Relative to NTBC, STDB had 24% greater apparent-P and 23% greater apparent-K uptake rates. The results indicate that improved conditions for nutrient uptake provide a competitive advantage for production with STDB relative to no-till treatments.

Fertilizer placement may cause non-uniform nutrient distribution in the soil, making it diffi cult to determine whole-fi eld fertility by traditional sampling strategies. Our objectives were to determine P and K distribution after repeated applications in no-till and strip-till soils and to develop improved sampling procedures to estimate soil P and K levels on a corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] rotation with crops planted at 76-cm row spacing. Three trials near Pesotum, IL, received blends of 0–0, 22–42, 33–62, 44–83, 55–104, 66–125, and 77–145 kg P–K ha –1 in fall 2007 and 2009 before corn planting. Applications were broadcast-applied in no-till (NTBC) and strip-till (STBC) and deep-banded in strip-till (STDB) 15 cm below the surface in the crop row (IR) using real-time kinematic (RTK) satellite navigation. Every year soil P and K was measured at 10-cm increments to a 30-cm depth at 0, 19, 38, and 57 cm from the IR. Subsurface banding reduced P and K levels in the surface and increased them at the point of application, or deeper with the highest rate, while broadcast applications increased surface levels. Soil-surface K levels were greater at IR likely because of K leaching from senescing standing crops. Soil-test results indicated no need to adjust fertilizer rate based on tillage or fertilizer placement. A sampling ratio of 1:3 IR to between the crop rows (BR) seemed adequate to estimate soil fertility across a wide range of P- and K-fertilizer rates and soil test levels where the location of the fertilizer band or planting row is maintained constant.

Published in Agron. J. 103:1862–1869 (2011) Posted online 6 Oct 2011 doi:10.2134/agronj2011.0149 Copyright © 2011 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. S is an important crop in the United States, with 31.1 million ha planted in 2010 (USDA/NASS, 2010). In 2008, 62% of full-season soybeans and 76% of double-cropped (planted aft er wheat harvest) soybeans in the United States were planted under no-tillage or some other conservation tillage system (CTIC, 2008). No-till is oft en preferred over conventional tillage because it can result in operational cost savings to farmers, reduce soil erosion (Trewavas, 2004), and conserve soil water (Williams et al., 2009). No-till soybean production has challenges, however. Soybean typically follows corn in rotation, and the large amount of corn crop residue on the soil surface at planting can be a challenge for no-till soybean production. Soils covered with crop residue have higher albedo, which slows warming and evaporation of water in the soil surface, oft en resulting in delays in planting or germination, and slow early growth (Jones et al., 1994). Such delays can be detrimental to soybean yield (De Bruin and Pedersen, 2008). Th e strip-till system is one in which a narrow (15–25 cm wide) band is tilled to a depth of 10 to 20 cm and the new crop row planted atop this strip. Th is system provides most of the soil and water conservation benefi ts of no-till, while improving seedbed condition similar to conventional tillage systems (Jones et al., 1994; Morrison, 2002). Improved seedbed conditions by removing crop residue from the planting row in strip-till relative to no-till has been shown to enhance seed germination, faster early plant growth, and grain yield for corn in soils that tend to be cool and wet in the spring (Vyn and Raimbault, 1992; Morrison, 2002; Vetsch and Randall, 2002; Randall and Vetsch, 2008). Compared to corn production, relatively less work has been done to assess benefi ts of strip-till for soybean production (Vyn et al., 1998; Randall and Vetsch, 2008). Another possible advantage to strip-till is the opportunity it provides for simultaneous deep banding of fertilizer materials. Deep banding of fertilizer, especially P, may be benefi cial to reduce surface P concentrations and lower potential environmental concern related to water runoff from fi elds with high P levels at the soil surface (Duiker and Beegle, 2006; Randall and Vetsch, 2008). In addition, deep banding of fertilizers has been hypothesized as an alternative to increase nutrient availability and improve fertilizer use effi ciency. In much of the U.S. Corn Belt soybean production is rainfed. In nutrient-stratifi ed systems where P and K concentrations are high in the soil surface, excessive drying of that layer during reproductive stages—when soybean accumulate about 75% of their total P and K (Hanway and Weber, 1971)—may limit nutrient uptake (Yin and Vyn, 2002). However, Fernandez et al. (2008, 2009) showed greater apparent K uptake in the top 5 cm of a vertically stratifi ed no-till soil when intermittent rainfall provided adequate moisture during the growing season. Similarly, inconsistent response to deep banding of fertilizers has been reported for soybean seed yield. Some have reported yield advantages with deep band compared to broadcast fertilizer (Ebelhar and Varsa, 2000), while others have reported no advantage (Borges and Mallarino, 2000; Yin and Vyn, 2002; Rehm and Lamb, 2004). Th e limited amount of information on soybean production in strip-till and the ABSTRACT

Nitrogen (N) application to crops generally results in increased nitrous oxide (NO) emissions. Commercially available, enhanced-efficiency N fertilizers were evaluated for their potential to reduce NO emissions from a clay loam soil compared with conventionally used granular urea and urea-ammonium nitrate (UAN) fertilizers in an irrigated strip-till (ST) corn ( L.) production system. Enhanced-efficiency N fertilizers evaluated were a controlled-release, polymer-coated urea (ESN), stabilized urea, and UAN products containing nitrification and urease inhibitors (SuperU and UAN+AgrotainPlus), and UAN containing a slow-release N source (Nfusion). Each N source was surface-band applied (202 kg N ha) at corn emergence and watered into the soil the next day. A subsurface-band ESN treatment was included. Nitrous oxide fluxes were measured during two growing seasons using static, vented chambers and a gas chromatograph analyzer. All N sources had significantly lower growing season NO emissions than granular urea, with UAN+AgrotainPlus and UAN+Nfusion having lower emissions than UAN. Similar trends were observed when expressing NO emissions on a grain yield and N uptake basis. Loss of NO-N per kilogram of N applied was

Millions of acres of cropland with as low as 6 inches annual precipitation are used for production of winter wheat (Triticum aestivum L.) in the Pacific Northwest of the USA. Despite soil conservation advances, soil erosion continues to be a problem. This on-farm study analyzed seed-zone soil water under farmerimplemented fallow tillage practices to find out if very low-disturbance systems are possible. A low-disturbance, wide-blade undercutter sweep treatment was similar or superior to the farmer’s more intensive conventional tillage system. A subsequent test at four paired no-till-conventionally-tilled summer-fallow sites demonstrated that a single pass of an undercutter sweep in the no-till field could preserve seed-zone moisture comparable to the more intensive multiple-pass conventional tillage. Despite conventional wisdom, summer-fallow soil mulches do not need to be finely pulverized or repeatedly tilled to be effective.

A 2-yr winter wheat (Triticum aestivum L.)―faflow rotation continues to be the most common cropping system in much of the U.S. Pacific Northwest. The sustainability of soils in the region depends on our ability to halt or greatly reduce wind and water erosion. An incomplete understanding of how tilled summer fallow preserves seed-zone moisture for timely fall crop establishment has slowed efforts to optimize tillage techniques for creating profitable and erosion-resistant systems. This 2-yr study created a series of soil mulches at two sites representing major soils in the region. It was found that timing and depth of mulch creation had consistent effects at all four site-years. Tillage performed in mid-June to depths of 10 and 15 cm preserved up to 0.01 kg kg ―1 greater water content than no or 5-cm tillage, an amount of water that can make substantial differences in the germination of winter wheat. The later or shallower tillage treatments produced water contents similar to zero tillage below the 15-cm depth. Temperature profiles at 1-cm resolution demonstrated different shapes under different mulch treatments, which may prove useful in making quick mulch performance comparisons in the field. To optimize the timing and depth of summer fallow tillage, it will be necessary to characterize spring water storage plus the potential for end-of-summer water storage for each soil type.

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Reduced tillage results in lower production costs and thus may have economic advantages for farmers. However, yield penalties, specific yield risks, or higher nutrient requirements may counteract the positive effects of reduced tillage. This study investigates long-term tillage effects (moldboard plow, and deep and shallow chisel plow) and their interactions with N fertilizer input on yields and economic performance in a corn (Zea mays L.)-wheat (Triticum aestivum L.)-potato (Solanum tuberosum L.)-wheat rotation in southern Germany. Conventional tillage (CT) and reduced tillage systems provided comparable economic returns. The systems of reduced tillage required higher surface-dribbled urea ammonium nitrate solution (UAN) fertilizer to corn and potato to be as efficient as the CT system. This may have implications for the overall environmental assessment of reduced tillage systems. For moderate- and higher-risk-averse producers, CT with usual fertilizer practice was more efficient than all other management options for the whole rotation. Farmers' risk aversion has no impact on the choice of the most efficient tillage and fertilizer management for potato (CT with usual fertilizer practice) and for corn (reduced tillage with increased fertilizer level). For wheat, the results show a high impact of risk aversion on the optimal choice of the tillage and fertilizer system. With increased energy prices, the economic savings of the reduced tillage systems due to reduced fuel use may be offset by higher fertilizer requirements since nitrous fertilizer prices are highly determined by energy costs.

Deep zone tillage is a strategy used to alleviate compaction problems, including plow pans, and to improve internal drainage. Midwestern soils do not typically form a defined plow pan under normal production practices. Despite lack of scientific evidence for yield benefits associated with deep tillage, it is still used in Minnesota as a low cost alternative to tile drainage. To evaluate the soil and economic impact of deep zone tillage on crop yield when a restrictive layer is lacking, a 20-acre field was deep zone tilled to a 20-inch depth, every other 12 rows at 30-inch spacing. After zone tilling, the entire field was ridge tilled. Ridge tillage confines wheel traffic to the same rows, reducing the percent of the field trafficked. All crop and soil measurements were collected in the depressional and upland areas of the field to distinguish if zone till is of benefit in different landscape areas. Crop yields were measured for two seasons following zone tilling a ridge-tilled field. Zone till failed to increase corn and soybean yields. A restrictive layer was not observed in this field and as a result, potential economic losses occurred due to deep zone tillage.

Despite possible agronomic and environmental benefits, the diffusion of soil conservation tillage systems in Italy is currently rather low. The aim of this study was to compare the performance of different soil tillage techniques, in an effort to identify suitable soil management options for irrigated crops in Central Italy. An experiment was carried out on maize and soybean from April to October in two consecutive years (1993 and 1994) in Maccarese (a coastal location near Rome). The systems compared were: conventional mouldboard ploughing (CT), minimum tillage, ridge tillage and no-tillage (NT). In 1993, actual crop evapotranspiration was measured throughout the growing season on NT and CT soybean, using a micrometeorological technique. No significant differences due to soil tillage were found for grain yield and yield irrigation water use efficiency (IWUEy), except for soybean in 1994, in which yields and IWUEy were 59 % higher on conservation tillage treatments compared with CT. In 1994 soybean yield water use efficiency was 10.1 and 9.5 kg ha)1 mm)1 for NT and CT respectively. The results suggest that the adoption of soil conservation tillage is feasible, for the specific cropping system, with equivalent or better performances as conventional tillage. L'articolo é disponibile sul sito dell'editore: http://www.onlinelibrary.wiley.com

Summary Apera spica-venti is a winter annual grass and, increasingly, a severe weed problem in autumn-sown crops. Non-inversion tillage has become more common in Denmark in recent years, but may accentuate problems with A. spica-venti. These problems may be avoided, if selected preventive and cultural weed management practices are adopted. To this end, we conducted a 4-year field study investigating the effects of crop rotation, tillage method, location and limited herbicide input on A. spica-venti population dynamics and crop yield. Additionally, detailed studies were performed on the fate of A. spica-venti seeds when incorporated to different soil depths. The location with a lighter soil texture, cooler climate and higher rainfall favoured A. spica-venti growth and consequently crop yield loss, especially in the crop sequence comprised only of autumn-sown crops and with non-inversion tine tillage. Incorporating A. spica-venti seeds in the soil improved their survival, explaining the higher A. spica-venti proliferation seen with tine tillage as opposed to direct drilling. The rotations including an even mixture of spring- and autumn-sown crops did not lead to noteworthy changes in the A. spica-venti population, irrespective of tillage method. Thus, in many regions, management of A. spica-venti will require rotations that balance autumn- and spring-sown crops.

Shallow sampling depths are recommended for collecting soil samples for lime and fertilizer recommendations when using conservation tillage. Some subsoiling implements used to disrupt the compacted horizon in some southeastern USA coastal plain soils can also disturb the surface soil. Our objective was to compare sampling depths for lime, P, and K recommendations in a conservation tillage system that includes paratill subsoiling. One-half of a 14-acre field was managed with conventional tillage. The other half was managed with conservation tillage which consisted of using a six-shanked paratill followed by planting. Soil samples from 0 to 3 inches and 0 to 6 inches were collected for four years on each side of the field around points in a 50-ft × 50-ft grid. The field was in a corn (Zea mays L.)-cotton (Gossypium hirsutem L.) rotation. Soil P and K concentrations differed for sampling depths in most years for both tillage systems. Generally, these differences were small but fertilizer P and K recommendation rates for the two sampling depths were the same more often for conventional tillage than for conservation tillage. After a lime application in 2002, pH of the soil 0 to 3-inch depth in the conservation tillage half of the field was 5.89 in 2003, 6.07 in 2004, and 6.29 in 2005 while the pH of the soil collected from the 0 to 6-inch depth was about 6.1 each year. When using the 0 to 6-inch sampling depth in fields managed with this conservation tillage system, it appears a separate sample for soil pH from a shallower depth may be beneficial in the years subsequent to a lime application.

Arable farming on suitable land in semi-arid environments is hampered by low and erratic rainfall and droughts. To use this land effectively, techniques, such as water harvesting may improve soil water storage and increase agricultural productivity. Laboratory experiments were conducted to assess two reservoir tillage methods under different slopes, rainfall intensities and soil densities. A commercial trailed tillage tool (Aqueel) was used to form discrete soil depressions by compression of the soil and a soil scooping device with similar dimensions was used to make depressions in shear by lifting the soil out. The results show that, for the sandy loam used in this study, reservoir tillage is an effective method of harvesting water under high-intensity rainfall of short duration common in semi-arid areas. It reduced surface run-off by 95% on 10° slopes when depressions were staggered and positioned with their long axis across slope. However, high initial soil bulk densities lead to a significant reduction in the volume of the depressions formed in compression and to internal compaction. Increasing vertical load on the Aqueel resulted in an increase in depression volume without an increase in internal compaction but at high bulk densities the depression volumes remained small and high implement load damaged the depression function and stability. This suggests a need for a pre-loosening tillage operation for compacted soils and the need to design new implements to form depressions in shear.

Management practices may influence soil N levels due to crop uptake and leaching. We evaluated the effects of three tillage practices [no-till (NT), strip till (ST), and chisel till (CT)], four cover crops [hairy vetch (Vicia villosa Roth), rye (Secale cereale L.), vetch 1 rye biculture, and winter weeds or no cover crop], and three N fertilization rates (0, 60–65, and 120–130 kg N ha 21 )o n NH 4–N and NO3–N contents in Dothan sandy loam (fine-loamy, kaolinitic, thermic, Plinthic Paleudults), and N uptake by cotton (Gossypium hirsutum L.) and sorghum [Sorghum bicolor (L.) Moench] from 2000 to 2002 in central Georgia. Nitrogen content was higher in vetch and vetch 1 rye than in rye and weeds. Soil NH4–N content at 0 to 30 cm was higher at harvest than at planting, and higher in NT or vetch with 120 to 130 kg N ha 21 than with other treatments. The NO3–N content at 0 to 120 cm varied with date of sampling and was higher with vetch than with rye and weeds. The NO3–N content at 0 to 10 cm was higher in CT with vetch than in NTand STwith rye or weeds. From November 2000 to April 2001 and from November 2001 to April 2002, N loss from crop residue and soil at 0 to 120 cm was higher with vetch than with other cover crops. Nitrogen removed by cotton lint was higher with rye than with other cover crops in 2000 and higher with 0 and 60 than with 120 kg N ha 21 in 2002, but N removed by sorghum grain and cotton and sorghum biomass were higher with vetch than with rye, and higher with 120 to 130 than with 0 kg N ha 21 . Because of higher N supply, vetch increased soil mineral N and cotton and sorghum N uptake compared with rye, but also increased the potential for N leaching. The potential for N leaching can be reduced and crop N uptake can be optimized by mixing vetch with rye.

Conservation tillage systems can play an important role in reducing soil erosion and improving soil quality with the extra benefit of being equal to or more economical than conventional tillage; however, yield variability still remains a major concern among farmers. Field experiments were conducted in 2003 through 2004 and 2004 through 2005 in northern Greece to determine the effect of seeding rate (100, 150, 200, and 250 kg ha -1 ) on wheat establishment and grain yield under three tillage systems (minimum, reduced, and conventional tillage). In addition, labor time and fuel consumption for wheat production under these tillage systems were compared. For all tillage systems, the greatest number of wheat plants was recorded at the two highest seeding rates (P < 0.05). However, wheat plant numbers, averaged over seeding rates, were reduced by 11 to 17% in minimum tillage compared with conventional and reduced tillage systems in both growing seasons. Ear numbers were unaffected by tillage systems but generally increased with the increased seed rate. However, differences were not found in grain yield either among tillage systems or seeding rates. Regarding labor time and fuel consumption, 50 and 53% savings was achieved with minimum tillage, respectively, and 43 and 48% with reduced tillage in comparison with conventional tillage. These findings indicate that wheat can be grown successfully under conservation tillage systems with yields equal to those of conventional tillage and lower labor and fuel inputs. Increasing of seeding rate favored crop establishment in all tillage systems, but it did not provide any grain yield advantage.

Although zone tillage can result in favorable in-row seedbed environments for high crop yield while providing soil conservation characteristics similar to no-till, it necessitates a wide row width planting system. The objective of this study was to evaluate various zone-till systems for soybean [Glycine max (L.) Merr.] production. This study was conducted in southwestern Ontario from 1998 to 2000 on nine fields with clay contents between 133 and 354 g kg 21 and a minimum 5-yr continuous no-till history. Tillage systems evaluated were fall moldboard, fall zone-till 15- and 30-cm deep, spring coulter tillage, and no-till. The no-till and moldboard systems were planted in equally spaced 19-, 38-, 57-, and 76-cm rows plus a twin-row configuration consisting of two 19-cm rows centered 76 cm apart. Only single 76-cm and twin-row configurations were planted in the zone-till and coultertill systems, where tillage was conducted in strips centered 76 cm apart. Twin-row configurations in no-till, spring coulter-till, and fall zone-till systems often increased yields over those obtained with single 76-cm rows, with yields that were always similar to those obtained with no-till planted in 38- or 19-cm rows. Depth of fall zone tillage did not affect soybean yield. Fall zone-till yields never exceeded those obtained with no-till, even in environments where no-till yields were less than those obtained with fall moldboard systems. Spring coulter tillage did not increase yields over those obtained with no-till. Future research evaluating zone-till systems for soybean should consider using twin-row planting configurations.

Biculture legume-cereal cover cropping may enhance above- and belowground biomass yields and C and N contents. The increase in C and N supply to the soil has the potential to improve soil quality and crop productivity compared with monoculture cover crop species. We examined above- and belowground (0- to 120-cm soil depth) biomass yields and C and N contents of a legume [hairy vetch (Vicia villosa Roth)], nonlegume [rye (Secale cereale L.)], and biculture of legume and nonlegume (vetch and rye) cover crops planted without tillage in the fall of 1999 to 2001 in central Georgia. After cover crop kill in the spring, cotton (Gossypium hitsutum L.) and sorghum [Sorghum bicolor (L.) Moench)] were planted using three tillage practices (no-till, strip till, and chisel till) with three N fertilization rates (0, 60 to 65, and 120 to 130 kg N ha '). The field experiment was arranged in a split-split plot. treatment with three replications on a Dothan sandy loam (fine-loamy, kaolinitic, thermic, Plinthic Kandiudults). Aboveground biomass yield of rye decreased from 6.1 to 2.3 Mg ha ' from 2000 to 2002, but yield of hairy vetch varied (2.4 to 5.2 Mg ha -1 ). In contrast, biomass yield of vetch and rye biculture (5.6 to 8.2 Mg ha -1 ) was greater than that of rye and vetch planted alone in all years. Compared with winter weeds in no cover crop treatment, C content in rye (1729 to 2670 kg ha -1 ') was greater due to higher biomass yield, but N content in vetch (76 to 165 kg ha -1 ) was greater due to higher N concentration, except in 2002. As a result, C (2260 to 3512 kg ha -1 ) and N (84 to 310 kg ha -1 ) contents in biculture were greater than those from monocultures in all years. Similarly, belowground biomass yield and C and N contents were greater in biculture than in monocultures. In 2001, aboveground biomass yield and C and N contents in coyer crops were also greater in strip till with biculture than in other treatments, except in chisel till with vetch and biculture, but belowground biomass yield and N content were greater in chisel till with biculture than in no-till, strip till, and chisel till with weeds. Cotton lint yield was lower with biculture than with rye, but sorghum grain yield and cotton and sorghum biomass (stems + leaves) yields and N uptake were greater with biculture than with rye. Because of higher biomass yield and C and N contents, biculture of hairy vetch and rye cover crops may increase N supply, summer crop yields, and N uptake compared with rye and may increase potentials to improve soil organic matter and reduce N leaching compared with vetch.

The present investigation is an effort to develop an effective management plan for the identified critical subwatersheds of Nagwan watershed located in the eastern part of India using a precalibrated and validated Soil and Water Assessment Tool (SWAT) model. In all 60 combinations of various management treatments including crops (rice, maize, peanut and soybean), tillage (zero, conservation, field cultivator, mould board plough and conventional practices) and levels of fertilizer (existing, half of recommended and recommended) have been studied. This study revealed that crops like maize, peanut and soybean could not replace rice since they resulted in higher sediment yield compared to rice. The tillage practice with mould board plough has been found to have a more appreciable impact on the sediment and nutrient losses than conventional tillage practices for the existing level of fertilizer. Sediment yield decreased in case of zero tillage, conservation tillage and field cultivator compared to conventional tillage. On the other hand, nutrient losses increased in case of zero and conservation tillage for all levels of fertilizer compared to the other tillage treatments. In conclusion it can be stated that the sediment yield is highest in case of mould board plough followed by conventional tillage field cultivator, conservation tillage and least in zero tillage practices, whereas the nutrient losses were found to be just in the reverse order with tillage practices, indicating highest nutrient losses in mould board plough tillage practices. In view of the sediment yield and nutrient losses, the conventional tillage practice was considered to be the best as the sediment yield is less than the average soil loss and nutrient loss is within the permissible limit. Copyright © 2005 John Wiley & Sons, Ltd.

Potential agronomic and soil conservation benefits of modified no-till (NT) systems make them appealing for corn (Zea mays L.) production in the northern Corn Belt where adoption of NT has been limited due to yield reductions on these colder soils. A 4-yr (1997-2000) experiment was conducted on a high P- and K-testing Port Byron silt loam (fine silty, mixed, mesic typic Hapludoll) to determine the effects of four tillage systems [no-till (NT), Rawson zone till (ZT), fall strip till (ST), and conventional tillage practice (CT)] on corn production and cone index (CI; penetrometer resistance) in continuous corn and corn following soybean [Glycine max (L.) Merr.]. Eight treatments, four tillage systems (main plots) with starter fertilizer at rates of 0 and 168 kg ha -1 of a 9-10-24, were arranged in a split-plot design with four replicates. Surface residue coverage after planting was maintained at high levels (>40%) with NT, ZT, and ST, whereas coverage averaged only 25% with the CT practice. Cone index during the period of early plant growth was significantly less for the ZT and ST systems compared with the NT and CT systems, but CI did not exceed 1.3 MPa. Four-year average yields of continuous corn grain ranked according to tillage were CT > ZT = ST > NT. A significant tillage × year interaction indicated equal yields for CT and NT in the first 2 yr but 1.0 to 1.2 Mg ha -1 less with NT in the last 2 yr. Tillage system did not significantly affect corn grain yields following soybean when averaged across years. Starter fertilizer increased yields by 0.5 Mg ha -1 on this high-testing soil for all tillage systems in both crop rotations. Surface residue and corn yields following corn and soybean can be optimized using modified NT systems (ZT and ST) and starter fertilizer in these well-drained, loess soils.

Peanut (Arachis hypogaea L.) in the USA is generally seeded after several primary tillage operations that may include disking, chisel plowing, moldboard plowing, and bedding (conventional tillage systems). Concerns over erosion and production costs have increased interest in reduced tillage systems. Production in reduced tillage systems minimizes ability to incorporate fertilizers below the pegging zone, and residue on soil surface could impact movement of calcium sulfate (CaSO 4 ) into the soil, reducing Ca availability to pegs. Research was conducted from 1997 through 1999 to compare peanut yield and gross economic value of virginia market type peanut planted in conventional and strip tillage systems. Preplant fertilizer did not affect response to tillage. Response did not differ among conventional tillage systems consisting of disk, disk and chisel, or disk and moldboard plow or among reduced tillage systems. Pod yield of peanut grown in the most effective conventional tillage system exceeded yield when peanut was strip-tilled into stubble of the previous crop, strip-tilled into a wheat (Triticum aestivum L.) cover crop, or strip-tilled into beds prepared the previous fall without a cover crop. Tillage system and CaSO 4 rate affected pod yield and gross value independently. Gross value increased when CaSO 4 was applied regardless of tillage system. These data suggest that preplant fertilizer at relatively low, remedial rates does not affect peanut response to tillage systems. These data also suggest that tillage system does not have a major impact on peanut response to CaSO 4 . Collectively, these data indicate that the highest peanut yields occur in conventional tillage systems.

Conservation tillage practices have come into greater use in recent years. However, studies have shown that using these practices in rice (Oryza sativa L.) on soils prone to salinity problems can reduce yields. An agronomic study was conducted during 1995 and 1996 at the University of Arkansas' Pine Tree Branch Experiment Station near Colt on a soil complex consisting of a Calloway silt loam (fine-silty, mixed, active, thermic Glossaquic Fragiudalf), Calhoun silt loam (fine-silty, mixed, active, thermic Typic Glossaqualf), and Henry silt loam (coarse-silty, mixed, active, thermic Typic Fragiaqualf), in areas that had a history of salinity damage to rice. The experiment was arranged in a randomized complete block design with three replications and four tillage treatments (conventional tillage, deep tillage with a paratill implement, attempted deep tillage with a chisel plow, and no-till) per replication. Enterprise budgets were used to determine the relative profitability of the four tillage systems (conventional, no-till, chisel plow, and para-till), in order to determine whether or not the increased production costs incurred using tillage would be offset by increased returns. Sensitivity, breakeven, and statistical analyses were performed to determine whether there was any significant difference in yields and net returns among tillage practices. No significant difference was demonstrated among the three treatments using tillage; no-till, however, was significantly different from the other three, having considerably lower yields. When averaged across years and treatments, yields from tilled plots averaged 72.15 cwt/acre. Yields from no-till plots averaged 62.37 cwt/acre. Net returns above total costs for tilled plots, when averaged across years and treatments, averaged $230.25/acre. Net returns above total costs for no-till averaged $173.03/acre. It is therefore recommended that some form of tillage be used in order to reduce the concentration of salts in the rice root zone. However, it is not possible to recommend one form of tillage as being superior to the others examined in this study.

Conservation tillage techniques have gained widespread, but not universal, use in irrigated corn (Zea mays L.) production. This study was conducted to evaluate yield impacts associated with conservation tillage methods when compared with conventional techniques in a replicated field experiment for 17 consecutive years in Nebraska (1976-1992). Six tillage treatments were imposed on continuous corn production and replicated three times. Tillage treatments ranged from traditional (disk and surface plant) to no-till (slot plant on existing ridge). Post-plant operations were uniformly applied to accommodate furrow irrigation. Over the life of the project the conservation tillage treatments (ridge till, rotary till, and slot plant) had a 4 bu/acre increase in grain yield over the conventional treatments (those having chisel, disk, or lister operations). The advantage of the conservation tillage systems was amplified by corresponding lower production costs. The rotary, ridge, and slot tillage systems had S7.72, S14.22, and $16.22/acre lower annual tillage and herbicide costs (1990 dollars), respectively, than the conventional tillage system with a disking operation. The conservation tillage treatments significantly lowered stalk rot and residual spring soil nitrate N concentrations. Other comparisons showing significant differences were list vs. chisel and disk for harvest population and soil potassium concentrations, and ridge vs. rotary for harvest population. None of the other comparisons tested had significant differences for grain yield or other soil parameters. Overall, this study indicates that conservation tillage on irrigated continuous-corn is advantageous over conventional methods.

Soil conservation tillage systems, including ridge-tillage, often reduce surface water contamination by pesticides because soil erosion and surface runoff are reduced. However, the effects on losses through subsurface drainage tile are somewhat uncertain. Our field study quantified the effects of four tillage practices in continuous corn (Zea mays L.) and corn-soybean [Glycine max (L.) Merr] rotations on herbicide and nitrate N losses in tile drainage water. Fertilizer and pesticide application methods were uniform for ridge, moldboard, chisel, and no-till systems. Pesticide and nitrate N leaching losses were significantly affected by crop rotation. Tillage practice had little influence on nitrate N and pesticide losses to the subsurface drainage water within a corn-soybean rotation. However, ridge-till and no-till resulted in larger losses of atrazine than the moldboard plow and chisel based systems under continuous corn. Tillage system did not affect the timings of peak tile flow occurrences, although peak tile flow volume was affected by tillage, presumably because each system had its own macropore system related to preservation or annual destruction of biopores by tillage. Corn yields were significantly higher under corn-soybean rotation than with continuous-corn for all tillage practices. These results indicate that continuous corn production is not an environmentally sustainable practice for this area because it resulted in higher nitrate N leaching losses to groundwater, received higher N-applications, and resulted in lower corn yields than the corn-soybean rotation. The results also reinforce the need for studies on chemical placement, rate, and timing for various tillage practices to reduce tile drainage losses of agricultural chemicals.

Reduced tillage has increased dramatically over the past several years and is expected to continue to increase in the future. Continuous no-till may become a popular tillage system with growers to facilitate compliance with government programs to control soil erosion. The objective of this research was to evaluate the long-term effects of four tillage systems and five fertilizer regimes on corn (Zea mays L.) yield. A 20-yr continuous-corn tillage x fertility study was conducted from 1970 to 1990 on an Ebbert silt loam (fine-silty, mixed, mesic Argiaquic Argialbolls), an imperfectly drained soil at the Belleville Research Center, Belleville, IL. Starter fertilizer did not increase corn height within a tillage system. Height was greater in no-till compared with conventional till (moldboard plow), reduced till (chisel plow), or alternate till (2 yr no-till, 1 yr moldboard plow) with or without a starter fertilizer. There was no difference in population among tillage systems due to fertilizer treatment. Corn population was lower in no-till compared with conventional till regardless of fertilizer treatment. Starter fertilizer did not increase yield in any tillage system. Corn yield averaged 5 to 7% lower in no-till compared with conventional till or reduced till where a starter fertilizer was applied. There was no difference in yield among tillage systems when NPK was broadcast. Corn yield was equal in conventional till, alternate till, reduced till, and no-till with fertilizer applied broadcast on an imperfectly drained soil. Continuous no-till with an imperfectly drained soil does not reduce corn yield.

Heavy clay soils, such as vertisols of the Texas Blackland Prairie (Houston Black clay [fine, montmorillonitic, thermic Udic Pellusterts]), are difficult to manage for crop production. Such soils typically require high draft for tillage; have limited opportunities for mobility, tillage, and planting; and produce variable crop performance when associated with highly variable weather patterns. This study compared the soil and plant nutrient distributions and yield performance of an experimental no-till farming system with a farming system using modified conventional chisel-till soil management. Raised wide beds and controlled traffic were used for both systems [...]

This paper examines the extent to which stochastic variation in crop yields and erosion rates affect the economic feasibility of, and farmer's willingness to adopt, minimum and no tillage in a northern Idaho watershed. Stochastic variation in yield is evaluated by sampling an empirical frequency distribution of the ratio of yields between conservation and conventional tillage. Variability in yield due to tillage system and weather are separated from variability caused by soil type and management. Stochastic variation in erosion rates is determined by sampling the distribution of erosion prediction errors for the Universal Soil Loss Equation. Expected utility maximization is used to identify the optimal choice of tillage systems for different risk preferences. Stochastic variation in yield due to tillage practice and rainfall was found to have a proportionately greater effect on yield than errors in predicting erosion rates. For the soils, crops and land treatment practices evaluated, risk averse farmers would prefer conventional tillage to minimum and no tillage.

Four bullock-drawn tillage implements (mouldboard plough, chisel plough, sweeps, and shovels) were evaluated on a hard-setting Alfisol. Measurements included draft requirement, bulk density, cone index, soil crust strength, water content of the plough-layer and crop yield. Changes in bulk density and cone index due to tillage decreased with time and were negligible by the end of the growing season. After tillage with a mouldboard plough the crust was stronger than after tillage with other implements. The shovel cultivator enabled the soil to store more water, and required least draft per unit effective area of cut

Stochastic dominance analysis of two tillage systems, conventional tillage and no-tillage, for five crop rotations, wheat-fallow, grain sorghum-fallow, continuous wheat, continuous grain sorghum, and wheat-grain sorghum-fallow, shows that risk-averse managers prefer a conventional tillage wheat-sorghum-fallow system. Small changes in production costs or yields lead to indifference between this system and the no-tillage wheat-sorghum-fallow and no-till and conventional wheat-fallow systems. Participation in the basic government commodity program generally increases average net returns and lowers variation of returns. Government commodity program payments calculated under a variety of scenarios do not generally encourage the use of no-till practices for grain sorghum and wheat in the central Great Plains.

Annual crop production in the Canadian prairies is undergoing significant change. Traditional monoculture cereal cropping systems, which rely on frequent summer-fallowing and use of mechanical tillage, are being replaced by extended and diversified crop rotations together with the use of conservation tillage (minimum and zero-tillage) practices. This paper reviews the findings of western Canadian empirical studies that have examined the economic forces behind these land use and soil tillage changes. The evidence suggests that including oilseed and pulse crops in the rotation with cereal grains contributes to higher and more stable net farm income in most soil-climatic regions, despite a requirement for increased expenditures on purchased inputs. In the very dry Brown soil zone and drier regions of the Dark Brown soil zone where the production risk with stubble cropping is high, the elimination of summer fallow from the cropping system may not be economically feasible under present and near-future economic conditions. The use of conservation tillage practices in the management of mixed cropping systems is highly profitable in the more moist Black and Gray soil zones (compared with conventional mechanical tillage methods) because of significant yield advantages and substantial resource savings that can be obtained by substituting herbicides for the large amount of tillage that is normally used. However, in the Brown soil zone and parts of the Dark Brown soil zone, the short-term economic benefits of using conservation tillage practices are more marginal and often less profitable than comparable conventional tillage practices.

Wind erosion and blowing dust on conventionally tilled winter wheat (Triticum aestivum L.)-summer fallow cropland in eastern Washington, USA, reduces soil productivity and can contribute to poor air quality. Conservation tillage during fallow has long been known to curtail erosion and dust, but conventional tillage (CT) is still practiced on more than 80% of the cropland in the region. This paper reports the economic results of a 5-yr (1995-1999 harvest years) tillage system study at Lind, WA. The site averages 244 mm of annual precipitation, and the soil is a Shano silt loam (coarse-silty, mixed, superactive, mesic Xeric Haplocambids). Tillage systems were (i) CT, (ii) minimum tillage (MT; herbicides and tillage), and (iii) delayed MT (DMT; herbicides and delayed tillage). Wheat grain yield across years ranged from 1.79 to 5.20 Mg ha -1 , but there were no differences in grain yield among tillage systems in any year or when analyzed across years. Tillage systems were economically equivalent based on market returns over total production costs, but DMT was slightly less profitable than CT based on market returns over variable costs. Economic analysis indicates that no subsidies should be required to entice producers to switch from CT to MT fallow because the systems are equally profitable. Because there is no short- or long-term economic sacrifice for converting to the soil-saving MT system, it represents a win-win solution for farmers and the environment.