Corn (Zea mays L.) residue removal at high rates can result in negative impacts to soil ecosystem services. The use of cover crops could be a potential strategy to ameliorate any adverse effects of residue removal while allowing greater removal levels. Hence, the objective of this study was to determine changes in water erosion potential, soil organic C (SOC) and total N concentration, and crop yields under early-and lateterminated cover crop (CC) combined with five levels of corn residue removal after 3 years on rainfed and irrigated no-till continuous corn in Nebraska. Treatments were no CC, early-and late-terminated winter rye (Secale cereale L.) CC, and 0, 25, 50, 75, and 100% corn residue removal rates. Complete residue removal reduced mean weight diameter (MWD) of water-stable aggregates (5 cm depth) by 29% compared to no removal at the rainfed site only, suggesting increased water erosion risk at rainfed sites. Late-terminated CC significantly increased MWD of water-stable aggregates by 27 to 37% at both sites compared to no CC, but earlyterminated CC had no effect. The increased MWD with late-terminated CC suggests that CC when terminated late can offset residue removal-induced risks of water erosion. Residue removal and CC did not affect SOC and total soil N concentration. Particulate organic matter increased with lateterminated CC at the irrigated site compared to no CC. Complete residue removal increased irrigated grain yield by 9% in 1 year relative to no Ruis et al. in Bioenergy Res 2017 Can Cover Crop Use 2 removal. Late-terminated CC had no effect on corn yield except in 1 year when yield was 8% lower relative to no CC due to low precipitation at corn establishment. Overall, late-terminated CC ameliorates residue removalinduced increases in water erosion potential and could allow greater levels of removal without reducing corn yields in most years, in the short term, under the conditions of this study.

Cover crops (CCs) are generally perceived to improve soil properties, yet available research suggests that CC impacts, particularly on physical properties, can be inconsistent. Length of time after CC adoption and CC species such as grass and legume CCs could differently influence CC effects, but experimental data are few. This study quantified 12‐yr cumulative impacts of grass CCs including cereal rye (Secale cereale L.) and grain sorghum [(Sorghum bicolor (L.) Moench] and legume CCs including Austrian winter peas (Pisum sativum L.) and soybean (Glycine max L.) CCs on soil physical and fertility properties under long‐term (∼30 yr) continuous no‐till corn (Zea mays L.)–soybean–winter wheat (Triticum aestivum L.) rotation on a silty clay loam in the western Corn Belt. Legume CCs did not alter soil properties, but grass CCs improved soil aggregation and increased organic matter concentration although water infiltration, water retention, plant available water, and most soil fertility properties were unaffected. Grass CCs increased the proportion of large water‐stable aggregates (2–8.0 mm) by 31 to 45% in the 0‐ to 15‐cm depth. Grass CCs also increased mean weight diameter of water‐stable aggregates by 34% and organic matter concentration by 11% in the upper 7.5‐cm depth. Results indicate that grass CCs improved some soil properties unlike legume CCs. Long‐term (15 yr) no‐till use before CC adoption, fine texture, and high organic matter level of the soil may explain the small grass CC and no legume CC effects. Overall, grass CCs impacted some soil properties but legume CCs had no effects in this silty clay loam after 12 yr. Core Ideas Legume cover crops (CCs) had no effects on soil properties after 12 yr. Grass CCs increased aggregation and organic matter but did not affect water infiltration, retention, and availability. Grass CCs had more impact on soil properties than legume CCs. Long‐term (15 yr) no‐till before CC adoption, fine texture, and relatively high soil organic matter may explain the small CC effects.

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In Nebraska, early adopters of conservation tillage, especially those using no‐till planting, had some concerns regarding planter performance, early season weed control, and possible yield reductions. Selected tillage and planting systems were used long term to evaluate effects on soybean [Glycine max (L.) Merr.] and grain sorghum [Sorghum bicolor (L.) Moench] yield, soil properties, and residue cover in a nonirrigated rotation. The six tillage and planting systems selected for evaluation were: no‐till, no‐till with row‐crop cultivation, disk, double disk, chisel, and plow. In 1981, two sets of field plots were established near Lincoln, NE, on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls) so that both crops could be evaluated each year. Measurements were not taken until completion of one crop rotation cycle. After this cycle, for the first 3 yr of yield measurements, no differences occurred in grain yield among the tillage and planting systems. After five additional years, differences in yield were measured, with no‐till tending to have the greatest yield for both crops. Row‐crop cultivation of no‐till soybean did not result in any measurable yield differences, but for grain sorghum, row‐crop cultivation resulted in an average yield decrease of 6 bu/acre. Soil organic matter tended to be greatest for the continuous no‐till system and lowest for the plow system. The plow system had slightly less penetration resistance within the 4‐ to 8‐in. depth than the other treatments, whereas, the double‐disk system was slightly greater within the 2‐ to 6‐in. depth. Draft and power requirements for planting in the selected tillage and planting systems were not different The major difference among the tillage and planting systems was residue cover remaining after planting. No‐till had the most residue cover, but there was no appreciable accumulation of residue over the 10 yr of continuous use of the tillage and planting systems. For the last 5 yr, no‐till tended to have the greatest yield for both crops. Thus, for the soil and conditions evaluated, no‐till yields were as good as the other systems during early years, and were better after 5 yr of continuous use. Thus, producers adopting no‐till and other residue management practices have the opportunity to enhance profitability because of the same or greater yields and reduced production costs by eliminating tillage operations. Research Question Early adopters of conservation tillage, especially those using no‐till planting, had concerns regarding planter performance, weed control, and possible yield reductions. Six tillage and planting systems were used in a long term study to evaluate effects of tillage on soybean and grain sorghum yields, soil properties, and residue cover in a nonirrigated rotation. Literature Summary Tillage and planting systems that leave a protective cover of crop residue on the soil surface have been shown to reduce soil losses, and are among the least costly erosion control practices. Few tillage and planting studies hav...

The benefits of grass barriers or hedges for reducing offsite transport of non-point-source water pollutants from croplands are well recognized, but their ancillary benefits on soil properties have received less attention. We studied the 15-yr cumulative effects of narrow and perennial switchgrass (Panicum virgatum L.) barriers on soil organic C (SOC), total N, particulate organic matter (POM), and associated soil structural properties as compared with the cropped area on an Aksarben silty clay loam (fine, smectitic, mesic Typic Argiudoll) with 5.4% slope in eastern Nebraska. Five switchgrass barriers were established in 1998 at ~38-m intervals parallel to the crop rows in a field under a conventional tillage and no-till grain sorghum [Sorghum bicolor (L.) Moench]-soybean [Glycine max (L.) Merr.]-corn (Zea mays L.) rotation. Compared with the cropped area, switchgrass barriers accumulated about 0.85 Mg ha -1 yr -1 of SOC and 80 kg ha -1 yr -1 of total soil N at the 0 to 15 cm soil depth. Switchgrass barriers also increased coarse POM by 60%. Mean weight diameter of water-stable aggregates increased by 70% at 0 to 15 cm and by 40% at 15 to 60 cm, indicating that switchgrass barriers improved soil aggregation at deeper depths. Large (4.75-8 mm) macroaggregates under switchgrass barriers contained 30% more SOC than those under the cropped area. Switchgrass-induced changes in SOC concentration were positively associated with aggregate stability (r = 0.89***) and porosity (r = 0.47*). Overall, switchgrass barriers integrated with intensively managed agroecosystems can increase the SOC pool and improve soil structural properties.