Can Cover Crop Use Allow Increased Levels of Corn Residue Removal for Biofuel in Irrigated and Rainfed Systems?

Abstract

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.

Corn Stover Harvest, Tillage, and Cover Crop Effects on Soil Health Indicators

“…At this location and at the studied removal rates, 5 yr of harvesting corn stover did not decrease soil health, but POM-c data suggest that changes may be occurring. Long-term monitoring should continue to assess corn stover harvest sustainability.Abbreviations: C0, chisel plow with no stover removal; MBC, microbial biomass C; NT0, no-till with no stover removal; NT35, no-till with moderate stover removal; NT60, no-till with high stover removal; NTR35, no-till with moderate stover removal and rye cover crop; NTR60, no-till with high stover removal and rye cover crop; PMN, potentially mineralizable N; POM-C, particulate organic matter C; POM-N, particulate organic matter N; SHI, soil health indicators; SMAF, Soil Management Assessment Framework; SOC, soil organic C. C orn residues protect soils from the erosive forces of water and wind, maintain soil organic C (SOC) stocks, cycle essential plant nutrients, replenish the C that creates and sustains aggregation, and provide food and energy for the microbial community Ruis et al, 2017;Wilhelm et al, 2007Wilhelm et al, , 2010. Removing an excessive amount of corn stover, defined as the harvested portion to distinguish it from residues left in the field, can result in soil degradation (Blanco-Canqui et al, 2014;Halvorson and Stewart, 2015;Moebius-Clune et al, 2008).…”

“…Removing an excessive amount of corn stover, defined as the harvested portion to distinguish it from residues left in the field, can result in soil degradation (Blanco-Canqui et al, 2014;Halvorson and Stewart, 2015;Moebius-Clune et al, 2008). However, without stover harvest, producers can encounter residue management problems with subsequent crops and therefore often increase their tillage intensity to reduce surface residues (Al-Kaisi et al, 2015;Sindelar et al, 2013;Swan et al, 1987).A review of stover harvest literature suggests that 40% removal by mass (i.e., 60% remaining in the field) was an upper limit for maintaining SOC and preventing erosion (Ruis et al, 2017;Wilhelm et al, 2010). Johnson et al (2014) concluded that the minimum average residue return required to sustain SOC is 5.7 ± 2.4 Mg ha -1 yr -1 , which could require 30 to 70% residue cover (Smith et al, 1990 core Ideas…”

“…A review of stover harvest literature suggests that 40% removal by mass (i.e., 60% remaining in the field) was an upper limit for maintaining SOC and preventing erosion (Ruis et al, 2017;Wilhelm et al, 2010). Johnson et al (2014) concluded that the minimum average residue return required to sustain SOC is 5.7 ± 2.4 Mg ha -1 yr -1 , which could require 30 to 70% residue cover (Smith et al, 1990 core Ideas…”

“…C orn residues protect soils from the erosive forces of water and wind, maintain soil organic C (SOC) stocks, cycle essential plant nutrients, replenish the C that creates and sustains aggregation, and provide food and energy for the microbial community Ruis et al, 2017;Wilhelm et al, 2007Wilhelm et al, , 2010. Removing an excessive amount of corn stover, defined as the harvested portion to distinguish it from residues left in the field, can result in soil degradation (Blanco-Canqui et al, 2014;Halvorson and Stewart, 2015;Moebius-Clune et al, 2008).…”

“…Cover crops may help offset some of the soil risks posed by removing higher stover quantities (Blanco-Canqui et al, 2014;Bonner et al, 2014;Moore et al, 2014;Osborne et al, 2014;Pratt et al, 2014;Ruis et al, 2017;Stetson et al, 2012;Wegner et al, 2015). This effect is dependent on the cover crop having sufficient germination success and growth.…”