Stacked crop rotations and cultural practices for canola and flax yield and quality

Canola (Brassica napus L.) and flax (Linum usitatissimum L.) are important oilseed crops, but improved management practices to enhance their yields and quality are needed. We studied the effect of stacked versus alternate‐year crop rotations and traditional versus improved cultural practices on canola and flax growth, seed yield, oil concentration, and N‐use efficiency from 2006 to 2011 in the northern Great Plains, USA. Stacked rotations were durum (Triticum turgidum L.)‐durum‐canola‐pea (Pisum sativum L.) (DDCP) and durum‐durum‐flax‐pea (DDFP). Alternate‐year rotations were durum‐canola‐durum‐pea (DCDP) and durum‐flax‐durum‐pea (DFDP). The traditional cultural practice included a combination of conventional tillage, recommended seed rate, broadcast N fertilization, and reduced stubble height. The improved cultural practice included a combination of no‐tillage, increased seed rate, banded N fertilization, and increased stubble height. Canola stand count was 36–123% greater with the improved than the traditional cultural practice in 2006, 2009, 2010, and 2011. Canola pod number and oil concentration were 3–36% greater in the improved than the traditional practice in 2007 and 2010, but trends reversed by 5–19% in 2008. Flax stand count was 28% greater with DFDP than DDFP in 2007 and 56% greater in the improved than the traditional practice in 2010. Flax pod number, seed weight, seed yield, N content, N‐use efficiency, and N‐removal index varied with crop rotations, cultural practices, and years. Canola growth and oil concentration increased with the improved cultural practice as well as flax growth, yield, and quality enhanced with alternate‐year crop rotation and the improved cultural practice in wet years

Exploring impacts of process technology development and regional factors on life cycle greenhouse gas emissions of corn stover ethanol

This paper examines impacts of regional factors affecting biomass and process input supply chains and ongoing technology development on the life cycle greenhouse gas (GHG) emissions of ethanol production from corn stover in the U.S. Corn stover supply results in GHG emissions from -6 gCO2eq./MJ ethanol (Macon County, Missouri) to 13 gCO2eq./MJ ethanol (Hardin County, Iowa), reflecting location-specific soil carbon and N2O emissions responses to stover removal. Biorefinery emissions based on the 2011 National Renewable Energy Laboratory (NREL) process model are the single greatest emissions source (18 gCO2eq./MJ ethanol) and are approximately double those assessed for the 2002 NREL design model, due primarily to the inclusion of GHG-intensive inputs (caustic, ammonia, glucose). Energy demands of on-site enzyme production included in the 2011 design contribute to reducing the electricity co-product and associated emissions credit, which is also dependent on the GHG-intensity of regional electricity supply. Life cycle emissions vary between 1.5 and 22 gCO2eq./MJ ethanol (2011 design) depending on production location (98% to 77% reduction vs. gasoline). Using system expansion for co-product allocation, ethanol production in studied locations meet the Energy Independence and Security Act emissions requirements for cellulosic biofuels; however, regional factors and on-going technology developments significantly influence these results

Primed acclimation of cultivated peanut (Arachis hypogaea L.) through the use of deficit irrigation timed to crop developmental periods

Water-deficits and high temperatures are the predominant factors limiting peanut production across the U.S., either because of regional aridity or untimely rainfall events during crucial crop developmental periods. In the southern High Plains of west Texas and eastern New Mexico, low average annual rainfall (450. mm) and high evaporative demand necessitates the use of significant irrigation in production systems. In this west Texas study, the primary objective was to develop irrigation schemes that maximized peanut yield and grade while reducing overall water consumption. Therefore, a large-scale field experiment was established in 2005 and 2006 that utilized 15 treatment combinations of differing rates of irrigation (50, 75, and 100% of grower applied irrigation) applied at different periods of peanut development (early, middle, and late season). Precipitation patterns and ambient temperatures showed greater stress levels in 2006 which likely reduced yields across all treatments in comparison to 2005. Yields were reduced 26 (2005) and 10% (2006) in the lowest irrigation treatment (50% full season) compared with full irrigation (100% full season); but early-season water deficit (50 and 75% in the first 45. days after planting) followed by 100% irrigation in the mid- and late-seasons were successful at sustaining yield and/or crop value. Root growth was significantly enhanced at 50% irrigation compared with 100% irrigation, through greater root length, diameter, surface area, and depth, suggesting greater access to water during mid- and late-season periods. These results suggest that early to mid-season deficit irrigation has the potential to maintain peanut yield without altering quality, and to substantially reduce water use in this semi-arid environment

Soil quality regeneration by grass-clover leys in arable rotations compared to permanent grassland: Effects on wheat yield and resilience to drought and flooding

Intensive arable cropping depletes soil organic carbon and earthworms, leading to loss of macropores, and impaired hydrological functioning, constraining crop yields and exacerbating impacts of droughts and floods that are increasing with climate change. Grass and legume mixes traditionally grown in arable rotations (leys), are widely considered to regenerate soil functions, but there is surprisingly limited evidence of their effects on soil properties, resilience to rainfall extremes, and crop yields. Using topsoil monoliths taken from four intensively cropped arable fields, 19 month-old grass-clover ley strips in these fields, and from 3 adjacent permanent grasslands, effects on soil properties, and wheat yield in response to four-weeks of flood, drought, or ambient rain, during the stem elongation period were evaluated. Compared to arable soil, leys increased earthworm numbers, infiltration rates, macropore flow and saturated hydraulic conductivity, and reduced compaction (bulk density) resulting in improved wheat yields by 42–95 % under flood and ambient conditions. The leys showed incomplete recovery compared to permanent grassland soil, with modest gains in soil organic carbon, total nitrogen, water-holding capacity, and grain yield under drought, that were not significantly different (P > 0.05) to the arable controls. Overall, grass-clover leys regenerate earthworm populations and reverse structural degradation of intensively cultivated arable soil, facilitating adoption of no-tillage cropping to break out of the cycle of tillage-driven soil degradation. The substantial improvements in hydrological functioning by leys will help to deliver reduced flood and water pollution risks, potentially justifying payments for these ecosystem services, especially as over longer periods, leys increase soil carbon sequestration