|THAPA, VESH - New Mexico State University|
|GHIMIRE, RAJAN - New Mexico State University|
|VANLEEWEN, DAWN - New Mexico State University|
|SHUKLA, MANOJ - New Mexico State University|
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/13/2021
Publication Date: 11/8/2021
Citation: Thapa, V.R., Ghimire, R., Vanleewen, D., Acosta Martinez, V., Shukla, M. 2021. Cover crop effects on soil organic matter components and soil aggregate size distribution in a semiarid cropping system [abstract]. ASA-CSSA-SSSA Annual Meeting Abstracts.
Technical Abstract: Cover cropping can improve soil health and resilience in semiarid cropping systems by increasing soil organic carbon (SOC) and nitrogen (N) pools, biological activity, nutrient cycling, and aggregate stability. The main objective of this study was to evaluate the response of soil organic matter (SOM) components and other soil health indicators to different cover crops in limited-irrigation winter wheat (Triticum aestivum L.)-fallow/cover crop-sorghum (Sorghum bicolor L. Moench)-fallow/cover crop rotations. Cover cropping treatments included pea (Pisum sativum L.), oats (Avena sativa L.), and canola (Brassica napus L.); mixtures of pea + oats (POmix), pea + canola (PCmix), pea + oats + canola (POCmix), and a six-species mixture (SSmix) of pea + oats + canola + hairy vetch (Vicia villosa Roth) + forage radish (Raphanus sativus L.) + barley (Hordeum vulgare L.); and a fallow. Soil samples were collected in the summer of 2019 and 2020 from the 0–15 cm depth of each plot established in fall 2015. Soil inorganic N was 7–36% lower with cover crops than fallow. The PCmix had 48–73% greater 24-h-carbon dioxide-carbon (CO2-C) than fallow, canola, and SSmix at termination time. Thirty-six days after termination, particulate organic carbon (POC) content was 61–69% higher with pea, SSmix, and POCmix than fallow. The SOC content was 9.3–22% greater with oats than pea, canola, POmix, and SSmix. Similarly, total N content with oats was 10% and 22% higher than with SSmix and canola, respectively. The greatest increases in SOC and total N concentrations were observed in intermediate-sized aggregates (250 µm–2 mm and 53–250 µm). The oats and SSmix had 36–49% higher wet aggregate stability (WAS) than fallow. Principal component analysis (PCA) revealed SOC, pH, labile organic nitrogen (LON), mineral-associated organic nitrogen (MAON), and microbial biomass carbon (MBC) as the most influential indicators of soil health. Oats as a cover crop could improve soil health and resilience of cropping systems through increases in SOC accumulation in semiarid environments.