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ARS Home » Pacific West Area » Kimberly, Idaho » Northwest Irrigation and Soils Research » Research » Publications at this Location » Publication #423852
Research Project: Improving Management Practices for Irrigated Western Cropping and Dairy Systems to Contribute to Sustainability and Improve Air Quality

Location: Northwest Irrigation and Soils Research

Title: Barley, Corn, and Wheat Residue Decomposition as Affected by Tillage and Nitrogen Rate in Semi-arid Conditions

Author
item Rogers, Christopher
item THURGOOD, GARRETT - University Of Idaho
item DARI, BISWANATH - North Carolina A&t State University
item SIHI, DEBJANI - North Carolina State University
item MARSHALL, JULIET - University Of Idaho

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2025
Publication Date: 12/7/2025
Citation: Rogers, C.W., Thurgood, G., Dari, B., Sihi, D., Marshall, J.M. 2025. Barley, Corn, and Wheat Residue Decomposition as Affected by Tillage and Nitrogen Rate in Semi-arid Conditions. Agrosystems, Geosciences & Environment. https://doi.org/10.1002/agg2.70229.
DOI: https://doi.org/10.1002/agg2.70229

Interpretive Summary: Research was conducted to determine residue management practices for farmers under fallow conditions in semi-arid regions common in the western United States. Increased interest in this practice has arisen as drought and reduced water levels in surface water bodies and aquifers have arisen. Research was conducted in Idaho to assess rates of residue decomposition based on crop type (corn, barley, wheat), tillage (surface/none and incorporated), and fertilizer-N rate (0, 56, 112 kg/ha) at three sample times (spring, summer, fall). Fertilizer-N additions did not increase decomposition but incorporation by tillage and crops with lower carbon:nitrogen ratios did. These results give growers an ability to estimate the amount and time for residue breakdown to occur. These results will improve residue management for cereals in semi-arid regions.

Technical Abstract: Understanding crop residue decomposition under fallow off-years in semi-arid regions is of increasing interest due to need to recharge limited water resources. This study was conducted to assess residue decomposition of various cereal residues and management practices combinations under these conditions. Research was conducted during the 2018 and 2019 growing seasons at Aberdeen, ID and residue decomposition bags were used to assess crop type (barley, corn, and hard red wheat; HRW, soft white wheat; SWW), tillage (surface and incorporated), and supplemental fertilizer-N rates collected at three timings (spring, summer, and fall). Corn, barley, HRW, and SWW C:N ratios were 62, 74, 105, and 87, respectively. Crop type and tillage effected residue decomposition at each sampling, but fertilizer-N had no impact. Decomposition was greatest from post-harvest to spring with incorporated corn having the largest amount 37.2% and surface barley, HRW, and SWW the least averaging 20.5%. At the completion of the study patterns were largely the same with little to no change from spring for surface applied residues compared to 60.5% decomposition losses from corn. Added fertilizer-N decreased C:N ratio at the spring sampling but not in the summer or fall. First-order decay constants ranged from 0.00075 for surface HRW to 0.00300 for incorporated corn resulting. This equates to a range of 231 to 929 d for 50% of residue to decompose. Additions of fertilizer-N to increase residue decomposition were not supported by the data but incorporation of residue by tillage and lower C:N crop types did result in more rapid decomposition.