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ARS Home » Plains Area » Sidney, Montana » Northern Plains Agricultural Research Laboratory » Agricultural Systems Research » Research » Publications at this Location » Publication #329575
Title: Nitrogen balance in response to dryland crop rotations and cultural practices

Author
item Sainju, Upendra
item LENSSEN, ANDREW - Iowa State University
item Allen, Brett
item Stevens, William - Bart
item Jabro, Jalal - Jay

Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2016
Publication Date: 9/8/2016
Publication URL: http://handle.nal.usda.gov/10113/63158
Citation: Sainju, U.M., Lenssen, A.W., Allen, B.L., Stevens, W.B., Jabro, J.D. 2016. Nitrogen balance in response to dryland crop rotations and cultural practices. Agriculture, Ecosystems and Environment. 233:25-32. doi:10.1016/j.agee.2016.08.023.

Interpretive Summary: Nitrogen is a major nutrient usually applied in large quantity to increase crop yield and quality. Excessive nitrogen application through fertilizers and manures, however, can degrade soil and environmental quality by increasing soil acidification, nitrogen leaching, and emissions of ammonia and nitrogen oxide gases. Nitrogen application in excess of crop’s need can also result in reduced yield. Additional nitrogen inputs include dry and wet (rain and snow) depositions from the atmosphere, biological nitrogen fixation, and irrigation water. An account of nitrogen balance using nitrogen inputs and outputs and retention in the soil can identify dominant processes of nitrogen flow and provides a framework to measure agroecosystem performance and environmental sustainability. We evaluated nitrogen balance based on nitrogen inputs and outputs and soil nitrogen sequestration after seven years in response to five dryland crop rotations (two 4-years stacked and two 4-years alternate-year rotations and one monocropping) and two cultural practices arranged in a split-plot design in the northern Great Plains, USA. Stacked rotations were durum-durum-canola-pea (D-D-C-P) and durum-durum-flax-pea (D-D-F-P). Alternate-year rotations were durum-canola-durum-pea (D-C-D-P) and durum-flax-durum-pea (D-F-D-P). Monocroppping was continuous durum (CD). Cultural practices were traditional (conventional till, recommended seed rate, broadcast N fertilization, and reduced stubble height) and ecological (no-till, increased seed rate, banded N fertilization, and increased stubble height). Total annual N input due to nitrogen fertilization, pea nitrogen fixation, atmospheric nitrogen deposition, crop seed nitrogen, and nonsymbiotic nitrogen fixation was lower in CD than other crop rotations, regardless of cultural practices. Total nitrogen output due to crop grain nitrogen removal and N losses due to denitrification, volatilization, plant senescence, nitrogen leaching, gaseous nitrogen emissions, and surface runoff was lower in traditional CD and D-F-D-P than traditional D-C-D-P and ecological D-C-D-P, D-D-C-P, and D-F-D-P. Nitrogen sequestration rate at 0-125 cm from 2005 to 2011 ranged from 40 kg N ha-1 yr-1 for ecological D-D-F-P to 52 kg N ha-1 yr-1 for ecological CD. Nitrogen balance ranged from -39 to -36 kg N ha-1 yr-1 with CD compared to 9 to 25 kg N ha-1 yr-1 with other crop rotations in both cultural practices. Because of reduced reliance on external nitrogen inputs and increased grain nitrogen removal, nitrogen flow, and N surplus, crop rotations with legumes, nonlegumes, and oilseed crops in the rotation can be productive and environmentally sustainable compared with monocropping, regardless of cultural practices.

Technical Abstract: Nitrogen balance provides a measure of agroecosystem performance and environmental sustainability by taking into accounts of N inputs and outputs and N retention in the soil. The objective of this study was to evaluate N balance based on N inputs and outputs and soil N sequestration after 7 yr in response to five dryland crop rotations (two 4-yr stacked and two 4-yr alternate-year rotations and one monocropping) and two cultural practices arranged in a split-plot design in the northern Great Plains, USA. Stacked rotations were durum (Triticum turgidum L.)-durum-canola (Brassica napus L.)-pea (Pisum sativum L.) (D-D-C-P) and durum-durum-flax (Linum usitatissimum L.)-pea (D-D-F-P). Alternate-year rotations were durum-canola-durum-pea (D-C-D-P) and durum-flax-durum-pea (D-F-D-P). Monocroppping was continuous durum (CD). Cultural practices were traditional (conventional till, recommended seed rate, broadcast N fertilization, and reduced stubble height) and ecological (no-till, increased seed rate, banded N fertilization, and increased stubble height). Total annual N input due to N fertilization, pea N fixation, atmospheric N deposition, crop seed N, and nonsymbiotic N fixation was lower in CD than other crop rotations, regardless of cultural practices. Total N output due to crop grain N removal and N losses due to denitrification, volatilization, plant senescence, N leaching, gaseous N (NOx) emissions, and surface runoff was lower in traditional CD and D-F-D-P than traditional D-C-D-P and ecological D-C-D-P, D-D-C-P, and D-F-D-P. Nitrogen sequestration rate at 0-125 cm from 2005 to 2011 ranged from 40 kg N ha-1 yr-1 for ecological D-D-F-P to 52 kg N ha-1 yr-1 for ecological CD. Nitrogen balance ranged from -39 to -36 kg N ha-1 yr-1 with CD compared to 9 to 25 kg N ha-1 yr-1 with other crop rotations in both cultural practices. Because of reduced reliance on external N inputs and increased grain N removal, N flow, and N surplus, crop rotations with legumes, nonlegumes, and oilseed crops in the rotation can be productive and environmentally sustainable compared with monocropping, regardless of cultural practices.