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United States Department of Agriculture

Agricultural Research Service

Research Project: ECOLOGICALLY-SOUND PEST, WATER AND SOIL MANAGEMENT STRATEGIES FOR NORTHERN GREAT PLAINS CROPPING SYSTEMS

Location: Agricultural Systems Research Unit

Title: Tillage, cropping sequence, and nitrogen fertilization influence dryland soil nitrogen dynamics

Author
item Sainju, Upendra

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2013
Publication Date: June 1, 2013
Repository URL: http://handle.nal.usda.gov/10113/56967
Citation: Sainju, U.M. 2013. Tillage, cropping sequence, and nitrogen fertilization influence dryland soil nitrogen dynamics. Agronomy Journal. 105(5):1253-1263.

Interpretive Summary: Nitrogen is a major nutrient required in ample amount to sustain malt barley yield and quality. Nitrogen fertilization can increase malt barley yields, but excessive application can degrade soil and environmental quality by increasing soil acidification, N leaching, and emissions of N2O, a highly potent greenhouse gas responsible for global warming. Information is needed on management practices that can optimize N availability for crop growth, increase N-use efficiency, sustain crop yield and quality, and reduce N fertilization rate and the potential for N loss under dryland malt barley production in the northern Great Plains. The effects of tillage and cropping sequence combination and N fertilization rate were studied on N contents in dryland crop biomass, surface residue, and soil at the 0- to 120-cm depth, and estimated N balance from 2006 to 2011 in eastern Montana. Treatments were no-till continuous malt barley (NTCB), no-till malt barley-pea (NTB-P), no-till malt barley-fallow (NTB-F), and conventional till malt barley-fallow (CTB-F), each with 0, 40, 80, and 120 kg N ha-1. Biomass and surface residue N were greater in NTB-P or NTCB than in CTB-F and NTB-F in all years, except in 2006 and 2011, and increased with increased N rate. Soil total N (STN) at 0 to 60 cm decreased at 254 kg N ha-1 yr-1 from 2006 to 2011, regardless of treatments. At most depths, soil NH4-N content varied, but NO3-N content was greater in CTB-F than in other cropping sequences in all years, except in 2006. Estimated N balance after accounting for all sources and sinks of N after six years was greater in NTB-P with 40 kg N ha-1 than in other treatments. No-till continuous cropping increased biomass and surface residue N storage but conventional till crop-fallow increased soil available N. Because of increased soil N storage and reduced N fertilization rate to malt barley, NTB-P with 40 kg N ha-1 may be used as a management option to reduce N loss due to leaching, volatilization, and denitrification compared to other treatments for dryland malt barley production in the northern Great Plains.

Technical Abstract: Management practices are needed to reduce dryland N losses through N leaching and N2O emissions (a greenhouse gas) by increasing soil N storage and reducing N fertilization rate without influencing crop yields. The effects of tillage and cropping sequence combination and N fertilization rate were studied on N contents in dryland crop biomass, surface residue, and soil at the 0- to 120-cm depth, and estimated N balance from 2006 to 2011 in eastern Montana. Treatments were no-till continuous malt barley (Hordeum vulgaris L.) (NTCB), no-till malt barley-pea (Pisum sativum L.) (NTB-P), no-till malt barley-fallow (NTB-F), and conventional till malt barley-fallow (CTB-F), each with 0, 40, 80, and 120 kg N ha-1. Biomass and surface residue N were greater in NTB-P or NTCB than in CTB-F and NTB-F in all years, except in 2006 and 2011, and increased with increased N rate. Soil total N (STN) at 0 to 60 cm decreased at 254 kg N ha-1 yr-1 from 2006 to 2011, regardless of treatments. At most depths, soil NH4-N content varied, but NO3-N content was greater in CTB-F than in other cropping sequences in all years, except in 2006. Estimated N balance after accounting for all sources and sinks of N after six years was greater in NTB-P with 40 kg N ha-1 than in other treatments. No-till continuous cropping increased biomass and surface residue N storage but conventional till crop-fallow increased soil available N. Because of increased soil N storage and reduced N requirement to malt barley, NTB-P with 40 kg N ha-1 may reduce N loss due to leaching, volatilization, and denitrification compared to other treatments (GRACEnet Project).

Last Modified: 10/1/2014
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