Improved Management Practice to Enhance Dryland Crop Yields and Environmental Quality.

Improved Management Practice to Enhance Dryland Crop Yields and Environmental Quality

Upendra M. Sainju

USDA-ARS

Sidney, MT

Management practices are needed to sustain dryland crop yields and quality while improving environmental quality. The effects of cropping sequence and N fertilization on crop yields and quality, soil C and N sequestration, N losses from soil profile, and net global warming potential and greenhouse gas intensity were evaluated on a dryland agroecosystem 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. With or without N fertilization, annualized malt barley grain yield was greater in NTB-P and NTCB than in CTB-F and NTB-F. Malt barley protein concentration was lower but grain plumpness was higher in NTB-P with 40 kg N ha^-1 than most other treatments. The amount of N fertilizer required for sustaining malt barley yield and quality was lower in NTB-P than NTCB at 80 kg N ha^-1. Soil organic C and total N were higher in NTB-P than in CTB-F and NTB-F with or without N fertilization. Estimated N balance after six years was positive and greater in NTB-P with 40 kg N ha^-1, indicating N gain than losses due to leaching, denitrification, and volatilization in other treatments. Net global warming potential and greenhouse gas intensity after accounting for all C sources and sinks were lower in NTB-P than other cropping sequences at 0 kg N ha^-1 and lower in NTB-P and NTCB than CTB-F at 80 kg N ha^-1. Because of favorable malt barley grain yield and quality, increased soil C and N sequestration, reduced N fertilization rate and N losses, and lower net greenhouse gas emissions, NTB-P with N rates between 40 to 80 kg N ha^-1 may sustain crop yield and quality while improving environmental quality in dryland cropping systems.