Improving nitrogen balance with irrigation practice and cropping system
Journal of Soil and Water Conservation
Nitrogen (N) balance based on N inputs, outputs, and retention in the soil shows N flows that measure agroecosystem performance and environmental sustainability. Complexity of measurements of some parameters and constraints on time, labor, and cost have resulted in limited studies on N balance in agroecosystems. The objective of this study was to measure N balance based on N inputs and outputs and soil N retention in response to irrigation and cropping system from 2006 to 2011 in the northern
... 1 in the northern Great Plains. Treatments were two irrigation practices (irrigated versus nonirrigated) as the main plot and five cropping systems (conventional till barley [Hordeum vulgare L.] with N fertilizer [CTBN], conventional till barley without N fertilizer [CTBO], no-till barley-pea [Pisum sativum L.] with N fertilizer [NTB-P], no-till barley with N fertilizer [NTBN], and no-till barley without N fertilizer [NTBO]) as the split plot treatment arranged in a randomized block design with three replications. Compared with other cropping systems, total N input due to N fertilization, pea N fixation, soil N mineralization, atmospheric N deposition, crop seed N, and nonsymbiotic N fixation was 15% to 64% greater with NTB-P in the irrigated practice and 32% to 69% greater in the nonirrigated practice. Compared with CTBO and NTBO, total N output due to grain N removal, denitrification, volatilization, plant senescence, N leaching, gaseous N (NO x ) emissions, and surface runoff was 66% to 74% greater with NTB-P, CTBN, and NTBN in the irrigated practice and 46% to 53% greater in the nonirrigated practice. Nitrogen sequestration rate at the 0 to 10 cm depth varied from 6 kg N ha -1 y -1 with irrigated CTBO to 37 kg N ha -1 y -1 with irrigated NTBN and nonirrigated NTB-P. Nitrogen balance ranged from -54 kg N ha -1 y -1 with nonirrigated NTBN to 30 kg N ha -1 y -1 with irrigated NTB-P, with greater N surplus for irrigated NTB-P and lower N deficit for nonirrigated NTB-P. The NTB-P can sustain agronomic performance due to similar grain N removal and enhance environmental sustainability due to decreased N loss to the environment while reducing external N inputs, regardless of irrigation practices.