Nitrogen Budget Components for Continuous Corn in the Northern Corn Belt.

Nitrogen budget components for continuous corn in the Northern Corn Belt. Nitrogen (N) is one of the primary inputs for corn (Zea Mays) production and has significant consequences if under or over supplied. Under application results in reduced grain yield and over application results in negative environmental quality consequences. It was hypothesized that drainage water management strategies intended to enhance productivity and mitigate negative off-site water quality impacts would enhance N uptake and grain yield while reducing environmental losses due to subsurface drainage and atmosphere flux. The objective of this experiment was to quantify N budgets for continuous corn from a field-scale experiment in the northern Corn Belt. The experiment was conducted on a farmer’s field and included two drainage water management strategies: conventional free drainage and controlled drainage. Data were collected between 2012 and 2015 from two management zones, 14 and 22 ha, respectively. A mass balance approach was used to estimate N storage, and input and output components. Storage was estimated from residual soil N measurements and residue returned to the soil. Input data included estimates of wet and dry deposition of N plus fertilizer N. Outputs included N loss from subsurface drainage discharge, grain export from the field and gaseous N flux. Results showed controlled drainage resulted in lower N load from subsurface drainage. Results also showed that soils managed under controlled drainage generally acted as sources of nitrous oxide. Controlled drainage exhibited slightly more residual soil nitrate at the end of the growing season compared to conventional drainage and corn grain N uptake was slightly greater for conventional compared to controlled drainage.