In-season N Management for Irrigated Corn using Optical Sensors: Effects on Soil N. (A08-bausch528729-oral)
Authors:
W.C. Bausch* - USDA-ARS
J.A. Delgado - USDA-ARS, Ft. Collins, CO
Abstract:
Spatial and temporal variability of soil N supply conjoined with temporal variability of plant N demand makes conventional N management impractical for site specific N applications. The objective of this study was two-fold: (1) monitor in-season plant N status using ground-based remote sensing to recommend fertigation to meet crop N requirements and (2) determine residual NO3-N in the soil profile before and after the growing season to evaluate in-season N management. The study site was a commercial center-pivot irrigated corn field in eastern Colorado. Two areas within the field [NE Wedge (very sandy) and SW Wedge (less sandy)] were selected and soil sampled to a depth of 3 m in 0.3 m increments. Prior to planting, residual NO3-N in the crop root zone (upper 1.5 m) was 13 and 85 kg ha-1 for the NE Wedge and SW Wedge, respectively. Five fertigations were applied to the field (farmer practice) versus three to the NE Wedge and one to the SW Wedge. Soil NO3-N in the top 1.5 m at the end of the growing season was 17 and 54 kg ha-1 for the NE and SW Wedges, respectively.
Results showed that in-season N application was reduced based on crop "need", grain yield was not reduced, and crop root zone soil NO3-N levels at the end of the growing season were reduced which minimizes potential N leaching and degradation of the environment.
Speaker Information: Walter Bausch, USDA-ARS, Water Management Research Unit AERC-CSU Foothills, Fort Collins, CO 80523-1325; Phone: (970) 491-8264; E-mail: [email protected]
Session Information: Tuesday, November 4, 2003, 12:55 PM-5:55 PM Presentation Start: 2:30 PM
Keywords: N management; canopy reflectance; radiometers; soil N