Economic feasibility of variable-rate nitrogen application utilizing site-specific management zones

Variable-rate technology (VRT) has been developed to variably apply crop inputs to manage in-field variability. Although growers have begun to adopt VRT, its profitability is uncertain in N management. The objective of this study was to assess the economics of uniform vs. variable-rate N fertilizer application under two N application scenarios (farmer vs. custom applications). On-farm studies were conducted on two continuous corn (Zea mays L.) fields in northeastern Colorado under furrow and center-pivot irrigation during the 2000 and 2001 growing seasons. The N management strategies were uniform, grid-based, site-specific management zone-constant yield goal (SSMZ-CYG) and site-specific management zone-variable yield goal (SSMZ-VYG). Profit and loss software was used to analyze the economics of each N management strategy and determine which N strategy was most profitable. Results from three site-years consistently indicated that less total N fertilizer (6-46%) was used with the SSMZ-VYG N management strategy when compared with uniform N management. Net returns from the SSMZ-VYG N management strategy were $18.21 to $29.57 ha(-1) more than uniform N management. Results of this study suggest variable-rate N application utilizing site-specific management zones are more economically feasible than conventional uniform N application.