Crop Management Zones Agronomic and Economic Successes.
Rajiv Khosla and Dwayne Westfall. C013 Plant Sciences Bldg., Dept. of Soil & Crop Sci-CSU, Dept. of Soil & Crop Sci-CSU, Fort Collins, CO 80523-1170, United States of America
Management zones were formally introduced as a means to manage in-field spatial variability nearly a decade ago. Several methods of management zone delineation have been proposed and researched throughout the United States and elsewhere. Overall, the results have been variable. However; in the Western Great Plains region of the United States, management zones based on bare-soil color have been shown to be promising. The objective of this paper is to summarize the agronomic and economic successes we have had over the last seven years with regard to bare-soil color based management zones. Researchers at ColoradoStateUniversity initiated a large-scale multidiscipline precision agriculture project in 1997. Research sites were located on several large-scale production irrigated maize fields in Eastern Colorado. Fields were divided into management zones based on bare-soil color. Fields were managed using both traditional uniform N application and a management zones approach. Several parameters were measured and compared between management including: grain yield, biomass, N uptake, N-use efficiency, soil texture, soil organic matter, soil bulk density, and economic returns. Management zones based on bare-soil were found to be significantly different with regard to soil physical properties (soil texture, bulk density, and organic matter). Grain yields and N uptake from irrigated maize fields were also found to be consistently different between management zones. When comparisons were made between traditional uniform N applications and variable N applications based on soil-color based management zones, the variable N application based on site-specific management zones were found to be more economically efficient than the uniform N application strategies. Overall, research conducted over the last seven years indicates that bare-soil management zones are agronomically effective and economically viable means of increase nitrogen-use efficiency.