Submitted to: European Conference on Precision Agriculture Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 20, 2001
Publication Date: N/A
Technical Abstract: Availability of affordable positioning systems and yield monitors for many crops has stimulated interest in site-specific management of crop inputs such as irrigation and fertilizers. Using yield monitors, farmers can now directly measure the effects of varying inputs on crop yield. In 1999-2000, the effects of a range of water and N-fertilizer rates on maize grain yield were determined using two commercial center pivot irrigation systems modified to provide site-specific water and fertilizer applications to management zones as small as 100m**2. One system (CP1) was sited on fairly uniform soils while the other (CP2) was sited on variable soils (12 soil map units). At both sites, maize grain yield increased with increased irrigation amount. Yield increased with N-fertilizer rate on CP1, but yields were not different for the two N-fertilizer rates on CP2. Yield responses to total water varied among the soil map units. Irrigation increased a rainfed yield of 2 Mg/ha to 11 Mg/ha on one soil, but only increased yield on another from 4 Mg/ha to 7 Mg/ha. Basic information is now available to make specific irrigation and fertilizer application recommendations for individual soils. Using such recommendations, irrigation managers will be able to allocate their water resource where it will be most beneficial.