Irrigation and N-fertilizer combinations for site-specific management of corn

摘要

Efficient management of irrigation and N-fertilizer requires knowledge of soil variability and crop response to these inputs. Automated measurements can be used to indicate plant stress throughout the growing season and may help indicate timing andamount needed of these inputs. In 1999, a 6-ha center pivot, modified to provide site-specific irrigation, was used to impose irrigation and N-fertilizer treatments on 396 separate corn (Zea mays) plots (9 m by 9 m) on highly variable soils. Treated plots were arranged in randomized complete blocks where space allowed and incomplete blocks where space was limited. Two N-fertilizer rates (135 and 225 kgN/ha) and four irrigation rates (0 percent, 50 percent, 100 percent, and 150 percent of a base rate) were applied within each of twelve soil mapping units representative of the southeastern Coastal Plain. The four irrigation treatments, averaged across N-fertilizer and soils, produced corn grain yields of 6.4, 8.8, 10.1,and 10.7Mg/ha. Canopy temperatureswere measured on eight separate days using non-contact infrared thermometers (IRTs). Soil moisture of the surface 6 cm was measured on two days when canopy temperatures were measured. Preliminary analysis suggests this information will be useful to researchers and precision farming innovators interested in managing spatial variation, especially within the southeastern Coastal Plain and similar sandy areas.