RAINFALL DISTRIBUTION UNDER A CORN CANOPY - IMPLICATIONS FOR MANAGING AGROCHEMICALS

A greater understanding of the spatial patterns of water inputs to soil will aid the development of agricultural practices to reduce leaching and runoff of agrochemicals. This study was initiated to investigate the process of stemflow, and to provide quantitative data on the distribution of rainfall under a corn (Zea mays L.) canopy. Rainfall distribution under the canopies of replicate conventional till corn plots was investigated by placing rainfall collectors at discrete locations within small 1.6-m by 0.76-m areas of the plots. Collection cups were also fixed around the stalks of individual corn plants to quantify stemflow. Results obtained from eight storm events in 1987 revealed that corn plants channel 19 to 49% of the total rain inputs down the stem to the base of the stalk. This stemflow plus the rainfall impinging directly in the planting furrow, accounted for approximately 42% of the total water inputs from a given storm event. These increased water inputs to the planting furrow may have implications in modeling solute leaching and runoff as well as to modifying current fertilizer and pesticide application methods.