Sprinkler and Corn Canopy Effects on Water Application Characteristics

Water application characteristics of a very low pressure spray sprinkler (40 kPa), a low pressure spray sprinkler (100 kPa), a medium pressure impact sprinkler (170 kPa), and a high pressure impact sprinkler (345 kPa) were evaluated under field conditions. Average field application rates varied from 42 to 156 mm h and maximum 5-min application rates varied from 54 to 226 mm h. Both were inversely related to sprinkler nozzle pressure in a manner that can be described by a logarithmic relationship. Maximum 5-min and 10-min application rates were, respectively, about 20 and 10% higher than average rates for the irrigation events. The 100, 170, and 345 kPa sprinklers produced application uniformity coefficients of 95% for single events and up to 99% for sequential events. About 70% of applied irrigation water reached the soil surface within a 200-mm diameter area at the base of corn plants. Maximum water application rates at the base of corn plants were amplified from three to four times when compared with above-canopy rates.