Irrigation Practice for Corn Production in Relation to Stage of Plant Development

Abstract

An experiment involving 13 irrigation treatments was conducted on Tripp very fine sandy loam to study the importance of maintaining a low soil moisture tension during different stages of plant development on corn production. Corn was planted in 30-inch rows on soil that was near field capacity wetness to 6 feet and a stand of 19,000 plants per acre was obtained. Soil moisture determinations were made at the beginning of the season, before and after each irrigation and at the end of the season. Net water input from irrigation was measured. Plant sampling was initiated 33 days after planting and was repeated at weekly intervals in some treatments. Corn production as shown by height measurements, dry matter production, ear development, and yield of grain was materially influenced by irrigation. A low soil moisture tension throughout the growing season (irrigated when a tension of 400 cm. water occurred at a 6-inch depth until July 23 and at a 12-inch depth later) was essential for obtaining maximum vegetative growth and a maximum yield of 153 bu./acre; the total use of water was 21.4 inches with 14.2 inches supplied by irrigation. Three irrigations supplying 7.0 inches of water that maintained a low soil moisture tension during the stage of growth before tasseling through silking produced 144 bu./acre; the total use of water was 15.6 inches. The latter practice may be important where there is a shortage of irrigation water during the regular season and the soil moisture supply can be replenished by precipitation or a later irrigation. Where a high soil moisture stress was alleviated during the tasseling period by an irrigation, there was an appreciable effect of that irrigation on yield of grain although the yield was appreciably less than where a low soil moisture tension was maintained throughout the tasseling and silking period. The fairly large yield of grain without irrigation (69 bu./acre) points out the importance of having the root zone filled with water at the time of planting.