Effects of Phosphorus Rate, Placement, and Tillage on Irrigated Corn

This study was designed to look at the feasibility of placing fertilizer phosphorus into the soil at a depth of 8 inches or more with a chisel plow. Broadcasting fertilizer phosphorus before incorporating it into the soil by tillage or row banding as a starter fertilizer at planting time are the most commonly used methods of phosphorus fertilizer application. These methods of fertilizer P application as well as the effects of chisel plow placement on the growth of corn plants throughout the growing season were to be compared under both chisel plow and moldboard plow tillage. In addition, the distribution of fertilizer P in the soil was to be examined in comparing the placement methods. Leaf, plant, and grain analyses were also to be used in determining the phosphorus status in the corn plants grown on plots on which the various placement methods had been applied. Effects of varying rates of fertilizer P were to be monitored in a like manner. Finally, effects of irrigation levels were to be studied to determine the results of placement on the phosphorus nutrition and grain yield of corn under varying moisture conditions. Advisor: Robert A. Olso