Fertilizer Scheduling, Yield, and Nutrient Uptake of Irrigated Corn1

Abstract

AbstractOne method of reducing nutrient loss by leaching is to schedule applications of fertilizer with small amounts applied at frequent intervals. Four fertilizer application schedules were compared for effect on grain yield and nutrient uptake of irrigated corn (Zea mays L.) on Troup loamy sand (Grossarenic Paleudult). The number of weekly applications of N, P, and K were 6, 8, 10, and 12 as four separate treatments but total amounts of nutrients were held constant.Nitrogen and P uptake were not influenced by increasing the number of fertilizer applications. However, there was a negative correlation between K uptake and number of fertilizer applications. Yield was positively correlated with K uptake. Grain yield was 9,659 kg/ha for six fertilizer applications and 7,965 kg/ha for 12 applications of fertilizer.Another separate experiment was conducted in 1977 and 1978 on a Ruston loamy fine sand (Typic Paleudult). Treatments consisted of populations and rates of fertilization. One treatment was considered here for the purpose of comparing yield with N, P, and K uptake between years and between soil types. Grain yield in 1978 (10,200 kg/ha) was about 80% of the 1977 yield (12,700 kg/ha) and N uptake in 1978 was about 80% of the 1977 level. Grain yield divided by total N uptake was identical for both years. The ratio of grain yield divided by nutrient uptake (GNR for N, GPR for P, and GKR for K) was highest for P in 1978 but the value for K was about the same in 1977 as in 1978.The GNR of 62 for Ruston agreed closely with the average GNR of 59 for Troup but the GPR of 254 and GKR of 43 for Troup were lower than those for Ruston. These ratios make it possible to compare nutrient utilization efficiencies between different production management systems, years, and soil types.