Soybean Response to Tillage and Nitrogen, Phosphorus, and Potassium Fertilization1

Abstract

AbstractConservation tillage is being increasingly recommended as a means of reducing both cost of tillage and soil erosion. A study was conducted for two years with the objective of evaluating the performance of a determinate soybean [Glycine max (L.) Merr.) cultivar, Sprite, planted in narrow rows on a Nicollet (Aquic Hapludo1ls)‐Webster (Typic Haplaquolls) complex, with different tillage systems and different levels of N, P, K fertilization for higher yield. Variables studied included: (i) three tillage systems (disk, chisel plow, and moldboard plow tillage) and (ii) three levels of N, P, and K fertilization (P at 0,74 and 111 kg/ha; K at 0,186, and 279 kg/ha; and N at 0, 135, and 270 kg/ha). Plant population was unaffected by the treatments. Phosphorus and K applications increased soil and leaf P and K contents over time and with application levels. Tillage had no significant effect on grain yield. Lodging was significantly increased by P application. Lodging, plant height, and grain yield were significantly increased by K application. Nitrogen application increased lodging and plant height, but not yield. It was concluded that soybean can be successfully grown with reduced tillage in central Iowa without a yield reduction or change in fertility requirement. Soybean responded to K application when the soil test levels were medium to high.