Corn response to fertilizer placement treatments in an irrigated no-till system

Corn (Zea mays L.) plants express unexpected K-deficiency symptoms when gro wn under certain conservation tillage production systems on high-K-testing soils. This field study was conducted to determine if K fertilizer treatmen ts interact with P and N planting-time fertilizer placement treatments to a ffect crop growth, nutrient composition, and yield in an irrigated no-till corn production system on high-K-testing soil. The 3-yr study was conducted on Lowry silt loam soils (coarse-silty, mixed, superactive, mesic Typic Ha plustolls) near Pierre, SD. Fertilizer placement (main plot) treatments con sisted of P and N fertilizers that were applied with the corn planter to (i ) the soil surface, (ii) the seed furrow, or (iii) a band 5 cm to the side of the seed furrow and 5 cm deep. Fertilizer products containing K, also ap plied at planting time, provided a with-g subplot comparison with subplots that received no added K fertilizer. Corn plants were sampled for root pull resistance, shoot dry weight, and shoot mineral nutrient composition at th e tassel stage of development and grain yield. Data combined over the 3 yr of the study revealed that added K fertilizer had no effect on grain yield and did not interact with P and N fertilizer placement treatments to affect grain yield. When P fertilizer was placed with the seed and N fertilizer w as plated in a 5- by 5-cm band, corn plants had 185 kg root(-1) pull resist ance, 0.26 g shoot(-1) P accumulation, and 10.5 Mg ha(-1) grain yield. Howe ver, when P and N fertilizers were applied to the soil surface, corn plants had significantly less root pull resistance (151 kg root(-1)), P accumulat ion (0.22 g P shoot(-1)) and grain yield (10.1 Mg ha(-1)). Added K fertiliz er decreased shoot dry weight (added K = 97 g shoot(-1), no K = 103 g), dec reased P accumulation (added K = 0.22 gP plant(-1), no K = 0.25 g), increas ed shoot N concentration (added K = 19.3 mg N g(-1), no K = 19.0 mg), and h ad no significant effect on K concentration or accumulation. We conclude th at, although planting-time fertilizer placement was important for optimum c orn growth and yield production in irrigated no-till systems, added K ferti lizer did not interact with fertilizer placement to improve yield on the hi gh-K-testing soils used in this study.