Corn Response to Fertilizer Placement Treatments in an Irrigated No‐Till System

Abstract

Corn (Zea mays L.) plants express unexpected K‐deficiency symptoms when grown under certain conservation tillage production systems on high‐K‐testing soils. This field study was conducted to determine if K fertilizer treatments interact with P and N planting‐time fertilizer placement treatments to affect 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 Haplustolls) near Pierre, SD. Fertilizer placement (main plot) treatments consisted 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 applied at planting time, provided a with‐K 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 the 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 was placed in a 5‐ by 5‐cm band, corn plants had 185 kg root−1 pull resistance, 0.26 g shoot−1 P accumulation, and 10.5 Mg ha−1 grain yield. However, when P and N fertilizers were applied to the soil surface, corn plants had significantly less root pull resistance (151 kg root−1), P accumulation (0.22 g P shoot−1) and grain yield (10.1 Mg ha−1). Added K fertilizer decreased shoot dry weight (added K = 97 g shoot−1, no K = 103 g), decreased P accumulation (added K = 0.22 g P plant−1, no K = 0.25 g), increased shoot N concentration (added K = 19.3 mg N g−1, no K = 19.0 mg), and had no significant effect on K concentration or accumulation. We conclude that, although planting‐time fertilizer placement was important for optimum corn growth and yield production in irrigated no‐till systems, added K fertilizer did not interact with fertilizer placement to improve yield on the high‐K‐testing soils used in this study.