Placement of Preplant Liquid Nitrogen and Phosphorus Fertilizer and Nitrogen Rate Affects No‐Till Wheat Following Different Summer Crops

Abstract

Because of improved equipment technology, many producers in the eastern Great Plains are planting winter wheat (Triticum aestivum L.) no‐till (NT) into previous crop residues, but management of fertilizer N and P remains critical. This field study was conducted from 1998 through 2003 in southeastern Kansas on a Parsons silt loam soil (fine, mixed, thermic, Mollic Albaqualf). The objectives were to determine effects and interactions of previous crop [corn, Zea mays L.; grain sorghum, Sorghum bicolor (L.); and soybean, Glycine max (L.) Merr.], preplant placement method of liquid N–P fertilizer [subsurface‐knife (KN), surface‐band (SB), and surface‐broadcast (BC)], and fertilizer N rate (22, 45, 90, and 134 kg N ha−1) on NT winter wheat yield, yield components, and nutrient uptake in a 2‐yr cropping rotation. Wheat yields averaged 3.73, 3.56, and 2.97 Mg ha−1 following soybean, corn, and grain sorghum, respectively. However, as fertilizer N rate increased, yield differences between previous crops decreased. Grain yields also were influenced by placement of N–P fertilizer, averaging 3.68 Mg ha−1 for KN, 3.40 Mg ha−1 for SB, and 3.19 Mg ha−1 for BC. Plant and grain N responses indicated that grain yield differences were primarily related to greater immobilization of both fertilizer and soil N following grain sorghum, compared with soybean and corn, and to better utilization of KN N–P than surface‐applied. Fertilizing with greater N rates applied as a subsurface band, especially if following grain sorghum, may be necessary to maximize NT wheat yield potential in the eastern Great Plains.