Optimum Spacing of Preplant Bands of N and P Fertilizer for Winter Wheat

In previous field studies a 46 cm spacing of preplant bands of N and P fertilizer has caused uneven growth of winter wheat (Triticum aestivum L.), with better growth immediately atop the preplant bands. Narrower spacing of fertilizer bands could improve plant growth uniformity and grain production by winter wheat. The objective of this study was to evaluate N-P fertilizer band spacing on wheat growth and grain yield. The effect of P band spacing on fertilizer P uptake from a preplant band was studied in the greenhouse with winter wheat. Phosphorus uptake from the fertilizer band was influenced by the lateral distance from the wheat row to the P band at 33 days after planting. By 40 days after planting, however, uptake of fertilizer P was the same from bands placed 0, 10, and 20 cm from the wheat row, while P uptake was significantly less from the band placed 30 cm from the row, apparently due to another row of wheat shielding the fertilizer P from uptake. Field studies consisting of combinations of spacings of preplant bands (25, 38, and 50 cm) and rates of P fertilizer (0,6, 12, and 24 kg/ha), all with 84 kg N/ha, were conducted on winter wheat. All treatments were deep-placed preplant band applications of liquid ammonium polyphosphate (APP, 10-15-0) and anhydrous ammonia (82-0-0). Wheat was drilled perpendicular to the direction of the preplant band application. Early season growth of winter wheat increased with increasing P rate and by decreasing the distance between preplant bands. Final grain yield, however, was influenced only by P rate, and not by P band spacing. Plant samples taken from 12.5 cm of drill row centered over the band and 12.5 cm of drill row centered between preplant bands of each treatment indicated differences between those areas in dry matter production, P uptake, spike density, and grain yield due to P rate and band spacing. Thus, more uniform growth resulted from the closer band spacing of 38 and 25 cm which could result in higher grain yields under optimum wheat production conditions.