SPRING WHEAT RESPONSE TO FERTILIZER PLACEMENT AND NITROGEN RATE WITH LIMITED MOISTURE

Plant response to fertilizer placement under dryland conditions is dependent upon interactions between moisture, the crop, and root access to applied fertilizer. This study was conducted to determine response of spring wheat (Triticum aestivum) to fertilizer placement and nitrogen (N) rate under limited moisture conditions in a conservation tillage system. Field trials were conducted over a three-year period, from 1987-1989, with broadcast and band fertilizer placements applied at the recommended N rate or at 1.5X this rate, all with a uniform application of P, K, and S in a randomized complete block design. Banded fertilizer stimulated plant growth early in the growing season (Feekes 5-6) and produced dry matter with increased N and P concentration and content. As drought conditions developed over the course of the growing season, grain yield differences due to fertilizer placement and N rate diminished. There were, however, straw yield increases at harvest with band fertilizer placement. Early plant response to banded fertilizer may be beneficial early in the growing season, under conditions when nutrient uptake from broadcast applications is limited due to the lack of moisture needed to move surface applied nutrients into the root zone.