Wheat Response to Time and Placement of Phosphorus Fertilizer

Agricultural field with green triticale ears before ripening and harvesting, close-up.

Phosphorus management in winter wheat production can be impacted by the previous crop in the rotation. As an example, wheat grown in Arkansas might follow either rice or soybean. Phosphorus availability in wheat grown following rice could be limited by saturated soil conditions that alter phosphorus forms making it less available for upland crops. Additionally, since wheat is a cool-season crop, cooler soil temperatures can slow phosphorus diffusion increasing the need for supplementation.

In this article, researchers at the University of Arkansas have conducted trials to determine if phosphorus placement and timing would have any effect on wheat grown following rice. Phosphorus banded with the seed or supplied after a topdress after seeding did result in greater biomass early on, but there were no differences in yield between banding and any broadcast application made before early spring (late March/early April).

Traditionally, farmers have waited until spring to make phosphorus applications after assuring a proper stand. That approach may still make sense, but these results also show that phosphorus banded at planting supports early growth.