Corn Response to Long‐Term Phosphorus Fertilizer Application Rate and Placement with Strip‐Tillage

Abstract

Core Ideas Results showed a significant effect of P fertilizer rate and placement in early season whole plant P uptake, ear leaf P concentration, grain P concentration, and yield over the course of this study but particularly after multiple years of treatment application. Early P uptake in corn was consistently higher with deep band P fertilizer applications and with starter fertilizer with the planter. The long‐term evaluation of P fertilizer placement showed that deep‐band P placement only seldom resulted in higher yields. The use of starter fertilizer increased average grain yield, particularly for high‐yielding systems. Multiple years of phosphorus (P) fertilizer application may be needed before the agronomic and environmental effect of P fertilizer placement and application rate become noticeable. The objective of this study was to evaluate the long‐term effects of P placement on corn (Zea mays L.) with strip‐tillage. The study was conducted for 10 yr at two locations in Kansas in a corn and soybean (Glycine max L.) rotation from 2006 to 2015. Strip‐tillage was conducted before corn and soybean were planted without previous tillage. Phosphorus fertilizer placement and rate treatments included a control, broadcast at 20 kg P ha−1 and 39 kg P ha−1, deep‐band at 20 kg P ha−1, and 39 kg P ha−1, in a factorial combination with two starter fertilizer treatments (with and without starter fertilizer). Response parameters included V6 whole plant P uptake, ear leaf P, grain P concentration, and yield. Phosphorus fertilizer increased crop response parameters when compared to the control including yield for some years or across years at the two locations. However, corn response was similar among the P rate‐place treatments with generally higher values for the P rate of 39 kg P ha−1. The use of starter fertilizers in combination with broadcast or deep‐band P fertilizer resulted in greater P uptake, ear leaf P and grain P; however only increased yield at one location. Results from this study showed similar corn yield for deep‐band and broadcast P fertilizer under strip‐tillage and starter fertilizer increased yield for a high‐yielding, low soil test P location.