In furrow starter and broadcast phosphorus and potassium fertilization for corn

Abstract

Many studies have shown that starter fertilization can increase early corn growth, nutrient uptake, and grain yield. Research has also shown that band application of small amounts of P and K fertilizers are more efficient than similar rates applied broadcast. Little research has focused on studying how starter P and K rates can supplement larger broadcast rates, such as those used for a 2-year rotation. The role of starter fertilization and its benefits could be different in these conditions. Starter fertilization could supplement broadcast P and K rates applied to low-testing soils when high concentrations of these nutrients are needed near young roots. On the other hand, small starter fertilizer rates could be sufficient to attain maximum yield of one crop in soils testing near optimum in P and K. To test these possibilities, this on-farm study assessed the response of corn grain yield, early growth, and early P and K uptake to in-furrow liquid starter fertilization compared with responses to broadcast P and K fertilization rates commonly used by farmers. Materials and Methods Thirteen trials were established over a period of 3 years in Iowa farmers’ fields varying in soiltest P and K values, soils, and tillage system. Five fields were managed with no-tillage and the others were managed with chisel-plow tillage. Treatments were a control, a commercial liquid starter mixture (3-18-18 N-P2O5-K2O) applied in the furrow, broadcast P and K, and broadcast P and K plus starter. The P and K starter rates applied were 10 to 14 lb/acre of P2O5 and K2O. Broadcast P and K fertilizers were applied for corn as a single application of the average P and K removed in corn and soybean grain. Phosphorus rates were 100 to 110 lb P2O5/acre across sites, and the K rate was 120 lb K2O/acre. Plots at each trial measured 50 ft in length and 15 to 23 ft in width (depending on the width of the planter used). Four replications were arranged as a randomized complete-block design. The producers applied 107 to 134 lb N/acre, and a rate of 60 lb N/acre was applied by hand at planting time.