Corn Hybrid Response to Starter Fertilizer in a No-Tillage, Dryland Environment

A dryland corn (Zea mays L.) production system that has gained popularity in Kansas involves planting as early in the spring as possible so that pollination occurs under more favorable moisture and temperature conditions. Cool soils that occur with early planting in high-residue production systems can reduce nutrient uptake. Starter fertilizer applications have been effective in enhancing nutrient uptake even on soils high in available nutrients. Corn hybrids may differ in their response to starter fertilizer. The objective of this study was to evaluate corn hybrid response to starter fertilizer in a no-tillage, dryland environment. This field experiment was conducted from 1993 to 1995 at the North Central Kansas Experiment Field, located near Belleville, on a Crete silt loam soil (fine, montmorillonitic, mesic Pachic Arguistoll). Treatments consisted of five corn hybrids and two starter fertilizer treatments. Fertilizer treatments were starter fertilizer (30 lb N and 30 lb P₂O₅/acre) or no starter fertilizer. Starter fertilizer was applied 2 in. to the side of and 2 in. below the seed at planting. In all 3 yr of the experiment, grain yield, maturity, and total P uptake (grain plus stover at maturity) were affected by a hybrid × starter fertilizer interaction. Starter fertilizer consistently increased yields, reduced the number of thermal units needed from emergence to midsilk, and increased total P uptake of Pioneer 3346, Dekalb 636, and Dekalb 591, but had no effect on ICI 8599 and Pioneer 3563. When averaged over the 3 yr of the experiment, starter fertilizer increased grain yield of responding hybrids (hybrids in which the 3-yr average yield was increased by the use of starter fertilizer) by 13 bu/acre. Starter fertilizer increased V6 stage above ground dry matter production and N and P uptake of all hybrids evaluated. Ear leaf N and P concentrations also were increased by starter fertilizer, regardless of hybrid. Results of this work show that starter fertilizer can increase grain yield and be feasible for some hybrids, whereas yields of other hybrids are not affected. Research QuestionConservation tillage production systems are being used by an increasing number of farmers in the central Great Plains. A dryland corn production system that has gained popularity in Kansas over the past few years involves planting as early in spring as possible so that pollination occurs in June when temperatures are more moderate and moisture is more favorable than in July when conditions are hot and dry. When this production system is used in high-residue situations, the risk of cool soils interfering with root growth and nutrient uptake is greater. Corn hybrids differ in rooting characteristics that influence nutrient uptake and may differ in their response to starter fertilizer. The objective of this study was to evaluate starter fertilizer effects on yield, growth, and nutrient uptake of corn hybrids grown in a no-tillage, dryland environment on a soil high in available P. Literature SummaryNo-tillage systems have proven effective in maintaining soil quality and reducing soil erosion. The amount of residue left on the soil surface can cause soils to remain cool, which limits root development and reduces nutrient uptake of corn seedlings. However, starter fertilizer can be applied close to the seedling to improve nutrient uptake. Starter fertilizer has proven to be beneficial even on soils high in available nutrients. Corn hybrids differ in morphological and physiological root characteristics that influence nutrient uptake. Studies in the southeastern USA have reported differential corn hybrid response to starter fertilizer in a high-yield, irrigated environment. This experiment evaluated starter fertilizer effects on yield, growth, and nutrient uptake of corn hybrids adapted to the western Corn Belt grown in a no-tillage, dryland environment. Study DescriptionThis research was conducted from 1993 to 1995 at the North Central Kansas Experiment Field, near Belleville, on a Crete silt loam soil. Soil test P (Bray-1) was 43 ppm (high range). Treatments consisted of five corn hybrids (IC1 8599, Pioneer 3563, Pioneer 3346, Dekalb 636 and Dekalb 591). Fertilizer treatments consisted of starter fertilizer (30 lb N and 30 lb P₂O₅/acre) or no starter fertilizer. The starter fertilizer combination was made using urea-ammonium nitrate solution (28% UAN) and ammonium polyphosphate (10-34-0). Starter fertilizer was applied 2 in. to the side of and 2 in. below the seed at planting. Immediately after planting, knife applications of anhydrous ammonia were made to all plots to bring the total amount of N applied to 180 lb/acre. Planting dates were 26 Apr. 1993, 19 Apr. 1994, and 24 Apr. 1995. Applied QuestionHow does starter fertilizer affect yield, growth, and nutrient uptake of corn hybrids? On this high soil test P soil, starter fertilizer increased early season growth and nutrient uptake of all hybrids tested in all 3 yr of the experiment. However, this early season response to starter fertilizer did not translate into increased grain yield for all hybrids (Table 1). Starter fertilizer consistently improved yields, shortened the time from emergence to midsilk, and increased total P uptake (grain plus stover at maturity) of Pioneer 3346, Dekalb 636, and Dekalb 591, but had no effect on IC1 8599 and Pioneer 3563. Average yield increase from starter fertilizer application for responding hybrids was 13 bu/acre. Results of this work suggest that responses to starter fertilizer can be very economical for some hybrids even on soils high in available P, particularly when corn is planted early in a high-residue production system. Table 1Starter fertilizer effect on grain yield, number of thermal units from emergence to midsilk, and total P uptake (gram plus stover) of corn hybrids, average 1993–1995. HybridStarterYieldThermal units to midsilk†Total P uptakebu/acrelb/acreICI 8599With150115138Without148120538Pioneer (3563With174118740Without171122340Pioneer 3346With188122147Without174138640Dekalb 636With175123543Without161137937Dekalb 591With176119144Without165130437Hybrid × starterFLSD(0.05)9714†Thermal units are defined as the average daily temperature in degrees Fahrenheit minus the base of 50 with 86°F as the maximum.