Corn Response to Fluid Fertilizers Placed Near the Seed at Planting

As corn producers strive to improve the efficiency of fertilizer use in corn (Zea mays L) production, placement of fertilizer near the seed is a management option that should be given serious consideration. The positive effect of fertilizer placed in a band close to corn seed when soil test values for P and/or K are lower than in the high range has been frequently documented in the literature. Placement of fertilizer very near the seed at planting, frequently referred to as “pop-up” is gaining in popularity. Rate of adoption of this practice by crop producers has accelerated in recent years raising several questions. To address these questions, this study was conducted for the purpose of evaluating the impact of three fluid fertilizers applied at two rates and placed near the seed at planting on corn emergence, early growth, P uptake, and yield. All combinations of three factors (fertilizer grade, rate of application, placement) were combined in a complete factorial in fields of six cooperating farmers. Three fluid fertilizers were applied at two rates either with the seed or in positions above or below the seed with a small amount of soil between seed and fertilizer. Use of 10–15–0 (10–34–0) near the seed at 93.5 L ha⁻¹ in sandy soils reduced emergence. In the same sandy soils, application of 4–4.4–8.3 (4–10–10) and 3–8-15 (3–18–18) had no impact on emergence. Placement of all grades near the seed had no effect on emergence in the fine-textured soils. The data lead to the conclusion that the rate of N, rather than the rate of N plus K, in the fertilizer to be placed near the seed should be the major consideration. Early growth and P uptake by young corn plants was improved by fertilizer placed close to the seed in fine-textured soils; but not sandy soils. Five of six sites selected had high or very high levels of soil test P. Therefore, fertilizer placed near the seed did not have a positive effect on yield. Measured reductions in yield paralleled reductions in emergence. Results of the study show that placement of fertilizer near the corn seed at planting can be an effective management practice with minimal risk if soils are not sandy.