Corn grain yield, early growth, and early nutrient uptake as affected by broadcast and in-furrow starter fertilization

In-furrow starter fertilization for corn (Zea mays L.) is being preferred to alternative starter application methods by farmers in the U.S. Corn Belt. This study assessed corn grain yield, early growth (V5 to V6), and early P and K uptake responses to in-furrow P-K starter fertilization with or without broadcast P-K fertilization for 2-yr corn-soybean [Glycine Max (L.) Merr.] rotations. Sixteen trials were conducted on Iowa fields managed with no-till or chisel-plow tillage. Soil-test P (STP) was 5 to 77 mg P kg^-1 (Bray-P₁), and soil-test K (STK) was 88 to 237 mg K kg^-1 (ammonium acetate). Treatments replicated four times were a control, 3-8-15 (N-P-K) liquid starter at 5 to 7 kg P ha^-1 and 10 to 14 kg K ha ^-1, granulated P-K fertilizer broadcast at 49 to 66 kg P ha ^-1 and 112 to 140 kg K ha^-1, and broadcast plus starter. Nitrogen was applied across all treatments. Fertilization increased grain yield at nine sites (0.80 to 2.11 Mg ha^-1). Starter fertilization produced less yield than broadcast fertilization at five sites (0.30 to 1.48 Mg ha ^-1 less), four of which tested low in STP (≤15 mg P kg ^-1). Starter fertilization in addition to broadcast fertilization did not increase yield further at any site. Starter fertilization increased corn early growth and P and K uptake more than broadcast fertilization did at most sites. In-furrow starter P-K fertilization for corn is not an effective practice when applied in addition to 2-yr broadcast P-K fertilization rates for corn-soybean rotations.