Corn growth and yield response to starter fertilizer in phosphorus‐sufficient soils

Abstract Previous research on starter fertilizer application has shown significant grain yield improvement; yet the greatest responses often occur on fields below the critical soil phosphorus (P) threshold. This study aimed to (i) investigate the impacts of starter fertilizer placement on corn growth, nutrient uptake, and grain yield in P‐sufficient soils and (ii) determine whether the timing of planting influences corn response to starter fertilizer placement across different growing environments. Field experiments were conducted at three locations in eastern South Dakota from 2021 to 2023, comparing an early with a normal planting date utilizing different starter fertilizer combinations, placements, and rates. Liquid fertilizers were used with and without zinc, placed in the seed in‐furrow at a lower (IFL) and a higher (IFH) rates, 5 × 5 normal rate placement (5 × 5), a combination of IFL and 5 × 5 placement and a control treatment without starter fertilizer application, with nutrient rates 10, 15, 25, 35, and 0 kg P 2 O 5 ha −1 , respectively. The planting timing did not significantly influence corn response to starter fertilizer placement across the locations. Starter fertilizer placement, relative to the control, increased early‐season growth stage by 3.2% and 2.3%, plant height by 0.75 and 3.1 cm, dry matter production by 83 kg ha −1 , N and P uptake by 3.1 and 0.34 kg ha −1 , respectively. However, these improvements did not translate into increased whole season crop physiological parameters or grain yield. Therefore, this result indicates that starter fertilizer application will not be necessary on P‐sufficient soils for yield increased in eastern South Dakota.