Corn grain yield, yield components, and potassium nutritional status as affected by potassium fertilization timing

Abstract

Potassium (K) management is key to maximizing corn ( Zea mays L.) yield potential. We evaluated the effects of K fertilization timing on tissue‐K concentration, grain yield, and yield components (i.e., number of kernel rows per ear, kernels per row, and 1000‐seed weight). Seven field trials were conducted across Arkansas in 2024 and 2025. Fertilizer‐K was applied (112 kg K ha ⁻¹ ) either preplant or in‐season, targeting V6, V10, V12, V14, VT, and R2 growth stages, in addition to a no‐K control. Due to differences in crop development rate, recorded growth stages occasionally differed from the target. Preplant soil sampling classified soil‐test K as very low (<61 mg K kg ⁻¹ ; sites 2, 4, and 5), low (61–90 mg K kg ⁻¹ ; sites 3 and 6), medium (91–130 mg kg ⁻¹ ; site 7), and optimum (131–175 mg K kg ⁻¹ ; site 1). Across three K‐deficient locations (sites 4, 5, and 6), K application at V10 and V12 increased tissue‐K concentration similar to preplant fertilization ( p ≤ 0.05). Yield recovery was most consistent when fertilizer‐K was applied by VT. At site 4, yield recovery extended through R2–R4, with grain yield averaging 11% above the control. No yield response to K fertilization was observed at sites 1, 6, and 7 ( p  > 0.05). The number of kernel rows was unaffected by K fertilization timing, whereas kernels per row and 1000‐seed weight responded at selected sites, with maximum values reaching up to 13% and 28% above the control, respectively. Timely diagnosis of K deficiency allows in‐season K fertilization to rescue yield potential.