Phosphorus and potassium interaction in maize: enhancing yield and soil health under Nepalese agroecosystems

Phosphorus (P) and potassium (K) are essential nutrients for maize growth and productivity, but their imbalanced application limits yield and soil fertility in Nepalese mid-hills. This study evaluated the interactive effects of P and K on maize yield, physiological responses, and residual soil nutrients to develop site-specific nutrient management strategies. The experiment was conducted in Kaski District, using a split-plot design with four P levels (0, 50, 100, and 150 kg P 2 O 5 ha −1 ) as main plots and three K levels (0, 25, and 50 kg K 2 O ha −1 ) as subplots, replicated three times. Maize variety Rampur Hybrid-10 was grown under standard crop management practices. Growth, yield components, tissue P and K content, and post-harvest soil-fertility were measured. Results showed that P significantly increased grain yield, biomass, straw yield, and thousand-grain weight, with the highest grain yield (5,820 kg ha −1 ) at 150 kg P 2 O 5 ha −1 . K also improved grain yield, with maximum yield (5,430 kg ha −1 ) at 50 kg K 2 O ha −1 . A synergistic effect was observed under combined P150 × K50, resulting in 6,120 kg ha −1 grain yield. Tissue nutrient analysis confirmed enhanced P and K uptake with balanced fertilization. Residual soil P and K increased under higher P and K applications, while soil pH and organic matter remained stable. The study demonstrates that balanced P and K management improves maize productivity and supports soil fertility. Site-specific nutrient application can reduce yield gaps and promote sustainable maize production in Nepal. Long-term trials are recommended to validate these findings across diverse environmental conditions. This study is based on original field experimentation and laboratory analysis conducted under Nepalese mid-hill agroecosystem conditions.