Integrated Nutrient Management Enhances Potato Yield and Quality Under Acidic Soil Conditions

ABSTRACT Soil acidity and unbalanced fertilization constrain potato yield and processing quality in Kenya's highlands. This study evaluated the effects of organic manure, lime, and mineral fertilizers applied alone or in combination on potato yield and tuber quality across two cropping seasons (2024 short rains and 2025 long rains) at ADC Farm in Sirikwa, Nakuru County, Kenya. A randomized complete block design with three replications and nine nutrient management treatments was used. Yield components (marketable, unmarketable, and total) and quality attributes, including specific gravity, tuber dry matter content, total soluble solids, titratable acidity, and harvest index, were measured. Integrated nutrient management consistently improved performance. The combined application of organic manure and NPK (nitrogen–phosphorus–potassium) fertilizer produced the highest total tuber yields (58.50 t ha −1 in the 2024 short rains and 65.54 t ha −1 in the 2025 long rains), followed by organic manure combined with diammonium phosphate (DAP) (49.67 and 54.01 t ha −1 ), while the control recorded the lowest yields (27.83 and 31.66 t ha −1 ). Integrated treatments also improved quality attributes, with higher specific gravity and tuber dry matter content, as well as increased harvest index (up to 53.2%). Total soluble solids increased with fertilization, while titratable acidity showed limited variation among treatments. Generally, integrating organic manure with mineral fertilizers enhanced potato yield and tuber quality under acidic highland conditions, demonstrating its effectiveness as a sustainable nutrient management strategy for improving productivity and processing suitability.