Biogas bioslurry, which is normally a bio-digestion product from livestock refuse, can be utilized as an inorganic fertilizer, thus boosting not only soil fertility but also crop growth and yield. Its use can mitigate climate change by reducing methane gas emissions, which are associated with the direct application of fresh animal manure. The current study was carried out on farmer’s fields based at Wusi-Kishamba and Werugha wards in Taita Taveta County, Kenya, and it aimed at investigating the effect of bioslurry coupled with synthetic fertilizer on potato (Solanum tuberosum L.) growth and yield. There were four treatments: sole bioslurry, sole fertilizer (DAP), bioslurry + DAP, and control, which were replicated five times in a randomized, complete block-designed layout. Data were collected on plant growth (plant height and leaf length) and yield (marketable and unmarketable tubers and the number of tubers plant⁻¹). The results indicated a general increase in plant height from week one to week seven, where peak values were noted with sole slurry, sole fertilizer, and bioslurry + DAP treatments, which recorded 9, 18, and 43% taller plants, respectively, relative to control. Further, the combined application of bioslurry and DAP fertilizer significantly (p ≤ 0.05) improved potato growth and yield. For instance, there was a higher (23.3 t ha⁻¹) yield in bioslurry + DAP treatment compared to the respective least record of 14.2 t ha⁻¹ in control. Therefore, the study recommends a synergistic application of synthetic fertilizer (DAP) and bioslurry to potato crops for optimal crop growth and production.

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.