Effect of Biofertilizers and Farmyard Manure on Growth and Tuber Yield of Potatoes (Solanum tuberosum L.) in Highlands of Kenya

Poor soil fertility is among the significant constraints to potato production in Kenya. Increased potato production currently depends on the use of chemical fertilizers for nutrients. The prices of chemical fertilizers continuously increase, becoming unaffordable for small-scale farmers who mostly grow potatoes. Therefore, the continuous use of chemical fertilizers such as NPK may cause complete depletion of other macro and micronutrients in potato production areas of Kenya. In addition, it increases the cost of inputs and triggers environmental pollution. The objective of this study was to evaluate alternative soil amendments using different biofertilizers in potato production. Two field experiments were conducted during the 2019 and 2020 seasons using two potato varieties (Shangi and Kenya mpya). The treatments were 30 t ha-1 of farmyard manure (FYM), two different biofertilizers (Trichoderma asperellum, T.R., and Bacillus subtilis, B.A.) applied at a rate of (150 mL/10 kg) and NPK (0 and 100 kg ha-1) as negative and positive controls respectively. Field experiments were carried out in randomized complete block design in a split-plot arrangement. The results indicated that FYM+TR increased potato yield and plant height by 19.81% and 18.99%, respectively, compared to the control. FYM+TR also increased tuber dry matter, marketable tuber weight, and potato grade by 25.15% 18.99%, respectively, compared to the positive control. The study recommends using FYM+TR and FYM+ BA for potato production in Kenya as they were found to increase crop performance and subsequent yield, which is beneficial to the environment and safe for farmers.