Optimization of biofertilizers on potato blight, performance and farm returns using biochar and manure in combination with fertilizer

Abstract

Bio-fertilizers form a valuable interaction tool with soil dynamics in improving crop yield despite their inferior yield compared to inorganic fertilizers. However, optimizing bio-fertilizers using carrier material and combination with inorganic fertilizer while minimizing detrimental effects associated with chemicals is not fully comprehended. Field experiment was conducted to study effects of Mycorrhizae and Trichoderma optimization using manure and biochar (carrier) in combination with Diammonium Phosphate (DAP) applied at 50 %, 75% and 100% (500 kg ha^-1) the recommended rate on late blight, growth, yield and farm income. A survey was also conducted to establish fertilizer usage by potato farmers. The most widely used fertilizer was DAP. Plots without fertilizer recorded the highest late blight severity (RAUDPC of 0.45), lowest height (39.37 cm), stem count (2.81) and yield (0.29 t ha-1) followed by plots with 50% DAP. Yield observed from DAP rates differed significantly (P≤0.05). However, there was no significant difference among combinations of biofertilizer with 75% and 100% of DAP. Trichoderma and Mycorrhizae increased yield by 74%, 70% and 71% respectively relative to control. Manure on average improved Trichoderma and Mycorrhizae effects on late blight, stem count and yield by 55%, 56% and 76% respectively while biochar improved by 50%, 51% and 75% respectively. Combination of DAP (75% and 100% rates) and biofertilizer had significant increase in net farm returns. Conversely, higher marginal rate of return was observed in plots with mycorrhizae and manure as carrier. Improved yield and net income from biofertilizer plots could be attributed to their low costs and less bulky. Manure as carrier material provided additional nutrients support, stable environment and more micro-organism resulting in microbial consortium build up. The study concluded that bio-fertilizers combined with carrier material in combination with chemical fertilizers improved yield and farm net income, thereby could be an alternative to conventional