Comparative Study of Selected Macro and Micronutrients in Bio Slurry Samples from Different Feed Stocks and Inorganic Fertilizers

In Kenya overuse of inorganic fertilizers have rendered soils in arable areas acidic leading to poor crop production and hence great risk of food insecurity. An alternative source of plant nutrients that can also address soil acidity is needed if the country is to be food secure. Bio slurry, a by-product from the biogas plant, can successfully be used to improve crop productivity and soil health. This study was conducted to determine the levels of macro and micro nutrients in bio-slurry from different feed stocks and compare with nutrients from conventional chemical fertilizers. Physical parameters were determined on site. The samples were digested using protein digestion method for nitrogen and acid digestion method for phosphorus, potassium, sodium and magnesium. Phosphorus was then determined using UV-Vis while metals a flame emission spectrophotometer was used. The levels of macro and micronutrients were found to be significantly high in bio slurry samples than in select inorganic fertilizers. This study indicates that bio slurry has basic pH and can be used to raise the pH of acidic soil upon prolonged application. In addition, pig waste slurry can serve better as a planting fertilizer due to its high P content while Cow dung slurry would best serve as a top dresser due to the high nitrogen content.