Human feces compost as an organic fertilizer for sweet corn cultivation in volcanic soil of Mt. Merapi, Indonesia

Volcanic material sedimentation of Mt. Merapi causes changes in surface soil's physical and chemical properties that reduce soil fertility. The eruption of the mountain also builds volcanic soil layers, which are generally porous and have a low water-holding capacity. The chemical properties of this layer have low nutrient content and organic matter. Solid human feces composted for 30 days has a water content of 51.62%, carbon 15.62%, nitrogen 1.50%, and phosphorus 6.45%. The potential of nutrients possessed by human feces compost has the opportunity to be used as a source of fertilizer for plants because the plant, animal biomass, and human excreta are essential components of material and energy flow in ecosystems. However, the human feces compost as an organic fertilizer has not yet been widely utilized. Therefore, the research aims are to study the potential of sanitized human feces composts to improve the fertility of volcanic soil from Mt. Merapi Indonesia and find its optimum dosage for sweet corn cultivation. Volcanic soil from Mt Merapi was brought to the greenhouse from the mountain area and used as media to cultivate sweet corn plants. The research was conducted using a completely randomized design (CRD) with five treatments consisting of four dosages of human feces compost and one control treatment using cattle manure. The four dosages of composted human feces were applied in the volcanic soil with the dose of 5, 10, 15, and 20 tons/hectare. Organic fertilizer from cattle manure with a dose of 20 tons/hectare was used as a control. The result showed that human feces compost has similar potential as cattle manure (control treatment) in increasing the growth and yield of sweet corn. Furthermore, the result also showed that the optimum dosage of organic fertilizer from human feces compost to increase sweet corn's productivity was 15 tons per hectare. Key words: human feces, soil quality, sweet corn, organic fertilizer, Indonesia