Effect of green manure on the availability of Phosphorus and Potassium nutrients in Vertisols

Abstract

Abstract The need for rice as a staple food continues to increase, increasing the demand for land. However, the soil’s availability of nutrients is decreasing due to inappropriate and excessive use of chemical fertilizers, causing soil degradation. Green fertilizer is an effective effort to reduce excessive use of chemical fertilizers. The research aims to determine the use of green manure in influencing the availability of phosphorus and potassium nutrients. The research was conducted on Vertisols in Weru District, Sukoharjo Regency. The research was carried out using experimental methods. There were 10 treatments with 3 replications (A: Control; B: NPK Fertilizer 200 kg/ha; C: Straw 10 Tons/ha; D: Kirinyuh 10 Tons/ha; E: Water spinach 10 Tons/ha; F: Water Hyacinth 10 Tons/ha; G: NPK 100 kg/ha + Straw 5 Tons/ha; H: NPK 100 kg/ha + Kirinyuh 5 Tons/ha; I: NPK 100 kg/ha + Water spinach 5 Tons/ha; J: NPK 100 kg/ha + Water Hyacinth 5 Tons/ha). The results show that green manure affects the availability of phosphorus and potassium nutrients. Kirinyuh fertilizer (5-10 tons/ha) gives the highest results in providing phosphorus and potassium nutrients in Vertisols. Using green fertilizers can offset chemical fertilizers by increasing the availability of phosphorus and potassium nutrients.