Soil Fertility Index on Various Rice Field Management Systems in Central Java, Indonesia

The purpose of this research was to assess the condition of soil fertility and compare the soil fertility index in various rice field management systems. This research was conducted from July until December 2018 in the rice fields of Girimarto District, Wonogiri Regency with a survey method and land sampling by purposive sampling (intentionally) at a depth of 0-20 cm rice fields with organic, semi-organic and conventional management systems. Soil samples were taken from 9 main points with 3 replications so that a total of 27 soil samples were obtained. The chemical properties of the soil tested by the laboratory are soil reaction (pH), Total Nitrogen (Total N), Available Phosphorus (Av-P), Available Potassium (Av-K), Cation Exchange Capacity (CEC), Base Saturation (BS), Soil Oganic Carbon (SOC) and Aluminum Saturation (Al saturation). The results showed that three rice field management systems have the same soil fertility index criteria, which are medium. In organic rice fields that have implemented organic farming systems for 6 years, have a soil fertility index value of 0.630, semi-organic rice fields with a SFI value of 0.557 and also organic rice fields with a SFI value of 0.545. Soil fertility index of organic rice fields is significantly higher than that of semi-organic rice fields and conventional rice fields.