Soil quality assessment of the rainfed lowland ricefields under organic and conventional farming systems in Kaliwungu (Central Java)

Rainfed lowland rice is grown in land where the irrigation systems depend on rainwater. The use of chemical fertilizers in large quantities in order to improve production of rice will result in soil quality degradation. In order to improve the condition of the soil, a system of organic farming was provided. The aim of this study was to quantify soil quality in rainfed lowland ricefilds using soil quality indexes (SQI) and to compare SQIs of farming system under organic and conventional fertilization. The sample consists of seven sample points on soil fertilized organically and three sample points on soil which is managed in a conventional way, each taken from 5 subpoints at a depth of 0–30 cm and analyzed for 12 soil variables. The best representative soil quality variables forming a minimum data set (MDS) were selected using principal component analysis (PCA), and soil quality scores were obtained using both linear and non-linear scoring functions. The study results indicate that in case of organic farming system, the soil quality was better (SQI = 2.079) when compared to its quality in the conventional farming system (SQI = 1.397). The selected indicators used as the MDS are soil porosity, cation exchange capacity (CEC), soil organic carbon, C/N ratio, soil permeability, available-P (Av-P), and electrical conductivity (EC)