Soil Properties and Macrofauna Community in a Converted Intensive Rice Field into an Organic Polyculture in Malang Regency, Indonesia.

Farmers in Malang cultivated rice intensively due to water availability, but yields reduced gradually. It might also reduce soil productivity and increase pest attacks. Sorghum is one of the easiest crops to be cultivated, and Leguminosae are known as pioneer cover crops. Therefore, the conversion field to organic polyculture was needed using sorghum and legumes. The research aims were to evaluate soil fauna dynamics and soil properties in the 3, 6, and 12 months after converting (mac) into an organic polyculture. Micro-climate and soil properties were recorded including air temperature (°C), day length (hours), rainfall (mm), soil water content (%), organic matter content (%), electrical conductivity (mS.m-1), pH, and bulk density (g.cm-3). Soil macrofauna was sampled using hand sorting for five plots (20 × 20 × 10 cm) in each field. Identified soil macrofauna was used to determine the density, frequency, Important Value Index (IVI), Shannon Diversity Index (H'), Evenness Index (E), Simpson Dominance Index (D), diversity t-test, and Indicator Value. The Canonical Correspondence Analysis (CCA) was used to analyze the interaction among abiotic properties and macrofauna using PAST 4.05. Results showed that the improvement of soil properties, including soil organic matter and soil macrofauna, was recorded at six mac compared to the intensive rice field, and continuously at 12 mac. The richness, diversity, and evenness of soil macrofauna taxa were higher in the converted field than in the intensive one due to organic polyculture. Moreover, we recorded a better proportion of detritivores and predators in the converted field after 12 months. Based on Indicator Value analysis, the dominant fire ants (Solenopsis sp.) in the intensive rice field might be considered as a potential indicator of unhealthy soil in the intensive rice fields. Whereas in the converted field the dominancy of these ants greatly decreased. We concluded that within six months conversion using the organic polyculture improved soil properties. [ABSTRACT FROM AUTHOR]