Macrofauna contributes to organic matter decomposition and soil quality in Himalayan agroecosystems, India

Abstract

In agroecosystems, rich soil biodiversity performs a variety of ecological services and contributes to sustainability of agriculture. In spite of the vast knowledge on this subject globally, the Himalayan mountain agroecosystems remain almost unexplored, and the agriculture is practiced on a subsistence level in the desire of suitable soil fertility management practices. This study was conducted on the soil macrofauna community and its influence on litter decomposition, nutrient release and soil quality in rainfed wheat-paddy cropping systems in two major agroecosystems in the central Himalayan mountains. Following local farmers' practice, Oak leaf litter (agroecosystem-I) and Pine forests leaf litter (agroecosystem-II) were used for farm yard manure (FYM) preparation for soil fertility restoration. Control (traditional cropfields) and treatment (macrofauna excluded plots) were maintained in this study. In both the agroecosystems, 11 soil macrofauna groups were recorded across 0–30cm soil depths over an annual crop cycle. Total macrofauna density in the rhizosphere zone of agroecosystem-I was significantly greater (P<0.01) than in agroecosystem-II (2477 vs. 2241indm−2), and it was particularly significantly greater (P<0.01) in the top soil (0–10cm depth) of agroecosystem-I (2321 vs. 1877indm−2). With regards to macrofauna taxonomic groups and population density our study area falls in the middle range reported for the world (taxonomic groups=11-22; population density=1637–9500indm−2). Decomposition of the Oak and Pine leaf litter was significantly lower (P<0.01) in macrofauna-excluded litter bags in agroecosystem-I (63.4 vs. 49.4%) than in agroecosystem-II (44.4 vs. 29.2%). Levels of available nutrients (NO3-N,NH4-N, PO4-P and available K) were significantly higher in the soil of control plots than in treatment plots. This study concludes that soil macrofauna plays an important role in litter decomposition and soil quality maintenance, and recommends that nutrient rich Oak leaf litter should be preferred over Pine leaf litter to promote macrofauna diversity and abundance and soil quality enhancement in the rainfed farming of Central Himalaya.