How effective are disturbance - tolerant, agroecosystem - nesting ant species in improving soil fertility and crop yield?

Study of the abundance, diversity and nest densities of agroecosystem-inhabiting ant species, in fallow, freshly tilled and cultivated farmers' fields revealed that Pheidole latinoda had highest abundance, nest density and disturbance-tolerance ability. Thirty-one arthropod morphospecies belonging to 12 orders were recorded in the nest entrance rim debris piles of this ant species. Hence, P. latinoda was selected to study the impact of nest rim debris soil on soil fertility and yield of two common crops, rice and tomato, widely cultivated in the Indo-Gangetic plains of India. Experimental field studies revealed that ant-related enrichment results in significant increase of the C, N and P contents of the bulk soil and a doubling of the soil microbial biomass. The soil enrichment significantly enhanced the yield of both the crop plants in a dose-dependent manner. A significant positive correlation was found between the ecophysiological traits including the specific leaf area, plant height and total plant weight of both rice and tomato plants, and the soil chemical constituents i.e. total C, N, P, NH4-N, NO3-N, microbial biomass C, N and P. The ecosystem engineering activities of P. latinoda ant colonies apparently enriched the soil via the nutrient cycling activities of the debris arthropods, on the externally discarded organic refuse. Since P. latinoda increases productivity via increase in soil fertility and also has the potential to suppress insect pests of crops, conservation of such ant species could enhance agricultural sustainability, through multiple pathways.