Interaction of above-and below-ground bioresources for improvement of chemical and biological health of soil

Abstract

Impacts of different land use systems on faunal density, nutrient dynamics and biochemical properties of soil were studied in different agrisilviculture systems of Jodhpur district of Rajasthan (India). The selected uses were tree (Zizyphus mauritiana, Prosopis cineraria, Acacia nilotica) and crop (Pennisetum glaucum, Vigna radiata, Sesamum indicum) combinations. Soil is aridisol, coarse loamy, mixed hyperthermic type. Populations of Acari, Myriapoda, Coleoptera, Collembola, other arthropods and total soil fauna exhibited significant changes with respect to different land use practices and tree species. In most of the cases, the populations of different groups of soil fauna were higher under the canopy of tree alone than in different cropping systems with tree. However, this was not true for V. radiata cultivated land which showed higher faunal population than that of tree field alone. Different groups of soil fauna demonstrated a significant positive correlation among themselves. The Coleoptera exhibited greatest association with all agrisilviculture fields. However, Z. mauritiana system indicated highest facilitative effects on all groups of soil fauna. Soil temperature and pH decreased but soil moisture, organic carbon, available nitrogen, phosphate-phosphorus, soil respiration and dehydrogenase activity increased considerably under the canopy of tree than that of open field. However, these chemical constituents did not differ between tree and crop field which may be due to an increased biotic activity in cultivated land. Soil temperature and pH of V. radiata field were lower than that of P. glaucum and S. indicum cultivated land. In contrast, the gradation of soil moisture, organic carbon and organic matter, nitrateand ammonical-nitrogen, phosphate-phosphorus, soil respiration and dehydrogenase activity was V. radiata> P. glaucum> S. indicum. Thus increase in soil temperature and pH might be mainly responsible for decrease in chemical and biochemical constituents of cultivated land in desert. Negative correlation of soil temperature with different soil characteristics except pH shows that the increase in soil temperature is not conducive for soil health in desert. The negative correlation of soil pH with other chemical and biological properties of soil may be due to reduction in soil pH as a result of litter decomposition and humic acid formation. A positive and significant correlation among organic carbon, nitrate- and ammonical-nitrogen, available phosphorus, soil respiration and dehydrogenase activity clearly reflects increase in soil nutrients with the increase in microbial and other biotic activity. Z. mauritiana field harbouring V. radiata crop was best for agrisilviculture practices in arid region. The increase in soil nutrients and microbial activity is associated with the increase in soil faunal population. This suggests that litter addition and decomposition in arid agrisilviculture system induce activities of microbial and faunal resources for improving chemical and biological health of soil.Additional keywords: agrisilviculture; fauna; nutrients; respiration; dehydrogenase activity.