Effect of tree canopy management in agroforestry system on soil quality in central India

The present study dealt with the effect of canopy management of Albizia procera (planted at 8 m x 4 m spacing) in a 10-years old agroforestry system on soil quality indicators. Study comprised of five treatments viz., control (pure crop i.e. wheat), pure tree (without intercropping), zero pruning + intercropping, 50% pruning + intercropping and 75% pruning + intercropping. Soil samples were taken from all treatment plots and analyzed for 15 physical, chemical and biological properties. The quality of the soil was assessed by using two approaches viz., linear score function (LSF) and principal component analysis (PCA). Based on nature of land-use and management goal, minimum data set was identified. Soil properties which play important role in soil quality and soil functions in hot semi-arid region of northern plains were identified. The indicator values were converted into unit-less scores (0 to 1), based on critical values; and these scores were integrated into a single soil quality index (SQI) with the help of PCA. Tree pruning significantly affected most of the soil quality indicators. Maximum SQI was observed from 50% pruning plot (0.489) and minimum from pure crop (0.356). The improvement in SQI over experimental control ranged from 17.42 to 37.36%. The PCA revealed that soil organic carbon, microbial biomass carbon, porosity, water holding capacity and bulk density of soil were important contributing indicators in soil quality. The SQIs based on LSF and PCA were found highly correlated with biomass yield and had sensitivity of 1.38 and 2.00, respectively.