Soil indicators as a tool to assess changes in soil properties in guava orchard ecosystem

The aim of this experiment was to assess the changes in soil properties using physical (bulk density, porosity, water holding capacity, soil organic carbon), biological (soil respiration, dehydrogenase activity and microbial population) and chemical (available nutrients) indicators under guava orchard soil management system. A decrease in bulk density and increase in porosity and water holding capacity was confirmed from this study. Linear regression analysis revealed that Bulk Density (BD) had inverse correlation with Water Holding Capacity (WHC) (r=-0.82**) and porosity (r=-0.88**). Porosity and WHC were strongly associated with Soil Organic Carbon (SOC) content (r=0.68** to 0.76**). Soil respiration ranged between 51.8 + 7.4 to 71.9 + 5.0 mg CO₂ kg" soil day across different treatments. Dehydrogenase activity was highest (0.62 to 7.13 ug TPF g"¹ h"¹) in surface soil (0–10 cm) and decreased down the depth to 30 cm soil depth (0.08 to 2.42 u, g TPF g" h"). An increase in microbial activity was observed in soil treated with organic mulching, biofertilizers and vermicompost. Linear regression analysis indicated that porosity or WHC could explain around 60–70% variation in microbial respiration and enzymatic activity as independent variables. The study, thus confirmed that biological indicator along with physical and chemical could be considered as a potential tool to assess the changes in some soil properties under short-term fruit orchard soil management in order to predict the best treatment combinations for sustaining soil health in low fertile soils of subtropical region.