Enhancing soil health and fruit yield through Tephrosia biomass mulching in rainfed guava (Psidium guajava L.) orchards

Abstract

Tephrosia candida, a leguminous green manuring crop, exhibits superior biomass production and notably higher concentrations of carbon, nitrogen, phosphorus, potassium, and essential micronutrients. The research was undertaken to standardize the quantity of Tephrosia candida biomass for mulching in high density guava orchard. The experiment was initiated in the year 2019 comprising of four treatments viz. T₁ = 3.0 kg dry biomass per square meter of the plant basin, T₂ = 2.0 kg dry biomass per square meter of the plant basin, T₃ = 1.0 kg dry biomass per square meter of the plant basin and T₄ = control (No mulch). The treatments were imposed in the plant basin of a 12-year-old guava (cultivar: Allahabad Safeda) orchard planted at a spacing of 1.0m x 2.0m, accommodating 5000 plants per hectare. Each treatment was replicated five times. The present investigation recorded the data pertaining to the effects of the treatments during the third year of experimentation. Mulching with 3 kg of biomass per m² resulted in hastening of the winter bud stage by 29.17 days, increase in trunk diameter by 50.47%, fruit yield of winter crop by 42.25%, fruit weight by 11.00%, specific leaf area by 18% over the control. Moreover, there were notable increases in the levels of leaf total chlorophyll, total nitrogen, phosphorus, potassium, iron, zinc and manganese. Additionally, there was a marked reduction in total anthocyanin content of the leaves during the winter dormancy. Biomass mulching at rates of 3.0 kg/m² or 2.0 kg/m² significantly improved soil properties, including EC, available nitrogen, available phosphorus, exchangeable potassium, DTPA extractable micronutrients (Fe, Zn, Cu, and Mn), and C_tot, C_tot, C_frac1,2,3,4, and microbial biomass carbon within 0 to 15cm and 15 to 30cm soil depths. The FDA and DHA peaked in April 2022 and reached minimum values in January 2022, in both soil depths.