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

Abstract

Leguminous crop Tephrosia candida has high biomass production and contains a substantial quantity of nutrients within its biomass. Starting in 2019, a long-term study was done to find the best Tephrosia candida dose for mulching in guava orchards. The study had four treatments: T₁ = 3.0 kg dry biomass m⁻² of the plant basin, T₂ = 2.0 kg, T₃ = 1.0 kg, and T₄ = control (no mulch). Every year, the treatments imposed in the month of August. The third year (2021–2022) results indicated that mulching with 3 kg of biomass m⁻² increased trunk diameter, fruit yield, fruit weight, specific leaf area, total leaf chlorophyll, and leaf macro- and micro-nutrients. At 3.0 kg m⁻², mulching improved soil properties such as EC, available nitrogen, available phosphorus, exchangeable potassium, DTPA extractable micronutrients (Fe, Zn, Cu, and Mn), total organic carbon (C_toc), soil organic carbon (C_soc), organic carbon fractions, and microbial biomass carbon between 0–0.15 m and 0.15–0.30 m. There was an increasing trend in dehydrogenase activity (DHA) and fluorescein diacetate (FDA). The Tephrosia leaf litter exhibited decay constants of 1.27 year⁻¹, and the carbon content was 40.11%. Therefore, applying Tephrosia biomass mulching at a rate of 3.0 kg m⁻² is a viable long-term solution for enhancing soil fertility and sequestering carbon.