Impact of agroforestry intervention on carbon stock and soil quality in mid-hills of Nepal

Traditionally, planting trees on agricultural land including livestock is a very common practice in the mid-hills of Nepal. Trees on farms fulfill the demand for fuel wood/timber including fodder used to feed the livestock. Animal urine/dung is used as a bio-fertilizer that increases soil fertility. However, very few studies have been conducted on assessing carbon (C) stock and soil quality in agroforestry systems. This study was carried out to estimate the C stock and soil quality in agroforestry and agricultural land in the Kaski district of Nepal. Silvo-horto-agro system and agricultural land were selected from Site 1 (900–1000 m and west) and Site 2 (700–800 m and west). Total C stock was higher in the agroforestry at Site 1 (98.57 t ha⁻¹) than agroforestry at Site 2 (64.73 t ha⁻¹). Soil organic C, pH, and available potassium were higher in agroforestry than agriculture sites. Total nitrogen was higher in agroforestry than agriculture at Site 1. Available phosphorus was higher in agriculture than agroforestry at Site 1. Soil quality index (SQI) was good (0.8) and fair (0.6) in agroforestry and agriculture at Site 1. SQI was fair (0.6) in agroforestry and poor (0.5) in agriculture at Site 2. Altogether, the application of farmyard manure and vermi-compost including the higher vegetation density contributes to enhancing the soil quality in agroforestry systems. Further research on C stock including various soil quality indices is necessary under various kinds of agroforestry systems for a better understanding of their contribution towards climate change mitigation.