Ameeta Adhikari, currently serves as the Assistant Laboratory Officer of the National Soil Services Centre, Department of Agriculture under Ministry of Agriculture and Livestock. She holds a Bachelor of Science Degree with Honours in Microbiology. She is currently working in the field of Soil microbiology, focusing on isolating beneficial microbes from soils associated with various commercial crops cultivated across different regions of the country. These microbes are being studied for their potential use in biofertilizer production and possible applications in bio-prospecting processes.While working in this field, she has recognized the crucial role of molecular biology and biotechnology, mainly the use of sequencing machines and PCR techniques for identifying microbes at the strain level. Therefore, this is an area that she is currently interested in and keen on exploring more about.
Altitude, Land Use and Soil Depth Effects on Earthworm Density and its Relationship to Soil Properties in an On-Farm Study
Ameeta Adhikari 1 · Yadunath Bajgai 2,3 · Jimba Rabgyal 3 · Rattan Lal 2 · Nima Tshering 1 · Sarda Gurung 1 · Tashi Wangdi 1
Earthworms play a critical role in soil ecosystem functions through the cycling of organic matter and nutrients. However, some land uses or environmental conditions provide more favorable habitats for them than others. Therefore, the objectives of this study were to evaluate the prevalence of earthworm density and its relationship to land uses and soil properties. The study was conducted in three districts in Bhutan-Wangdue Phodrang, Chhukha, and Dagana-across three land uses: organic fields (OrgF), conventional fields (ConF), and natural vegetation(NatV). It also accounted for three altitudinal gradients (high-, mid-, and low-altitudes) and three soil depths. The results indicated that overall earthworm density at high-altitude sites was significantly (P < 0.001) higher than that at mid- and low-altitude sites. Further, across altitudes and soil depths, OrgF sites exhibited a significantly (P < 0.001) higher earthworm density (120 earthworms m⁻²) compared to NatV (56 earthworms m⁻²) and ConF (43 earthworms m⁻²) sites. Moreover, earthworm density decreased significantly (P < 0.001) and successively with increasing soil depth. The coefficient of determination (R² ≥ 0.51; P < 0.001) demonstrated a positive and moderate relationship between earthworm density and soil organic C and total N in OrgF sites, whereas this relationship was weak (R² ≤ 0.22) in ConF sites and absent in NatV sites. In conclusion, substituting chemical fertilizers with organic manures could increase earthworm density by enhancing soil health through the cycling of organic materials and nutrients in the soil. These findings provide empirical evidence for the prevalence of earthworms in different land use types across altitudinal gradients and offer valuable decision-making insights for land users and policymakers alike.