Soil Fertility Index, Soil Evaluation Factor, and Microbial Indices under Different Land Uses in Acidic Soil of Humid Subtropical India

Abstract

A study was conducted to examine the impact of land use on soil fertility in an Entisol in the Jalpaiguri District of humid subtropical India. The natural forest served as a control against which changes in soil properties were compared. Soil samples were collected from four different depths (0–25, 25–50, 50–75, and 75–100 cm) of soil from four land uses (viz. forest, home garden, arecanut plantation, and agriculture) and examined for pH, organic carbon (OC), electrical conductivity (EC), cation exchange capacity, available nitrogen (N), phosphorus (P), exchangeable calcium (Ca), magnesium (Mg), potassium (K), aluminum (Al), microbial biomass carbon (MBC), microbial biomass nitrogen (MBN) and dehydrogenase activity (DHA). Soil pH (5.7), OC (2.29%), N (386 kg ha−1), and P (22.54 kg ha−1) were greatest in forest soil, followed by soil from arecanut plantation, agriculture, and home garden. The greatest Ca (0.892 cmol kg−1), Mg (0.527 cmol kg−1), and Al (1.86 cmol kg−1) were found in the arecanut plantation, whereas K (0.211 cmol kg−1) was greatest in forest. The greatest content of diethylenetriaminepentaacetic acid–extractable copper, zinc, manganese, and iron (2.25, 1.66, 4.86, and 7.65 ppm, respectively) were found in forest. MBC (558 mg kg−1), MBN (26.67 mg kg−1), and DHA (33.03 μg TPF 24 h−1 g−1) was greatest in forest soil. Soil fertility index varied from 13.13 in arecanut plantation to 18.49 in forest. The soil evaluation factor ranged from 5.32 in agriculture to 6.56 in forest. Pearson's correlation matrix revealed strongly significant positive correlation of soil fertility index and soil evaluation factor with soil properties.