Forest Conversion to Agriculture and Its Effect on Soil Quality Indices

The variation in soil quality due to land use change from forest to rainfed agriculture, rainfed agriculture under forest, and irrigated cultivation in the forested region of Lordegan, Iran, was investigated. A total of 240 soil samples from depths of 0–10 cm and slopes of 0–5% gradient across different land uses including 80 samples for chemical and physical analyses, another 80 samples for biological analyses, and 80 soil cores for bulk density measurements were gathered. Eighteen soil quality indices were assessed. The results indicated that the average diameter weight of soil particles was highest in the forest land use (0.40 mm) and lowest in the irrigated cultivation land use (0.29 mm). The highest amount of particulate organic carbon was found in coarse particles under forest land use at 1.01%, whereas the lowest amount was observed in irrigated cultivation at 0.21%. The highest microbial biomass carbon was recorded in the forest land use at 19.26 g/kg of soil, whereas the lowest was in irrigated cultivation at 7.94 g/kg of soil. This study demonstrated that any alteration in forest land use significantly reduces soil quality.