Particle size distribution and hydraulic conductivity of soils under different land use systems in Nandurbar district

Abstract

The climate of Nandurbar district is typically hot and dry, with an average annual rainfall of about 767 mm. In this region, agriculture, horticulture, forest, and pasture are the dominant land use systems; therefore, these four systems were selected for the study. Two representative sampling sites were chosen under each land use type from different locations across the district. Soil samples were collected at 20 cm depth intervals, starting from the surface and extending down to the bedrock. The soil profile depth reached up to 100 cm under agricultural, horticultural, and forest lands, whereas in pasture lands it extended up to 80 cm. Soil physical properties such as bulk density, particle density, hydraulic conductivity, and particle size distribution play an important role in influencing plant growth. These characteristics directly or indirectly affect water movement, root penetration, aeration, and nutrient availability, and therefore must be carefully considered in land evaluation and planning for sustainable land use. Analysis of particle size distribution provided an overall understanding of the soil’s physical condition and offered insight into its potential chemical and biological behavior. The soils across most land use systems were predominantly clayey in texture. However, in pasture land, the lower soil layers exhibited a silty clay texture. Sand content across the different systems ranged from 1.5 to 12.5 percent, silt content from 21.5 to 42 percent, and clay content from 45.5 to 71 percent. The highest sand percentage was recorded at 60–80 cm depth under pasture land, while the lowest was found in the 0–20 cm layer of forest land. Similarly, maximum silt content occurred at 60–80 cm depth in pasture land, whereas the minimum was observed at the same depth under agricultural land. Clay content was highest at 60–80 cm depth in agricultural land and at 40–60 cm depth in forest land, while the lowest clay percentage was recorded at 60–80 cm depth under pasture land. Hydraulic conductivity among the different land use systems ranged between 0.58 and 1.03 cm hr⁻¹ and generally decreased with increasing soil depth. In agricultural lands, values varied from 0.61 to 1.03 cm hr⁻¹; in horticultural lands from 0.63 to 0.86 cm hr⁻¹; in forest lands from 0.58 to 0.94 cm hr⁻¹; and in pasture lands from 0.62 to 0.81 cm hr⁻¹. The highest hydraulic conductivity was observed in the surface layer (0–20 cm) under agricultural land, whereas the lowest value was recorded at 80–100 cm depth under forest land.