Assessment of the effects of land use pattern on distribution of sulphur fractions in soil

Abstract

In the present investigation, various forms of sulphur (S) viz., total S, organic S, inorganic S and available S were estimated in soils under four different land uses viz., Rice-rice, rice-green gram, mango orchard and a fallow. Soils samples were taken up to a profile depth of 0.60m at 3 depths i.e. 0-0.20m, 0.20-0.40m and 0.40-0.60m. Thesoils were found to be slightly acidic to moderately acidic in reaction (5.83-6.59), showing an increase along the depth irrespective of the land use pattern. Soil organic carbon (SOC) content (mean 5.5 gkg-1) was found well above the low level of SOC in soils. Calcium carbonate content, bulk density and clay content of soils didn’t maintain any definite pattern along the depth. All forms of S were found to decrease along depth irrespective of the land use patterns. The available S content ranged from 12.2 to 21.4mgkg-1 of soils. The relative preponderance of all the forms of S followed the order: mango orchard> fallow> rice-rice> rice-green gram. On an average organic S and available S fractions constituted 93 and 6 per cent of total S respectively. A correlation matrix revealed that all the forms of S maintained a significant positive correlation with SOC content while a negative correlation with pH of the soils. The results of the study will be useful in managing the different fractions of S in soils in order to maintain its availability well above the critical level.