Impact of Crude Oil Contamination on Soil Physicochemical Properties around the Sildubi Oil Spill, Borhola, Assam

Crude oil contamination can affect the soil physicochemical properties and it is a serious constraint on the rice ecosystem near the oil drilling sites. The objective of this study was to identify the effects of crude oil contamination through oil exploration on soil health and the horizontal distribution of soil nutrients in rice field soils in the Sildubi area, Jorhat district, Assam. Soil samples were collected at a depth of 0–15 cm from the drilling site and from the four directions (East, West, South and North) in a circular mode with a radius of 500 and 1000m away from the oil spill. Each sample was mounded with four replications. Samples were analyzed for physicochemical properties by using standard methods that reflect soil nutrient status.

The percentage of organic carbon, organic matter and soil pH are found to be higher at the drilling site compared to the results obtained in the rice field soils, apart by 500 and 1000m from the central zone. Similarly, bulk density, moisture percentage and electrical conductivity were found to be lowest in the soils of the drilling site. In our study, considerable variation in the horizontal distribution of soil nutrients was also observed. The highest P, Ca and nitrogen contents were recorded in the oil-contaminated soils compared to soils collected from 500 and 1000m radius. The total soil Fe was significantly higher in the samples collected at 1000m. Spilled crude oil is certainly responsible for alterations in soil physicochemical properties and the horizontal distribution of some plant-specific nutrients. High concentrations of Fe and P observed due to crude oil contamination have been developing Fe stress situations reducing crop production in nearby agricultural lands.