Impact Assessment of Oil Spillage on Farmlands of Some Communities in Ilaje Area of Ondo State, Nigeria

This study investigated the impact assessment of oil spillage on farmlands of some communities in Ilaje Area of Ondo state. Three farmlands were considered in the course of this study. Two of the three farmlands were within the Ikorigho and Otumara communities that recently experienced oil spillage and they are about 300 m from each other. While the third farm was within the Igbokoda community which is geographically similar but has not experienced oil spillage, it was used as control. The farmland was delineated at each area by the grid technique and soil samples were collected at 0-20 cm depth of the ground. Some physiochemical properties that reflect soil nutrient content and fertility status （pH, electrical conductivity, moisture content, organic matter, nitrogen, phosphorous and cation exchange capacity （CEC）） were determined using standard methods and results from the three areas were compared. There was a significant decrease in the calcium （Ca）, magnesium （Mg）, potassium （K） and organic matter, as well as a significant increase in the electrical conductivity, moisture content and phosphorous content of the oil-spill affected farmlands at Ikorigho and Otumara when compared with the non-affected farmland at Igbokoda. The acidic nature of the farmlands could not be attributed entirely to the oil spill since the control farmland at Igbokoda was slightly acidic. The results show that oil spillage has adversely affected the nutrient level and fertility status of farmland at Ikorigho and Otumara communities, which needs urgent remediation.

Impacts of Forest Gaps on Soil Properties After a Severe Ice Storm in a Cunninghamia lanceolata Stand

During January–February 2008, a severe ice storm caused significant damages to forests in southern China, creating canopy gaps and changing soil nutrient availability and enzyme activity. To understand the relationships between gap size, changes in the soil environment and the effects that these changes have on soil processes, we investigated the effects of gap size on soil chemical and biological properties in the forest gaps in a Cunninghamia lanceolata stand in northern Guangdong Province, southern China. Ten naturally created gaps, five large(80–100 m^2) and five small(30–40 m^2), were selected in the stand of C.lanceolata. The large gaps showed a significant increase in light transmission ratio and air and soil temperatures and a decline in soil moisture, organic matter,N and P compared with the small gaps and the adjacent canopy-covered plots in the 0–10 cm soil. The differences in organic matter and nutrient levels found between the large and small gaps and the canopy-covered plots may be related to changes in environmental conditions. This indicated rapid litter decomposition and increased nutrient leaching in the large gaps. Moreover, the lowest levels of catalase, acid phosphatase and urease activities occurred in large gaps because of the decline in their soil fertility. Large forest gaps may have a region of poor fertility, reducing soil nutrient availability and enzyme activity within the C.lanceolata stand.