Impact of soil pollutants on diversity and abundance of earthworms in cauliflower crop
Imran Ahmed Raja, Nazia Ehsan, Naureen Rana and Anas Sarwar Qureshi
The present study was designed to elucidate the effect of soil pollutants on diversity and abundance of earthworms in a winter vegetable crop (cauliflower). Collection was done through November to January and samples were anesthetized in alcohol, preserved in 10% formalin solution. The soil and water analysis was performed by atomic absorption spectrophotometry. The Shannon-Weiner Diversity Index (Hʹ) of sampling site (Chack 204) was 1.803, evenness was 0.302 and dominance was 0.831. A significant difference of abundance was observed (t=12.62, p=0.0066 at p<0.05). The pH of sewage water was recorded as 5.833 and sewage water irrigated soil was 6.28, whereas pH of canal water was 7.66 and canal water irrigated soil was 7.88. A significant difference of physico-chemical characteristics of sewage water and canal water was observed as following pH, p=0.0043), DO (p=0.0112), TDS (p=0.043), TSS (p=0.015), turbidity (p=0.0028), Pb (t=11.4 p=0.0076), Zn (p=0.0192) except temperature and heavy metals including Co, Cd, Cr, Mg and Ca. Similarly, significant difference of physico-chemical characteristics of sewage water irrigated soil and canal water irrigated soil was recorded as for Pb (p=0.0014), Zn (p=0.0001), Cr (p=0.0366), Mg (p=0.001) and Ca (p=0.0003) except temperature, Co and Cd. Significantly positive correlation occurred between earthworms abundance and temperature at site 1 (p=0.0246) and at sampling site 2 (p=0.0156). It is conceivable from the present data that earthworm population proves to be better and beneficial for non-polluted soil. Environmental factor, such as temperature is very important for earthworm management. The abundance of earthworms was low in cold months of winter. The harsh condition of winter seems to be limiting factor for abundance of earthworm. Acidic pH and high concentration of heavy metals badly affect the diversity and abundance of earthworms.