Impact of Pollutants on Paddy Soil and Crop Quality

Paddy soils, used most often for rice cultivation, are flooded and submerged soils that exhibit prominent set of properties as result of extensive saturation. Among these, redox potential (Eh) and pH fluctuations are the most important characteristics of paddy soils indicating variation in oxidation-reduction reactions of soil components like oxygen (O2), nitrogen (N), iron (Fe), manganese (Mn), sulfur (S), and carbon (C). Reckless use of inorganic fertilizers and pesticides and irrigation with polluted water for intended rice crop yields have raised heavy metal pollution problems especially lead, cadmium, and arsenic in soil environment. Besides, various macro- and micronutrients including nitrogen and potassium and excess of salt water and fluorine also negatively affect the crop quality and yield. Accumulation of heavy metals and other pollutants in soil and their introduction in food chain through uptake by rice and vegetables are of major concern. Therefore, management practices including artificial submergence, plowing, puddling, organic manuring, leveling, liming, and fertilization play vital role in development of paddy soils. Various techniques are adopted for remediation of polluted paddy soil that includes excavation, chemical stabilization, soil washing, phytoremediation, and thermal desorption. Further investigations are required for identification of soil flora and fauna for remediation purposes.