Applications of stable and radioactive isotopes in soil science.

Development and refinement in nuclear techniques have revolutionized agricultural science. In soil science, radioisotopes have proved a blessing par excellence in terms of their potential in solving many mysteries. Many researchers have worked with radioactive isotopes (radiotracers) and have found them quite helpful in soil fertility management for quantification of biological nitrogen fixation, availability of nutrients in the soil, fertilizer use efficiency, residual effect of applied amendments, salinity of soil and water, methods of fertilizer application and relative efficiency of applied organic manures. Total evapotranspiration and its partitioning into contributing components in many ecosystems have been successfully quantified through this technique. The suitability of plants to drought or salinity conditions was also evaluated using radiotracers utilizing the inherent concept of δ 13 C discrimination in plants. Radioactive isotopes 10 Be/ 9 Be, 14 Si/ 13 Si, 87 Sr/ 86 Sr and 14 C play an important role in soil erosion, soil formation and clay mineralogical studies. 15 N isotopic dilution techniques are also finding favour in groundwater monitoring, soil water recharge, soil and water pollution assessments.