DEVAKUMAR, A. S.JAYALAKSHMI, H. G.2019-07-052019-07-052018-08-23Th-12123http://krishikosh.egranth.ac.in/handle/1/5810112011In order to sustain the productivity of degraded soils especially the acidic soils, one of the emerging approaches is biochar amendment. Soil amended with different concentrations of biochar showed a positive influence on growth of Calophyllum inophyllum seedlings. Considerable changes were seen in soil physical and chemical properties over 180 days after amendment. Important chemical change is reduction in soil pH, and the physical change is increased surface area. Increase in surface area will be effective in retaining the applied moisture and nutrients in the rizhosphere which can be accessed by plant. Higher surface area also improves soil porosity that improves root respiration. Increase in the major and minor nutrient concentrations was also evident suggesting sufficient nutrient availability. These changes are critical in chemical and biophysical interactions between plant and soil. Among four concentrations of rice husk biochar tried 10,000 kg ha-1 along with soil moisture maintained at field capacity is found to be most effective in increasing plant growth. There was a significant increase in plant growth after 180 days of treatment. It is important to note that the growth of Calophyllum inophyllum seedlings did not show noticeable reduction in growth when grown at 50 percent less moisture, but amended with 10,000 kg ha-1 of biochar. This has lot of implications in terms of conserving moisture, because moisture is a major natural resource in scarce under rainfed conditions. Further soil moisture is likely to decrease due to reduced rainfalls in tropical conditions due to global warming.ennullThesis