Samarappuli, L.Yogaratnam, N.Karunadasa, P.Mitrasena, U.2012-06-252012-06-251992Journal of the Rubber Research Institute of Sri Lanka72pp.39-48https://dl.nsf.gov.lk/handle/1/8713Studies carried out on the use of Neutron Probe in soil/water relations indicate that this can be used as an effective technique in immature Hevea plantations. It had been possible to establish a fairly reliable calibration curve for the subsurface soil 10 - 160 cm the calibration curve obtained is moisture content, Qv = 0.52 CR - 0.39, where CR stands for Count Ratio. It appears that during dry period, distances varying from 0 - 1.2m from the trunk of the tree are suitable for assessing the water content of the soil profile. The available soil water storage capacity of 104.2 mm with the upper lower limits of 235.5 131.3mm, respectively, is likely to be the amount of water that is available to the plants, both rubber covers over a period of 12 months.AgricultureSoil MoistureArticle