A Management Strategy of Using Gypsum for Reclamation of Salt Affected Soils

Field sampling was done from a farmer's field in Paharpur Salinity Control and Reclamation Project (SCARP) area in Dera Ismail Khan district, North West Frontier Province of Pakistan at a regular grid spacing of 14 m × 14 m. Surface samples (0–0.25 m) thus collected were analysed for soil pH, electrolyte conductivity and gypsum requirement. These data were used to develop a management strategy of using variable rates of gypsum for reclamation purposes. Statistical analysis of the data showed that electrolyte conductivity and gypsum requirement had a very high coefficient of variation. Application of geostaistics to these data showed that all the three measured soil properties were spatially distributed in the field. Semivariograms for soil pH were described using linear model while spherical model was the best for fitting EC and GR data. The range of influence for the omni directional semi variograms was about 31 m for EC and about 51 m for GR. GR was found as the best criterion for dividing the field into difftrent management zones. The field was divided into three management units based on this criterion for reclamation purposes.