Reclamation of saline and sodic soil by using divided doses of phosphogypsum in cultivated condition

In this method, while the land is under cultivation, small quantity of phosphogypsum (PG), which is less than the theoretically required doses and irrigation water, were applied for reclamation purposes. A field experiment was conducted in Saraykoy-ANKARA for three years. As amendments, a total of 7.5 and 15.0 t ha-1 PG doses were applied to the field plots of 100 m2 in three consecutive years. In this reclamation method, cultivation process and plant roots contributed to the improvement of soil physical and chemical properties. Following the divided application of PG doses, a total of up to 7.5 and 15.0 t ha-1, improvement ensured by the applications were 10 and 8 times more than expected results. This was calculated by using gypsum requirement (GR) equation. It was found out that in order to leach 50% of the soluble salt from the soil profile, required depth of leaching water is approximately 2.3 times of soil depth to be reclaimed. Divided dose of amendments allow a more flexible planning in the reclamation process.   Key words: Saline-sodic soil, alkaline, reclamation, industrial gypsum, phosphogypsum, exchangeable sodium, divided amendments application.