Agassi, M., Soil Erosion Research Station, Ruppin Inst., P.O. Emeq Hefer, 60960, Israel
Shainberg, I., Inst, of Soils and Water, ARO, The Volcani Center, Bet Dagan, 50250, Israel
Warrington, D., Inst, of Soils and Water, ARO, The Volcani Center, Bet Dagan, 50250, Israel
Ben-Hur, M., Inst, of Soils and Water, ARO, The Volcani Center, Bet Dagan, 50250, Israel

In ridged and furrowed potato fields, we studied the beneficial effect fo phospho-gypsum (PG) and of the diked-furrows technique on runoff and erosion control. Spreading 10 t ha−1of PG over the soil surface after seeding reduced runoff from the field 6-fold and reduced soil loss from the ridges to the bottom of the furrows 20-fold. In the diked-furrows treatment there was no runoff at all and ridge erosion was similar to that of the control. The effect of 5 and 25% slope and addition of PG on runoff and erosion from the same sandy soil (Typic Rhodexeralf) was studied in the laboratory using a rain simulator. When the slope was increased, soil loss increased 2-fold and 12-fold in the PG treatment and the control, respectively. PG was very beneficial in preventing soil erosion from the steep slope. The dissolution of PG by the rainwater and the ensuing release of electrolytes decreased soil erosion by: (1) increasing the fraction of rain that penetrated into the soil, (2) increasing the stability of the aggregates at the soil surface, and (3) enhancing the rate of entrained sediment deposition. © 1989 The Williams & Wilkins.