USE OF AN HYDROPHILIC POLYMER TO IMPROVE WATER STORAGE AND AVAILABILITY TO CROPS GROWN IN SAND DUNES .2. CABBAGE IRRIGATED BY SPRINKLING WITH DIFFERENT WATER SALINITIES

Agrosoak(R), a polyacrylamid (PAM) hydrophilic gel was tested as a soi l conditioner for increasing the water absorbing capacity of sand dune s. This enabled the replacement of an expensive drip irrigation system with an inexpensive, more commonly used sprinkling method. Cabbage (B rassica oleraceae L.) was irrigated by sprinkling with double line-sou rce technique to achieve different water amounts and salinity levels ( 1.9-7.8 dS.m-1), and with different concentrations of Agrosoak added t o the soil (0.00, 0.15, 0.30, 0.45% by weight). Agrosoak increased wat er availability which indeed contributed to the increase in the yield of the crop irrigated with saline water. However, it was confirmed tha t this particular PAM enriched the soil solution with Na+ reducing the yield when irrigated with fresh water. The results indicated that Agr osoak may have increased the water use efficiency with plants grown on sandy soils when the crop is tolerant to Na+. The use of a modified t ype of PAM, that will not release sodium to the soil solution, is reco mmended.