USE OF AN HYDROPHILIC POLYMER TO IMPROVE WATER STORAGE AND AVAILABILITY TO CROPS GROWN IN SAND DUNES .1. CORN IRRIGATED BY TRICKLING

The polyacrylamid (PAM) hydrophilic gel Agrosoak(R) was tested as a so il conditioner for improving water availability to crops grown on sand dunes. Com (Zea mays L.) was grown in the field, in a factorial desig n array using four rates of Agrosoak (0.00, 0.15, 0.30, 0.45% by weigh t in the upper 25 cm of the soil), three water amounts (70, 85 and 100 % of the recommended Class A evaporation pan ratio), and two water sal inity levels (1.2 and 6.5 dS.m-1). Irrigation and fertilization were p rovided by trickling. The water storage capacity of the soil increased with the rate of Agrosoak but the applied water was accumulated and s tored in the vicinity of the emitters leaving relatively dry sections between the drippers. This caused a reduction in the density of the pl ants. Even so, yield components, except shoot dry weight per meter (co b yield per plant and per meter, and shoot dry weight per plant) incre ased with the Agrosoak application rate. Concentrations of nitrogen an d sodium in the leaves increased, but phosphate and potassium were una ffected by the Agrosoak application rate with the use of fresh water o r brackish water. The use of Agrosoak did not avoid salinity damage to the plants. The results show that the use of trickle irrigation with PAM soil conditioner require a reevaluation of the method of irrigatio n.