ChileanJAR

Water economy was studied in two factorialtrials in dry land wheat sowed in 1983 and 1984 in the coastal range of chilean VI Region, under a marine-mediterranean climate and predominantly clays soils. The factors studied were: variety (early vs. semi.early). date of seeding (early vs. normal), nitrogen fertilization (none vs. 150 kg N/ha). During the growing period rainfall was 690 mm in 1983 and 1.113 mm in 1984. Pan evaporation in the same periods were 660 mm and 764 mm. Field capacity for hold available water was 204 mm in 1983 and 268 mm in 1984. Losses due to percolation and run-off averaged 54 and 55% of total suministred water in 1983 and 1984, respectivily. Evapotranspiration since the end of winter till harvast, in the nitrogen fertilizad treatments, averaged 172 mm in 1983 and 248 mm in 1984. Spring evaporation in the control plots (without vegetation) was 150 mm in 1983 and 246 mm in 1984. The ET_a/ET_o relation in the year 1984 was close to K_c values stated in the FAO 33 Irrigation and Drainage Manual, except during the period of grain ripening. This data shows that in this year the crop did not suffer important water delicit. Inversely in the less rainy year 1983, the relalion ET_a/ ET_o was notoriously smaller to K_c, during the heading and grain formation periods. That shows that the growing of the crop was probabily impaired in this periods, by water delicit.