Water balance in a young almond orchard under drip irrigation with water of low quality

The water balance of young almond trees (Amygdalus communis L. cv. Atocha grafted onto 'Pestaneta' almond rootstock), drip-irrigated with low quality water, was determined during two and a half years. Four irrigation treatments based on the reduction coefficients of Class A pan evaporation were used to determine the water uptake of this species, although the water balance was only determined in the highest and lowest irrigation treatments. The water balance parameters for these treatments are shown and discussed in detail. The ETc calculated for the two treatments differed markedly during summer, reaching values of 4.3 and 3.3 mm per day (for the highest and the lowest irrigation treatments, respectively), during the last year of the experiment, coinciding with the months of highest evaporation. When various vegetative and productive parameters were studied in relation with the irrigation treatments, no clear conclusions were reached. This was mainly due to the excessive salinity of the irrigation water used (4.26 dS m(-1)), which limited the trees' vegetative growth and production rate, which in our case was 1583 kg ha(-1) compared with the 2955 kg ha(-1) obtained when less saline irrigation water (0.8 dS m(-1)) and similar irrigation water volumes (408 and 368 mm, respectively) were used for the same cultivar (Atocha). (C) 2000 Elsevier Science B.V. All rights reserved.