Supplementary irrigation in forages: towards sustainable intensification in productive systems with grazing

Abstract

The objective of this work is to develop information to improve the management and design of irrigation in grazed pastures, with rational use of water and soil. Two irrigation strategies were evaluated, for fescue and alfalfa, in plots with grazing and under controlled conditions (lysimetry). The water consumption of both crops was determined by lysimetry and the crop coefficients were adjusted (the results are being processed). In fescue there was a difference in the annual dry matter yield of the irrigated treatments compared with the rainfed, but the irrigated treatments did not differ from each other. The average yield of the irrigated treatments was 41% and 56% higher than that of the rainfed for the first year and second year of the pasture, respectively. The annual irrigation amount was 248 and 246 mm for frequent irrigation and 179 and 178 for spaced irrigation. The management of spaced irrigation meant a saving of 38% of the water pumped compared to frequent irrigation. In alfalfa, the accumulated production (30 months) did not show a significant difference between the irrigated treatments, but it did between irrigated and dry land. Seasonal productivity indicates the convenience of irrigating alfalfa in summer, with a 43% increase in yield in the second year and 4.3 times more in the last year. Management with spaced irrigation and irrigation sheets that do not return the soil to field capacity, increase the effectiveness of precipitation, saving water and energy for irrigation.