Avaliação de um sistema de irrigação por aspersão em uma área do município de Mossoró-RN.

Abstract

A study was conducted at the "Rafael Fernandes" Experimental Farm of the "Escola Superior de Agricultura de Mossoró", at Mossoró,RN, Brazil, with the objective to evaluate the performance of a sprinkler írrigation system. The methodology used was that proposed by Merriam and Keller (1978), The tests were carried out under different climatic conditions using 12 and 18m spacing between sprinklers along the lateral and risers heights of 0 . 5 ; 1.0 and 2,0m. The parameters studied were the average precipitation, water distribution uniformity, and water losses by evaporation. The results showed that the average precipitation was not affected by the riser height. The best water uniformity distribution were obtained with the riser at 2m high and with the smallest spacings (12 x 12 and 12 x 18m). The 18 x 18m spacing presented satisfactory water distribution uniformity. In general, the water distribution uniformity decreased with increasing windspeed and the effect of this climatic factor was more pronounced with the riser at 2m high. The climatic factors (windspeed, temperature and air relative humidity) had greater effect on the water losses by evaporation than the riser height or spacing between sprinklers. The losses increased significantly with increasing windspeed. The tested speeds (2.34 to 6.28 m/s) caused water losses by evaporation that ranged from 6,30 to 19.75%, Under the climatic conditions of Mossoró city and considering the specifications of the tested sprinkler írrigation system, it is advised the use of the sprinkler spacing of 18x18m and the riser height of 2m, with the irrigations being conducted preferably at morning.