摘要
During the cultivation periods of 2001 (a dry year) and 2002 (a wet one), an experimental cotton field was irrigated using a subsurface and a surface drip system. Both systems included drip-lines 17-mm in diameter, with emitters discharging 3.8 l/h and spacing 1 m. The treatments included four irrigation levels. These were equal to 120%, 100%, 80% and 60% of the net crop water requirements during each irrigation interval. For their calculation the FAO56–Penman–Monteith methodology that estimates crop evapotranspiration was utilised. From the statistical analysis of the harvested cotton plantations it has been found that during the dry year (2001) the seed cotton yields were significantly higher where the subsurface irrigation system was used and the irrigation applications met the 80% and 60% of the crop water needs. During the two experimental years the higher irrigation applications, 120% and 100% of the crop water needs, gave seed cotton yields that did not differ significantly for both systems (subsurface and surface).