Microirrigation Management for Double-cropped Vegetables in a Humid Area

Installation of microirrigation tubing below the tillage zone and/or at wide spacings could make microirrigation more profitable for supplemental irrigation of vegetable crops in humid areas such as the southeastern U.S. coastal plain. Two surface (surface 1 and surface 2, either one or two tubes/bed) and one subsurface (Subsurface 2, two tubes below each bed) microirrigation treatments and two application frequencies, high (three times per day) and low (one time per day), were evaluated for cowpea, green bean, squash, and muskmelon production in the spring seasons and for broccoli in the fall seasons. The same irrigation equipment was used in both years and for three years prior to the experiment. There were few yield differences among irrigation treatments, both for tubing placement and irrigation frequency. There was no yield reduction for the surface 1 treatment, although it received only half the irrigation volume as the other treatments. Therefore, for the irrigation systems evaluated, the surface 1 system would be more profitable for vegetable production in the southeastern coastal plain. All yields were as high or higher than industry yields, except for broccoli, which was slightly lower. These results demonstrate the feasibility of multicropping vegetables with the same irrigation system. The satisfactory performance of the microirrigation tubing after five years of use indicates a high probability that the longevity of this system may be sufficient to make it profitable for use with lower-valued crops and other vegetable crops.