MICROIRRIGATION MANAGEMENT FOR DOUBLE-CROPPED VEGETABLES IN A HUMID AREA

Installation of microirrigation tubing below the tillage zone and/or a t wide spacings could make microirrigation more profitable for supplem ental irrigation of vegetable craps in humid areas such as the southea stern U.S. coastal plain. Two surface (surface 1 and surface 2, either one or two tubes/bed) and one subsurface (Subsurface 2, two tubes bel ow each bed) microirrigation treatments and two application frequencie s, high (three times per day) and low (one time per day), were evaluat ed for cowpea, green bean, squash, and muskmelon production in the spr ing seasons and for broccoli in the fall seasons. The same irrigation equipment was used in both years and for three years prior to the expe riment. 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 irr igation systems evaluated, the surface 1 system would be more profitab le for vegetable production in the southeastern coastal plain. All yie lds 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 satisfa ctory performance of the microirrigation tubing after five years of us e indicates a high probability that the longevity of this system may b e sufficient to make it profitable for use with lower-valued crops and other vegetable crops.