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Irrigating with a micro-irrigation (drip) system offers improved crop quality and yield with significant savings of energy and water. To deliver these benefits reliably, a grower's system must include chlorinations or some other effective water treatment program to prevent clogging, the most common problem of micro-irrigation. Step-by-step procedures of chlorination of micro-irrigation systems are discussed. Injected into micro-irrigation systems, chlorine kills the micro-organisms—bacteria, fungi and algae—that may be in a water source and are the most common system cloggers.
Drip-irrigated tomato (`Sunny') plants were treated with five levels of fumigant in combination with three levels of mulch. Fumigants were metham sodium at two rates, 475 and 950 L/ha, a 67% methyl bromide + 33% chloropicrin formulation (164.5 kg/ha, and a 98% methyl bromide + 2% chloropicrin formulation (329 kg/ha). Mulching levels were 1.25 mil silver on black polyethylene (plastic), blue-black latex mulch sprayed over the plant beds, and no mulch. Plants treated with metham sodium (950 L/ha) had a significantly higher number of marketable fruit than plants treated with no fumigant or the 98% methyl bromide + 2% chloropicrin formulation. Marketable fruit weight was not significantly affected by the five fumigation levels. Plants grown with black plastic mulch had a significantly higher marketable yield than plants grown with no mulch, 58,100 kg/ha vs. 50,800 kg/ha, respectively. The level of mulching did not significantly affect the marketable number of fruit.
In sweet corn field plots in Alabama, urea-ammonia nitrogen was applied to the soil through underground and aboveground drip fertigation systems. Dry nitrogen in the form of ammonium nitrate was surface band-applied as a control. Nitrogen rates of 67 kg/ha and 135 kg/ha were applied in either 2 or 4 applications by each of the 3 methods. P and K fertilizers were applied to all treatments in a dry form according to soil test recommendations. The underground drip pipe was placed 23 cm beneath the soil surface in each row. Nitrogen (wet or dry) rate of 135 kg/ha produced greater sweet corn yield than the 67 kg/ha rate with no effect of application number on yield in 1988, when rainfall was less than adequate. In 1987 and 1989, when rainfall was adequate, no differences occurred in yields regardless of number, rate, or method of application of nitrogen.