As drought conditions continue to persist across the state, the greater the need for techniques that reduce the risk of crop failure associated with these conditions. Since drought conditions are not unusual occurrences in Texas, such techniques should be incorporated into management practices of all vegetable production operations. As the state’s population continues to climb, less water will be available for crop production and the urgency of incorporating these techniques into standard production practices will increase.
In an attempt to encourage the adaptation of the most advanced techniques for managing limited water resources in vegetable production, a team of scientists from Texas AgriLife Extension Service conducted a series of demonstrations in the Winter Garden area. The results of two of these demonstrations are presented in this article.
The initial demonstration was established in cooperation with McFaddin Farms of Uvalde, Texas. In this demonstration, water-use efficiency of a Rainfall Capture system (RFC), and drip irrigation plus plastic mulch, was compared with that of conventional furrow irrigation in cantaloupe production. Drip irrigation was scheduled, based on soil moisture tension as indicated by tensiometer at a 12-inch depth. When a 45 centibars tension was reached, one inch of irrigation water was applied. The cooperator scheduled the irrigation in the furrow block using his normal procedure. No supplemental water was applied in the RFC block.
The RFC system was established on October 26, 1993, in order to capture and store sufficient moisture throughout the fall and winter months for use on cantaloupe to be grown the following spring. This system consisted of establishing two polyethylene-lined mini catchment basins, 22 inches apart, on an 80-inch wide raised bed. Each basin was approximately 10 inches wide across the top, 4 inches deep, and 3 inches wide across the bottom. Holes, spaced 3 feet apart, were punched in the plastic and filled with a bit of soil.
The drip- and furrow-irrigated blocks were established on April 4, 1996, and all blocks direct-seeded with the cantaloupe variety ‘Caravelle’ on April 12. Fruit yield and water-use data obtained in this demonstration are presented in Table 1.
|Irrigation methodz||Total yield (lbs/A)||Cull yieldy* (lbs/A)||% Marketable||Irrigation amt. (inches)|
|RFC (rainfall capture)||20,990||1,868||91||0.0|
|RFC + 2 Irrigation||19,928||2,650||87||2.0|
A second demonstration was established in 1995 in conjunction with Cargil Farms of Uvalde. In this demonstration, comparisons were made between drip irrigation, RFC, and plastic-mulched furrow-irrigated blocks. Due to weather conditions and scheduling conflicts, the RFC system was established just prior to planting on April 6. All blocks were direct-seeded, using the variety ‘Mission’, by April 15. The data obtained from this demonstration is shown in Table 2.
Drip irrigation greatly increased yields, as compared to furrow irrigation, at both locations (25,812 lbs/A and 29,621 lbs/A, compared to 13, 367 lbs/A and 16,988 lbs/A, respectively, for the drip and the furrow). In addition, applied water was reduced 16-20 inches in the drip blocks, respectively, at the Cargil and McFaddin locations. Surprisingly, under the conditions of these demonstrations, the RFC system resulted in higher yields than furrow irrigation.
A good measure of applied water-use efficiency is the ratio of total gallons of water applied to pounds of fruit produced. Ratios of 4.3 : 1 and 50 : 1 were obtained at the McFaddin farm from drip and furrow, respectively, whereas 7.4 : 1 and 33.4 : 1 were recorded at the Cargil location.
Approximately the same total volume of water (rainfall + irrigation water) was required to produce a cantaloupe crop exceeding 25,000 lbs/A with drip irrigation in both years of these demonstrations: 17 inches. In 1994, 4 inches of irrigation water was applied, via drip, while 13 inches was received from rainfall. In 1995, 8 inches of drip-irrigation water was accompanied by 9 inches of rainfall. Although sufficient rainfall was received during these demonstrations to enable a crop to be produced, fruit size was slightly reduced. Consequently, RFC alone is not a viable replacement for irrigation, but rather a supplement to irrigation in most areas. Additional work is needed to determine what effect RFC can have on the needs of crops watered by drip, furrow, and sprinkler methods.
Although both of these systems can increase production costs significantly, they may be required for successful production in the future if drought conditions persist and/or water for production becomes limited as a result of increasing population.
Adapted from the original publication by Frank J. Dainello, PhD, Extension Horticulturist – Commercial Vegetable Crops, Department of Horticultural Sciences, Texas A&M University
Publication updated April 2011