Delta Micro Irrigation Final Report

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DISCUSSION: There was a significant decrease in the amount of water used between the drip and furrow irrigated plots. A similar decrease in water usage has been seen in other studies comparing drip and furrow irrigated cropping systems. In 2000, a study comparing the impact of furrow and above- ground drip irrigation on the growth of hybrid poplars was initiated at the Rogers Mesa Research Center After the first year of study, researchers found that significantly less water was used in the drip irrigated plot. In addition, the average tree diameter in the drip irrigated plot was not significantly different than the furrow irrigated plot. The total yield per acre of squash resulting from the combination of drip irrigation and plastic mulch are similar to yields found under the same combination in Mexico. However, Colorado squash has much higher sugar levels. The Brix level of Mexico grown Kabocha squash typically ranges from 9-11 %, while average Brix levels in this study range from 11.6 to 16.37%. There was no significant differences in yields between the different colors of mulch. In 1998, the plots which had subsurface drip but no mulch had yields which were as high as those treatments with plastic mulch. However, in 1999, the subsurface drip irrigated plots with no mulch yielded significantly less than the mnlched treatments. Those treatments which were started with transplanted squash plants had higher total yields than those in the direct seed plots in 1998, with the exception of the plot which was snbsurface irrigated and had no mulch. This increase in yield may be in part due to lengthening of the growing season as a result of transplanting. The transplanted squash started flowering approximately 20 days before the direct seeded squash plants. However, an economic study would have to be conducted in order to determine if the extra costs associated with transplants would be profitable for growers. In some of the plots there was a significant amount of culled squash. A major part of the culls was due to sunburn. The skin of the Kabocha squash is very sensitive to sunburn. A good canopy cover is necessary to protect the squash from sunburning. In this study the rows were farther apart than would be found in a commercial setting. Thus squash growing in between the mulched beds would not always have an adequate covering of leaf canopy. The major pest problems were weeds and one insect species, the squash bug, Anasa tristis. Powdery mildew, Erysiphe polygoni, was spotty throughout the field but weather conditions never attained optimum conditions to create an outbreak serious enough to affect the squash plants. Weed competition may have depressed yields in the furrow irrigated plots. The major weed pests in 1998 and 1999 were common mallow (Malva neglecta Wallr.), lambsquarter (Chenopodium berlandieri Moq.), red root pigweed (Amaranth us palmeri S. Wats.) and bindweed (Convolvulus arvensis L.). A combination of the herbicides, 2-4-D (Dow AgriSciences, Indianapolis, IN) and Roundup (Monsanto Co., St. Louis, MO) were used on the furrow irrigated and non-mulched plots until the plants were too large to safely spray around. At this point all weeding in the non-mulched plots were handweeded on a weekly basis. In the mulch plots, 2-4-D and Roundup were used to control weeds in the open space between the mulched beds until the vines covered this ground. After the vines filled in between the mulched beds, weeds were pulled when they broached the leaf canopy of the squash plant. These weeds were not competing with the squash plants. Pulling was done so as to eliminate potential seed sources. Squash bug populations were treated with Diazinon AG (Novartis Crop Protection Inc., Greenboro, NC)) twice per season. Squash bug populations started building at the outside of the plots and moved in towards the middle of the squash plots. In 1998, squash bugs may have had an effect on the outermost row of the squash trial. This was the location of the black plastic mulch, transplanted, drip irrigated plots. Squash bugs are very difficult to control, with or without chemicals. Identification and treatment of squash bugs was made difficult by their clumped distribution in the squash field. Scouting for early infestations is also difficult because the squash bug are secretive in nature, and tend to stay near the base of the squash plant. The plastic mulch may have exacerbated the problem by providing a hiding place for the squash bugs at the point where the plant is growing through the mulch. The struggle for water and it's end use is surely to increase in the future. Currently, agriculture is the major user of water in the state of Colorado. But there are changes on the horizon as urban demands continue to escalate. This increase in usage in the urban areas will put more pressure on agricultural producers to conserve water. 6