Management Following selection of lands for irrigation, the construction of facilities to serve the lands, and the preparation of the land for irrigation, subsequent protection of water resources falls in the area of management. Selection of crops and cultural practices With the transition from dryland agriculture to irrigation, the addition of the water changes the effectiveness of the system and, hence, a new system of management needs to be developed. Varieties of crops grown before irrigation were probably drought resistant. These drought-resistant varieties, however, are seldom capable of making maximum use of a full water supply. Accordingly, a new variety is needed to give the highest yields under the new soil moisture regime. New cultural practices are also required; thus, plant population can be increased along with rate of fertilization. Different weed problems will arise and new crop rotations will be required to more efficiently use the water supply. In a longstanding recognition of these facts, the Bureau's development farm program has been aimed toward developing new practices to enhance this conversion of land use. On development farms many tests have been made such as demonstrations of new varieties, crop variety trials, studies of irrigation water use, evaluations of varying fertility levels, and development of better irrigation practices. New methods of weed control have been used, use of cheaper water control structures has been demonstrated, and trials have been made of new land-forming techniques such as bench terracing. Each makes a contribution toward protection of our water resources. Zinc and other mineral deficiencies in soil Studies of the need for minor elements have been an important part of the development farm program. For example, studies on the Bureau's Deep River Development Farm resulted in the disclosure of a zinc deficiency. Ameliorative measures were undertaken and an extension of the studies to other areas in the Great Plains region has shown a rather widespread deficiency of this element. Participating with land-grant colleges and the Extension Service, such factors are being brought to the attention of farmers so that increased crop production and better use of water resources may be realized. The economics of crop production involving these innovations have been studied on the farms. Certainly the adoption of new techniques and materials hinges heavily on the profit the farmer may gain by using the new technology available to him. Salt water conversion, cloud seeding, and long-range weather forecasting Looking ahead to future developments, the Bureau is cooperating in programs aimed at augmenting fresh water supplies with salt water conversion, more successful cloud seeding, and better watershed management facilities. Another factor requiring attention to optimize water use in irrigated areas is better long-range weather foreNo only would these forecasts assist farmers in planning operations, but it should be possible, as improved forecasts become available, to integrate such forecasts into the daily operation of irrigation distribution systems. casts. Minimum soil tillage Increased attention in the future should be directed toward improvement and wider acceptance of minimum tillage methods to lower costs, reduce runoff, and reduce soil pulverization. This would be largely a problem of designing farm equipment, coupled with development of herbicides that eliminate or reduce the need for cultivation. Need for accurate water measurements If irrigation is to become more precise, devices will be needed to accurately measure water being delivered to various fields within a farm. A corollary development would involve more precise soil moisture gages capable of integrating the soil moisture throughout the root zone. Agricultural machinery From the foregoing, it is seen that progress in agricultural machinery development is closely interwoven with progress in soil and plant management fields. Thus, new developments in one field are certain to result in new developments in the other. The development of new crop management systems often requires the development of new machines to put that system into operation. Development of efficient herbicide sprayers and the constant-volume pumps for liquid fertilizer application may be cited as examples. On the other hand new machines may be developed which cannot be used unless there is a concomitant change in the management system. Involved are such factors as better land development, or different shapes and sizes of beds and rows. Added improvements Irrigated farms will never reach a development stage in which further improvements are no longer fruitful. The technical innovations of tomorrow will gradually make even the most efficient farm seem less efficient as new standards of performance become possible. Through cooperation gradual improvement in farm irrigation systems and methods is being made. Each year additional fields are more precisely formed to make the job of water control easier and more efficient. Individual fields are getting larger as better grading machinery economically overcomes topographic obstacles. Underground pipes are being laid for irrigation water deliveries, head ditches lined, and more efficient irrigation and cultural methods are being adopted by farm operators on reclamation projects. REVIEW OF NEW MATERIALS, EQUIPMENT, AND TECHNIQUES FOR WATER RESOURCE MANAGEMENT General WATER SUPPLY IMPROVEMENT The application of new materials and equipment to increase runoff from watersheds has been the subject of many experiments during recent years, but has not been applied on a large area basis. This is probably due to the unfavorable cost-benefit relationship involved in the utilization of presently available materials and equipment. Chemicals for eradication of trees and brush The use of various chemicals, largely in spray form (either from airplanes or ground-operated devices), for the eradication of trees and brush has been practiced where there are extensive growths of nonbeneficial water-consuming vegetation, particularly phreatophyte growth such as salt cedar and willows in the Rio Grande and Colorado River Valleys. Because of rapid regrowth of the vegetation following chemical spray, frequent reapplications are necessary and the cost of successful treatment is high. The actual net water salvage or increased streamflow resulting from treatment has not yet been conclusively demonstrated. The development of more effective and less costly chemical techniques for the eradication of water-consuming nonbeneficial vegetation is a highly desirable area of research. Asphalt sprays and chemicals to waterproof soils Application of various chemical materials to stabilize and waterproof soil surfaces has been tested on an experimental basis as a means of increasing runoff. It has been demonstrated, for instance, that certain materials will break, down soil aggregates, thereby creating slick surfaces with very low infiltration capacity. The application of such chemicals has largely been avoided because of the increased erosion potential, the cost, and the development of unsightly areas. Application of asphalt sprays has also been attempted on certain watersheds. While this approach should not materially increase the erosion potential, it still presents the problems of initial and maintenance costs and appearance. Before a major breakthrough can be achieved to increase runoff by soil stabilization and surface treatment, it will be necessary to develop a more thorough understanding of the physicalchemical natures of various soils and the ways in which they can be compacted or sealed, either by equipment or chemical techniques. Plastics to increase runoff Techniques to increase runoff through the application of ground covers such as plastics have been attempted on an experimental basis. Initial and maintenance costs are high, and the benefits of increased water yield are offset by negative benefits from lost utilization of the land and unsightly appearance. Such applications, however, have potential for very small watersheds that might provide a supply for small towns or industrial plants. Carbon black, hexadecanol, and plastic films to increase melting and runoff Materials such as carbon black have been applied to mountain snowpacks to increase rates of melting and runoff. As melt rates are increased, the opportunity for loss by evaporation may be correspondingly decreased, and a total increase in runoff volume may be accomplished. Under certain conditions, there is a possibility of creating flood hazards by this approach. Another experimental trial is to reduce evaporation from snowpack by application of hexadecanol to create a monomolecular surface effect. This may increase runoff volumes, but should not accelerate the melt rate. Fatty alcohols, particularly mixtures of hexadecanol and octadecanol, offer great promise for evaporation control; however, the performance of commercial products with very similar constituents may vary widely. Much information is needed to develop specifications to assure the use of the most effective and economical materials. The Bureau has been working closely with leaders in the industry toward improvement of the composition and physical form of fatty alcohols to be used in evaporation work. Other new chemicals offered by industry are continually being tested. The use of floating plastic films to reduce evaporation shows some promise. This technique appears especially advantageous for small reservoirs and ponds. New plastics and chemicals needed to reduce evaporation Industry is being looked to for assistance in the production of lowcost, high-quality, reliable chemicals which have a maximum evaporation reducing ability and complete public health acceptance. Industrial development of new plastics for evaporation reduction offers additional avenues for possible water conservation. STORAGE IMPROVEMENT Cationic asphaltic emulsion soil stabilization Soil treatment as a method to reduce seepage in storage facilities would be restricted normally to specific areas, such as those around a dam. The use of additives, soil stabilizers, or water repellents would not be considered positive enough for extensive use. Limited studies made by the Bureau on newly developed cationic asphalt emultion indicate that this material may be mixed satisfactorily with soils to give a watertight lining. Industry can perform a valuable service by formulating specific emulsions for this use in sufficient quantity to make economical application feasible. Butyl, plastic, and asphaltic membranes The use of butyl rubber or plastic membranes, asphaltic membranes, and asphalt mats, planks, or sheets, will generally be restricted to small ponds or very small reservoirs. Cost is the principal factor in limiting more extensive use. Portland cement grout blanket The in-place application of an impervious portland cement grout blanket is believed possible with techniques similar to those employed with asphaltic materials. Industry may be able to develop a relatively cohesive cement grout and accompanying nozzles to perform this work. Evaporation reduction from reservoirs Remarks on evaporation reduction under preceding discussion are generally applicable to storage facilities. In addition, techniques and equipment for monolayer application are important factors. Reclamation research is concerned with several different methods to apply chemicals in various forms to lakes and reservoirs. The size of reservoir will have a bearing on the method used. Large reservoirs not exceeding 5,000 acres surface area can be best treated with surface dispensers. For larger reservoirs, aerial applications appear the most promising. Continuous or automatic application of powders or water slurries may be most effective on small ponds, depending on wind conditions. In the latter case, even intermittent manual applications may be satisfactory. EVAPORATION-REDUCING MATERIALS NEEDED The current program embraces the latest physical forms produced by industry, and equipment development is accomplished with representatives of many industries. industries. The Bureau foresees great need in the near future for large quantities of improved evaporation-reducing materials and new equipment for dispensing them under field conditions. Such equipment and materials should be available for a wide range of applications. AROMATIC SOLVENT METHOD OF WEED CONTROL AND OTHER NEEDS Many chemical agents are used for weed control on Bureau projects because they offer the most economical method of controlling vegetation that must be removed for efficient project operation. The Bureau works closely with industry in laboratory and field evaluation of new materials and equipment that are most appropriate for accomplishing a specific result. The aromatic solvent method of aquatic weed control is an outgrowth of this cooperation. HERBICIDE AND PESTICIDE FOR FIELD TRIALS New materials effective under certain methods of application and on special weed problems are needed. Improvement in the adjuvant components of herbicide formulations such as surfactants and carriers is desirable. Manufacturers of various pesticide products work closely with the Bureau in developing and furnishing new materials for evaluation, supplying quantities for field trials, and supplying herbicides which conform to our special requirements. COATING PLANT NUTRIENTS A new industrial technique of coating plant nutrients for controlled solubility may be useful for regulating the rate of dissolution of some promising soil-applies aquatid herbicides. ANTIFOULING PAINT Paint manufacturers can assist with development of improved antifouling paints to prevent the attachment of algae and other sessile organisms to irrigation structures. 86564 062- 5 |