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Footnotes Continued - Annualized Adverse NED Effects b. Crop residue use is maintaining, on or near the soil surface, the unha~vested plant parts. Sufficient residue encourages air and water movement into and through the soil. It maintains and improves soil structure. Crop residue use and reduced tillage encourages root development, controls soil erosion and minimizes soil compaction. Biological activities decompose crop residue. This process releases nitrogen, plant nutrients and compounds beneficial to soil condition. The results are a more porous soil structure, stimulation to root growth and increased water available to plants. Crop residue from an adequate conse~vation c~opping system provides a minimum of 1,000 pounds of plant aftermath every year. Cotton residue must be mixed with the soil near the first of the year to control insects and disease. This may leave the soil unprotected between January to April. Therefore, sandy soils may be subject to wind erosion. This erosion can be reduced by providing a cover crop, a rough soil surface or by windbreaks and barriers. Crop residue use with reduced tillage minimizes soil compaction. Crop residue use and minimum tillage has been estimated to cost three dollars per acre. c. Irrigation water manage~ent consists of making measurements and controlling the ratet amount and timing of irrigation water. This is a planned and efficient manner of suppling water according to plant needs. The irrigation water management plan provides for measuring soil moisture and applying necessary water during various stages of plant growth. This means monitoring the moisture in the soil then applying water at the right time and in the right amount. This also reduces the numbe~ of times plants are over or under irrigated. However, plants always have the water they need. This irrigation water management plan considers the site limitations of the specific conservation irrigation system. A system design considers soil, field slopes, irrigation ~un lengths, ditch capacity and structures. Laser land leveling and large field outlet (jackgates) structures were used on -s broad scale for the first time in Arizona in the Wellton-Mowhawk project. Uniform irrigation surfaces were made possible by laser controlled leveling equipment. Specially designed turnout structures consisting of field outlets, aprons and energy dissipators were required. These are capable of controlling over 20 cubic feet per second flows and were used consistently. Large heads of water and uniform soil surfaces helped reach the on farm goal of better water use and reduced deep percolation. An irrigation water management plan is applying water uniformily according to plants needs. It requires application records to illust~ate crop response by water use. These records require organized planning and consistently preserving evidence, either - good or bad. -25-