Managing Water: Economics of Complex Systems

To the many American farmers in the Midwest and East, water management for crop production is often left to the whims of nature. This laissez faire attitude may be sufficient in those areas experiencing regular and predictable rainfall. But in other areas of the United States, drought and reduced product quality are highlighting the need for water management mostly through the use of irrigation. In the and and semi-arid West, the shortage of water available for irrigation limits production. Without water, production of crops is not practical even with abundant land and favorable climate. Water costs, irrigation system costs, environmental concerns, and the complexity of matching available water to Plant requirements all dictate sound water management decisions.

Planning, implementing, and controlling are fundamental to successful water management as they are to all aspects Of farm management. Equally important is the understanding that water is a limited resource and that crop production, water management, and water delivery (irrigation) cannot be considered separately.

Crop Management Systems. A crop management system is a set of crop production activities used in a specific area. Crop management systems include the activities of seasonal land preparation; crop seed selection; application of fertility supplements; and crop protection from weeds, insects, and disease. A crop management system also may include the physical application of water to supplement soil moisture.

Water Management Systems

Water management systems are those parts of crop management systems that modify soil moisture to enhance plant growth. A water management system includes the use of tillage practices and crops based on their suitability for the local environment including the availability of water. Practices such as fallow cropping, contour cropping, terracing, and land drainage directly increase or decrease soil moisture. Plant varieties and planting dates determine water needs. A water management system also includes some method of obtaining and distributing water. This method commonly involves an irrigation system; however, "water harvesting" can supplement irrigation water by using land shaping techniques and soil conditioning to direct water to plants.

Water costs, irrigation system costs, and the complexity of matching available water to plant requirements highlight the importance of sound water management for crop production. (USDA Photo by Ron Nichols 89BW0917)

Irrigation Systems

Irrigation systems are techniques and technologies that capture, distribute, and add water to the soil to increase plant production. Traditionally, irrigation systems consisted of ditches designed to use gravity to move water from one location to another. This is still a popular irrigation method in some areas, although electric motors and combustion engines now make pumping irrigation water a high pressure through pipes and sprinklers commonplace.

New low-pressure irrigation method! such as drip and trickle systems that apply limited amounts of water directly around individual plants have become popular. System capacity, energy requirements, and water quality and quantity requirements are factors the decision-maker must consider when planning ar irrigation system.

Planning and Implementing Water Management

Managing water requires recognizing the crop's water needs and devising a plan for addressing those needs. In the arid West, crops almost always face a level of risk because of inadequate or poorly distributed rainfall that requires additional water as an input. In other areas of the country, risk levels are lower, as the potential losses from not providing additional water are not as great.

Of equal concern is the availability of water. Many areas have soils and climate suitable for growing many types of crops, but seasonal rainfall limits choices. The problem is compounded by a lack of water available for irrigation. In some cases, water may be available at a prohibitive cost or of an unacceptable quality.

Once a plan is developed, the farm manager must consider the financial aspects of planning for water management. These include evaluating the longterm capital needed for investment in irrigation wells (where appropriate), delivery pipes or ditches, and water application technology, as well as determining whether the plan is likely to generate enough cash to pay off borrowed capital. Flexibility should also be considered. Can crops and water application rates easily be altered?