A close look at the other planets, now possible with space technology, should draw attention to the benefits of water and our responsibility of good stewardship. The hydrolic cycle of earth provides tremendous benefits.

The decision of when to irrigate forages is critical to both forage yield and quality. But irrigation decisions can also be costly. Wasted water is a loss in the pocketbook and an unwise use of resources.

Scheduling irrigation involves making a decision of how much water to apply and when. Three factors enter into the decision: water needs of the plants, water availability, and storing capacity of the soil around the roots. When to irrigate should be greatly influenced by water needs of the plants. Water availability also plays a role if water is not available at all times. Understanding how much water the plants can store near their root systems will help managers balance plant needs with water availability.

Water is continuously used by plants, but the rate of use varies depending on the atmospheric conditions, age, species, and growth stage of the plants. During irrigation, water is stored in the unsaturated soil available at a later time. It is worth noting that air is also needed in the soil. So soil flooded with water forcing air from the soil is not productive. But soil will hold onto water and plants must spend extra energy to capture it during parched conditions. Water that can be stored and applied continuously is best but if storage is too expensive or impractical, the soil can be used to store some water. The type of soil and its ability to store water is an important knowledge for wise irrigation.

Some plants exhibit physical characteristics when needing water, such as color changes (alfalfa turns darker) or wilting (sugar beets, grains). But not all plants respond so obviously and some physical changes may be the result of nutrient deficiencies. Fruit trees are an example of plants that need closer observation to determine water needs. Species selection should reflect the local availability of water. Alfalfa, wheat, and oats are species that flourish with plenty of early-season water. Corn and other species need water late in the season. Species with shallow roots will require more frequent irrigation than plants with taproots. Know the needs of the selected species to improve irrigation scheduling.

A look at the four seasons may provide a general understanding of soil and plant needs. If soil becomes very dry during the summer and fall and winter do not provide adequate rainfall or snow cover, moderate fall irrigation may prepare the soil for better seedbed preparation and seed germination. Water available in winter in areas where freezing does not occur may be wisely used for irrigation. Spring irrigation may be needed for germination and ititial growth of annuals. If water is more available in spring, as it is in many places, consider moistening the soil to 3.3 to 6.6 feet (1-2 meters) as water storage. Soil sufficiently wet will not benefit from additional spring irrigation which may cool the soil and delay germination. Summer is usually a time of irrigation. How often to irrigate is more likely the driving question. Light, frequent irrigating is usually the most beneficial.

Most forage crops are best harvested during vegetative growth stages. Since this is a time of continuous growth and early root development, water should be available throughout this stage for most species. Perennials with developed taproot systems, heavier irrigation may be better. If temperatures are extreme frequent irrigations may cool the plant. Consider the growth stage of the plants when irrigating.

When water is moved and distributed there is water lost is the move. This type of loss, water conveyance, should be minimized. When water is applied, there is additional inefficiency. Some plants receive too much (those around the sprinklers) while others receive too little (those on the field edges). Too much and too little reflect the ability of the soil to hold the water. Most water loss during application comes from runoff and deep percolation (water passing through layers down deep into the soil).

Having moved and applied the water, a look at how the water is being used. Most would think overwatering is the greatest misuse of water but if water application is not wasted but still not enough to stimulate improved yield and quality the water is not well used. You can be 100% efficient and still unproductive. Irrigation is only successful when accompanied by a commitment to provide sufficient water. Similarly, water must be available by the desired plants and not lost to weeds or surface evaporation. Soil permeability, plant spacing, ridges, and timing of irrigation will influence how much of the applied water is used by the desired plants. A key to guide irrigation might be: Place sufficient water where it can most efficiently be used by the plant roots and prevent it from being lost. There are many opportunities for managers to fine tune their stewardship of water.

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