Saturday, November 01, 2014

Managing Drought Risk on the Ranch

Finding Feed: Alternative Forages

Selecting the right forages and using efficient management practices with limited irrigation water or under drought conditions can result in reasonable forage production with reduced input costs. Seeded forages are usually classified as cool- or warm-season and can be either annuals or perennials.

Water Use of Alternative Forages

In general, warm-season forage crops are more water use efficient than cool-season crops. Annual forages are more water use efficient than perennial forages. Legumes tend to be less water use efficient than grasses; annual legumes are more water use efficient than perennial legumes. 

Water use efficiency estimates for warm-season annual grass forages such as foxtail millet, sudangrass, and sorghum-sudangrass hybrids range from 2.5 to 3.5 inches of water per ton of yield. Efficiency for oats, a cool-season annual, is estimated at 4.5 to 5.5 inches per ton; cool-season perennial grasses at about 5 to 6 inches per ton; and alfalfa at 6.5 to 7.5 inches per ton. 

Under limited water allocations, forage water use efficiencies will be different in terms of the total pounds of dry matter produced per inch of water applied than when crops have the water amounts needed to express their full production potential. 

Water use efficiency information can be used as a guide along with establishment, fertilizer and harvesting costs to determine which forage will be the most likely to be profitable in a producer’s production system.

Stocking Rates on Alternative / Emergency Forages

Estimating the potential stocking rate for grazing alternative forages can be challenging.

A general guideline is that one can estimate one AUM of grazing for every 1500 lb of standing forage. The larger amount of standing forage is used because of losses associated with grazing such as trampling, fouling, and unpalatable plants or plant parts, such as the lower stems. This guideline and harvest efficiency can be increased (or decreased) depending on the type of standing forage and grazing management. As an example, a 20 acre field has an estimated 1.5 tons (3000 lb)/acre of standing forage. Twenty acres times 3000 lb equals 60,000 lbs. Sixty thousand divided by 1500 (lbs per grazing AUM) equals 40 total AUM. Further information on stocking rates can be found at: http://www.ianrpubs.unl.edu/sendIt/ec158.pdf.

Forage & Emergency Pasture Alternatives

Alfalfa

"When (the alfalfa) didn’t get tall enough to really make hay out of it, the best use was to graze it. When it’s that slow growing and when there’s little moisture on it, it doesn’t bloat cattle like it does when it grows fast."

Alfalfa is the most productive and versatile forage legume grown in Nebraska. Cutting alfalfa for hay or silage has been the traditional method of harvesting, but grazing because drought has limited other pasture resources is a viable option. The potential of bloat is the primary concern when grazing alfalfa, however, there are management techniques that can greatly reduce the risk and make alfalfa a valuable emergency pasture source. Further information on grazing alfalfa can be found at: http://www.ianrpubs.unl.edu/sendIt/g2030.pdf.

Wheat

Winter wheat is commonly grazed in the southern plains and to a lesser extent in the central plains. Depending on location, wheat has the potential to provide excellent grazing during early spring to early summer. As with all grain crops, the economics associated with grazing versus grain harvest must be considered. Further information on grazing wheat can be found at: Grazing Winter Wheat in Nebraska http://www.ianrpubs.unl.edu/sendIt/ec185.pdf.

Corn

"I think before, I would have thought, “I have to drive out my cows. If I run out of hay, I’ve got to start feeding in August already, and I’ll have to buy hay if I run out.” Now I think grazing first. I could graze the corn if I had to. I could seed a little extra ground to some forage crops and graze that. I can rotate my cows around to save grass even in a dry year, and probably survive. So the cow herd… maintaining that, I’m not thinking about selling animals. I’m thinking about utilizing every little piece of ground that I can to keep them fed."

Grazing of corn residue after grain harvest has long been a common practice and economical source of late fall and winter feed. Some producers have planted corn specifically for summer to early fall grazing, but fields initially intended for grain production can be grazed as an alternative. Strip grazing of the standing corn is recommended to minimize trampling waste. 

Grazing of drought-stressed dryland corn is also a possibility. However, nitrate accumulation in the stressed corn plants is an important issue. (possible toxin and nitrate links) Important factors that affect nitrate levels in the corn will be plant growth stage, severity of drought, and amount of nitrogen fertilizer that has been applied. Before grazing, thorough nitrate testing of plants from throughout the field is recommended. If there is adequate moisture in the drought-stressed corn, harvesting it for silage is also an option. The ensiling process will significantly reduce nitrate levels in the feed.

Soybeans

Using and salvaging soybeans for forage is possible. They make good hay and silage. Soybeans are high in quality and can also be grazed. Bloat, while a concern, is less of a problem than for alfalfa. Some general recommendations for soybeans include grazing when fields are in the green pod stage (R4 to R5). Strip graze soybean fields as this will increase efficiency and utilization. In addition, the cattle should have access to some other forage, either another grass pasture or hay or silage because the soybeans by themselves may be too rich for most categories of animals.

The National Drought Mitigation Center | 3310 Holdrege Street | P.O. Box 830988 | Lincoln, NE 68583–0988
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