Greg Lardy: Drought-stressed field crops for emergency forage
July 5, 2012
Much of Tri-State Livestock News’ coverage area has been under drought conditions for several months now. This week’s high temperatures have negatively impacted pastures as well as adversely affecting field crops. In this column, I will share a few tips and pointers on making the most out of drought-stressed field crops.
• Drought-stressed small grains can be harvested as hays, silages or grazed. Crops in this category include wheat, barley and oats. Nitrate accumulation in small grains is a major issue with each of these crops. Be sure to collect a representative sample and test it for nitrates before grazing or feeding these forages. Obviously, yield is negatively impacted by drought conditions. In many cases it may be economically advantageous to graze these forages rather than harvesting as a hay or silage. Nitrate accumulation will impact this decision.
• Drought-stressed corn can be harvested as silage. The NDSU Extension Service has an excellent bulletin to help calculate the cost and value of drought-stressed standing corn. Access it at http://www.ag.ndsu.edu/drought. Scroll down and look for the section on Economic Concerns and click on “What is the Value of Standing Corn for Silage.”
Depending on the severity of drought, the corn may not have formed ears. In this case grain production will be zero. In well-eared corn silage, the grain makes up about 50 percent of the weight of the silage on a dry matter basis. The lack of grain will affect the yield and also reduce energy content. The protein content, however, may actually be greater than corn silage put up under normal growing conditions, especially if the silage is chopped before the plant has matured.
Table 1 details average composition of some of the forages I’ve discussed in this article. It is important to get silage tested prior to feeding to ensure that rations are balanced and provide proper nutrition for livestock.
• Drought-stressed soybeans can be harvested as either silage or hay. The quality of soybean hay is quite good, particularly if it is put up with a minimal amount of leaf loss. Typical crude protein content of this hay ranges from 16 percent to 21 percent and it has about 75 percent to 80 percent the energy content of corn silage when compared on a dry matter basis.
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To harvest soybeans as silage, be sure to test the moisture content and aim for about 65 percent moisture in the silage. As the soybean plant matures and leaf drop starts to occur, forage quality will be lost.
• Drought-stressed sunflowers can be salvaged as silage. Any other means of harvest of this crop is not practical. Even in a drought, sunflower plants do not dry down enough to make hay out of the crop. To make good quality silage with sunflowers, add a drier feed to the silage pile. If it’s not added, the effluent losses from seepage of excess moisture will be significant and costly.
Sunflower silage has higher levels of crude protein but lower levels of energy than corn silage. It can be used as a portion of the diet for beef cows and backgrounding calves.
In the past, producers have successfully blended corn and sunflowers together in a silage pile. One load of sunflower silage added to 3 to 4 loads of corn silage is a ratio that has worked well. Be sure to check the moisture content of both the corn and sunflower crops and calculate the ratio needed to achieve a 35 percent dry matter (65 percent moisture) blend in the final silage pile.
Adding other dry feeds to sunflower silage can also be an effective means to achieve a 35 percent dry matter final silage blend. Depending on feed availability and nutrient needs of the livestock, consider blending straw, grass hay, grain screenings, or cereal grains with chopped sunflowers to achieve the proper moisture level. As a starting point, 5.5 tons of sunflowers at 25 percent dry matter and one ton of grass hay at 90 percent dry matter would result in a silage dry matter of 35 percent; reducing effluent losses to a manageable point.
• Grazing is an option for salvaging all of these crops. Grazing may be a very effective means of capturing some value from a failed crop, but consider the availability of proper fencing as well as water supplies for livestock in the fields intend for grazing. If renting fields from someone else, be sure to estimate the amount of standing forage available and factor in trampling, waste and grazing selectivity (the cattle are not going to eat everything in the field) into the amount paid for rent.
• Nitrates will be an issue with drought-stressed crops, especially small grains, corn and sunflowers. The ensiling process will reduce the nitrate content by approximately 30 percent through fermentation. Testing theses feeds before feeding them will help minimize potential nitrate problems.
Information on these and many other drought-related topics can be found on the NDSU drought Web page at http://www.ag.ndsu.edu/drought/.
Don’t forget that the most important nutrient for livestock in drought conditions is water. This is often overlooked, but performance will suffer greatly if adequate quantity and quality of water is not available.