Nutritive Value of Drought Soybeans

Drought stricken soybean plants can be used as a forage crop. Allow plants to mature as much as possible before harvesting. Some pod or bean development enhances feeding value of plants harvested either as hay or silage. Soybean forages are high in calcium (about 1.3% on a DM basis). For this reason it should be avoided as the major forage for dry cows.

If ensiling, it is important to ensile before plant moisture drops below 60-65%. If possible, mix soybeans with other forages, preferably during ensiling, to enhance their palatability. If plants are high in moisture and lack pod or bean development, add 100-200 lb of ground grain per ton when direct-cutting rather than wilting to 60-65% moisture.

Stems are not very palatable, and if animals have the opportunity, they will sort them out. Chopping hay and feeding it in a total mixed ration (TMR) will help prevent sorting, and stretch forage supplies.

If soybean forage contains substantial amounts of developed beans, reduce the amounts of other fats and oils in the ration, or the ration may be too laxative. Also, it may be difficult to dry down pods for hay if beans are too well developed. Soybeans can be pastured. If cows are removed before all stems are eaten, there may be regrowth.

The table below gives some estimates of the nutrient content of soybean forage on a dry matter basis:
Expected Nutrient Content of Soybean Forage.

Stage of Maturity
CP% ADF% Nel Ca% p% Mg%
Avg silage, hay
17.7 35 .54 1.25 .49 .34
Avg hay
16.5 35  .55  1.20  .47  .32
 mid bloom
17.8 35  .57  1.25  .49  .34
 seed developing
17.5 35  .59  1.20  .47  .32
 seed dough stage
16.8 35  .61  1.15  .45  .30

The dry matter content for average silage is 28%, while that for hay is 88%. Test soybean forage or mixed forages containing soybeans to enable proper ration balancing.

Precautionary note

You need to consider some of the herbicide restrictions. If you look on page 118 in the 1995-1996 Agronomy Guide, you will fine Table 6-17. Feeding restrictions on soybean forage and grain. Unfortunately with few exceptions, most soybean herbicides do not allow feeding the soybean plant as forage. The exceptions are Basagran, Lexone, or Sencor, and Lasso/MicroTech. I suspect that the reason that most of the newer herbicides donUt allow this use is because the ingredients simply never received a forage tolerance. Soybeans are not typically harvested as forage and it costs the manufacturer a great deal of money to conduct tolerance/residue studies. Think about how few product we have labeled on alfalfa. Although this explanation may not help, its what on the product use label.

Bill Curran, Asst. Prof. of Weed Science
Agronomy Dept. Penn State

Author: Richard S. Adams, Emeritus, Professor of Dairy Science

Virginia Ishler, Program Assistant of Dairy and Animal Science
324 Henning Building, University Park, PA 16802
(814) 863-3912