Silage is an option as time is running out for soybean maturity.
In some areas, double crop soybeans are having trouble reaching maturity. Ideally, soybeans should be reaching the R6 stage with full seed fill to be considered for grain production. Some of the soybeans I have seen in Centre County are still in early R5 and the prospects for reaching R6 before frost is slim. Typically it takes two weeks to move from R5 to R6. One option for these fields would be to salvage the fields for forage.
One consideration would be whether the herbicides used for the soybean production for are labeled for forage production. Many are not. Refer to Table 2.4-16 in our Agronomy Guide. Another consideration is that forage yields in field with short double crop soybeans may be low and not worth the effort. If the beans have good growth, then they could produce 1-2 tons per acre or so and of reasonable good quality. Typically soybean silage can be pretty good with forage quality in the 18-20% protein stage with a relative feed value of 125-150 RFV. Once the soybeans are frosted, the forage quality drops quickly. So if a frost is forecast, it may be prudent to think about the potential for salvaging the crop.
Soybeans can be left in the field and may contribute some N to the following crop, but the amount is uncertain. Soybeans themselves are not a great overwinter cover crop. Some of these fields will have volunteer wheat or barley that could serve as a cover crop in addition to the standing soybeans.
Source : psu.edu