Drought Stricken Soybeans..Should I Leave Them or Take Them for Forage?

Shawn Conley, State Soybean and Wheat Specialist University of Wisconsin, Madison

To read this article from its original blog, click here.

Late soybean plantings followed by dry conditions have some northern WI growers considering chopping their soybean as a forage. Before you even consider this option make sure you check the label of the pesticides applied to the crop before you grease the chopper.

  • Let’s start with the herbicides first. In short, outside of glyphosate (25 day) and a handful of pre’s and posts (please refer to Table 3-3 in A3646, Pest Management is WI Field Crops) most soybean herbicides are listed as “not permitted” for forage use.
  • Next, many common insecticides used for soybean aphid management implicitly state “Do NOT graze or feed treated forage or straw to livestock” (please refer to A3646, Pest Management is WI Field Crops) .
  • Lastly, fungicide labels are as equally exclusive with pre-harvest intervals ranging from 14 days to “Do NOT graze or feed soybean forage or hay” (please refer to A3646, Pest Management is WI Field Crops) .

If you somehow pass the gauntlet of “Do not” or “Not Permitted” and the forage value is greater than the grain value then the highest protein and yields are obtained from soybean harvested at the R6 to R7 growth stage. Harvesting soybeans for forage between the R1 and R5 stage will result in a very high quality silage, but dry matter yields will be reduced significantly. Forage quality will be reduced from R5 soybean forward if a conditioning process is used during harvest as conditioning will cause significant seed shattering.

Here are some options for you to consider to help think through the forage versus grain decision.

Option # 1: Soybean haylage considerations

  • What is my realistic tonnage expectations?
    • Late planted drought stricken soybean will yield ~1 to 2 tons of dry matter per acre.
  • What is it going to cost me to harvest and put this crop up?
      • Mowing ($14.20 per acre)
      • Swathing ($7.75 per acre)
      • Haylage (Chopping, hauling, & packing bunker; $49.20 per acre)
  • How should I price this crop?
    • If you were to price the soybean forage based on expected grain yield and CBOT then realistic yield levels would range from 15 – 25 bu per acre at $7.95 per bu (local cash price: 8/22/18). Expected forage value range would be $119.25 to $198.75 per acre.

Option #2: Green manure considerations

  • I am tired of throwing money at this crop……….
    • Though you will save on harvest costs the average cost of a plow down disk operation is $19.70 per acre.
  • How much will I save on next years fertilizer bill?
    • By not harvesting the crop you will not remove the 30# P and 85# K (estimated removal rates of P2O5 and K2O for 15-25 bu per acre soybean grain and straw (A2809)).
    • You may contribute 20-40 pounds of N to next years corn or wheat crop.

Neither of these prove to be particularly attractive options. However I would encourage growers, crop consultants, and nutritionists to weigh the true economical value of each option carefully before proceeding.

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