This year we’ve seen quite an increase in baling of soybean residue in the area. I’ve also heard this in other parts of the State. Soybean residue can be used for bedding, or for feed as roughage or mixed with distiller’s grains. In speaking with farmers and livestock producers, there’s perhaps a number of reasons why we’re seeing an increase in soybean residue acres baled this year. While we’re not short on corn residue, the late harvest delayed baling of corn residue for some and they were looking for another forage source. Hay prices have been higher this fall and continue to increase, making soybean residue a less expensive alternative. Some crop growers may also have been seeking added income.
Some colleagues and I addressed questions we were receiving in a recent UNL CropWatch article. Questions have centered around the value of this residue. I’ve shared in previous articles that approximately 1 ton of corn/grain sorghum residue is produced for every 40 bushels. For soybeans, it takes 30 bushels to produce 1 ton of crop residue. So to give an example, a corn field averaging 240 bu/ac would result in approximately 6 tons of residue/acre. In comparison, a soybean field averaging 60 bu/ac would only produce 2 tons of residue/acre.
In general, there’s not too much difference in the amount of nutrients removed from corn vs. soybean residue.
- Corn (17 lbs N, 4 lb P2O5, 34 lb K2O, 3 lb S)
- Soybean (17 lbs N, 3 lbs P2O5, 13 lbs K2O, 2 lbs S)
To determine the value of these nutrients, one would need to know the current fertilizer nutrient price per pound. Value also includes maintaining soil properties, which is harder to place a value upon. Based on the research, it’s recommended to leave at least 2 tons/acre of residue in the field to maintain soil organic matter. More needs to be retained for many fields to prevent excessive soil erosion and some fields should not be harvested. In previous articles, I shared our best management practices to consider for removal of corn residue. In the corn field example above, 6 tons of residue are available. Removing 2-3 tons of residue still leaves 50% or more residue on this field. In comparison, the soybean field with 2 tons/acre of residue at harvest is already at the 2 ton/acre limit to maintain soil organic matter. Regular soybean residue removal is not recommended as it is expected to result in reduced organic matter and increased soil erosion.
Soybean residue is a lower quality feed than corn, sorghum, and wheat residue. Forage tests show a range of 35-38% total digestible nutrients (TDN) and 3.9-4% crude protein; these numbers are less than wheat residue. For comparison, forage tests from corn residue ranged from 47-54% TDN and 4.5-6.5% crude protein (sorghum residue would be similar). The highest edge of those ranges would be similar to average grass hay.
USDA showed a price of $50/ton for soybean residue. Assuming 88% dry matter (DM), then that is $162 to $189/ton of TDN with 4% crude protein. In comparison, corn residue bales were $60 to 65/ton. Assuming 83% DM and 50% TDN, corn residue is a better deal (on an energy basis) at $150 to $156/ton of TDN with 5-6% crude protein. For perspective, good grass hay is $85 to $100/ton. Assuming 88% DM and 55-60% TDN, it is $160 to $205/ton TDN. A true economic analysis would take into consideration the residue removal costs, nutrient removal, and potential for soil loss (even though it’s hard to put a value on that). The 2018 Nebraska Farm Custom Rates shows rates for cornstalk raking and baling. Soybean residue removal numbers aren’t provided.
As a source of dry matter, soybean stubble is a low cost source for feedlots. However, soybean stubble is less valuable than both corn and wheat baled residue on an energy basis. The reduced feed quality and higher cost of the feed value doesn’t justify the economics of baling and feeding soybean residue for cow-calf producers. From a short-term and long-term soil productivity perspective, including for soil and water conservation, soybean residue removal is not justified for agronomic and economic purposes. Factors such as late harvest delaying baling of corn residue, higher hay prices, and opportunity to sell soybean residue may have resulted in more soybean residue baling this year.