Three new soybean crushing plants are expected to open in North Dakota in the next few years. Soybean hulls are one of the lower value by-products of soybean crushing. Due to their nutrient values, both soybean meal and soybean hulls have been used as soil amendments in home gardens, but their field scale use has been prohibitively expensive due to the demand from the livestock industry. Hulls have a lower nutritional value than soybean meal, therefore the demand for them is lower. With large amounts of by-product soon to be generated in North Dakota due to soybean crushing, it is likely that substantial quantities would occasionally become available for a greatly reduced price. In such a scenario, farmers may wonder whether soybean hulls could be used as a source of fertilizer. Pelleted soybean hulls contain roughly 30 - 35 lbs of nitrogen, 3 - 4 lbs of phosphorus and 20 - 25 lbs of potassium per ton. They have a carbon to nitrogen ratio of around 30 : 1, which is similar to soybean residue and is higher than the typical ratio for manure, which is 15: 1 but lower than other residues such as corn stalks or wheat straw. Therefore, we can expect that while soybean hulls would eventually release nitrogen during the growing season, supplying some amount of synthetic nitrogen would be necessary in order to ensure optimal crop growth. The hulls would likely act as a slow release fertilizer, supplying nutrients mid-season.

To evaluate the potential of utilizing soybean hulls as a supplemental slow-release nitrogen source in crop production by measuring yield impact and soil residual nitrogen after harvest, by comparing to standard synthetic fertilizers.

Research results will be reported to the ND Soybean Council and published in the CREC annual research report. Results will also be posted to the CREC blog and on social media (Facebook and Twitter), and shared during workshops and tours at the CREC. Positive results from this study could be used to design more targeted research projects on this subject in subsequent years.

Update:

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Any avenue that allows soybean crushing facilities to market and put excess products to good use locally at no extra cost to them is also beneficial to soybean farmers. That is because the efficient management and handling of soybean grain and its by-products by crushing plants results in greater grain in-take capacity and possibly better prices for famers. This could be a new market opportunity for soybean by-products without the need to modify the hulls any further. Utilization may also reduce the need to import as much nitrogen fertilizer. This practice could be particularly feasible for those operating near the crush plants.