Soybean commodity prices have fluctuated over the last 10 years considerably, making profit margins for SC soybean farmers narrow at times. When prices are high and yields are good, some farmers elect to harvest corn at a higher moisture ( > 18%) and dry the corn in order to get it out of the field earlier than letting it field dry. In that scenario, some farmers have then followed the corn with ultra-late planted soybean. While this practice carries quite a bit of risk, soybean seed sold late in the season is often sold at a reduced-price, thus lowering input costs associated with the soybean. While several thousand acres of double cropped soybean behind corn were planted in the 2021 growing season, there are several questions associated with this practice. Furthermore, an economic analysis is needed to determine at which point performing this practice is not profitable in terms of yield and commodity price.

This proposal is for one year of research at the Edisto Research and Education Center in Blackville, SC where a field representing typical soybean production for the region will be utilized. Corn will be planted in mid to late March and managed throughout the growing season in accordance with Extension recommendations. Corn plots will then be harvested at various moisture levels once the corn has reached full maturity or black layer. Soybean will then be planted immediately following corn harvest and managed throughout the remainder of the growing season.

Treatments will include two different corn hybrid maturities, followed by three different soybean maturity groups planted at various timings depending on harvest moisture of the corn. Additional treatments will include evaluating nematicide on the corn and soybean in nematode infested fields and the impact that double-cropping soybean behind corn will have on nematode populations; evaluating the use of at-plant nitrogen on soybean when planted in an ultra-late scenario; and evaluating drilled vs. 30-inch row planted soybean.

This research would be valuable to SC soybean farmers by providing them with information on this practice, developing best management practices for double cropping soybean behind corn, and generating a dataset that can be used to determine the economics associated with this practice.

- To determine best management practices for double-crop soybean behind corn in terms of planting date, row spacing, use of nematicide, at-plant nitrogen, and maturity group.
- To assess the economics and risk associated with planting ultra-late planted soybean in a double-crop scenario behind corn.

The expected output/deliverables of this research will be shared with soybean growers in South Carolina and throughout the Southeast. Information exchange will be through the use of newsletters, social media (Twitter and Facebook), Extension publications, Clemson University Edisto REC Seminar Series, field days, and grower meetings.

Key Performance Indicators:
This research will determine if a specific maturity group soybean is best for this planting scenario in addition evaluating to the use of a nematicide, at-plant nitrogen, and determining optimum row spacing. These results could alter how soybean farmers participate in planting ultra-late soybeans both from an agronomic and economic standpoint. The key performance indicator will be to define the most profitable scenario.

Soybean farmers in South Carolina have historically taken advantage of double cropping soybean behind small grain, in addition to planting full-season soybean. In order for farmers to take advantage of the maximum profit generated per acre per year, double cropping is a desirable planting scenario, and it works well in our region. Over the last several years, when commodity prices have been considered high, some farmers in SC have taken advantage of double cropping soybean behind corn rather than leaving the field fallow. While this scenario associates quite a bit of risk with it, a considerable number of acres are planted annually in SC with this scenario. In this project we would like to evaluate this planting scenario from a whole system approach, including agronomic, pest, disease, fertility, and economic parameters associated with planting soybean behind corn in SC, in order to provide farmers with best management practices for this scenario.