Improving productivity and profitability through sustainable means of production is one of the challenges that producers face in the midst of weather extremes and limited resources. Use of cover crops to enhance soil health and benefit the following crop is gaining importance. Cover crops prevent soil erosion, suppress pests, scavenge nutrients from the soil and build soil organic matter. In this project we are evaluating the benefits of a winter cover and double cropping on soybean yield, weed suppression and pest suppression. We will also look at soil health effects and effects on water use.

Following are the activities proposed:
1. Establish and maintain a crop rotation including winter Brassica carinata (carinata), winter oats and a corn-soybean summer rotation. The rotation will be established such that there will be enough plots to represent all winter and summer crops in a given year
2. Produce soybean under 3 trial conditions: following winter carinata, following winter oats and following winter fallow
3. Measure and compare soybean yields, oil quality and quantity
4. Estimate weed diversity in soybean plots
5. Scout for and document insect pests and common diseases of soybean; rate significantly occurring diseases
6. Estimate nutrient benefits from carinata and oats to the following soybean
7. Monitor and compare soil health in terms of soil organic matter
8. Field days, county meetings, in-service trainings and personal visits will facilitate dissemination of information from the research trial

timely progress reports that include crop performance data, soil health data, related pest data, and farmer feedback

Updated August 24, 2021:
Group VII Pioneer P76T54R2 soybean was planted on 25 May 2021 after fallow and oats (PD1) and on 16 June 2021 after carinata (PD2) at a density of 6 seed /ft row using a Monosem vacuum planter. PD1 and PD2 received 25, 50, and 75 lbs. per acre N, P2O5, and K20 on 1 June 2021. Weeds were controlled with Stalwart applied at 24 oz/acre and Basagran applied at 24 oz per acre on 2 July 2021. A second application of Roundup applied at 32 oz/acre and Stalwart applied at 24 oz per acre was conducted on 13 July 2021. Soybeans will be managed using commercial recommendations for soybean production in Florida (https://edis.ifas.ufl.edu/pdf/AG/AG18500.pdf). Soil physical and chemical properties are being monitored to a depth of 4’.

Soybeans planted after winter fallow, oats and carinata are similar in growth and development as of 19 August 2021 (Fig. 1). The crop is currently being monitored for weeds, insects and diseases. No major pests and diseases were observed as of 19 August 2021. Yield and quality will be reported after harvest. Nutrient benefits from carinata and oats as compared to winter fallow will be compared on the following soybean crop along with soil health benefits through changes in soil organic matter, and residual nutrients will be reported at the end of the season.

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Updated March 22, 2022:

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Updated March 22, 2022:
After soybean was harvested in November, 2021, the plots were split into two. The two treatments were broadcast and drilled cover crop. Carinata seed was either broadcast or drilled in to reflect two common practices used in the region for cover crop planting. The purpose of the study is to compare cover crop stand establishment using the two methods. Stand counts were determined 60days after planting and 120 days after planting in both drill and broadcast treatments. Soybean residue biomass coverage was also determined (40 ft diagonally at 6 inch intervals). Carinata in both treatments will be harvested in mid-May. Yield in both treatments will be compared. Effect of residue coverage on cover crop establishment, growth and yield will be determined.

Impact of Cover Crops and Double Cropping on Soybean Yield and Profitability
University of Florida

Improving productivity and profitability through sustainable means of production are one of the challenges that producers in the US eastern Region face amid weather extremes and limited resources. Use of cover crops to enhance soil health and benefit the following crop is gaining importance. Cover crops are known to prevent soil erosion, suppress pests, scavenge nutrients from the soil and build soil organic matter.
A crop rotation including winter Brassica carinata (carinata), winter oats in a corn-soybean summer rotation was established with enough plots to represent all winter and summer crops each year. The objective of this study was to evaluate the performance of soybean yield, oil quality, and quantity in response to winter history.

Summary
Soybeans were planted in mid-May (following a winter fallow) and late May (following a winter crop; either oats or carinata). The trial plots were scouted for insect pests and common diseases of soybean.
Winter history Seed yield (kg/ha) Stand Count (Plants/m2) Biomass (kg/ha) Height (cm) Branch no.
Mean SE Mean SE Mean SE Mean SE Mean SE
Oats 1122.4 192.2 19.4 0.5 2914.3 297.4 22.19 0.26 2.75 0.23
Carinata 1148.1 177.3 20.1 1.3 3286.4 425.1 22.56 0.21 2.69 0.33
Fallow 1402.0 373.4 21.1 0.5 3596.4 528.6 23.25 1.45 3.06 0.50

Soybean in all treatments were harvested in November 2021. Yields and biomass of soybean was not significantly different among treatments. Results indicate that cover crops such as carinata can be successfully used as a double crop with soybean without negatively impacting soybean yield. Carinata provides the additional winter revenue that is otherwise not possible in a winter fallow situation. Carinata should be grown once in three years in the winter. The other winters in the 3 years period may have oats or other suitable cover crops.
The inclusion of a winter oilseed in the cropping system did not influence the performance of soybean. This suggests that soybean can be successfully double-cropped resulting in both economic and environmental benefits for producers within the region. Putting a brassica winter crop provides the benefit of both a cover crop and a winter cash crop. Carinata provides all the benefits of a cover crop-biomass returned to the soil, reduces nutrient run-off, improves soil moisture and in general improves soil characteristics as compared to fallow. Further, carinata seed has a market for drop-in renewable fuel and high protein feed supplements. Unlike other cover crops, it gives returns to the farmer in the form of an additional off-season income, while building soil health. Soybean is better suited to a rotation with carinata as compared to corn, cotton, or peanuts based on data so far, due to the timing of soybean planting. Moreover, inputs were not different in the two treatments.

Conclusion
Soybean can be double cropped with winter carinata providing opportunities to augment farmer revenue and improve soil properties. Carinata is a low-carbon non-food purpose grown oilseed for sustainable aviation fuel, renewable diesel and other bioproducts. Meal from carinata is approved for use as protein supplement in beef cattle. Studies are underway to get similar approval in dairy cattle as well. Therefore, a soybean-carinata rotation is a profitable pathway for eastern region, especially southeastern producers to have a cash crop and a cover crop that provides all the benefits of a cover crop while also generating revenue

Improving productivity and profitability through sustainable means of production is one of the challenges
that producers face in the midst of weather extremes and limited resources. Activities proposed in this
proposal will demonstrate improved productivity, reduced weed pressure in soybean by cover crop
mediated soil organic matter and soil health building.