2012 Annual Report for FNC12-853
Exploring the Potential for Fava Beans (Vicia faba) as a Spring and Fall Cover Crop in Upper Midwest
Summary
WORK ACTIVITIES
Our Fava bean cover crop project was started this past fall as planned. The cover crop is intended to go into fields that have just come out of vegetable production. In our case we choose to use two fields. One field had garlic in 2012 while the other had onions. These fields were disked and chiseled plowed in preparation for the Fava bean planting. A soil test was taken to document the baseline nitrogen as well as organic matter in the field.
We were able to locate and procure one variety of the small sized Fava beans and used this variety in our initial fall plantings. How to seed this bean was originally a concern of ours, with our existing grain drill being one option or the use of the local conservation district corn planter that can be rented. Review of the bean seed size focused our attention on the corn planter which we rented for use in our plantings.
The four row corn planter spacing was set to 5 inch in-row spacing and the 36 inch row-to-row spacing was left unchanged. Changing row spacing is difficult on this corn planter. We instead seeded 300 foot rows and ran the planter twice over the field just offsetting 18 inches to end up with an 18-inch final row width.
The Fava bean planting took place late September which is later than we preferred but likely representative of when many produce fields could be cleared, prepared, and seeded. This late seeding was worrisome but we were still able to obtain 6-9 inches of top growth with ¼ inch to 3/8 inch diameter stems on very good field germination. The plants did not quickly winter kill even with frequent mild frosts. It took days into the 20’s to significantly retard growth. Even in early December we had alive and damaged but still green foliage in place throughout the field.
Interestingly it was the Fava beans that attracted deer the most where they would dig through the snow to eat the top growth. Digging plants at this early December stage when end-of-season growth was completed, it was encouraging to see a root system at least 6 inches long with a large number of single nodules in place.
RESULTS
Here are our observations to date:
- We were encouraged to see that even in our northern location (above the 45th parallel) Fava beans planted late September could obtain a healthy 8 inches of growth and produce a fair number of root nodules. Soil tests in the spring will tell us the differential level of nitrogen building from this Fava bean cover cropping.
- Plant germination and growth was very consistent across two test plots in different locations on the farm.
- We believe deer foraging in the fall may be a significant concern for maximum plant biomass and nitrogen fixing.
- There may be benefits to perform a test on plant biomass and nitrogen fixing in root nodules based on length of plant development to determine how many days of growth to reach a threshold level of nitrogen fixing. Doing a feed test on the root system itself at the different levels of growth may provide valuable data.
WORK PLAN 2013
We plan to implement a spring and fall-planted fava bean cover crop trial this year. Because fava beans can be sown at soil temperatures between 35 and 45 degrees Fahrenheit, early spring offers a promising window to establish a stand of fava beans before the first vegetable or corn planting (~May 15). We plan to plant as soon as we can get on the field in the spring.
Our spring-planted experiment will compare different small-seeded fava bean varieties at three different seeding rates (drilled at 100 and 200 lbs/acre and precision planted at ~150,000 seeds/acre), all planted at the same time. The fall-planted experiment will compare the same three fava bean varieties on two different dates (mid-July and mid-August), with 100 and 200 lb/acre seeding rates for the mid-July planting, and 200 lb/acre for the mid-August planting. Our plots will be 10 feet by 100-300 feet with 3 replications arranged in a Randomized design.
Fava bean varieties used will be small-sized fava beans (~250-550 grams/1000 seeds), unlike the larger varieties grown for human consumption. When selecting the three varieties to research, we are looking for varieties with similar lengths to maturity, but different growth characteristics. We will compare one determinate variety, such as “Taboar”, an indeterminate variety such as “Imposa”, and a zero-tannin variety such as “Tabasco”, also indeterminate. The different branching patterns will be compared through the different seeding rates, exploring whether fewer seeds can be used to produce an equivalent amount of biomass/N, thus reducing seed costs. The zero-tannin variety is significant because it can be used for livestock feed, offering growers an alternative market for harvested seed.
For biomass and nutrient analysis, aboveground plant tissue will be sampled and combined from three ¼ sq. m. quadrants per plot. This sample will be taken at the usual time of corn planting in the spring-planted experiment, and just before the first forecasted killing frost in the fall-planted experiment. A Pre-sidedress Nitrate Soil Test conducted in the summer after fava bean cover crops will be used to assess the relative potential of the cover crop to supply nitrogen to the next crop as compared to a no cover crop control.
OUTREACH
We shared our results verbally with a few farmers this season but plan to collect enough data, and if acceptable to the Michigan Small Farms Conference Committee, share this information with the larger Northern Michigan small farm conference at their annual meeting.