Cover crops have been used for decades on diversified vegetable farms. Over the past 5-10 years there has been a resurgence in the use of cover crops as nutrient management, nutrient scavenging, and water quality have come under increasing scrutiny and focus.
Several researchers at OSU have conducted work on the use of cover crops in both field crop and specialty crop systems. In 2005 and 2006, Andy Wyenandt (graduate student) and Dr. Mac Riedel (emeritus Dept. of Plant Pathology), worked on several cover crop combinations to determine which mixtures seemed to be the best fit for most pumpkin operations in Ohio. Based on the goals at the time to select a cover crop or mixture that persisted through the growing season and generated enough biomass to suppress weeds and soil borne diseases such as Fusarium, determined that fall seeded winter rye was one of the best options.
One unexpected outcome of this research overwhelmingly embraced by growers who adopted this management practice was how clean the fruit were at harvest, requiring little or no additional washing, especially during rainy autumn weather. Later research focused on modifying a solid stand of winter rye using modified tillage to create more suitable planting or transplanting zones. Now that soil building and ecology has becoming increasingly more important to growers, cover crop mixes are being used that go beyond just covering the soil, and seek to increase beneficial microbial activity in the soil.
On September 21, 2017, five cover crop mixtures were broadcast seeded and then worked into the soil using a cultimulcher at the Western Ag Research Station in South Charleston with the purpose of being used in a pumpkin seeding or transplanting demonstration in 2018. The cover crop mixes range from simple to diverse, with some of the same earlier goals to cover the soil, reduce weeds and diseases, keep the fruit clean, and enhance soil building and microbial activity.
The cover crop mixes were purchased through Walnut Creek Seeds. The species, ratios, seeding rate, and cost are as follows:
- Scavenger mix (60 lb/A, $36/A) – 94% winter rye, 6% tillage radish
- Nitro plus mix (60 lb A, $44/A) – 74% winter rye, 22% crimson clover, 4% nitro radish
- Soil builder plus mix (50 lb/A, $56/A) – 60% winter rye, 20% crimson clover, 16% hairy vetch, 4% tillage radish
- Nitro soil builder mix (60 lb/A, $88/A) – 30% winter rye, 27% winter barley, 17% crimson clover, 11% hairy vetch, 6% sun hemp, 3% tillage radish, 3% cabbage, 3% sunflower
- Custom blend (58 lb/A, $197/A) – 34% crimson clover, 52% Pacific gold mustard, 14% tillage radish
Three-foot swaths of each 30’ plot were sprayed out with glyphosate on 15’ row spacing that will be rototilled for transplanting pumpkins in late May or early June. Images shown below are of initial seeding and growth in the fall, followed by growth in the spring as of May 7th. Though some cover crop mixes listed up to eight plant species, most of them winter killed, leaving only winter rye, crimson clover, and hairy vetch seen growing in any of the plots.
There will be additional reports on this demonstration project as the season progresses, and it will be a stop during the pumpkin field day on August 23rd.