Are you looking for cover crops to fill a fallow period as small grains, snap beans, or other crops are harvested? Extension agronomist Heidi Reed explains that establishing cover crops in summer grants an opportunity to branch out beyond our fall-planted standbys.
The Northeast Cover Crops Council has come up with an excellent species selector tool (covercrop.tools/species-selector) that can help you determine the best species for your location based on plant hardiness zone, soil type, crop rotation, and goals.
The tool also provides information on growth traits, planting and termination information, and cost.
A list of potential summer cover crops for Pennsylvania is presented below. For more detailed information on any of the listed species, visit the species selector tool.
These grasses listed here are all are summer annuals, meaning they will winter kill.
First is Japanese millet, which can grow in flooded soils and standing water and is adapted to soil with a pH as low as 4.5.
Japanese millet is very responsive to nitrogen and can produce 1,500 to 3,500 pounds per acre of biomass.
Pearl millet is another option and does best under hot conditions. It is fast growing and is a moderately good smother crop.
Sorghum-sudangrass, aka sudex, is a fast grower that reaches 6 to 12 feet tall and has great biomass potential (4,000 to 8,000 pounds per acre) in the presence of lots of soil nitrogen.
Sudangrass has similar yield potential in the presence of lots of soil nitrogen. It is excellent subsoiler with thicker roots than most grasses.
Sudangrass is a good forage, but prussic acid and nitrate content can be a problem. Explore improved forage types with reduced prussic acid.
Teff has high heat and drought tolerance and can produce up to 5,000 pounds per acre of biomass. It is an excellent weed suppresser with fine foliage and leaves a clean field for a following crop.
Planting legumes can also have benefits. These will typically winter kill in Pennsylvania’s climate. Remember to inoculate each with appropriate rhizobium species.
One option is berseem clover. It does not thrive on droughty soils due to a shallow root system, but it has a high potential for biomass (1,200 to 3,000 pounds per acre) and nitrogen production (70 to 150 pounds per acre).
Cowpea is fast growing and is a good biomass and forage producer (2,500 to 4,500 pounds per acre) with high nitrogen fixation potential (70 to 150 pounds per acre).
Soybean (also known as forage soybean) is good for nitrogen fixation, biomass and forage potential.
Spring pea (also known as yellow pea or Canadian spring pea) can be planted early for lush growth (1,000 to 2,500 pounds per acre of biomass) and is good in grazing mixes.
Other options include sunn hemp, forage radish, forage turnip, mustard, buckwheat and sunflower.
Make sure to consider potential herbicide residual issues, pest life cycles, termination strategies and timing, and cost when choosing a cover crop species or mixture.
Summer-planted cover crops can add diversity to your crop rotation, help hold or fix nitrogen for your next crop, suppress weeds, protect soil, provide pollinators or livestock food, and more.
If you would like assistance navigating the selection tool or would like to talk through your cover cropping plan, reach out to your local agronomy educator, Natural Resources Conservation Service conservationist, or conservation district ag specialist.