Don’t Delay Planting Cover Crops

Cover crops have a host of benefits, but there isn’t a single species that does it all.  You need to determine what your goal is for your field and select a cover crop species that will do that.  Secondly you need to plant it at the appropriate time so it has sufficient time to do what you intended it to do.  Cover crops are just like cash crops, they respond well to moderate to high fertility and good available moisture; a field that has low fertility will have a marginal cover crop growth as well. Fields with a history of manure applications or planned applications are excellent locations for cover crops.

What’s your goal?

Nitrogen fixation (legumes)
Nitrogen scavenging (grasses taking up and storing leftover N from soil)
Soil Building (organic matter and soil structure improvement)
Erosion Fighting (soil-holding ability of roots and vegetation)
Weed Fighting
Forage/Grazing
Quick Growth
Alleviate Compaction
Reduce Nematodes
Attract Beneficial Insects

What goals cover crops achieve.

Nonlegumes/Grasses (Annual ryegrass, Barley, Oats, Rye, Wheat, Buckwheat and Sorghum-sudan)

Roles: Most scavenge nitrogen, improve soil organic matter and soil structure, prevent erosion and provide forage.
Grasses have relatively quick growth.

Legumes (Berseem clover, Cowpeas, Crimson clover, Field peas, Hairy vetch, Medics, Red clover, Subterranean clover, Sweet clovers, White clover and Woollypod vetch)

Roles: Fix nitrogen, improve soil organic matter and soil structure, prevent erosion and provide forage.
Legumes typically have slower growth than grasses.

Brassicas (Mustards, Radish and Rapeseed)

Roles: Prevent erosion, suppress weeds and soilborne pests, alleviate soil compaction and scavenge nutrients

When should you plant?

Early or mid-September is an ideal time to plant legume and brassica cover crops in southern regions of Pennsylvania.  This allows them to develop sufficient growth in the fall to achieve the goals you set out to accomplish.  Control weeds with tillage or with glyphosate prior to planting to ensure a weed free seed bed.

If you can’t plant until early or mid-October; it is too late for legumes and brassicas. Grass cover crops such as annual ryegrass and winter small grains such as triticale, wheat and rye are the best options at that time. In November cereal rye is the best option because it germinates at the lowest temperature of any cereal grain, 34 degrees.

Demonstration Trials, Cover Crop Mixtures for Dairy Farms
Considering the interest in cover crops by farmers, the general public, and others, the Crop Management Team at Penn State has establish cover crop demonstrations on dairy farms across Pennsylvania since the fall of 2010. We are focusing on cover crop mixtures because of the way species complement each other to meet producer goals and reduce risks of failure of any particular species. The cover crop demonstrations are funded by a NRCS Conservation Innovation Grant. Visit http://extension.psu.edu/cover-crops for a list field days this fall and the species mixtures.

For more information refer to the SARE Managing Cover Crops Profitably and the Penn State Extension Cover Crop webpage.

Andrew Frankenfield, Agricultural Educator, Penn State Extension, Montgomery County