Insights on Cover Crops from the PASA Conference
Posted: February 16, 2014
Penn State's Charlie White, Mena Hautau and area farmers learn about cover crops at on farm field day in Berks County.
Having worked on vegetable farms for the past few years, the Pennsylvania Association for Sustainable Agriculture (PASA) conference tends to mark the beginning of another season for me. Coming out of the winter doldrums after a short hibernation, I always leave this conference inspired, excited and ready for the sprint towards harvest. This year was no different, I left PASA’s 23rd annual conference full of new ideas, finding myself daydreaming about cover crop mixtures and scheming about soil health management strategies.
During my years apprenticing on farms, I took a keen interest in cover crops with the realization that we can grow our own fertility. We grow cover crops to protect and enrich the soil and they host numerous benefits to improve your farm. Charlie White, Penn State Extension, discussed the advantages of cover crops at PASA workshop, “Improving Soil Health with Cover Crops.” As I learned, there are many qualities of cover crops. Let’s look at a few of them. Cover crops:
- Protect soil from erosion. Cover crops hold soil in place and prevent erosion due to wind and rain while also reducing soil crusting. Long-term use increases water-infiltration, reducing run-off.
- Improve soil health. Leguminous cover crops such as hairy vetch, clover, or peas, adds nitrogen to the soil by converting atmospheric nitrogen to soil nitrogen, making it useable to plants. Cover crops also add organic matter to the soil, which is broken down plant material that promotes beneficial soil microbial life. In addition, they enhance nutrient cycling, or the means by which nutrients are added, removed and changed in the soil.
- Conserve soil moisture. Cover crop residue increases water infiltration while reducing evaporation, making the soil more resistant to drought conditions.
- Reduce weed pressure. Cover crops can effectively smother weeds and out-compete them for light, nutrients and water. A few also add root exudates that provide a natural herbicide effect.
Throughout the weekend’s workshops, exhibits and keynote speeches, the conference’s theme, “letting nature lead the way” made me think more about how we can incorporate natural systems into our agriculture fields. Adding cover crops to your rotation effectively mimics the continuous cover soils have in nature.
One interesting benefit of continuous plant cover discussed, was the increase in mycorrhizal fungi. “Mycorrhizal fungi are beneficial soil organisms that form a symbiotic relationship with living roots,” White explained. The fungi get sugars from the plants and the plants get more nutrients and water because the thin strands of mycorrhizae act like additional thin roots, scavenging deep into the soil and into hard to reach pores. White also explained that, “the fungi’s thread-like network of fungal biomass known as hyphae or mycelluim, can improve soil aggregation by exuding a glue-like compound called glomalin”. This binding agent helps soil particles stick together into aggregates that resist erosion and maintain soil porosity. Mycorrhizal fungi do best when we grow hosts including grasses, most vegetables and legumes. In contrast brassicas, and buckwheat are not hosts and the number of mycorrhizae will slowly decrease until another host crop is grown. By using cover crops, and having roots year-round in the soil, you are providing a habitat for mycorrhizae to thrive and ultimately benefit your soil.
White spoke adamantly about cover crops and all their benefits to soil health. As I was listening to his presentation, I asked myself how I could incorporate more cover crops into a rotation. Here are some questions to ask yourself when selecting cover crops and incorporating them into a rotation from “Managing Cover Crops Profitably.”
- What is your primary problem or objective? Do you want to provide nitrogen, add organic matter, improve soil structure, reduce soil erosion, control weeds, or manage nutrients?
- Where, when and what do you want to plant?To decide how to fit in your cover crop plantings, look at a long-term crop rotation of your farm, preferably 18 to 36 months. For each field, write in planting and harvest periods. From this plan, find open periods in each field that corresponds to cover crop establishment. Here are some examples of plantings you could include in your rotation:
Over-wintering cover crops such as hairy-vetch, rye or clover provide erosion protection and can add nutrients back to the soil. They should be seeded six weeks before the first hard frost and incorporated when flowering in early spring.
Quick-growing summer annuals are good to use in a summer fallow period for 6 – 8 weeks. Crops such as buckwheat, sorghum-sudangrass, or cow peas can add nitrogen, control weeds, prevent erosion, and add organic matter.
Winter annual cover crop can be seeded with spring grain or frost seeded into winter grains. Full-year perennials or biennials can help rebuild fertility or organic matter. Spring-seeded Yellow blossom sweet clover is a good fit.
There are many options for cover crop selection and timing, please refer to the resources at the bottom for more information and examples.
Cover crops can serve a wide variety of services dependent on your objectives. For information on soil health and including cover crops in your rotation, some helpful resources are the free online book, “Building Soils for Better Crops”, made available by Sustainable Agriculture Research & Education (SARE). Also check the Penn State Extension website on cover crops.