Planting Cover Crops Enriches the Soil.
By T. Eric Nightingale
UC Master Gardeners of Napa County
The long summer of vegetable gardening can leave your soil in need of some rejuvenation, a perfect job for cover crops. Also known as “green manure,” cover crops are a natural and easy way to keep your garden soil healthy. They return nutrients to the soil, improve soil texture, prevent weeds and reduce erosion. The most effective and frequently used cover crop plants are legumes, grasses, grains and brassicas.
Returning nitrogen, a primary plant nutrient, to the soil is possibly the most important role of cover crops. Legumes are extremely good at this. They nurture Rhizobia, bacteria that converts nitrogen in the air into ammonia. Plants can later process this ammonium to obtain nitrogen from it. Rhizobia can't live in the soil on their own, however, so they use the roots of certain plants as a host. Some companies even sell seed with Rhizobia added to the mix. Legumes used as cover crops include fava beans, hairy vetch and clovers.
Brassicas such as radish and mustard are widely used as cover crops in vineyards. You have probably seen them flowering around Napa Valley. These plants grow deep (sometimes as deep as four feet), strong roots that break up the soil, letting water flow deeper into the ground.
Well-hydrated soil not only helps your plants, but allows for more soil organism activity. Grasses such as barley and ryegrass also help to break up the earth, but also allow for the introduction of high amounts of organic matter when they are turned back into the soil. It is common to use many different types of cover crops, in a mix, to provide as much benefit as possible to your garden.
Helping to retain moisture, improving soil texture and increasing fertility all contribute to a robust soil ecosystem. When this system of microbes, fungi, bacteria and other organisms is functioning as intended, the likelihood of soil-borne diseases greatly reduces. Even a garden needs to eat its greens to stay healthy.
Fall is a great time to plant cover crops, since many gardeners take a break between vegetable crops. You can sow cover crops directly from seed, broadcasting them by hand over the soil after tilling it lightly. Cover the seeds with a thin layer of soil to protect them while they germinate. You can add a small amount of fertilizer to give the young plants a jump-start on life. You will get a large return on this small investment when the plants grow.
Cover crops can also be used in the summer. Grasses such as sorghum, soybean and cowpea are often grown at this time. Also used are buckwheat and sunflower, giving the added boon of attractive flowers.
When the cover crops are at the end of their lives or you want to plant something else, turn them into the earth. Their organic matter will break down and further improve the soil. Alternatively, you can mow them and leave them on top of the soil as a mulch. They will eventually decay but in the meantime will further decrease water loss and erosion.
Cover crops also suppress weeds by blocking the sunlight, keeping weed seeds from germinating. If they are left on the soil surface as a mulch, they continue their weed-prevention duties. Some cover crop flowers feed bees, and fava beans, a popular cover crop, are edible and delicious.
There has been extensive research and testing on cover crops in recent decades. Their wonderful features make them sound like a cure-all for anything that ails your soil. In truth, they are one of many contributors to a healthy and productive garden. There is no doubt, however, that any garden will benefit from cover crops.
Workshop: U. C. Master Gardeners of Napa County will hold a workshop on the different kinds of poinsettias and other potted plants for holiday decorating using color and shapes. The workshop will be held on Thursday, December, from 7:00 p.m. to 8:00 p.m., at the Napa County Library, 580 Coombs Street, Napa. This is a free workshop and registration is not required.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County (http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.
- Author: Kathy Keatley Garvey
Talk about a pollen-packing bumble bee.
A yellow-faced bumble bee, Bombus vosnesenskii, displayed quite a heavy load of orange pollen recently as it foraged on hairy vetch in the Hastings Preserve, Carmel, owned and operated by the University of California, Berkeley.
Did you know that Monday, June 15 marks the start of National Pollinator Week?
It's sponsored by the Pollinator Partnership, which offers these fast facts about pollinators:
- About 75 percent of all flowering plant species need the help of animals to move their heavy pollen grains from plant to plant for fertilization.
- About 1,000 of all pollinators are vertebrates such as birds, bats, and small mammals.
- Most pollinators (about 200,000 species) are beneficial insects such as flies, beetles, wasps, ants, butterflies, moths, and bees.
- In the United States, pollination produces nearly $20 billion worth of products annually
In observation of National Pollinator Week, the UC Davis Department of Entomology and Nematology is planning an open house at its bee garden, the Häagen-Dazs Honey Bee Haven, from 5:30 to 7 p.m., Friday, June 19. The half-acre bee garden is located on Bee Biology Road, next to the Harry H. Laidlaw Jr. Honey Bee Research Facility, west of the central campus.
Activities will include bee observation and identification, honey tasting, sales of native bee houses to support the haven, and information about low-water plants.
You're likely to see such pollinators as honey bees, bumble bees, sweat bees, syrphid flies, and butterflies.
The open house is free and open to the public. The garden, planted in the fall of 2009 during the tenure of Lynn Kimsey, then interim chair of the UC Davis Department of Entomology and Nematology, is now managed by Christine Casey, staff, and Extension apiculturist Elina Niño, faculty.
It showcases the work of the UC Davis Art/Science Fusion Program, co-directed and co-founded by Diane Ullman and Donna Billick; and the work of students in Entomology 1, taught by Ullman and Billick. The state-of-the-art fence that circles the garden is the work of Eagle Scout Derek Tully of Boy Scout Troop 111, Davis.
The bee garden is open daily from dawn to dusk.
- Author: Kathy Keatley Garvey
Ever heard of Schinia sueta?
It's a moth.
We spotted this little moth, from the Noctuidae family, in a meadow at the Hastings Preserve in Carmel in early May during the BugShot Macro Photography Course, taught by Alex Wild, John Abbott and Thomas Shahan.
The day-flying moth, as identified by butterfly experts Art Shapiro of UC Davis and Greg Kareofelas, an associate of the Bohart Museum of Entomology, stood out.
Schinia sueta is widespread in western North America. We were waiting for it to spread its wings in the meadow, filled with lupine, vetch and California golden poppies, and it finally did!
Speaking of moths, the Bohart Museum is hosting a "Moth Night"--the first of its kind held by the museum--on Saturday night, July 18 from 8 to 11 just outside its location, 1124 Academic Surge on Crocker Lane, UC Davis campus. Yes, that's 8 to 11. At night.
You'll learn how to collect moths and how to identify them. You won't see Schinia sueta, but you'll see other moths! The event is free and open to the public. It's also the last weekend open house of the academic year.
The Bohart Museum houses a global collection of nearly eight million specimens. It is also the home of the seventh largest insect collection in North America, and the California Insect Survey, a storehouse of the insect biodiversity. Noted entomologist Richard M. Bohart (1913-2007) founded the museum.
The museum's regular hours are from 9 a.m. to noon and 1 to 5 p.m. Mondays through Thursdays. The facility is closed to the public on Fridays and on major holidays. Admission is free. More information on the Bohart Museum is available by contacting (530) 752-0493 or Tabatha Yang, education and public outreach coordinator at tabyang@ucdavis.edu.