Community Science at Pasadena Community Garden

Community gardeners grow cover crops to fight the effects of extreme heat and drought

Summers in Los Angeles are getting longer and hotter.  When it’s hot and dry for days on end, edible plants struggle to survive.  Do you wonder what you can do about it? Experienced gardeners tell us to focus on “growing” healthy soil. Healthy soil not only increases the yield and nutritional value of edible plants, it also helps the soil hold moisture and reduces heat-trapping gasses in the atmosphere.  Some of the healthy soil practices we can easily adopt in our food gardens include the use of compost, mulch, no till, and cover crops. 

What are cover crops? 

Cover crops are not grown to eat. they are grown to feed the soil. Some examples include fava beans, vetch, oats, barley, buckwheat, and daikon radish. They are cut down when they start to fully flower and their roots are left in the soil.  Depending on the type of cover crop you choose, they can add nitrogen and other nutrients, boost the soil’s ability to hold water, bust up compacted soil, smother weeds, help control pests and disease and attract the beneficial insects we need to pollinate many edible plants.  Cover crops aren’t a quick fix. They require a medium to long-term investment in your soil.  But the results will be worth your while. (Learn more here.)

Last fall, Pasadena Community Garden participated with three other sites around Los Angeles in a community science healthy soil experiment featuring a cover crop of fava beans. Favas and other legumes add nitrogen to garden soil (nitrogen is an essential nutrient needed for plant growth.)  Next, community gardeners planted corn, a crop that requires a lot of nitrogen and a fair amount of water. Our goal was to see if the favas improved corn yield and soil health. Check out our four-minute video explaining how it worked: https://vimeo.com/528185810.  And here are some photos of the Black Aztec Corn we grew.

We planted in heavily compacted soil that  hadn’t been worked for decades.  Students from Dr. Michael Vendrasco’s soils class at Pasadena City College prepared the site – not an easy task! Next, we tested the soil to get baseline data and planted our favas seeds. In March, we cut down the favas, making sure not to disturb the roots. In April, we planted Black Aztec corn and harvested it in August.

The corn grown with favas and an inoculant produced almost three times as many ears as the corn we grew with no previous favas.  Our soil data has not yet been analyzed for nutrients, soil organic matter and water holding capacity. Stay tuned.

Planet Earth Observatory started this investigation three-year years ago with a small grant from the National Oceanic and Atmospheric Administration (NOAA) with further assistance from Dr. Michael Fox at Cal Poly Pomona’s College of Agriculture and Drs. Hossein Zakeri and Kyle Brasier at Cal State Chico. Since then, we have conducted our community science healthy soils investigation in over 10 community, school and other public gardens around Los Angeles County.

The future is clear: we need to find ways to save water and create local, healthy food systems as the climate heats up and dries out. Would you like to participate in our healthy soils investigation at your community garden?  Would you like to grow favas in your individual plots?   Send me an email and we’ll help you get started. lydia@planetearthobservatory.org

Lydia Breen is a master gardener and member of Pasadena Community Garden. She is certified by the American Meteorological Society to teach climate and weather to K-12 students. In 2017, she founded Planet Earth Observatory (PEO) and launched “Climate Change in A Hungry World,” a community science healthy soils investigation. 

Pasadena City College students help prepare the soil for a community science healthy soils investigation featuring fava beans and corn at Pasadena Community Garden