Support on the Grow for Climate-Smart Vegetable Farming

California vegetable researchers are putting climate-smart farming practices to the test, measuring whether reduced tillage, compost, cover crops, and more efficient irrigation can conserve water, build soil, and reduce greenhouse gas emissions without sacrificing production.

The work is particularly relevant on California’s Central Coast, where intensive vegetable production makes both soil health and water use critical concerns.

Reduced Tillage Builds Soil

Reduced- or no-till farming practices help protect soil from erosion and have become increasingly important as growers look for ways to build soil health.

The practice is enjoying a revival as a way to sequester more carbon in soils rich in organic matter.

Darryl Wong, Executive Director of the University of California, Santa Cruz Center for Agroecology, published his 2023 PhD thesis on no-till organic vegetable farming.

In addition to the climate benefits, reduced tillage brings other advantages that make it easier to farm the soil.

“As soil quality improves via an increase in soil organic matter, a host of secondary benefits arise, including better aggregation, increased aeration, increased soil nitrogen, preservation of soil structure, preservation of earthworms and soil fauna, improved infiltration, soil moisture conservation and water holding capacity, moderating soil temperatures, reduced germination of weeds, natural mixing of soil potassium and phosphorus and improved drainage,” Wong wrote.

But reduced tillage in organic vegetable crops makes weed control and incorporating cover crops challenging.

Once Wong found tools that could break down weeds and cover crops by crimping them, he discovered the success of the system varied by vegetable crop.

“The yield data shows a difference between the lettuce and the broccoli yields,
with no-till lettuce seemingly struggling more than broccoli to produce a similar yield to the tillage treatments,” he wrote. “Broccoli, while it has a higher nutrient demand than lettuce, also has a much deeper and more active root system which could have accounted for some of the difference.”

Dry-Farmed Tomatoes

In coastal areas of California and Oregon, dry farmed tomatoes are already a profitable crop for small farmers.

You plant tomatoes and irrigate them to establish contact between the roots and the soil and then let the plants mine the soil for moisture left from the winter rains. This practice saves water and reduces emissions caused by pumping water through the season.

The result is lower yields, but the delicious fresh tomatoes fetch a premium from consumers who have heard about their extraordinary flavor.

“New Leaf Markets has been promoting dry farmed tomatoes for decades at this point, and we have the benefit of having the local climate that dry farmed tomatoes will thrive in,” said Maroka Kawamura, Senior Category Manager for produce at New Leaf Markets. “With local farmers, markets and restaurants, dry farmed tomatoes get word-of-mouth recognition in the area. Because of all of this we have customers waiting for their annual arrival and price is not a factor. Retail-wise, we historically land about two dollars higher per pound on dry farmed compared to beefsteaks.”

Most growers choose the Early Girl variety for dry farming. But the California Department of Food & Agriculture is financing UCSC Professor of Plant Ecophysiology Jarmila Pittermann and graduate student Viridiana Castro into other varieties. They are studying whether some might suffer less yield loss because of drought stress damage or allow farmers to continue dry farming tomatoes should water shortages become more severe.

A Helping Hand

California actively supports farmers with technical advice on climate-smart practices and help accessing available subsidies.

The California Department of Food & Agriculture’s Healthy Soils Program has offered subsidies for practices that sequester more carbon including reduced tillage, compost, cover crops, and crop rotations.

The State Water Efficiency & Enhancement Program (SWEEP) supports growers for changes that improve their irrigation efficiency and reduce emissions from the energy needed to move water.

SWEEP grants totaling more than $150 million have been awarded for projects that will save 800,000 Olympic size pools of water over the expected lifespan of the projects, according to the CDFA..

The CDFA also cooperates with the University of California on a network of experts who help growers implement these projects, and with the details of gaining financial support for those practices.

Farmers have responded enthusiastically to both Healthy Soils and SWEEP.

“The programs the California Department of Food and Agriculture has been working on have been extremely popular,” said Hope Zabronsky, Associate Director for Climate Smart Agriculture and Resilience at the University of California Cooperative Extension. “Those programs have been 200% to 300% oversubscribed.”

Zabronsky leads a group of 10 Cooperative Extension advisors statewide who specialize in helping growers adopt climate-smart practices.