Innovative Rice Farmer Achieves “Net Carbon Negative” Rice Production  

Greg Massa is the owner and operator of Massa Organics, a diversified farming operation near Glenn, about 30 minutes southwest of Chico. For more than 25 years, leaning on his academic training as a biologist, Greg has been steadily and persistently making improvements and changes to his crop mix and farming techniques to improve the resilience, biodiversity and soil health of his farm. What was once a conventionally-farmed monocrop rice operation now produces exclusively organic rice, almonds, mandarins, and sheep. 

Greg has made good use of California’s Healthy Soils and SWEEP incentives programs over the years to help with this transition, as well as federal NRCS programs. Here are some of his practices that have been supported by climate smart grants and that Greg continues to use:

• Applied compost and cover crops to improve soil health without using synthetic fertilizers, which supported a transition to organic
• Installed a hedgerow along the edge of a mandarin orchard to increase beneficial insect and pollinator habitat
• Applied compost on no-till rice for a three-year period to improve soil fertility
• A Healthy Soils Program research grant compared treatments in an almond block of compost, cover crop and a combination of both, and found a yield increase with the combination plot and, when the nuts were laboratory tested, they found 50-100% more nutrients in the nuts compared to a nearby conventional farm 
• SWEEP grant supported the conversion of a 40-acre flood irrigated rice field into a sprinkler-irrigated almond orchard

Greg has made other innovations that haven’t relied on grant support. For example, years ago he stopped mowing and flaming the cover crops in his almond orchards because he didn’t like using so much propane, and instead he grazes sheep to terminate the cover crops at least 90 days before harvest so there is no risk of food safety issues caused by animal waste. He had to do a lot of trial-and-error to figure out the optimal timing for moving the sheep after they ate the grass and before they started chewing on the bark and low-hanging leaves. 

He is also using a modified prune harvester for off-ground harvesting of the almonds so he can keep his orchard floor covered with vegetation year-round (a fundamental principle of soil health) rather than having the bare ground needed for conventional harvesting that is done by shaking the trees and sweeping the nuts up from the ground. 

Five years ago, Greg got interested in tackling the challenge of reducing the carbon footprint of his rice production system. To appreciate what is involved, it’s important to first understand how California rice is conventionally produced. 

In spring, rice farmers level their fields with laser-guided equipment to get it as flat as possible, then inject liquid chemical fertilizers into the soil. Fields are then flooded with about five inches of water, and sprouted rice seeds are flown on with crop duster airplanes in April and May. The water is maintained at just the right level to kill weeds yet still allow the germinating rice to get to the surface and survive. Herbicides and insecticides are often applied in the summer. When the rice matures in the fall, growers drain the fields and harvest with combines that cut and thresh the grain, and transport it to mills for drying. Finally, in the winter, the plant residues are incorporated into the soil and the fields are flooded again, creating habitat for migratory birds which are populous in California’s rice growing region located along the Pacific Flyway.

The practice of flooding rice fields in the winter was adopted by the industry more than 30 years ago as an alternative to the polluting practice of burning the residue to get rid of the rice straw before the next growing season. Unfortunately, there is an unintended environmental consequence of flooding which is that flooded rice paddies are a significant source of methane emissions, a potent greenhouse gas. Under the anaerobic conditions caused by flooding, the submerged plant residue is decomposed by methanogenic bacteria that thrive without oxygen and produce methane. The amount of methane released from any given field varies depending on the amount of crop residue and the duration of the flooding. 

California’s approximately 500,000 acres of rice production emit 1.3 to 1.5 million metric tons of CO₂e per year (methane, carbon dioxide and nitrous oxide). According to the U.S. EPA, this amounts to 1.8% of California’s agricultural GHG emissions. 

In 2024, Greg worked with a researcher named Michael Schuppenhauer from Lawrence Berkeley National Laboratory who agreed to take scientific measurements of the soil carbon levels as well as the methane, carbon dioxide and nitrous oxide coming from his experimental rice paddies. What they found after one growing season is remarkable: The organic no-till techniques that Greg was experimenting with were net carbon negative — in other words, rather than his rice field emitting greenhouse gases, it not only reduced emissions but it also stored carbon in the soil. 

Here’s how he did it: To substitute for fossil fuel-based fertilizers, he prepared the field in the fall of 2024 by applying compost and then direct seeding cover crop mixture into rice stubble left over from the previous harvest, using a mixture of 10 varieties including brassicas, legumes, wheat, barley and other grains. He didn’t flood the field in the winter, eliminating a significant source of methane and saving a lot of water.

In the spring, without removing the mature cover crop, Greg sowed the rice seed directly into the cover crop stand. Driving the heavy tractor and seeder over the cover crops flattened them down during the same tractor pass used to open a shallow furrow and deposit the seeds.  He then flushed the field with water to germinate the seeds, and removed it within about three weeks so the rice seed didn’t rot, giving little time for anaerobic decomposition of the cover crop and minimizing methane production. As the crop grew through the summer, Greg applied no herbicides or insecticides. All told, he used three tractor passes compared to the more typical five to six, saving fuel, labor, and reducing carbon dioxide emissions. He also saved a lot of water that would normally be sitting in the field during the first phase of the growing season. The field that year produced an amazing stand of rice with high yields. 

This was an encouraging experiment, and Greg has since converted all of his rice fields to no-till production.  Of course, with any new system, unforeseen new challenges arise and Greg is working to mitigate those as well.  For example, last year a new weed emerged in his fields, becoming the first known record of this weed in California rice.  He has had to revert to some occasional shallow tillage to control it.  

Greg sees climate change as the biggest challenge of all, as shifting weather patterns affect California.

“My cover crops haven’t been great the last two years due to flooding from atmospheric river rain events. In 2024, our first rain of the season totaled 8 inches.  The fields flooded and the cover crop seeds rotted in the ground.  But I keep trying.  Eventually I hope to get it right.”

To us, Greg is the embodiment of the person that climate smart agriculture grants are meant to serve: A farmer ready to implement regenerative farming practices with the help of financial incentives that underwrite the risks that come with innovation, for the benefit of all Californians. 

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