Carbon Capture and the Circular Water Economy: Better Together

I had the privilege of presenting at the Irrigation Association (IA) Show last week in Las Vegas on how smart irrigation leads to more efficient carbon capture. The topic is as timely as it gets—both water efficiency and carbon sequestration are high-visibility issues right now around the world—and the audience represented many of the top minds in irrigation and agriculture.

The heart of my message is that the circular water economy begins and ends with agriculture. In the process of running water through that virtuous circle—from source water to its use in farming, domestic or industrial contexts, then to treatment and re-use in industry or farming, to further treatment and release to the environment, where it becomes source water again—agriculture is also the most efficient and effective means of capturing carbon. What's more important is that in the process of capturing that carbon, farmers and ranchers also turn water and other inputs into food, feed, fiber and fuel.

Tech Bias

My presentation was prompted by the publication last year of "Getting to Neutral" by scientists at the Lawrence Livermore Laboratory in California. In their effort to create a carbon-neutral California, they drove straight to a variety of high-tech solutions destined to appeal to a room full of engineers, like low-oxygen pyrolysis or machines that grab carbon from the air, condense it, and pump it underground. The closest they got to agriculture was a suggestion to produce "purpose-grown crops" like biomass crops to fuel pyrolysis plants or dense forests whose trees could turn carbon into standing wood.

Ironically, the Lawrence Livermore Laboratory is just a few miles from some of the world's most productive farmland and some of its most creative, ambitious farmers. California is the nation's salad bowl, its fruit basket, and its bowl of nuts. It's also home to some of the most advanced irrigation systems in the New World, from the massive canal projects that deliver huge quantities of water to the state's farms to computer-driven, sensor-governed drip irrigation systems that spoonfeed individual plants in a field.

Smart Irrigation Time

This is the time for the carbon agenda and the smart irrigation agenda to combine forces. Drip irrigation acreage rose an amazing 900% between 1984 and 2018, according to the California Farm Water Coalition . At the same time, sprinkler irrigation fell 49% and gravity/flood irrigation acreage declined by 33.7%. Farmers in California and—evidenced by the widespread interest of attendees at the IA Show—around the world have the means to manage their irrigation more precisely than ever, as well as a deep interest in efficiently stewarding our most precious resource.

Nationwide, tens of thousands of farmers have also taken on the 4Rs of Nutrient Stewardship, applying the right fertilizer source at the right rate at the right time to the right place.

That's important from a water quality perspective, which helps the circular water economy go 'round. But it's also vital in the fight against global warming. According to the US Environmental Protection Agency (EPA), 74% of the nitrous oxide emitted in the U.S. comes from agricultural soils. Nitrous oxide is a potent greenhouse gas and important contributor to global warming. It also represents a significant loss of soil nitrogen, a crucial nutrient in plant growth and an increasingly expensive input for farmers. Basically, if nitrogen wafts into the atmosphere as nitrous oxide, it's wasted. That nitrogen is not combining with carbon and other elements to create protein or other plant products that could help sustain us.??????

Smart Irrigation Getting Smarter

Meanwhile, an international team of scientists led by Dr. Dave Goorahoo at California State University, Fresno demonstrated that aerating subsurface drip irrigation water with Mazzei's AirJection system shifted soil microbe populations toward a higher proportion of aerobic denitrifying bacteria. Those population dynamics appear more likely to fix nitrogen in the soil rather than turn it into nitrous oxide.

A wide range of crops around the world supplied with aerated water through AirJection systems also produced better quality and higher yields than the same crops irrigated with un-aerated subsurface drip irrigation systems. Higher yields equal more carbon turned into food and other agricultural products, as well as root biomass and exudates that turn into soil organic matter.

Think about it. Irrigation systems that allow farmers to react to crop need with precise amounts of water delivered straight to the roots, aerated to create a more productive, higher-quality yield at harvest and a more favorable community of microbes in the soil—it sounds like smart irrigation is getting even smarter.

If humankind is going to make strides against climate change, we're going to have to tap into our most powerful tools and make the most of every opportunity we have. That effort will get a huge boost from smart irrigation and the smart irrigation experts like the people I met at the IA Show last week. And capturing carbon efficiently and productively is going to have to start and end with agriculture—just like the circular water economy does.