Which fruits and vegetables are best to plant for the environment
Venture into my backyard and youll see a kale patch, a riotous row of Cascadia snap peas and some straggly tomatoes that, except for one banner August, succumb each year to San Franciscos foggy summers. My vegetable patch is a produce factory. Every week, I can pick a hearty salad and as much oregano and thyme as I like. Except for the tomatoes, which I refuse to give up, these crops were selected by what my family would eat and what nature dictates will grow on my little spot on the planet. As a climate columnist, I wondered: Could I make better gardening choices for the climate? More importantly, does it even matter? Industrial agriculture produces an unprecedented amount of food. We can grow roughly five times more grain per acre today than a few centuries ago. Whereas growing a bushel of wheat once required laborers to work in fields for hours, modern farmers can do the equivalent in minutes. Fossil fuels make it possible. They power our tractors, fertilize our crops and supply herbicides or pesticides that kill weeds and bugs. If we are what we eat, we are, at least a little, composed of fossil fuels. Want to know how your actions can help make a difference for our planet? Sign up for the Climate Coach newsletter, in your inbox every Tuesday and Thursday. But this has come at an enormous environmental cost. By adding 90 times more energy per hectare to the food system compared to pre-industrial times, agriculture contributes about 25 percent of the worlds greenhouse gas emissions. It has also converted vast swaths of wilderness into rows of monoculture crops and left massive marine dead zones in places like the Gulf of Mexico because of fertilizer runoff. So I wanted to find out: Could my garden, fed by compost and drip-irrigated, beat Americas agricultural behemoth on the climate front? One alternative to industrial farming is regenerative agriculture . No strict definition exists , but this way of growing food emulates nature by building the fertility of the soil, usually by applying more compost and manure, rather than synthetic fertilizers, and avoiding plowing. While productivity per acre may not always rival their conventional counterparts, these farms are often more resilient and far easier on the environment. Pick up a handful of soil in fields of monoculture soy, corn or wheat, and it sifts through your fingers, largely stripped of organic matter and nutrients. Only successive rounds of fertilizer, herbicides and pesticides maintain its impressive productivity. On regenerative farms , the rich and crumbly black soil is held together by a mix of organic matter, nutrients and microorganisms, researchers say . This healthier soil, in turn, enables plants to grow better with less irrigation, fertilizer and fossil fuels. Theres no bright line dividing the two. Plenty of small, regenerative farmers use fossil fuels, while big growers are practicing no-till farming to build up solid carbon. Were just starting to learn where it makes sense to go big, and where we should grow locally. Tiffanie Stone, a researcher at Iowa State University, has done one of most comprehensive life-cycle analyses of growing crops at different scales, from seed to farm to plate. Her team, publishing in the peer-reviewed journal Science of The Total Environment , examined small-, medium- and large-scale farming from gardens to massive farms near Des Moines in the heart of Americas highly productive farmland. In theory, the state could feed itself many times over. In reality, 90 percent of the food is shipped from beyond its borders. Its a perfect place to examine the relative advantages of small vs. big agriculture. Stone and her co-authors measured four environmental effects global warming potential, fossil energy consumption, water use and land use from farming in the region. By looking at each one, at different scales, they could answer whether it made sense from an environmental point of view to grow a head of lettuce and other produce closer to home, or ship them 1,600 miles from California. In most climate calculations, food miles dont matter too much. Foods carbon footprint tends to come from growing, processing, storage and disposal, not transportation, which contributes around 10 percent of the total on average. So whether you grow it next door or on the other side of the country, the biggest difference for the climate is how its grown. When Stones team looked deeply at the environmental effects of producing different categories of food, from protein to vegetables, in the Des Moines area, they found small growers werent as inefficient as many assumed. In fact, midscale commercial farms and even home gardens had much lower environmental impact overall. In the Des Moines area, they found at least half of the regions food could be grown locally with lower emissions, energy and water compared to large factory farms if not always cheaper. Then they went one step further. They ranked the environmental impact of 18 vegetables grown in the area based on emissions and water use as part of a second study . A few crops offered the most environmental bang for the buck at the small scale: lettuce, carrots, onions, tomatoes and others (see chart). Small farms didnt perform quite as well compared to Big Ag on crops such as potatoes and pumpkins that store well or lend themselves to mechanized agriculture. But all vegetables grown on larger farms in the study consumed more water and energy compared to those on smaller farms. Does this mean all Iowans and all of us should grow their own lettuce? Maybe not. Not every state is blessed with such fertile soil. The states agriculture is also highly seasonal. Temperatures in January average below 32 degrees Fahrenheit. And thanks to economies of scale, as well as farming and fuel subsidies, it can still be cheaper to grow some kinds of lettuce in a massive California field and truck it across five states. Instead, Stone says, the results point the way to a much bigger role for small producers. Gardens and small farms can create a food system thats more resilient, less wasteful and better for the climate and communities while complementing the massive productivity made possible by conventional agriculture. We are only just starting to build out local food systems that do this in most places. After decades of focusing on size, it may take decades to rebuild the infrastructure and relationships to grow, distribute and sell produce closer to home. I have seen claims local is always better, but I havent found that evidence, says Stone. It depends on the context and the purpose. The pros are going to have higher yields. Were not arguing that point. But there can be other benefits. Ideally, it is a balance between efficiency and resilience. If the goal is to sequester carbon in the soil, I concluded theres very little ordinary individuals can do with tiny backyard plots. Even on large farms, some researchers contend, relying on soils as a major, additional carbon sink may be unrealistic . Even if every American had a garden, it would only displace a fraction of conventional agriculture. Just 2 percent of U.S. farmland is devoted to growing fresh fruits and vegetables. The majority of farmland grows commodity crops such as soy and corn, destined to be turned into livestock feed, biofuels or industrial ingredients such as high fructose corn syrup. So I asked Alessandro Ossola, an agronomist at the University of California at Davis, whether growing my own kale and snap peas was meaningful or merely symbolic. The amount of carbon that you get in your garden bed is a tiny fraction of the emissions from your lifestyle, he said. But gardens are driving positive change through food and plant production in general. They are essentially helping communities adapt to our new future. While agriculture has never grown so much food, it has lost variety and resilience along the way. He pointed to a Tuscan painting from the 1600s in one of his studies showing 115 varieties of pears growing in that region. Today, the United States grows about 10 commercially. If industrial farmers have spent the past century relentlessly focused on efficiency, he argues, the next century must also focus on resiliency. We are growing too much food, not too little, the majority of it for livestock, biofuel refineries and food manufacturers, rather than peoples tables. While industrial agriculture will supply most of our calories for the foreseeable future, it will pay to rediscover our relationship with healthier food and prepare for a more volatile climate future. Small-scale farming is key. Ossola plans to bring more gardens and small-scale farming to urban food deserts, reseed heirloom varieties of crops and reconnect people with nature. He points to the Agriculture Departments expanded urban agricultural program, and nonprofits like Fleet Farming in Orlando which turn private yards into gardens to feed the community, as new ways small-scale agriculture is returning to our cities. I see gardening as a way to reconnect us as humans with nature, he says. This can be done at a very small scale in your garden or even on your balcony. We need to reframe how we think of ourselves in the landscape. A nearly infinite set of resources on the internet and books promises to guide your gardening decisions. But most questions can only be answered by experience. Here are a few of the top tips from expert gardeners about how to get started. You can sign up for The Climate Coach column newsletter here .