My The vegetable garden is a jungle. The grass is waist-high, the weeds are eating away at my gardening tools, and representatives of all classes of the animal kingdom (perhaps even the Jabberwocky) are there enjoying a comfortable life, eating my salad greens and having fun with each other. I'm eating it.
It seemed like a good idea to let things go wild. I had recently learned about carbon positive agriculture (also known as carbon farming) and wanted to apply the principles to growing vegetables and fruit in the Blue Mountains on a small suburban scale. The goal is bushels of tastier tomatoes, giant zucchini, sweet raspberries, and tart, juicy apples than ever before.
Carbon positive farming (or gardening) is a simple concept of removing carbon from the atmosphere and putting it into the soil. Agriculture provides a potentially important part of the solution to combating the global crisis of climate change caused by excess carbon in the atmosphere and reduced soil fertility due to loss of carbon in the soil .
Professor Budiman Minasny, a soil scientist at the University of Sydney, says carbon makes soil work better. “When trees, plants, animals, and bacteria die, they form organic matter in the soil, and most of it, more than 50 percent, is carbon,” Minasny says.
That organic matter helps the soil form clumps, allowing water to spread out, while retaining and providing the nutrients plants need. The more carbon there is in the soil, the healthier the soil will be.
The most obvious way for backyard gardeners to return more organic matter to the soil is to compost all plant-based organic waste, including leaves. “Composting actually helps break down all the leaves and other stuff into a more stable form of carbon, which means it's not released right away,” Minasny says.
His backyard is always full of fallen leaves, but instead of throwing them away, he collects them and places them on the soil.
There are composting technologies that effectively decompose organic waste without producing large amounts of methane, a powerful greenhouse gas. This means layering nutrient-rich food scraps with less nutrient-rich materials like leaves, grass clippings, and even shredded newspaper and cardboard. If you don't have space for a compost bin, digging food scraps directly into the soil is also effective.
One carbon-positive technology that is gaining traction in agricultural settings is no-till or zero-till farming. Tillage (turning over the soil) releases a lot of nutrients to crops, but it also releases a lot of soil carbon into the atmosphere. Low-till or zero-till may involve simply turning over a narrow furrow and planting, or even planting in a hole without tilling the remaining soil. Leave the remaining soil alone.
Tried it. Somewhere in the jungle in my backyard are three cabbage plants that I planted a few months ago. I think I'm already burning the weeds and eating them for breakfast. Chalk that up as a failure.
Professor Alex McBratney, a soil scientist at the University of Sydney, isn't too keen on no-till growing backyard gardens. “Maybe I'm old-fashioned,” he says. “I'll be a proper gardener.”
A better solution, he says, is cover crops. The term refers to plants grown specifically to prevent erosion, slow weed growth, retain moisture, add nutrients, and reduce the risk of pests and disease. They are also an important part of carbon-positive agriculture.
Traditionally, backyard gardeners grow fruits and vegetables in the spring and summer, then harvest, leaving most of the soil fallow during the fall and winter. However, if gardeners only plant and harvest crops and do nothing else to improve the soil, they will likely deplete the quantity and quality of soil carbon over time, losing not only the crops but also the soil carbon. You will probably be exposed. Carbon is lost through air and erosion.
Cover crops return nutrients, especially carbon and nitrogen, to the soil during the fallow period and help prevent pests and diseases and drive out weeds. McBratney suggests planting a mix of grains (such as winter wheat or buckwheat), legumes such as peas and beans, and some cruciferous plants such as cabbage, cauliflower and broccoli, which are good at controlling fungal diseases. I'm doing it.
“We're just growing plants to grow biomass above ground and nitrogen and biomass below ground,” McBratney said. There is no need to stake legumes. They can lie on the ground and dig into the soil in the spring.
A more controversial technique in carbon farming is adding carbon as biochar. A type of charcoal made by burning organic materials under low oxygen conditions. There is no doubt that it adds carbon, but whether it can reduce carbon in the atmosphere overall is debatable. McBratney says that if you have non-compostable wood material and can burn it in a covered pit to make biochar, “there may be certain benefits for nutrient retention and microbial populations.” . Biochar can also be purchased at plant stores and online.
But a simpler technique, at least for sandy or light soils, is to mix clay with water and water the soil. “The more clay there is, the more likely it is to hold or grow carbon,” he says.
After a grueling and sweaty weekend, waist-high grass was uprooted with minimal impact on the surrounding soil and placed on the soil surface to hopefully return some of the grassy carbon to the soil. . Decomposes to reduce water loss. The heavy removal from the compost bin has increased the number of earthworms, and the newly exposed soil areas are covered with grass clippings and cardboard. Now I'm just waiting for the sun and rain to do the work.
