November 5, 2021
Healthy soil grows healthy food and helps farm businesses succeed. Healthy soil is also crucial in fighting climate change and creating resilient food systems. But how do farmers create healthy soil?
There are a variety of techniques that farmers can use to create healthy soil, many of which are rooted in ancestral farming practices created by African and Indigenous farming. Each farm uses different techniques according to what it’s producing and the particular location and character of the farm. Here are some common practices farmers use to increase soil health:
Farmers till, or plow, soil to break up compact soil, get rid of weeds and blend enriching materials like compost or cover crops into the soil. However, if soil is tilled too often, the valuable organic matter contained in the soil has a better chance of escaping (and being emitted into the atmosphere). Loose, tilled soil is also more likely to be eroded by running water when a rainstorm sweeps through. Meanwhile, low-till practices preserve the soil’s structure, allowing air, water and nutrients to move freely throughout the soil.
Farmers have been rotating the crops that they grow for centuries. In the 1890s, Dr. George Washington Carver did a series of experiments showing that by rotating crops that used nutrients (sweet potatoes) with crops that captured nutrients in the soil (peas and beans), he was able to reinvigorate the land and increase the yield of sweet potatoes by over 600% in a few years. These days, farmers build on Carver’s discoveries by rotating many crops through the same field. These rotations typically last 2 or 4 years. While what they grow depends on the farm and location, the benefits are the same: disorienting pests and diseases by moving their favorite foods, creating strong soil structure because of the plants’ different root lengths, and increasing the nutrients in the soil.
A cover crop is a crop whose primary purpose is to protect or improve the health of a soil, as opposed to being eaten by people or sold by the farm. Cover crops can pull nutrients like nitrogen out of the air and deposit them in the soil, for other plants to pick up later. They can protect the soil from being eroded by locking down loose soil with their roots. Many cover crops have other benefits, like enhancing soil bacteria and increasing the ability of water to penetrate the soil. This is another practice that was encouraged by the groundbreaking work of Dr. George Washington Carver.
By eating grass, clover or other forage crops, animals like cows or sheep can incorporate the nutrients from those plants into the soil through their manure. This practice was used by Indigenous tribes before cattle even set foot on North America, as tribes in the Great Plains moved buffalo to areas in need of regeneration. On farms, livestock typically eat cover crops (like the clover we mentioned earlier) or graze on forage crops like grass that are included as part of a rotation. The animals fertilize those fields with their manure, providing more nutrients for food crops that grow in that field later.
Compost is decomposed organic matter like food scraps and yard waste that can be used as a powerful fertilizer. Applying organic material to fields is also an ancestral practice, which can be traced back to West African agriculturalists using ash and food scraps to create “African Black Earth” in Liberia and Ghana; Indigenous farmers in the United States applying wood ash and fish waste to their crops, and the Terra Preta technique used by Indigenous farmers in the Amazon. As discussed in our previous blog, compost supercharges the amount of organic matter in the soil, which creates well-structured soil, provides nutrients for plants to grow, and reduces the amount of money spent on off-farm inputs like fertilizer.
Older testing methods focused mainly on the level of nutrients in the soil. Newer models like the one practiced by Pasa Sustainable Agriculture take into account the soil’s structure, levels of organic matter, and water-holding capacity. Programs like the Maine Soil Health Network, launched by MFT in partnership with the Wolfe’s Neck Center, are springing up to help farmers use these soil tests to make decisions about their farm management practices by tracking the impact of different practices over time.
In recent decades, farming practices like intensive tillage and use of chemical fertilizers have led not only to soil loss through erosion and run-off, but also greater carbon emissions and reduced carbon sequestration. Luckily, there is a lot of great work supporting healthy soils in Maine. Recent efforts include the formation of the Maine Soil Health Network and the passage of the state’s Maine Healthy Soils Program. By using these practices and others, farmers across Maine and the world are drawing on centuries of ancestral knowledge and science to grow their businesses and prepare for the impacts of climate change.