Soil: It is much more than Dirt

Aug 10, 2017 | Sustainable Agriculture |

The Dirt:

Have you ever thought about what lies beneath our feet? Soil is responsible for 95% of the food we eat and it supports life on Earth in many different ways. Healthy Soil = Healthy Food = Healthy People. But what exactly is healthy soil and why do we care?

As our name implies, at Dirt-to-Dinner we want to bring attention to how your food is grown and processed. Admittedly, there has been a significant focus on the “to-dinner” and not as much attention given to the “dirt.“ It is time to better understand the steps farmers take to maintain and improve soil health. Let’s go digging….

Why is soil important?

Many of us don’t give it a second look, but without soil (note: we won’t call it dirt) life on Earth simply would not exist. Consider this: 95% of our food is directly or indirectly dependent on soil. You wouldn’t be eating very well without it! Healthy soil is responsible for the ripe fruit you eat at breakfast, the crisp lettuce used in your salad for lunch, and the chicken you prepare for dinner. Thank you, Soil!

Soils deliver ecosytem services that enable life on earth (FAO)

Soil supports the foundation for our homes and infrastructure, it helps grow the fibers that weave our clothes, and provides the fossil fuels that keep our engines running. Not only is soil a fundamental ingredient for healthy nutrition, but it also acts as a purifier for our water and air and helps control both erosion and flooding.

Worldwide, soil health is of paramount concern. The Food and Agriculture Organization of the United Nations (FAO), in Status of the World’s Soil Resources, (2015) estimates that 33% of the world’s soil is moderately to highly degraded due to erosion, drought, loss of soil organic carbon, loss of biodiversity, destruction of ecosystems, habitat destruction, and pollution. (Source: FAO).

Global status of human degradation of soils. FAO

The World Wildlife Foundation has warned us that half of the topsoil on Earth has been lost over the past 150 years.

This is a huge problem! Soil is a finite resource, which means its loss and degradation is not recoverable within the average human lifespan. This is critically important because it threatens our ability to provide food for a growing population and jeopardizes the quality of our environment.

Loss of topsoil reminds us of the Dust Bowl in the 1930s.  Severe drought and wind whipped up the top soil in the Great Plains, which had been heavily tilled for the previous decade. Image source

The good news is that there are solutions to rebuilding soil health. There is a worldwide effort amongst government agencies, NGOs, and food and agricultural companies to provide education, research, and funding to farmers, ranchers and landowners to help improve, manage, and sustain healthy soils.

For too long, we have cared too much about what the soil can do for us, and each year it grows a little more tired, depleted, susceptible to pests, disease and water shortages, and we are all responsible. “It is up to us, farmers, ranchers, soil scientists, legislators and consumers, to invest in our soil once again. —Soil Health Institute

Healthy Soil – It’s in the Organic Matter!

Examing soil: The presence of earthworms is a good sign of soil health!

Do you grow your own veggies? If yes, you know that they grow better and have fewer pests and diseases if they are grown in a soil that is rich in organic matter. Adding composted kitchen scraps, well-rotted manure or bags of purchased compost to the soil supports the beneficial biota living in soil. This improves soil tilth, texture, aeration, drainage, and nutritional content.

The billions of microscopic bacteria, algae, fungi, protozoa, nematodes, earthworms, and beetles feed, digest and decompose the organic material and in turn release essential plant nutrients that are absorbed by the plants roots.

There is an exciting ecosystem living under our feet!

Microbes perform critical functions in soil food webs, such as decomposing organic materials, cycling nutrients, and improving soil structure. (USDA NRCS)

Increasing the organic matter in soils is the best thing land managers can do to improve the long-term health and performance of soil.

Soils high in organic matter will:

  • Absorb and retain water to help crops even through dry spells.
  • Provide nutrients for healthy root and plant growth for more bountiful crops.
  • Enhance microbial biodiversity and activity, which can help in the suppression of diseases and pests.
  • Resist erosion and compaction.
“Organic matter is anything that contains carbon compounds that were formed by living organisms. It covers a wide range of things like lawn clippings, leaves, stems, branches, moss, algae, lichens any parts of animals, manure, droppings, sewage sludge, sawdust, insects, earthworms and microbes.”  SoilHealth.com

A single gram of healthy soil contains millions of organisms, most of which we cannot see with the naked eye or have even discovered. (Photo: FAO)

Test your knowledge of soil!
Click on the image.

Farmers have always recognized how critical healthy soil is to the production of their crops. Over the past few decades, advancements in soil science, improved technology and resources, and a better understanding of best farming practices have helped farmers become better stewards of the land.

“Making” healthy soil…

Soil needs to be continually managed for optimal health and peak performance. Similar to how you can feed pre and probiotics to the microbes in your gut to improve health, farmers incorporate organic matter, such as crop residues, animal manure, compost, cover crops, and perennial grasses, and legumes to feed the microbial community in the soil.

These conservation farming methods include…

Crop rotation. A systematic approach to planting one crop followed by another to manage pests and soil fertility. Just like we don’t eat the same thing every day, soil cannot feed the same crop year after year. Plants of the same family generally should not be planted successively. Tomatoes, for instance, are heavy users of nitrogen and phosphorus. If you plant them in the same spot year after year, the soil will be depleted of these nutrients. Eventually, soil born pests and diseases will be happily munching away, and you will not be rewarded with an abundant harvest of summer tomatoes!

Increasing soil organic matter. As easy as keeping your soil covered with vegetation at all times. This is so that there is a natural process of photosynthesis, decay, and decomposition to feed the hungry microbes. Additionally, you can add composted leaves and food scraps, or well-rotted manure.

No-till and Conservation Tillage. These techniques leave the previous year’s crop residue on top of the soil and allow the next year’s crop to be planted directly into the remaining stubble. No-till farming also reduces fuel labor costs and builds soil structure and health.

Cover Cropping. Requires farms to keep the soil covered at all times to promote continuous root growth. This method is key to protect the soil surface from erosion. Cover crops also help recycle nutrients, enhance soil organic matter, and feed the soil microbial community.

Managed rotational grazing. Rotating livestock through a series of paddocks helps keep the grassland healthy above and below the surface by spreading nutrients and allowing plant life to rest and recover.

Farmers will also monitor their soil with a combination of tools, including their own observations, field test kits, lab based assessments, and satellite and remote sensing technology. University agricultural extension programs help farmers with soil assessment and prescriptions to improve soil health. For example, Cornell University has developed a soil assessment that measures numerous soil health indicators and (depending on the test results) may prescribe reducing tillage, planting cover crops, planning crop rotations, and/or adding organic matter, nutrients, and other amendments to soil.

Buckwheat. Cover crops are crops grown for the enrichment of the soil and include legumes, non-legumes or a combination of both.

Researchers agree that soil health improves through diversified crop rotations, minimal soil disturbance (no-till and reduced tillage), and the use of cover crops. These practices are the basic principles that underpin conservation agriculture.

Advancements in the science and biology of soil is captivating scientists, environmentalists, corporations, and governments around the world.  The potential of healthy soil goes far beyond the success of this year’s harvest. D2D will explore more of this topic in future posts.

Now, when taking fork to mouth, be sure to thank the millions of good bacteria that fed the soil that helped make your nutritious dinner. Remember, without soil, we wouldn’t exist!

The Bottom Line:

We cannot underestimate the importance of soil. It is the foundation for our food and well-being. It must be managed and cared for in order to to sustain the population of today as well as the population of our future.

Sources:

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