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Guest Opinions

Amazing Things Go On Underground

Written by USDA's Natural Resource Conservation Service Wyoming

There are more soil microorganisms in a teaspoon of healthy soil than there are people on the earth.

Millions of species and billions of organisms – bacteria, algae, microscopic insects, earthworms, beetles, ants, mites, fungi and more – represent the greatest concentration of biomass anywhere on the planet. Microbes, which make up only one-half of one percent of the total soil mass, are the yeasts, algae, protozoa, bacteria, nematodes and fungi that process organic matter into rich, dark, stable humus in the soil.

The best soil on most farms is found in the fencerow.

These undisturbed remnants of what soil properties were once like is no surprise to farmers who have dug into that soil. It’s crumbly, dark and loose, and it’s a model of soil structure and organic matter for farmers who are trying to make their soil healthier.

Tillage – or plowing – destroys the soil’s structure.

Tillage destroys “aggregation” or the soil’s structure, which is the habitat soil microorganisms depend upon to ensure critical soil functions like nutrient cycling. Tillage also reduces organic matter content and increases erosion, which reduces the sustainability of our food production system.

Tilling the soil up does not allow more water to soak into it.

Don’t believe it? Fill two containers with untilled and tilled soil and simulate rainfall on them. Watch the water stand on top of the tilled sample but soak down through the untilled sample.

Or, give them the slake test by placing clods of untilled and tilled soils on wire mesh at the top of water-filled jars. You’ll find if you submerge tilled soil just below the surface, it will soon collapse in a heap at the bottom of the jar, but untilled soil will still be intact, for the most part, even 24 hours later.

Tilling soils causes pores to collapse and seal over, causing more rain to runoff than soak in.

The Morrow Plots on the campus of the University of Illinois indicate soil organic matter content in prairie grass borders was 5.5 to 6.5 percent in 1876. Less than half of that is left. That’s the case with most prairie soils – oxidation of organic matter from tillage for row crops has reduced organic matter levels to between two to three percent today.

A farmer’s favorite cocktail mix might not be what you think.

Innovative farmers are breathing new life into their soil by seeding a “cocktail mix” of six to 12 plants to get diversity above-ground, which creates much-needed diversity below the ground. Through that diversity, farmers are mimicking the soil-building and microbial-friendly conditions of the diverse native prairies.

If you want your soil to be healthy, you shouldn’t see it very often.

That’s because you want that soil to be covered all the time, preferably with living plants. Keeping the soil covered all the time makes perfect sense when you realize that healthy soils are full of life. The microorganisms living in the soil need food and cover to survive – just like other living creatures.

Roots of some plants can grow three feet deep in 60 days.

That’s right, roots of daikon-type radishes are a biological alternative to deep ripping to alleviate soil compaction. After radishes winterkill, the channels created by the roots tend to remain open at the surface, improving infiltration, surface drainage and soil warming. The popular cover crop also is an excellent nitrogen scavenger.

What did President Thomas Jefferson know that we don’t? More than 200 years ago, Thomas Jefferson, a farmer and conservationist, used vetch, turnips, peas and clover as cover crops and in rotation. He used these crops on his Virginia plantation to build soil that he knew was being depleted with his tobacco cash crop.

Multiple benefits come from multiple species. The below-ground synergy created by crop rotations and multi-species cover crops can actually accelerate biological time by increasing organic matter, allowing crops to flourish in dry times while monocultures struggle. And as an added bonus, diverse cover crop mixtures work together to crowd out weeds, improve nutrient cycling and reduce plant diseases.

For more information about soil health, go to nrcs.usda.gov.