Soil Health - 4

It is little wonder farmers delight in the earthy smell of freshly dug soil. That aroma is also a sign that soil is healthy.

A healthy soil is mellow, can be easily dug and has a darker color reflective of higher organic matter levels. The structure is crumbly and breaks apart easily when handled. Earthworms should be abundant, along with white fungal strands of mycelium growth.

In the past several articles, I've focused on the importance of soil health and the importance of monitoring and measuring it. Healthy soils allow rainwater to penetrate -- preventing excess runoff, sedimentation, erosion, and reducing flooding. Healthy soils store more water, support greater root and plant growth and promote increased crop productivity.

There is no single recipe to improving soil health. The most important ingredient is a mindset that you want to tend the soil -- not just the crop.

The first step to soil health is to make sure it has the right physical and chemical characteristics to support biological life at its highest level. On our family farm, improvements have come from no-till and planting cover crops each year. We apply one ton of synthetic gypsum and 4 to 6 tons of compost every three years and do aeration tillage every four years.

After a decade of these practices, the nature of the soil has changed. We are reaping the benefits of a mellower soil that is more productive and more resilient against stresses and therefore less yield variable. In the near future, I want to explore adding humates and biologicals to see where they fit in and what value they add. Here's some of the practices farmers can adopt to improve soil health:

ADOPT NO-TILL

There is no doubt that no-till is often the foundation to keep as much residue on the surface as possible and protect the soil from erosion. It slows the decomposition of residue and produces more stable humic compounds, rather than releasing much of the carbon as carbon dioxide back to the atmosphere.

Refraining from tillage also keeps the natural soil structure intact and gives it an opportunity to build. However, no-till soils can compact slightly due to trafficking and poor health, and lack of aeration can affect microbial activity.

Tillage is a controversial topic. Not everyone will agree, but I've come to appreciate that some forms of vertical tillage can have some benefits. It helps process corn stalks or wheat stubble by slicing, dicing and shearing the material while throwing on a little soil to help stimulate residue decomposition. It also levels the seedbed, evenly distributes residue and remediates surface compaction and crusting. Depending on the design of the equipment, it can create divots in the soil that improves aeration and remediates compaction to a depth of 8 inches while improving water infiltration and aeration, and causing a spike in microbial activity.

INCORPORATE COVER CROPS

One of the keys to building soil health is to extend the amount of time plants are growing in the field. That is tough with annual crops such as corn and soybeans that have active root systems about four months of the year. Wheat, soybean double crop and alfalfa have root systems that extend that season. However, it's cover crops that can extend that green bridge to eight to 10 months depending on where the farm is at and if the crops overwinter.

Cover crops can protect the soil, suppress winter annual weeds, add back organic matter, scavenge soil nitrate and ammonium, and help create a better seedbed.

The true benefit of cover crops comes from root growth and the natural root leakage of sugars and nutrients. This leakage stimulates soil biology in the fall and spring, at a time of the year when the soil rhizosphere is generally inactive because there are no actively growing plants.

ADD COMPOST OR MANURE

To have soil health, it's necessary to feed the biology. Water-soluble carbon and nitrogen and plenty of it is needed to keep cycling carbon and nutrients back into the soil. Compost and livestock manures feed both the crops and soil organisms to help build tilth.

UTILIZE GYPSUM

I use a pelleted, mined gypsum (400 pounds per acre) annually or a synthetic agriculture gypsum product (1 ton per acre) from a citric-acid plant or power plant every three years. Regardless of source, gypsum provides both calcium and sulfur to plants. The calcium helps build soil structure by flocculating soil particles into more natural aggregates, which improves structure and tilth.

CONSIDER BIOLOGICALS

The biological product market is booming. I classify biologicals into groups: humates, enzymes or organisms or combinations of these components. Over the years, a lot of claims have been made about what these products can do, but few field measurements have been made to validate these claims and much of the results are anecdotal observations

Today we have tests like Solvita and Haney that can measure change in biology in the field. If the claims are true, then these biologicals can play a role in building soil health. I intend to do some testing and measuring this year and see where they fit as an ingredient in "my recipe."

Building soil health requires a system or combination of practices that help the biology flourish. Today we have the tools to measure what we try. Building soil health still doesn't happen overnight. It could take five or six years to see the cumulative benefits.

Dan Davidson can be reached at AskDrDan@dtn.com

(PS/AG)

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