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Manage residue to enhance no-till

Using vertical tillage tools with a no-till system can warm up the soil 
and unlock fertility in lower levels, increasing yield potential

No-till seeding has become a tried and true system of planting crops over a wide area of Canada and the U.S. No-till systems have evolved tremendously over the past 20 to 25 years and that evolution continues today. The next challenge will be to push beyond a yield plateau that many no-tillers have experienced in recent years.

When it comes to achieving higher yields, no-tillers have three major issues to tackle: cold and wet spring soils; high density in the lower portion of the topsoil; and large amounts of residual fertility locked in the no-till stover.

Cold wet soil slows machinery carrying capability, seeding emergence and vigour. higher density on the bottom part of the topsoil layer causes reduced nutrient uptake, reduced moisture carrying capacity and eventually reduced root growth and yield. Yields can be enhanced by releasing the fertility in the previous crop’s residue for the growing crop.

All of these limitations can be alleviated with the proper use of true vertical tillage tools.

Let’s use the following analogy: topsoil is similar to a lake or body of water. Different creatures have different preferences as to where they live in the water column. For example, algae live near the surface where they feed on higher-level nutrients and sunshine. Bigger fish prefer to live lower in the lower water column, and bottom feeders obviously live on the bottom. Some creatures move up and down through the water column as they feed. Soil is similar. Certain microbes and bacteria live in the upper portions of the topsoil, certain fungi prefer the middle of the soil profile and others, the bottom.

Move soil vertically

If you disturb the soil by totally inverting it, all of the creatures in the soil have to build and find new homes. It takes a while for their populations to recover. The beauty of vertical tillage is that because all the movement is vertical, the existing populations of creatures in the topsoil are not displaced or destroyed.

Large amounts of residue on the soil surface act like an insulating blanket keeping the topsoil cold. Reducing residue volume by processing with a vertical tillage machine accomplishes a number of things. It allows more sun and air into the upper portion of the soil surface for warming and reduces or pre-processes the amount of residue that the seeding equipment needs to deal with. Vertical tillage residue processing also begins the nutrient release process from the stover. Opening the very top of the soil adds air that warms the seedbed. You are not inverting or stirring the seedbed, just adding air.

A second analogy is that true vertical tillage is much like a wood stove. When you add air to a wood stove, you increase the amount of heat and combustion. When you add air to the seedbed portion of topsoil, the soil warms and the warmth increases soil life activity. You get a soil creature population “boom” or “bloom.”

There are many benefits to warming the top one and three-quarters to two inches of topsoil:

  • Seeding can occur many days earlier because the soil can carry the planting equipment.
  • Seeds are placed in an ideal warm environment with neither excessive or a depleted soil moisture.
  • Seed germination, vigour and speed of emergence are improved.
  • Populations of existing flora and fauna bloom to help in the nutrient uptake process.

Manage crop residue

Crop residue, especially corn, contains a large amount of nutrients. In a standard no-till system these nutrients are usually released late in the growing season, once higher temperature and rainfall cause decomposition. This usually happens too late to be used by the growing crop. If these nutrients are recycled more quickly using a vertical tillage tool pass, they will be available for the growing crop, giving the crop a boost, and potential yield gain.

Over time nearly all no-till soils stratify. The top two inches of topsoil — the layer that received direct fertilizer application and mechanical tillage soil movement — tends to become open and loose, and very high in nutrients.

The soil from two inches down to six or eight inches tends to get quite dense from lack of mechanical tillage, lack of direct fertilizer application and wheel traffic. This increased density reduces the soil’s ability to store water and exchange nutrients. Some no-till soils can become so dense that moisture and nutrient exchange can stall. A tell tale sign that this has occurred is two to three years of undigested residue visible on the soil surface.

Reduce soil density

There are a number of ways of helping alleviate this lower topsoil density issue. One is to pull a vertical shank that lifts the soil profile and shatters it without stirring it. In-line rippers are an example of this. Some vertical tillage systems offer the option of putting shanks into their framework to offer upper topsoil warming and lower topsoil fracturing. Just make sure that the shank is only moving soil vertically if you wish to keep the vertical tillage advantage.

Another option is to use vertical tillage tools that offer a jack hammer effect. Certain machines have rolling coulters that vibrate and shatter the lower topsoil density. Reducing density levels of the lower topsoil increases root growth and plant, water and nutrient uptake. It also increases the water holding capacity of topsoil, which can add to drought tolerance in certain years.

Adding all the positives of vertical tillage into a no-till system without displacing the gains that have been accomplished creates a synergy. Combining the benefits of vertical tillage — increased soil warming, increased residue breakdown and lower soil density —with the benefits of no-till’s improved soil structure, decreased soil erosion and soil conservation can lead to further yield increases.

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