Two Types Of Soil Compaction

Soil compacts when the pore space is reduced and bulk density is increased. Any activity that reduces pore space causes soil compaction. The major cause is traffic over the fields. Tractors, implements, livestock, and even humans can compact soil when traveling on field.

The facts that affect soil compaction include soil physical conditions, soil type as well as weight and design of the load on soil, distribution of the load over the number of axles and tires, and the number of trips made over the same area.

There are two types of soil compaction shallow and deep. Shallow compaction occurs near the soil surface and is influenced primarily by pressure applied to the soil surface. Freezing-thawing and wetting-drying cycles and even tillage can

Seeds require oxygen and water to germinate. For healthy plant and root development, roots must have oxygen in order to take up nutrients. Water is an essential component of photosynthesis. Soil with good structure is looser than compacted soil. To penetrate the soil, seedlings require a loose soil structure. Roots develop stronger and more extensive systems in porous soil.

As pore space is reduced by compaction, water flow through the soil is slowed down and even block. If water is applied to soil faster than it saturates into the soil, the excess runs off, often causing erosion, loss of plant nutrients and pesticides, and pollution of streams and other water. Runoff water is lost from the field. In compacted wet soils, water fills the few pore spaces left at the expense of air. The lack of air will cause nutrient uptake.

2.6 Tractor and machinery

Dual tires, compared to single tires, decrease pressure on soil, but the affected area is at least twice as large. Dual tires or even flotation tires do not prevent compaction; they merely change the distribution. “Testing at USDA’s National Tillage Laboratory indicate there is no crop yield increase for dual tires over single tires. Tandem axles on heavy trailers, such as grain wagons, liquid manure spreaders, and large sprayers, are a better way to spread the load over more

Even tracks create an ever longer footprint, this then spreads the weight over a larger surface area. All these approaches reduce the pressure on the soil and therefore reduce the depth of shallow compaction. By spreading the weight over more axles, deep compaction is reduced or eliminated.

2.8 Equipment and tillage operations

Tillage systems can either create or help to reduce soil compaction. Tillage operations break up soil into smaller particles. Some tillage equipment, such as mouldboard ploughs, may aerate the soil and increase filtration at the surface while creating a compacted layer just below the tillage depth. This layer is called a hard pan. Discs can also produce a hard pan just below tillage depth while over tilling the soil near the surface, especially where multiple passes are made the same year.

2.9 Number of passes

Just one pass over a field under poor soil conditions is enough cause damage. The first pass of a wheel can cause 80 percent of the potential compaction. Following passes causes additional compaction, but gradually less, compaction. After four passes, the additional compaction becomes very small and probably can be ignored. One option is to establish drive rows and take the compaction losses there, while protecting the rest of the field. This is one method to reduce compaction in the