By Rory Lewandowski
An unseasonably warm February led to mud management issues for many pasture-based livestock operations. Spring typically leads to our April showers and the “traditional” time of managing around mud. We just arrived in mud season a little earlier.
All this mud is an undesirable condition, from an animal performance, resource management and environmental perspective.
Graziers need to have a mud control plan as part of a comprehensive grazing management system.
Within a grazing system, mud does not just happen. Wet soils combined with livestock create mud.
How quickly mud is created depends upon the number of livestock in a given area, the weight of those livestock, the saturation level of the soil, the time of year, and the strength of the surface to support those livestock.
A thick, vigorous growing sod with light livestock pressure is most able to resist creating mud, while a thin, dormant sod cover with even light to moderate livestock pressure is least able to resist creating mud.
The pressure livestock exert on a surface depends upon their weight and hoof area in contact with the surface.
The chart below adapted from the University of Kentucky Extension Publication AEN-115, Appropriate All Weather Surfaces for Livestock, shows the amount of pressure applied by standing livestock in pounds per square inch:
Surprisingly, large livestock can exert more pressure than a 50-ton dozer because their weight is concentrated in a relatively small area.
When they walk, livestock can double the pressure applied to a surface because weight shifts from four feet to two feet.
This is important because our soils have a weight-bearing capacity.
According to the University of Kentucky AEN-115 publication, soft clay or sandy loam has a capacity of 14 psi, firm clay 28 psi and dry clay 42 psi. Wet soils lose supporting strength.
I could not find figures for sod cover, but it is reasonable to assume that adding a sod cover on top of these soils will increase the bearing capacity of the soil. The denser the sod, the more resistance it will have.
Walking through mud takes a toll on our livestock. Livestock require more energy in muddy conditions because mud reduces the insulating value of the hair coat and because walking in mud is strenuous.
Livestock may actually eat less because of the effort required to get to feed and water in mud conditions. As a result, daily gains decline.
Another adjacent chart in the University of Kentucky AEN-115 publication summarizes some of the effects of mud on cattle performance.
In addition to detrimental livestock effects, mud creates vulnerability to soil loss through erosion and water movement that is an environmental cost.
When a pasture sod base is beat up and turned into mud, there is an economic cost associated with losing some grazing potential.
We can also think of situations where viewing mud and livestock creates a negative view of agriculture, what could be termed “social” loss.
One practical tool to help graziers manage muddy periods and protect their pasture sod resources is the heavy use pad.
A heavy use pad provides a feeding area for livestock that minimizes mud creation and soil erosion. The “Cadillac” of heavy use pads is concrete, but for most grazing operations the use of geotextile cloth and stone is the more practical and economical choice.
Geotextile fabric creates a porous barrier between the soil underneath the fabric and the rock on top of the fabric. The porous nature of the fabric allows water/moisture to pass through it while the rock on top of it remains in place to provide a firm surface.
The first step in constructing a geotextile heavy use pad is to pick a site that has some reasonably good drainage. Level the area and remove the topsoil.
Lay out the geotextile fabric, taking care to avoid wrinkles. If the pad is larger than a single width of the fabric, make sure that there is approximately 2 feet of overlap in the succeeding passes.
Next, apply a layer of rock on top of the fabric, taking care not to rip or wrinkle the fabric. Generally, a four- to six-inch base layer of number 4 crushed limestone rock is laid on top of the fabric, followed by a 2- to 3-inch cover of a finer cover of dense grade aggregate or road mix.
Depending upon your budget, some pads may also incorporate gravel paver grids that help to reduce the volume of surface rock loss during scraping and cleaning of the pad.