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Good Grazing and Soil Health Protection When There’s Too Much Rain

By   /  July 6, 2015  /  Comments Off on Good Grazing and Soil Health Protection When There’s Too Much Rain

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map_specnews11_ltst_4namus_enus_650x366For much of Indiana, where I live, and a lot of other parts of the country June was quite wet. Some areas had in excess of 10 inches of rain dumped on them. A recent map from the Midwestern Regional Climate Center showed other areas in the 12 to 15 inch range. More than once I could have described the rain as “in sheets”. This isn’t fun if you are trying to work or drive in it. If this keeps up, perhaps I should consider building an ark.

It was just a few weeks back that I was starting to be a little concerned about how dry it was getting…that is not a problem now. Excess water has turned the focus more on trying to maintain forage quality and a rarity for this time of year, “pugging.” Saturated soils are more susceptible to animal pugging from their hooves breaking through the soil surface. Pugging forces soil particles together reducing pore space; causing compaction. This loss in pore space reduces water holding capacity, slows drainage, and can greatly reduce needed oxygen in the soil. Lack of oxygen means less soil microbes and less nutrients being available to plants. A typical soil should contain about 50% pore space, occupied by about half water and half air by volume. Soil particles of varying degrees of sand, silt, and clay, organic matter, and living organisms make up the remaining 50%.

Compaction indicated by a platy soil surface structure that decreases production and increases runoff.

Compaction indicated by a platy soil surface structure that decreases production and increases runoff.

You will not find a livestock farm without any compaction. You won’t find too many row crop farms without any compaction either, but that is a slightly different story and usually caused by different means. High traffic areas such as walkways or trails, along fences, and heavily used feeding and watering areas will almost always have compacted soils and almost can’t be avoided. Pastures can be managed to reduce pugging and thus compaction.

When you think about pugging, you normally think about early spring conditions; wet soils with limited new growth and residual dead forage left from the previous growing season. We can’t control the amount of rain we get, but we can impact what happens to that water. When a rain drop hits an impervious surface like your roof, concrete, blacktop or a highly compacted soil, it runs off. If it doesn’t find a permeable material with available space to soak into, then it keeps heading downstream. Too much not being absorbed can cause flooding. Each year, there is less permeable acreage due to new roads and new development, all with impervious surfaces. This means the rest of the land needs to be more efficient to maintain below ground aquafers and reduce flooding.

Mercy, where was I? Okay, here are some ways to reduce pugging and compaction on pastures. The shorter and less mature the forage, compounded with the lack of, or small quantity of dead plant residual from the previous year increases the burying and uprooting of plants from grazing livestock hooves, especially under wet conditions. With a small amount of cover and or new forage growth, you also have a reduced amount of live roots below the surface. You can probably see where I’m heading with this. The more growth you have above ground, the more live roots you have below the ground and that cover and those live root systems stabilize and protect the soil.

A healthy pasture soil with good soil structure, water infiltration, organic matter, root growth and life.

A healthy pasture soil with good soil structure, water infiltration, organic matter, root growth and life.

If we maintain good cover and don’t compact the surface layer, then the soil can perform as it is supposed to and readily collect a large amount of rainfall with its ideal permeable structure and store enormous amounts of water for later use and recharge the deep below ground aquifers. Where pastures with good management have returned to being good water accumulators, you suddenly notice that water and sediment control basins (dry dams) don’t have as much or any water in them with normal rains and those fields have a new incredible resilience to droughty periods which is easily seen in forage growth, health and production.

I was recently with a group of New Zealanders that were touring farms here in the states. The topic of cover and runoff came up while looking at a pasture fence line between two different managers. The over grazed side of the fence had bare spots, more weed issues, and evidence of soil movement and increased runoff. The managed side of the fence had been grazed just a few days prior and had an average of 4 to 6 inches of forage remaining, no soil visible with a nice amount of duff covering the soil surface. It was nice to hear one of the New Zealanders note that the over grazed side didn’t have a runoff problem, it had an infiltration problem! That comes from a country that is dominant in short perennial ryegrass and white clover.

Noteworthy remarks included “On the slope you have to leave more sward to maintain it.” “Down on the flat and where it will go to arable crops the next year, you can graze it down to the boards.” There was some humor in watching a couple people from Tennessee asking, “Can you say that again?” It’s all English, just not the same. Always a treat to be around those guys. (For reference, “arable crops” are planted row crops and “grazed to the boards” is the same as grazing down to the dirt or floor.)

On a grass-based dairy just a few days ago, pugging was starting to be an issue on some poorly drained soils. It is important on a dairy operation to try and maintain quality forage for milk production with sufficient intake. They were doing a good job of moving the cows every twelve hours to a new area to reduce the amount of time on any one area, but also were giving the cows a larger allotment than they normally would to lessen the impact during the wet period. Those fields will also be rested longer before being grazed again to allow for not only plant growth recovery, but to allow that plant to tiller more and regrow more new roots that will help heal those pugged areas. Longer rests after an instance like this will start the healing process. It is amazing what a growing plant can accomplish given the opportunity. Pugged areas need longer rest to recover, allowing plants to recover, tiller and re-establish themselves. If they don’t, you will see an increase of weeds in this area later on.

WAY too much rain here!

WAY too much rain here!

Too much rain can make it more challenging to manage pastures. Forage growth can increase, but forage quality can sometimes lower due to tied up nitrogen and lack of sufficient sunlight which can reduce crude protein and energy of the forage. Once things start drying out and the sun returns, forage generally improves.

Try and maintain good cover and adequate stop grazing heights during this wet weather. Those stop grazing heights for our cool season forages should be at least 4 inches, not the tallest stuff left, but the shortest! Move animals when possible to new paddocks when forage is dry and if that is not possible, move before sooner than later so they don’t gorge on wet forages increasing the risk of bloat, especially where forages are kept very vegetative.

Minimize high density grazing and any vehicular traffic when soils are wet. Maintain or increase organic matter of the soil over time by improving a maintaining plant cover and plant production. Longer rest periods will allow for deeper root growth and penetration and over time will increase soil organic matter and infiltration. Improved infiltration will mean less saturation and improved resilience to compaction during wet periods.

Keep on grazing!

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About the author

For more than 25 years, Victor Shelton, Indiana agronomist and grazing specialist with the Natural Resources Conservation Service, has provided advice about grazing’s best practices. He travels across the state conducting pasture walks, working one on one with farmers and participating in grazing talks. He also writes a newsletter called "Grazing Bites" as a way to talk about current and seasonal grazing issues and what farmers need to be prepared for.

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