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Adaptive grazing management improves soil health

Doug Peterson WFP-doug-peterson-grazing-soil.jpg
Cattle grazing can be an important tool for bringing degraded soils back to life.
Animal impact can add organic matter and fertility, and improve the soil biology.

Cattle are a wonderful tool for bringing degraded soils (cropland or pasture) back to healthy productivity. Animal impact (with proper timing and duration) can add organic matter and fertility, and improve the soil biology.

Managing the land with soil health in mind provides ecological and economic benefits. Doug Peterson is a rancher and soil health specialist--now retired from NRCS and doing private consulting and teaching with Understanding Ag, LLC, a regenerative agricultural consulting company that provides support to help clients reduce input costs, generate profits and ensure family farming futures.

This company recently started an on-line course (called Regen Ag 101) to help farmers, ranchers, gardeners and others better understand and implement soil health-focused regenerative agricultural principles and practices.

Peterson explains that in order to manage a piece of land for optimum soil health, six principles should be followed. Those include 1) Context; understand that your environmental, financial and social context will have an impact on the decisions you make. 2) Armor the soil; keep the soil covered to minimize bare ground. Bare ground is the enemy of healthy soil. 3) Minimize soil disturbance by utilizing reduced/no till practices on cropland and adaptive grazing strategies on pastures. 4) Increase plant diversity of all crop types, warm and cool season grasses and forbs. 5) Keep living roots in the ground all year and 6) Integrate livestock grazing. The idea of context was recently added to this list.

“In the past few decades we’ve learned a lot about how important healthy soil is, and plant diversity. Moisture is critical, and ground cover is crucial to help hold moisture in soil. Many people don’t understand how damaging bare soil is—allowing the moisture to evaporate,” he says.

Soil structure a factor

Soil structure is also a factor in water infiltration, and in preventing evaporation. “Once you have moisture in the soil, it’s all too easy to have it evaporate if the grass is too short and there’s too much bare soil. We’ve known for a long time that moisture is important but we haven’t understood how to manage, to maintain ground cover,” he says.

When grazing can be flexible, giving pastures more time to recover, there is more ground cover to capture the moisture. “Most places need a much longer recovery period than people realize. Even in arid areas, where people talk about a once-over graze, some regions may do best if grazed only every other year, especially in a drought.”

Your own situation should dictate how often and how long a certain pasture is grazed, rather than any set system or prescription for grazing.

It can vary from year to year. “This is why we changed the name from mob grazing or short-duration high-intensity grazing to adaptive multi-paddock grazing because it more accurately reflects what we are trying to do. We want to adapt to the given conditions, the class of livestock, the year/season, type of forage, etc. It takes some time to understand all this,” says Peterson.

“There are a few things we’ve tweaked in our own operation. There are times we can come back and graze a pasture quicker, and times we shouldn’t—because we need to build the soil and its structure to get more water infiltration,” he says.

With animals that need a higher plane of nutrition like yearlings or bred heifers, to get good animal performance you probably need to graze the plants before they are fully rested—before they mature. But after you do that, you give it longer rest periods and graze the more mature grass with cows, and invest in the soil by having it rested longer.

You can vary the class of livestock.

“If you graze the same pasture over and over with cows, or with yearlings, it won’t do as well as if you mix it up a little. It helps with the diversity because sometimes you can make cows eat some plants the yearlings won’t; you could make yearlings eat those but their performance would suffer. Diversity in management strategy is useful. Sometimes the plants need a long rest period and sometimes shorter.”

Understanding soil

It’s important to understand soil, and what builds aggregates. The most important thing for soils is not nitrogen or phosphorus; it’s what makes soil aggregate. “It needs to have that clumpy cottage cheese structure. When we dig up healthy soil it is somewhat loose and looks like cottage cheese,” says Peterson. It’s not tightly packed together.

The things that create/build aggregation include plant roots and soil biology. “We need good, deep root structure from diverse plants, to feed that biology. The number one food source for the organisms in the soil are the exudates off living roots. We need to make sure that we’ll have diverse, deep roots all year long to feed the soil biology all year long,” he explains.

“If we don’t have diversity in the roots we won’t have diversity in the nutrient cycle and there won’t be as much there for our cattle to graze. Bare soil, exposing the soil, or too-short canopy of grass degrades aggregation. Cutting it for hay is probably the most degrading thing we can do to grassland, even more than overgrazing. Not only are we not putting back anything (just taking biomass off), but we do it all at once. Even if we overgraze something, we do it over a longer period; it’s not such a sudden impact on the soil. If you cut and bale and take off the hay, it’s one huge swoop that happens so fast that the organisms in the soil don’t have a chance to migrate down or go dormant. It dries the soil so fast that many of those organisms don’t survive,” says Peterson.

“The soil is actually an aquatic ecosystem; those organisms must have moisture because they are swimmers. The bacteria, protozoa and nematodes can’t move around in dry soil. When we hay it, we dry it out so fast that they die. Overgrazing happens more gradually and gives them a chance to go into dormancy. They’re not functioning, but they go dormant and are still alive. But with haying, when you go suddenly from tall canopy to no canopy, it is devastating to the soil biology,” he explains.

If we do need to cut hay, it helps if we don’t cut too close (leaving more stubble—for more ground cover) and if we intermittently graze those fields so there is cattle impact—maybe haying one year and grazing the next. We need to make the haying less damaging, and leave more residual ground cover going into hot, dry periods.

In a drought it is easy to see the pastures that have been taken care of, and the pastures that are overgrazed (or fields that have been cut for hay). Good grazing management provides a buffer and insurance against drought because the land and plants can weather it better and recover more quickly.

[Heather Thomas writes from Salmon, Idaho]

TAGS: Soil Health
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