Researchers with North Dakota State University have dug up the dirt on why some grazing systems work better than others, especially in the northern Great Plains where drought can be a threat.
They studied the soil and roots of grasses to understand what happens under pasturing systems that range from continuous grazing to idled land where no grazing occurs.
They discovered why rotational grazing supports healthy pastures that can better withstand drought. They also found that idling the land for several years damages pasture health and its ability to capture and hold moisture.
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“There’s no substitute for good rainfall, but there are things you can do to try to mitigate it,” said Paul Nyren, director of North Dakota State University’s Central Grasslands Research Extension Centre.
Rotational grazing supported the healthiest root growth in the systems studied, Nyren said during Manitoba Ag Days in Brandon on Jan. 21. That root growth helped the grass plants tap moisture farther below the soil surface. The dying and regeneration of roots also helped improve organic matter in the soil, allowing water to penetrate better and be stored in greater amounts.
On the other hand, said Nyren, intensive continuous grazing resulted in low root vigour, which meant poorer forage production. The poorer root vigour was accompanied by lower soil organic matter and hardened clods, which made moisture penetration and retention less likely.
The worst conditions were found in idled land under the Conservation Reserve Program, where American producers are paid to leave land out of crop and pasture production. The results were low root vigour, limited root depth and low organic matter. Plants often became root bound and there was an excess buildup of surface litter.
Nyren said it was an indication that grazing is needed to keep grasslands productive and healthy.
