Thursday, October 02, 2014

Managing Drought Risk on the Ranch

Grazing Practices and Soil Moisture

Can my Grazing Practices Influence How Much Moisture is in the Soil?

Soil water is the most limiting plant growth factor on semi-arid rangelands. Grazing management influences the effectiveness of precipitation and soil moisture.

Plant and soil interactionsPlant Cover Improves Soil Moisture

Adequate plant cover must be left to optimize infiltration, the amount of precipitation that enters the soil.

Standing herbage and plant litter on the soil surface break the impact of rain drops on the soil and provide a physical barrier to runoff.

Plant litter and standing herbage reduce evaporation losses by moderating extremes in soil surface temperatures and by protecting the soil against drying winds.

 

 

Water intake (in/hr) of clay loam, silt, loamy sand, and sand in high vs low conditionSoil Compaction Leads to Runoff, Decreased Soil Moisture

Soil compaction and reduced protective plant cover generally reduce infiltration and increase runoff during heavy precipitation.

The potential for damaging soil structure or compacting soil generally is greater on wet compared to dry soils and greater on fine textured clayey or silty soils compared to coarse textured sandy soils. 

Numerous studies of livestock effects on rangeland watersheds conclude: non-grazed areas have higher infiltration rates than grazed areas. Heavy grazing reduces infiltration more than moderate or light grazing.

 

Practices to Optimize Use of Precipitation

Leaving adequate remaining herbage and allowing preferred species to maintain healthy root systems are the best approaches available for ranchers to optimize use of precipitation.

Year-to-year changes in pasture-use sequences, periodic full growing-season deferment, and moderate stocking rates can be used to enhance root length and function.

Overgrazing may cause drought-like conditions even with average precipitation.

For more on best management practices to optimize soil moisture, see "Before Drought"

Resources

Grazing Lands Hydrology and Erosion (in NRCS National Range and Pasture Handbook)

The National Drought Mitigation Center | 3310 Holdrege Street | P.O. Box 830988 | Lincoln, NE 68583–0988
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