Protect your Soil and Water

By Robert Fears

Editor's note: We discussed drought management in the September issue of The Cattleman, emphasizing the conservation of grass. We discussed the types of drought and how to help grass recuperate when rains return. In this second of 2 articles on drought management, we take a look at protecting the soil and preparing to capture rainfall.

"Dead plants, bare ground and erosion are the aftermath of drought," says Steve Nelle with the USDA Natural Resource Conservation Service (NRCS). "Implement measures to maintain soil condition and prevent erosion so that grass has a place to re-establish.

"The only real way to maintain healthy soil conditions on rangeland is to ensure that adequate litter and grass residue are returned to the soil. This layer of litter provides mulch to protect the surface from erosion and extreme heat and cold. The decomposing litter adds valuable organic matter content to the soil, which greatly improves water penetration and water holding capacity," Nelle explains.

"The only way to provide this litter and mulch is to graze conservatively and leave a
substantial amount of grass stubble. This is the key to maintaining healthy soil and vegetation on rangeland."

"Proper grazing management during a drought has a tremendous effect on a ranch's response when it does rain," explains Jason Hohlt with NRCS at Kingsville. "If the ranch is grazed down to where very little grass cover is left, rainfall is likely to run off, carrying soil with it. This type of accelerated erosion can strongly limit long-term land productivity.

"When adequate amounts of grass cover and litter are left in pastures, a large percentage of the rain is likely to infiltrate the soil and become available for grass growth. This is why 2 ranches side by side can look different as a drought starts to break. After an inch of rain, grass regains vigor and turns green on the ranch where adequate amounts of residual grass cover were maintained. On the ranch where adequate grass was not maintained, you cannot see any effects of rain because it ran off into the creeks and stock tanks. As is often said, 'It doesn't matter how much rain you get, it matters how much rain you keep.'

"How much cover is enough?" Hohlt asks. "It depends on the types of grasses in your pastures. In South Texas, most of the range is dominated by mid-grasses. Leaving at least 1,000 pounds per acre of standing grass in the pasture is the rule of thumb. This is roughly 6 to 8 inches of stubble height. Leaving this amount of stubble promotes an effective water cycle, conserves top soil and promotes good plant vigor," he says.

Watch water quality
Catastrophic droughts — the type we are experiencing in 2011 — are detrimental to water supplies. Ponds become dry, water well pressure drops, and rivers and streams stop flowing, leaving us with 2 options. We can either haul water or sell the livestock.

"If water levels are extremely low, build temporary fences around ponds to keep out livestock," says Mike Mecke, retired water specialist at Kerrville.

"As water quantities decrease in ponds, so does water quality. During drought, vegetation disappears from pond banks due to overgrazing and trampling. Cattle going in and out of ponds pack the soil with their hooves increasing water flow. Nitrates and salt from the soil are carried into the pond in greater quantities when it does rain, because there is no vegetation to filter them out of the runoff water. The dilution factor is less because of the low water level causing salt and nitrate concentrations to reach cattle toxicity levels."

"Check ponds regularly for blue-green algae blooms," warns Dave Sparks, D.V.M., Oklahoma State University food animal quality and health Extension specialist.

"Blue-green algae in dirty and drying ponds can cause fatal toxicity in all domestic animals that drink the remaining water. This culprit is not really an algae and may not even be blue-green. The problem is caused by a group of organisms known as cyanobacteria. Colors range from blue to bright green, but may also be red or purple. Often these organisms will show up like paint scum on the water's surface."

Increase water storage capacity
On the positive side, we can improve our water systems to store more water when it does rain to help us through the next drought. These 4 basic steps can help you determine the pond capacity you need.

1. Calculate livestock and wildlife annual water needs based on stocking rates and the estimated daily water intakes.
2. Add the annual water requirements and convert to cubic feet by dividing the total by 7.48 gallons.
3. Calculate pond dimensions necessary for storage of the calculated cubic feet of water.
4. Allow additional capacity for evaporation. A pond will lose 8 to 12 feet of water per year due to evaporation.

Determine how the pond will be expanded. Will it be wider, longer, or deeper?

Daily water intake by livestock and wildlife depends on animal size, air temperature, humidity, forage moisture and whether the females are dry or lactating.

For these reasons, information on livestock and wildlife water requirements varies by the information source. The Ranchers Reference Guide published by Texas A&M University presents approximate peak water requirements as 7 to 16 gallons per day for cattle, 8 to 12 for horses and 1 to 4 for sheep, goats and white-tailed deer.

Nelle says, "Those numbers are for average weather conditions. During extreme drought, the forage provides no moisture and animals need to drink more water than usual to maintain adequate hydration and rumen function."

Hohlt reports that NRCS usually plans for 15 to 30 gallons of water per head of cattle per day in South Texas. When estimating needed pond capacities, it is wise to use maximum livestock and wildlife consumption estimates. Water overcapacity is never bad.

"Once pond capacity problems have been corrected, water flow into the structures can be enhanced," says Mecke.

"Furrows and terraces can be built across slopes to channel water into ponds rather than letting it flow down hillsides, possibly causing soil erosion. The disturbed soil can be seeded in the fall with a grass/legume mixture if rain is expected. Vegetation produced from this seeding will help hold the soil in place and provide additional forage for wildlife and livestock.

"Expansion and new construction provides opportunities to redesign ponds to produce better water quality," continues Mecke. "Consider making banks vertical on 3 sides of the pond to provide increased water depth and to prevent livestock entry.

"Grade a gentle slope on the fourth side, fence it and install a gate that allows livestock to access the water at only 1 point. Gravel the pond entry to prevent erosion and mud transport into the water on livestock hooves.

"Limited access and deep water encourage cattle to drink and then leave instead of standing, urinating and defecating in the pond. Avoiding cattle feeding near ponds also discourages them from loafing around the watering areas," Mecke says.

Repair leaking ponds
It is a good time to repair leaking ponds while they are low or dry to avoid loss of precious water prior to and during the next drought. Remove trees and shrubs, either chemically or mechanically, from pond embankments to prevent roots from creating water channels that facilitate seepage. Increase pond depth and capacity by removing sediment from pond bottoms.

"Excessive seepage is prevented by reducing soil permeability," says Dr. Martin "Marty" Brunson, Extension professor, Mississippi State University. "If pond areas consist of small gravel or coarse sand to fine sand, and 10 percent or more clay and silt, it can be made relatively impervious by compaction. This is one of the least expensive sealing methods, but is limited to the described soil conditions.

"The compaction procedure is simple," Brunson continues. "Clear the pond area of all trees and other vegetation. Fill all stump holes, crevices and similar areas with impervious material. Scarify the soil to a depth of 8 to 10 inches with a disk, rototiller, pulverizer or similar equipment.

"Remove all rocks and tree roots. Roll the loosened soil under optimum moisture conditions to a dense, tight layer with 4 to 6 passes of a sheepsfoot roller. Make the compacted seal no less than 8 inches thick where the pond depth is 10 feet or less. If the water depth exceeds 10 feet, increase the thickness of the compacted seal proportionately since seepage losses vary directly with water depth," Brunson recommends.

"Pond areas containing high percentages of coarse-grained soils, but lacking enough clay to prevent seepage through compaction, can be sealed by blanketing," explains Brunson.

"Blanket the upstream slope of the embankment and the entire water impoundment area. Make the blanket from well-graded material containing at least 20 percent clay. Thickness of the blanket depends on water depth, but the minimum thickness is 12 inches for all depths up to 10 feet. Remove all trees and other vegetation. Fill all holes and crevices before hauling earth material from borrow area to pond site in tractor-pulled wheeled scrapers or similar equipment. Spread the material uniformly over the area in layers 6 to 8 inches thick. Compact each layer thoroughly, under optimum moisture conditions, by 4 to 6 passes of a sheepsfoot roller before placing the next layer. Spread a cover of gravel 12 to 18 inches thick on the top layer to prevent cracking."

Adding bentonite (fine-textured colloidal clay) is another method of reducing seepage in ponds. When mixed in the correct proportions with well-graded coarse-grained material, thoroughly compacted and then saturated, bentonite particles swell until they fill pores making soil nearly impervious to water. Upon drying, bentonite shrinks to its original volume resulting in cracks; therefore, sealing with bentonite is usually not recommended for ponds where water levels widely fluctuate.

A laboratory analysis of soil particle size distribution is required to determine bentonite application rates.

Protect riparian areas
Cattle tend to congregate in riparian areas during drought and extremely hot temperatures because of the shade and last remaining forage. Riparian areas should not be used for extended periods, because they may not recover within our lifetime from the heavy continual grazing.

Riparian areas are important because they help maintain watershed health. Healthy watersheds reduce runoff and improve water quality and quantity in streams, rivers and oceans. Good management of riparian zones is important for groundwater quality as well as surface water because creeks and rivers often channel water into aquifers.

"Fencing ponds, lakes, rivers and creeks will facilitate proper grazing management in these sensitive areas," Nelle says.

"Good riparian and shoreline vegetation catch and stabilize sediments and keep them out of the water. Furthermore, when livestock are grazed in these areas, dense vegetation traps manure that the plants use as fertilizer. Keeping manure out of ponds, lakes, rivers and creeks helps maintain water quality. At permanent fenced watering locations, some ranchers lay down coarse gravel to provide firm footing and to discourage cattle from loafing in these areas.

"Management in riparian settings should strive to provide short livestock grazing periods followed by long rest periods to maintain or enhance desired plant communities," Nelle explains. "In fact, only 2 to 4 weeks of grazing each year with a large number of animals may be appropriate to maintain good riparian vegetation. This type of flash grazing can take advantage of the large volume of high-quality forage, yet develop and maintain good riparian vegetation. Separate riparian pastures, combined with an observant and diligent manager, will permit this kind of specialized grazing."

Protecting plant, soil and water resources during drought will accelerate ranch recovery when it does rain.