Rangelands and pastures in the Coastal Bend of Texas are in very poor condition as a result of the ongoing drought since September of last year.
Many folks have held livestock as long as they could by supplementing them with hay and protein, and in the process, the standing grass on the rangeland has been removed by livestock to a point in which very little stubble remains. This very short stubble presents some problems including; weakening the plant root system and reducing the viability of the plant, and creating a situation in which the ability to capture rainfall adequately, when it does rain again, is greatly reduced.
Surface runoff, water infiltration and soil water storage are affected by vegetation, litter, rock cover, soil characteristics, surface crusting, soil texture, slope and rainfall intensity. The amount of runoff that occurs depends on the vegetation on the site.
Good vegetative cover enhances water infiltration because plant growth and residues break the velocity of the rain droplets, thus reducing surface sealing and compaction. The fate of each drop of water falling on the land depends largely on the kind of soil and the vegetative cover.
Research has shown that with good ground cover (60-75 percent of ground covered with plants and litter) the surface runoff from rainfall would be only two percent. If, however, one has poor ground cover (10 percent of ground covered with plants and litter) then 73 percent of rainfall received will runoff, and up to 5.5 tons per acre of soil loss could also occur.
Without good vegetative ground cover to help trap rainfall, some soil modification practice could be considered to improve rainfall infiltration and water conservation. Here are a few techniques for consideration:
Contour Furrows are grooves or ditches that can be made in the soil with various implements like plows, chisels, furrowers, etc. The furrows should be placed on the contour to collect runoff water and increase soil water storage. Terracing or installing terraces, differ from furrows in that they are larger and applied on the grade to allow for controlled runoff. Terraces are designed primarily for flood control and reduction of runoff and sedimentation on moderately steep slopes. A practice that has been used since the dust bowl days of the 1930s is Pitting. The practice involves the creation of small basins or pits to catch and hold precipitation on the site. Many tools can be used for pitting, and the equipment should be capable of gouging, digging or in some way creating pits in the soil surface.
Pitting has shown to increase forage production by as much as 100 percent and is best suited for medium textured soils with less than 8 percent slope.
Ripping rangeland, also known as chiseling or subsoiling, farmland is another practice that can be done to fracture soil layers and allow rainfall penetration. Ripping rangeland is usually done to a depth of 12 inches or less and can dramatically increase forage production.
The proper stocking rate (i.e., the number of livestock grazing per acre) should always be the first consideration in range water management. Any grazing strategy that enhances vegetative cover will improve rainfall infiltration and down stream water quality. Brush control should also be considered as a tool to improve water storage capacity on rangeland.
When vegetation is gone, and brush control is not needed, then soil modification practices should be considered, and in many cases this year, this option is looking like one that local rangeland managers should seriously consider.
Anytime rangeland is mechanically disturbed, there are potential hazards including possible weed invasion and accelerated erosion. There will be costs associated with mechanical treatments and they will vary greatly depending upon the price of fuel, the types of tractors and implements used, and whether the manager contributes his/her own labor.
The benefits and longevity of mechanical treatments are dependent upon follow-up grazing management. Without a reasonable grazing plan, forage production increases may not occur and/or will not persist for as long.
It is important to note that keeping grass root systems strong, by not overgrazing, even in a drought, will allow for quicker recovery when rainfall does again return to the region. In addition, a good dense stand of grass facilitates the movement of rainfall into the soil profile and will capture up to 98 percent of the rain that does fall.
More information on drought management may be found at http://texashelp.tamu.edu/004-natural/droughts.php.
Jeffrey Stapper is the Agricultural and Natural Resources Agent for Nueces County. Readers may contact him at (361) 767-5217.