How rain pulls the trigger to revegetate degraded desert range: The action begins in a dry rill in the New Mexico desert.
A short piece of 3-inch-diameter plastic PVC pipe lies lengthwise, staked and fitted snugly in the rill, which may be as small as 4 inches deep and 4 inches wide. Three smaller seed-filled pipes inside the bigger pipe are glued to its bottom, top, and side. When the rare rain comes, the rill becomes a streamlet. The seeders can also be used in large gullies.
The flowing water shortly breaks through a crepe paper cap on one end of the outer pipe. Water then begins shoving seeds from the lowest inner pipe through a mesh screen and into the channel. Heavier rains push the seeds out faster and lift the water higher in the pipe, so it goes to work on the middle and top tubes. The seedssideoats grama, a native prairie grassflow down the rill. Downstream, they're deposited in their seedbed: a moist channel bottom covered by a mulch of leaves and small branches also dropped by the slowing waterflow.
This seed delivery package is being evaluated by Jeff Herrick, a rangeland scientist with the Agricultural Research Service's Jornada Experimental Range in Las Cruces, New Mexico, and graduate student Ramon Gutierrez of Mexico's Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias.
The package was developed by Gutierrez and ARS scientists and costs about 75 cents. It exemplifies the new remediation strategy at the Jornada of mimicking nature's waysrelying heavily on trigger sites like the rill.
"Trigger sites have some natural advantage, usually access to water," says rangeland scientist Kris M. Havstad, who leads the ARS Jornada research team.
"This allows a little time and money to go a long way toward encouraging protective grasses and other ground cover on barren land. And the improvements can spread into the surrounding areas, slowing down wind erosion and desertification," says Herrick.
Another trigger site is a shallow basin where rainwater collects.
"We plan to study the trigger areas to see if the plants spread outward," says Herrick.By Don Comis, Agricultural Research Service Information Staff.
"Range Reseeding Goes With the Flow" was published in the November 1998 issue of Agricultural Research magazine. Click here to see this issue's table of contents.