|Hauser V L, - MITRE CORP.|
|Popham T W,|
Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 1, 1994
Publication Date: N/A
Interpretive Summary: Conservation tillage is highly recommended as a method to increase water conservation and reduce runoff and erosion. Two methods of conservation tillage used on dryland in the Great Plains are no-tillage and stubblemulch tillage. In a ten-year study at Bushland, Texas, a comparison of the two systems showed both are effective water conservation practices. No-tillage ehad reduced infiltration and great runoff because of soil crusting. However, no-tillage also had improved water conservation because a reduction in evaporation rate more than offset increased runoff, thus more precipitation was conserved as soil water. The result of this research indicates that more intensive cropping with less fallow may be possible on dryland by using no-tillage management. Both no-tillage and stubblemulch tillage provided excellent wind erosion control.
Technical Abstract: Dryland crops produce limited amounts of residue, thus the water conservation benefits of no-tillage (NT) may be reduced. We compared infiltration, runoff and water conservation effects of NT with stubblemulch (SM) tillage at Bushland, TX, in the semiarid southern Great Plains. From 1981 to 1992, we cropped six field-sized (2 to 4 ha) graded-terraced watersheds in a dryland, 3-yr, winter wheat (Triticum aestivum L.)-sorghu [Sorghum bicolor (L.) Moench]-fallow sequence with NT and SM treatments. Runoff was measured with "H" flumes and infiltration differences was measured with a rainfall simulator. Soil water storage during fallow was used to evaluate water conservation effectiveness. Infiltration rates declined more rapidly with NT than with SM, although residue coverage exceeded 50% on NT. Cumulative infiltration after 2 h of simulated rainfall was 90% greater on SM than on NT for initial tests conducted during fallow after sorghum, and 26% greater during fallow after wheat. Infiltration was greater on SM because tillage destroyed the consolidated surface crust, decreased bulk density, and increased surface roughness and depression storage capacity. Storm runoff averaged 25.5- and 40.1-mm per year for eight cycles of WSF for SM and NT treatments, respectively, with most runoff occurring during fallow periods. Despite greater surface runoff from the NT system than from the SM system, NT management resulted in improved water conservation due to reduced evaporation. Total plant available soil water storage during fallow after sorghum was 18% greater with the NT treatment and 10% greater during fallow after wheat than for the SM treatment. More intensive cropping with less fallow appears possible on drylands by using NT management.