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United States Department of Agriculture

Agricultural Research Service

Title: Olton Soils: Distribution, Importance, Variability and Management

Authors
item Unger, Paul
item Pringle, Fred - NRCS

Submitted to: Experiment Station Bulletins
Publication Type: Experiment Station
Publication Acceptance Date: November 15, 1997
Publication Date: N/A

Interpretive Summary: Olton soils occur on about 1.26 million acres of land in Texas and eastern New Mexico. About 79% of them are in cropland, 18% are in rangeland, and 3% are used for non-agricultural purposes. About 45% of the cropland is irrigated. The main crops are cotton, wheat, grain sorghum, and corn. To develop recommendations for better management of Olton soils, we measured soil profile depth, texture, bulk density, organic matter content, CaCO3 equivalent, pH, cation exchange capacity, water retention, and water infiltration at 12 widely separated locations. Most soil characteristics differed considerably among locations. Total water infiltration and infiltration rates at 10 minutes differed greatly among sites and seemed to be more affected by bulk density of the surface horizon than by other measured factors. Soil compaction caused low water infiltration at some locations. The soil profile could be filled with water (about 4 inches) at tmost locations by applying water for 20 hours or less, but more time would be needed at some other locations. Applying water for a longer time, however, is not practical because tailwater runoff and/or deep percolation losses of the water become excessive. Practices such as conservation-bench and level-bench terraces, contours, blocked furrows, and reduced- and no- tillage systems can be used to conserve water from rainfall on Olton soils because they reduce runoff, increase infiltration, or reduce evaporation. Irrigation water can be conserved by using improved water application techniques, tailwater recovery systems, and reduced- or no-tillage farming. Use of these practices has increased crop yields on soils that are similar to Olton soils. We, therefore, believe they would increase yields on Olton soils also.

Technical Abstract: Olton soils occupy 1.26 million acres of land in Texas and eastern New Mexico. About 79% of them are in cropland, 18% are in rangeland, and 3% are used for non-agricultural purposes. Irrigation is used on about 45% of the cropland. Major crops are cotton, wheat, grain sorghum, and corn. To develop improved management recommendations, we determined soil profile depth, texture, bulk density, organic matter content, CaCO3 equivalent, pH cation exchange capacity, water retention, and water infiltration at 12 widely separated locations. Most soil characteristics varied widely among locations. Cumulative water infiltration amounts and rates at 10 minutes were highly variable and seemed more closely related to bulk density of the Ap horizon than to other profile characteristics. Plowpans or other compacted soil conditions caused low infiltration at some locations. About 20 or fewer hours of water application would fill the profile with water (about 4 inches) at most locations, but more time would be needed at others. Longer application, however, is not recommended because tailwater runoff and/or deep percolation losses become excessive. Practices such as conservation-bench and level-bench terraces, contours, blocked furrows, and reduced- and no-tillage systems that conserve water from rainfall are applicable to Olton soils. These practices conserve water by reducing runoff, increasing infiltration, or reducing evaporation. Practices for conserving irrigation water include use of improved water application techniques, tailwater recovery systems, and reduced- or no-tillage farming. Crop yields have been increased where these practices were used on Pullman soils and should give similar results on Olton soils because Olton and Pullman soils are morphologically similar.

Last Modified: 10/24/2014
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