Impacts of An Integrated Crop-Livestock System On Soil Properties to Enhance Precipitation Capture.

Cropping/Livestock systems alter soil properties that are important in enhancing capture of precipitation by developing and maintaining water infiltration and storage. In this paper we will relate soil hydraulic conductivity and other physical properties on managed Old World Bluestem grassland, wheat-fallow-rye-cotton no-till rotation fields, and conventionally-tilled fields of a clay loam soil in west Texas.  The study was conducted  on a Pullman clay loam (38% clay content) at the TTU Sustainable Crop/Livestock Systems study site.  The continuous and integrated crop-livestock systems were replicated three times in a randomized block design. The site was irrigated with an underground drip system. The study compared continuous conventionally-tilled cotton (Gossypium hirsutum) and an integrated livestock-crop system with a perennial warm-season grass (Old World Bluestem, OWB) pasture (Bothriochloa bladhii) paddock and two paddocks (two stages) of a no-tillage rotation (wheat [Triticum aestivum]-fallow-rye [Secale cereale]-cotton).  Cattle exclosures were installed on the no-tillage rotation and OWB plots to test the effect of grazing.  At the time these measurements were made, the management systems had been in place for approximately 6 years.  Water infiltration rate was measured for the soil surface using the double ring infiltrometer. Bulk density was measured by the core method. Wet aggregate stability was performed on air-dried 1-2 mm diameter aggregates of the 0-5, 5-10, and 10-15 cm layers.  Penetration resistance (cone index) was measured at 1 cm intervals to a depth of 30 cm.  The infiltration rates and bulk density values measured for this clay loam soil were statistically the same (P>0.05) for all management systems.  The infiltration for the cropped sites ranged from 2.6 to 1.8 cm/hr.   Penetration resistance varied by crop rotation and depth (P<0.01).  The average cone index in the surface 30-cm (2.6 MPa) that was significantly lower in the rye planting of the wheat-fallow-rye-cotton rotation than the wheat planting of the same rotation.  The old World Bluestem had a greater aggregate stability (30%) than the conventionally-tilled cotton (20%). The conventionally-tilled cotton had the same aggregate stability as the wheat-fallow-rye-cotton rotation. Measurements of penetration resistance did not seem related to the infiltration rate or bulk density in this study.  The rye crop grown in the wheat-fallow-rye-cotton rotation had approximately half the resistance shown by the wheat crop in the same rotation.  The presence of cattle exclosures produced no significant differences in in infiltration rate or any soil property tested in the wheat-fallow and Old World Bluestem systems.