2010 Annual Report
1a.Objectives (from AD-416)
Knowledge of the effects of cropping systems on selected soil properties is needed to optimize productivity and develop sustainable agricultural systems. The effects of alternative dryland and irrigated crop and livestock systems on water infiltration, soil aggregation, and other soil properties will be defined through the following sub-objectives. 1.1 Determine the effect of agricultural management practice factors such as crop type, irrigation amount and type, tillage intensity, and residue cover on water infiltration aggregate stability carbon sequestration, soil microbial community structure, and enzymes that affect soil function. 1.2 Validate and further refine the Soil Conditioning Index and Soil Management Assessment Framework to assess the sustainability of management practices and systems.
Wind erosion and dust emissions are controlled by biological and physical processes and characteristics that must be determined to develop successful methods of dust mitigation. We will investigate basic biological and physical processes and characteristics of wind erosion and airborne dust needed to develop mitigation strategies using the following sub-objectives. 2.1 Quantify total airborne soil mass transport and fine particle dust emissions as affected by soil texture and cropping system. 2.2 Determine enzyme activities, microbial community composition, and chemical characteristics of fine particle dust from agricultural soils to identify the sources and origin of dust. 2.3 Validate and further refine the time fraction equivalent method for determining the threshold condition for soil movement in the field under natural wind and soil conditions. 2.4 Identify morphological traits that promote resistance to injury caused by abrasion of plants by sand particles during wind storms and determine the most resistant varieties of selected common crops.
1b.Approach (from AD-416)
Agricultural management practice factors such as crop type, irrigation amount and type, tillage intensity, and residue cover will be correlated with water infiltration, aggregate stability, carbon sequestration, soil microbial community structure, and enzymes that affect soil function. The soil conditioning index and soil management assessment framework, used to assess the sustainability of management practices and systems, will be evaluated and refined. Total airborne soil mass transport and fine particle dust emissions as affected by soil texture and cropping systems will be quantified. Enzyme activities, microbial community composition, and chemical characteristics of fine particle dust from agricultural soils will be used to identify the sources and origin of dust. The time fractions equivalent method for determining the threshold condition for soil movement in the field under natural wind and soil conditions will be evaluated and further refined. Morphological traits that promote resistance to injury caused by abrasion of plants by sand particles during wind storms will be identified and the most resistant varieties of selected common crops will be determined.
A new field wind tunnel was used to determine fine dust emissions on cropland and rangeland. Tests on agricultural silty and sandy soils in Texas and Kansas revealed significantly greater fine dust (PM10) emissions for silty soils than sandy soil surface textures. The emission rate is more related to the greater availability of easily transported fine dust particles in the soil than creation of fine dust through abrasion processes. In addition, tests of a conventionally tilled silty soil produced more fine dust than the same soil under no-tillage management. In another wind tunnel study of burned rangeland at the Sevilleta National Wildlife Refuge in New Mexico, cattle trampling did not affect dust emission rate while the dust emissions of the burned sites were twice that for the unburned sites. This research included the use of rare earth elements (REE) to identify the source areas of mobilized sediment. Data analysis of the REE is currently underway. This research clearly shows that soil properties and management are important factors controlling fine dust emissions.
Integration of livestock production into an integrated whole farming system for cotton production, and rotation systems that included sorghum under dryland every other year resulted in an increase of soil C and microbial biomass C and N in the surface horizon. This research may potentially impact the value of industrial carbon credits on the High Plains and, through improved crop rotations and tillage systems, conserve soil resources for future generations.
Our participation in the GRACEnet continues. Dryland research plots under different cropping systems and tillage treatments are in their 7th year. Soil sampling continues, and field measurements for water infiltration and availability will be done this fall 2010.
Field observations have revealed that wind erosion is a dynamic process characterized by intermittent periods of intense wind erosion activity interspersed with periods of inactivity. It has become increasingly apparent that future advances in our understanding of wind erosion will require instrumentation that is capable of high-frequency detection of sediment transport by wind. Attempts to develop improved piezoelectric sensors have been underway at the Cropping Systems Research Laboratory. Over the past few years we have been developing and field testing new instrumentation that could potentially provide a more precise and accurate measure of dynamic aeolian processes.
Cotton seedlings of different ages were placed in laboratory wind tunnels to determine the effects of wind blown sand abrasion on plant survival and subsequent recovery. These data will be used to advise farmers when cotton fields suffering from wind storms and sand erosion should be replanted with a new crop in order to be economically viable.
A method to determine the probability of wind erosion from dust source areas. In 1961, an underground nuclear test, called Project Gnome, was conducted beneath the Mescalero Sands east of Carlsbad, New Mexico, resulting in an unintentional venting of radioactive materials to the surface. Although remediation activities have been conducted, low levels of radionuclides are still detectable in surface soil samples, and when the wind blows, radionuclide contamination is sometimes detected in ambient dust samples. Recently, an attempt was made to monitor wind-driven processes at the Project Gnome site with the primary goal of determining the minimum wind speed, or threshold wind speed, at which sands are detached and transported. The site was monitored continuously for 112 days, and during active periods, and average threshold values were found to be around 10 m/s. This new information provides key data researchers can use to evaluate the probability of wind erosion from a source area when combined with local wind data.
Speeding up soil quality recovery detection in sandy soils under dryland production. Since the 1940s much of the land in the Southern High Plains region has been planted solely to cotton using conventional tillage practices, resulting in declining soil quality. In order to sustain future agricultural activities in this area, conservation practices such as minimum tillage and cotton rotations with sorghum are being implemented to reduce erosion and restore soil quality in dryland production. But it often takes many years before improvements can be seen. At Lubbock, Texas, we found that introducing a rotation of cotton with high biomass crops, such as forage sorghum and a winter rye cover crop, produced increases in microbial biomass carbon and nitrogen, and the activities of enzymes important for nutrient cycling in as little as three years. It took over five years to show improvements under rotations of cotton and grain sorghum compared to cotton monoculture. This is new information that growers and researchers can consider when identifying cropping systems that will result in improved soil quality and functioning.
Stout, J.E. 2010. Diurnal patterns of blowing sand. Earth Surface Processes and Landforms. 35(3):314-318.
Acosta Martinez, V., Bell, C., Morris, B., Zak, J., Allen, V.G. 2010. Long-term soil microbial community and enzyme activity responses to an integrated cropping-livestock system in a semi-arid region. Agriculture, Ecosystems and Environment. 137(3-4):231-240.
Acosta Martinez, V., Dowd, S.E., Sun, Y., Allen, V.G., Wester, D. 2010. Pyrosequencing analysis for characterization of bacterial diversity in a soil as affected by integrated livestock-cotton production systems. Applied Soil Ecology. 45(1):13-25.
Acosta Martinez, V., Burow, G.B., Zobeck, T.M., Allen, V. 2010. Soil microbial diversity, structure and functioning under alternative systems compared to continuous cotton. Soil Science Society of America Journal. 74(4):1181-1192.
Chappell, A., Van Pelt, R.S., Zobeck, T.M., Dong, Z. 2010. Estimating aerodynamic resistance of rough surfaces from angular reflectance. Remote Sensing of Environment. 114(7):1462-1470.
Van Pelt, R.S., Peters, P., Visser, S. 2009. Laboratory wind tunnel testing of three commonly used saltation impact sensors. Aeolian Research. 1(1-2):55-62.
Buschiazzo, D.E., Zobeck, T.M., Abascal, S.A. 2007. Wind erosion quantity and quality of an entic Haplustoll of the semi-arid Pampas of Argentina. Journal of Arid Environments. 69:29-39.
Song, Y., Deng, S.P., Acosta Martinez, V., Katsalirou, E. 2008. Characterization of redox-related soil microbial communities along a river floodplain continuum by fatty acid methyl ester (FAME) and 16S rRNA genes. Microbial Ecology. 40(3):499-509.
Sotomayor-Ramirez, D., Espinosa, Y., Acosta Martinez, V. 2009. Land use effects on microbial biomass C, ß-glucosidase and ß-glucosaminidase activities, and availability, storage, and age of organic C in soil. Biology and Fertility of Soils. 45(5):487-497.
Zobeck, T.M., Crownover, J., Dollar, M., Van Pelt, R.S., Acosta Martinez, V., Bronson, K.F., Upchurch, D.R. 2007. Investigation of soil conditioning index values for Southern High Plains agroecosystems. Journal of Soil and Water Conservation. 62(6):433-442.