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United States Department of Agriculture

Agricultural Research Service

Research Project: SOIL MANAGEMENT FOR SUSTAINABLE AGRICULTURAL SYSTEMS THAT PREVENT WIND EROSION AND ENHANCE THE ENVIRONMENT

Location: Wind Erosion and Water Conservation Research

2008 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.


3.Progress Report
Knowledge of the effects of cropping systems on selected soil properties is needed to optimize productivity and develop sustainable agricultural systems. A High Biomass Crop dryland study was evaluated and has shown that soil microbial populations and microbial chemical properties important for plant fertility were higher in winter cover crop rotations after only 3 years compared to continuous cotton or cotton-sorghum systems. However after 5 years, these soil properties were also differentiated (higher) in soil under sorghum–cotton rotation (without winter cover crop) compared to continuous cotton. The trends from this study are showing changes in soil quality as affected by dryland cropping systems, and have implications in water management and crop productivity in dryland farming. We conducted three sand abrasion experiments on cotton seedlings and found that during the recovery phase of growth, the relative growth rate (RGR) and net assimilation rate (NAR) of treated plants was greater than that of untreated controls. These findings suggest that cotton breeders selecting for traits that lend resistance to and/or recovery from sand abrasion should focus on specific physiological traits related to photosynthetic rate adjustments after abrasion. Two indexes currently proposed are the soil quality index (SQI) as determined by the soil management assessment framework (SMAF), based on measured soil properties, and the soil conditioning index (SCI) as determined using Natural Resources Conservation Service computer models. In a test of five cropping systems using three nitrogen levels, both SQI and SCI could separate the highest nitrogen level from the lowest level, but the SCI seemed to more clearer separate the nitrogen levels than the SQI. However, the SQI seemed to place the management systems into more groups, after accounting for the effect of nitrogen level, suggesting it can detect smaller differences in crop management systems due to tillage and crop. Extensive cultivation of coarse textured soils and cotton monoculture cropping systems has resulted in degraded soils that are prone to erosion by wind and water in the Southern High Plains of Texas. We imposed four tillage systems including two no-till scenarios and a modified ridge till system along with two rotation patterns of sorghum into the previous cotton monoculture for a period of six years on a degraded fine sandy loam. Rotation systems that included sorghum every other year also 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. (NP 202; Components 1, 4, and 5)


4.Accomplishments
1. Managing Soil Properties through Dryland Cropping Systems Intensities: In some areas of the Southern High Plains available irrigation water is becoming scarce due to the small amount of groundwater recharge occurring to the Ogallala Aquifer. Changes in soil properties (i.e., organic matter content) are needed to improve the ability of soils to store water for crop production while maintaining other important soil functions in dryland cropping areas. A high biomass crop dryland study has shown that soil microbial populations and microbial chemical properties important for plant fertility were higher in winter cover crop rotations after only 3 years compared to continuous cotton or cotton-sorghum systems. In addition, crushing energy (a measure of the soil stability against the forces of wind erosion) and the wet aggregate stability (a measure of the soil stability against the forces of water erosion) of the systems with cover crops were all greater than the conventionally tilled cotton system with no cover crop. The trends from this study are showing changes in soil quality as affected by dryland cropping systems, and have implications in water management and crop productivity in dryland farming. (NP 202; Components 1, and 4)

2. Cotton Seedling Abrasion and Recovery: Millions of hectares of crops are exposed to wind-blown sand abrasion each year, and in many instances the damage is thought to be severe enough to require replanting. We conducted three sand abrasive flux density treatment experiments on cotton seedlings and found that during the recovery phase of growth, the relative growth rate and net assimilation rate of treated plants were greater than that of untreated controls. These findings suggest that cotton breeders selecting for traits that lend resistance to and/or recovery from sand abrasion should focus on the physiological traits that affect the ability to remobilize assimilate from the tap root to rebuild the damaged canopy and the ability of newly formed leaves to up-regulate photosynthetic rate in response to increased sink demand. (NP 202; Component 1)

3. Not All Soil Quality Indexes Are the Same: Various methods have been proposed to evaluate the effects of land management practices on soil resources. Two indexes currently proposed are the soil quality index (SQI) as determined by the soil management assessment framework (SMAF), based on measured soil properties, and the soil conditioning index (SCI) as determined using Natural Resources Conservation Service computer models. This study was conducted to compare the indexes and test whether the SQI can detect smaller changes in soil management than SCI. In a test of five cropping systems using three nitrogen levels, both SQI and SCI could separate the highest nitrogen level from the lowest level, but the SCI seemed to more clearly separate the nitrogen levels than the SQI. Since soil quality indexes are now used to determine compliance for several farm programs or land management standards, knowledge of its strengths and weaknesses is very important and could have great impact on determining farm program compliance. (NP 202; Component 1)

4. Tillage and Rotation Effects on Soil Physical and Chemical Properties: Extensive cultivation of coarse textured soils and cotton monoculture cropping systems has resulted in degraded soils that are prone to erosion by wind and water in the Southern High Plains of Texas. New sustainable cropping systems are needed that improve crop productivity and economic viability while enhancing the environment. We imposed four tillage systems including two no-till scenarios and a modified ridge till system along with two rotation patterns of sorghum into the previous cotton monoculture for a period of six years on a degraded fine sandy loam. At the end of this period, the no-till systems had increased C contents by 0.1% in the upper 5 cm and had increased microbial biomass C and N in this layer as well. Rotation systems that included sorghum every other year also 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. (NP 202; Component 5)

5. Effects of Soil Physical and Chemical Properties on Dust Generation Potential: Fugitive dust from wind-eroding surfaces on cropland and rangeland negatively impacts agricultural sustainability, commerce, and environmental and human health. We have created fine dust evolution curves from surface soil samples collected at several locations in the western United States and Northern Mexico using a cone abrader and Tapered Element Oscillating Microbalance (TEOM). Splits of soils were also analyzed for particle size distribution, and soil C content. Dust generation potential (DGP) for rangeland soils was highly dependent on the percentage of the soil particles < 50 µm in diameter where the soil mineralogy was similar. For cropland soils the relationship between soil particle size distribution and DGP was much less apparent and appeared in certain cases to be positively correlated with soil organic carbon. Much more work is needed before guidelines can be established relating soil management with DGP. Development of best management practices that limit DGP for soil will result in increased air quality and sustainability of soil resources. (NP 202; Component 1)


6.Technology Transfer

Number of Non-Peer Reviewed Presentations and Proceedings3

Review Publications
Acosta Martinez, V., Rowland, D., Sorensen, R.B., Yeater, K.M. 2008. Microbial community structure and functionality under peanut based cropping systems in a sandy soil. Biology and Fertility of Soils. 44(5):681-692.

Acosta Martinez, V., Acosta Mercado, D., Sotomayor, D., Cruz, L. 2008. Microbial communities and enzymatic activities under different management in semiarid soils. Applied Soil Ecology. 38(3):249-260.

Last Modified: 7/28/2014
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