Location: Wind Erosion and Water Conservation Research
2023 Annual Report
Objectives
Objective 1: Determine changes in the factors associated with soil health across agroecosystems that are transitioning to dryland agriculture. Our aim is to provide new information on changes of soil organic matter that result in water conservation leading to better soil health-based management decisions.
Sub-objective 1A: Validate a method and categorize soil health across a range of management strategies by simultaneous measurements of key enzyme activities affecting soil biochemistry.
Sub-objective 1B: Examine effects of diverse management practices on microbial soil health and functions related to soil biogeochemical cycling and organic matter dynamics.
Sub-objective 1C: Define and measure soil degradation in various agroecosystems resulting from vegetation change and disturbance and how those factors affect soil crusting, surface erodibility, precipitation capture efficiency, and microbial transport on the fugitive dust.
Objective 2: Assess effects of climatic factors on water limited biotic and abiotic agroecosystem characteristics and processes affecting crop, water, and soil health management.
Sub-objective 2A: Use crop models to evaluate irrigation strategies that maximize water use efficiency and profits in US Southern High Plains cotton production.
Sub-objective 2B: Test whether nighttime CO2 enrichment or high frequency, short-term pulses of CO2 affect plant growth, leaf area or crop water use.
Sub-objective 2C: Define and inspect the theoretical dryland crop production limits achieved by soil management.
Sub-objective 2D: Model conservation agriculture (CA) effects on US Southern High Plains dryland cotton production.
Objective 3: Fundamental investigations of the quality and quantity of various sources of water for agricultural production in the Southern High Plains including groundwater, surface water, and rainwater.
Sub-objective 3A: Develop a method for assessing the value of rainfall, groundwater, and surface water for agricultural uses based upon water chemistry.
Sub-objective 3B: Assess the effects of salty irrigation water on soil surface crusting, erodibility, and soluble dust emissions.
Approach
The challenges that confront Southern High Plains (SHP) agricultural producers are associated with the rapid decline of the Ogallala Aquifer (OA) water table and intermittent rainfall that often is less than the amount required to sustain crop production. The water table’s decline combined with the region’s semi-arid climate is driving a transition from partially irrigated to almost entirely dryland agricultural production. In both marginally irrigated and dryland systems crop management will shift towards optimizing the remaining irrigation resources and adopting innovative crop and soil management approaches. The problems confronting SHP producers during this transition will require solutions that are specific to semi-arid agriculture, minimize risk, and support economic and environmental sustainability. In addition to identifying solutions appropriate for current climate conditions, management decisions will also depend on new knowledge of soil and crop interactions in an evolving CO2 environment. Thus, our project addresses climate factors associated with current highly variable SHP precipitation patterns and rising CO2 levels. Our research will quantify and provide a better understanding of the impacts of soil degradation, climate uncertainty, and changing water availability and quality in semi-arid agriculture. Specifically, we will: 1) develop and validate methods for soil health metrics and use them to evaluate management practices that promote water conservation; 2) account for climate variability when evaluating management practices that affect crop yield, water use and soil health; and 3) develop a method for evaluating water quality of the various sources of water used for production and increase understanding of soil salinity effects on surface crusting, erodibility, and hygroscopic dust emissions emanating from such surfaces. Our results will provide the knowledge needed to sustain agricultural production during the transition to dryland systems in the SHP and in other semi-arid production regions.
Progress Report
Our project plan addresses research conducted in the Southern High Plains (SHP) region. This region is a “working laboratory” to define best soil and water resource management practices for semi-arid dryland production applicable to other regions experiencing transitions from irrigation to dryland management due to frequent droughts due to changing climate. Our first year was successful in making significant progress on our three main objectives to provide a better understanding of soil health across regions including semiarid regions, evaluate current and future climate variability via modeling, and evaluate water quality on semi-arid agriculture. For Objective 1, we focused on determining the factors and management associated with improved soil health and mitigation of wind erosion and degradation, we made great progress in our three subobjectives. For Sub-Objective 1A, we received soil samples from 15 ARS locations across the nation providing us with a wide range of climatic zones, soil types, and diverse management comparisons (cover crops, manure, conservative tillage). We also conducted more than 30 soil measurements related to the chemical, physical and biological properties of the soils due to additional analyses from ARS colleagues participating in the project, as well as receiving the ARS Edminster Headquarters funded postdoc award. We initiated the data analyses to establish linkages between soil microbial community composition related to functions for soil organic dynamics, aggregation, and biogeochemical cycling across regions. For Sub-objective 1B, our team conducted soil samplings in 31 producer sites transitioning from irrigated to dryland cropping, and from no-tillage and wheat winter cover cropping to cotton production that will be compared to reference sites in the Conservation Reserve Program and the typical practice of irrigated tilled cotton monoculture. For Sub-objective 1C, an extended drought has limited our ability to assess the soils of representative cropping systems and obtain monoliths from other regions. This possibility was addressed in the contingencies for this sub-objective in the project plan. The ARS researcher at Big Spring, Texas, contacted key personnel at Texas AgriLife and USDA Natural Resources Conservation Service to locate the chosen cropping systems and make introductions with landowners/operators when conditions improve. The researcher at Big Spring contacted USDA Natural Resources Conservation Service personnel to access model from which the rainfall simulator and soil monolith tray mounts are based. Dust collection and filtration instruments for use with a portable wind erosion instrument were constructed and tested in the field. These instrument packages and sampling methods were demonstrated at the 11th International Conference on Aeolian Research in July 2023.
Considerable progress was made toward Objective 2 that addresses the effects of climatic factors on water limited biotic and abiotic agroecosystem characteristics and processes affecting crop, water, and soil health management. Pacific decadal variability (PDV) is marked by rapid shifts between two climate states that can last for decades and is extensive enough to influence average global surface temperature. Past research has shown that PDV influences the frequency and magnitude of El Niño and La Niña events. These have important effects on U.S. climate and agriculture. During FY 2023, the observed ocean, atmospheric, and satellite-derived cloud cover data were analyzed to study these PDV mechanisms. This analysis suggested that cloudiness variation associated with Walker circulations – large scale patterns of Pacific atmospheric rising and sinking motion – is an important factor in understanding PDV mechanics. The scientist in charge of Sub-objective 2B, "carbon dioxide (CO2)" enrichment on plant growth, leaf area and crop water use, has retired. A concerted effort is being made to identify candidates and fill this critical vacant position. Nevertheless, a paper was published reporting our elevated CO2 simulated studies using Canopy Evapotranspiration and Assimilation chambers. Results from these studies suggested that in semiarid climates with elevated CO2, peanut agroecosystems may experience increased soil metabolic activity due to increased autotrophic respiration, and increased populations of arbuscular mycorrhizal fungi in the soil. These increases are beneficial as they could enhance uptake of nutrients and water. For Sub-objective 2C, defining the theoretical dryland crop production limits achieved by soil management practices, data from various databases were successfully identified, collated, and formatted for crop modeling. Access to an undisturbed site had never been used for cropping or managed grazing, was sought, and obtained. For Sub-objective 2D, soil sampling nears completion. Basic soil analyses for pedotransfer functions are underway in preparation for future crop modelling efforts, and we are conducting a literature review and evaluation of soil pedotransfer functions. Preliminary work on a Southern High Plains agro-meteorological data dashboard using the R-based ‘Shiny’ interactive web platform is underway. For Sub-objective 2D, the Martin County soil core sampling, texture, and bulk density analyses upon which pedotransfer functions are based is nearing completion. Twenty-five weather stations and several sensors measuring atmospheric conditions and soil water content, respectively, have been deployed. These are collecting information covering 50,000 acres. Because crop and soil models require water inputs and because there was a lack of rainfall during the 2022 growing season in Martin and surrounding Texas counties modeling could not be done. Simulation runs with Energy and Water Balance Model to calculate the effect of different soil profiles (with and without caliche) on storage of different rainfall rates and amounts are ongoing effort and updated when soil hydraulic properties for the different soils are available.
For Objective 3, Sub-Objective 3A, we made progress on the development of a method for assessing the value of rainfall, groundwater and surface water for agricultural uses based upon water chemistry, as seasonal rains returned in May to the Southern High Plains of Texas. Rainwater samples were collected south of Big Spring from a convective storm on May 25, 2023. That same date, surface water samples were collected downstream of the rainwater collection point and immediately upstream of Beall’s Creek. Water samples were also collected from Beall’s Creek upstream of the intersection and at the Colorado River gauging station. Groundwater samples were collected twice a month in Lubbock County. Stream samples were collected once a month in the Upper Brazos Basin, this includes tributaries of the Double Mountain Fork and tributaries of the Salt Fork Brazos River. Surface water samples were collected twice a month at a stock tank (pond) in Hockley County. Surface water samples were collected at a saline playa at the Yellow House Ranch every 10 days when the playa was not dry. Within Objective 3, Sub-objective 3B, with the goal to assess the effects of salty irrigation water on soil surface crusting, erodibility, and soluble dust emissions, soils were collected, and sub-samples were sent to university collaborators for microphysical investigations. Over one hundred soil trays with soils at different salinities and sodicities have been tested for threshold velocity, erodibility, and dust emissivity. This sub-objective does not depend on climatic conditions and so has been prioritized and is ahead of schedule.
Accomplishments
1. Simulated effects of winter wheat cover crops in U.S. Southern High Plains dryland cotton production. In the semi-arid U.S. Southern High Plains (SHP) terminated winter wheat cover crops can reduce wind erosion but can also reduce the soil moisture available to a dryland cotton crop. To simulate crop rotations of terminated winter wheat followed by dryland cotton under a wide range of rainfall conditions, ARS scientists from Lubbock, Texas, used wheat and cotton crop simulation models to estimate the effects of winter wheat cover crops on soil water and dryland cotton yields under two SHP soil types. Winter wheat always reduced soil moisture during the spring, but after it was terminated wheat stubble reduced surface water evaporation and led to soil moisture recovery between termination and cotton planting. Compared to cotton grown in bare ground, yields from dryland cotton grown in wheat stubble were increased 50% of the time in one soil, and 67% of the time in the other, but the cotton grown in the wheat stubble almost always led to increased soil moisture at cotton harvest. Although this crop modelling study showed that a winter wheat cover crop had a mixed effect on dryland cotton yields, it also showed that the effects of the wheat stubble on reducing soil water evaporation had an important positive effect on conserving soil water. This finding can be used by dryland cotton producers in semiarid regions that are considering the use of cover crops in their operations.
2. Comprehensive overview of health and safety effects of dust. An ARS researcher at Big Spring, Texas, was one of four lead authors with over 20 supporting authors on an invited review of health and safety effects of dust in the Western Hemisphere. This contribution has been read over 600 times in the three months since it was accepted and published in Reviews of Geophysics. The review revealed that human exposure to dust can cause adverse health effects, such as asthma, Valley fever, and even death. Human health impacts in the southwestern U.S. alone costs over 13 billion dollars annually. Dust affects the environment by supplying nutrients to ecosystems, contaminating water and food, spreading pathogens, microplastics, heavy metals and radionuclides, and reducing solar and wind power generation. Dust is also one of the deadliest weather hazards particularly in the southwestern United States. Finally, the measures to mitigate these harmful effects include coordinated dust prediction and early warning, soil conservation, and public health surveillance. The trends gathered by this team will help in future management and public policy decisions aimed at improving quality of life and reducing the economic impacts of fugitive dust.
3. Playa dynamics and salinity: a study of playa lake chemistry. Water continues to play a critical role in the success or failure of West Texas farms, cattle ranches, and the rural communities they support. The issue of water quality and freshwater availability is of great concern across the Southern High Plains region. A quantitative method was developed by an ARS scientist in Lubbock Texas, that combines the transitory nature of playa lakes and the variability of salinity into a set of parameters that can be used to compare playas or other surface water sources. Regarding water quality, a variable was developed that describes the fraction of samples with salinity levels below the salt tolerance threshold for cattle. Regarding water availability, water depth measurements were used to compute the fraction of time that a playa contains water. The quantitative method developed and tested in this field study combines the transitory nature of surface water sources and the variability of water quality into a set of parameters that West Texas ranch owners can use to judge the relative value of surface water sources. This same technique can be applied to other surface water sources in the Southern High Plains region. This result is applicable to regions where salt concentration increases as the volume of the remaining irrigation-water in the aquifer decreases.
4. Soil health changes with transitions from irrigation to dryland making our management selections key to sustainability. The decline in groundwater supply in the Texas High Plains is forcing some growers to convert center-pivot irrigated cropland to other methods of irrigation or to dryland production. This transition can lead to declines in soil health. Scientists from USDA-ARS and Texas Tech University from Lubbock Texas, assessed short-term changes in soil health indicators in the transition from center pivot to subsurface drip and from center pivot to dryland in comparison to continuous center-pivot management. The study showed declines in soil water content, potassium, sodium, and soil organic carbon with these transitions. Severe drought in the final year revealed reductions in the soil microbial component and fungal groups, which are key to soil processes, and lower enzyme activities important in nutrient cycling. These findings suggest that transitioning to low water-input management in this environment complicates efforts to maintain microbial components of soil health. Longer-term comparisons are needed to monitor how management and different climatic conditions will also affect soil health with these transitions.
5. Cotton lint yield as a function of annual rainfall – a long-term assessment for the southern High Plains region of Texas. Agriculture in the Texas High Plains (THP) is in a transition phase of producing crops with a diminishing supply of irrigation-water from the Ogallala aquifer to dryland production systems. These dryland systems are prevalent in the southern counties of the THP. ARS researchers in Lubbock, Texas, used long-term dryland cotton lint yields from these counties as precursors of the future cotton production patterns that will emerge in this region. We calculated from 1972 to 2018 the ratio of dryland cotton lint yield per unit of annual rainfall at the county level. This ratio, crop water productivity (CWP), has units of mass per unit volume. We used cotton lint yield data provided by the National Agricultural Statistics and rainfall data provided by the National Oceanic and Atmospheric Administration. In this period (1972 – 2018), only 2011 with a record drought of 179 mm of rainfall failed to produce a harvestable cotton crop in the counties used in our analysis. The mean cotton lint yield plus or minus one standard deviation ranged from a high of 400 plus or minus one standard deviation of 175 kg/ha in Lubbock County to a low of 252 plus or minus one standard deviation of 44 kg/ha in Andrews County. However, the counties with the largest CWP greater than 90 g/m3 were Glasscock, Midland, and Martin counties. The importance of this result is that these counties are subject to extreme environmental conditions and yet cotton producers manage to produce a crop in most years. We conclude that management production methods used by these dryland producers represent the future schemes that will need to be adopted in other counties to sustain the emerging dryland cropping systems.
6. Effects of timing limited water on cotton during varying stages of development assessed. The depth to the water-table of the Ogallala aquifer under the Texas High Plains is increasing. As water suitable for irrigation gets deeper, it becomes less available; water-well capacities decrease and it gets more expensive to lift the water from deeper in the ground. By carefully timing sparse irrigation we might be able to maintain existing yields, or at least maintain agricultural profitability and sustainability. ARS scientists in Bushland and Lubbock, Texas, in conjunction with scientists at Texas Agrilife, used mathematical models to understand how timing deficit irrigation events would affect cotton yield. It was found that the late stage of peak blooming is when cotton is most sensitive to drought. These results help develop appropriate irrigation management strategies sustaining cotton production in the Texas High Plains.
7. High CO2 increased soil respiration and Arbuscular Mycorrhizal Fungi (AMF) in a semiarid peanut crop. Rising atmospheric carbon dioxide (CO2) is a main climate change driver, and soil respiration is the most relevant contributor to atmospheric CO2. Two critical questions that need to be addressed regarding climate change in semiarid regions are: 1) do elevated CO2 conditions, for example, 650 parts per million alter the size and composition of the soil microbial community, and the process of soil respiration; and 2) are these responses influenced by periods of soil water-deficit. This information is lacking for peanut agroecosystems, which can host rhizobia and AMF associations that are key to nutrient cycling. Studies were performed by ARS scientists from Big Spring and Lubbock, Texas, Texas Tech University, and collaborators in Australia, to simulate plant growth, leaf area and crop water use by peanut under elevated CO2 conditions using Canopy Evapotranspiration and Assimilation chambers. Results from these studies suggested that in semiarid climates with elevated CO2, peanut crops may experience increased soil metabolic activity due to increased respiration, and increased populations of AMF in the soil. These increases are beneficial as they could enhance uptake of nutrients and water and will impact crop yield.
Review Publications
Ghimire, R., Thapa, V.R., Acosta Martinez, V., Schipanski, M., Shukla, M.K., Angadi, S.V., Fonte, S., Mikha, M.M., Slaughter, L. 2023. Soil health assessment and management framework for water-limited environments: Examples from the Great Plains of the USA. Soil Systems. 7(1). Article e22. https://doi.org/10.3390/soilsystems7010022.
Eibedingil, I.G., Gill, T.E., Van Pelt, R.S., Tatarko, J., Li, J., Li, W. 2022. Applying wind erosion and air dispersion models to characterize dust hazard to highway safety at Lordsburg Playa, New Mexico, USA. Atmosphere. 13(10). https://doi.org/10.3390/atmos13101646.
Gitz, D.C., Baker, J.T., Lascano, R.J. 2022. Stable carbon isotope discrimination of cotton burrs and seeds as a season-long integrator of crop water stress. American Journal of Plant Sciences. 13. Article 12. https://doi.org/10.4236/ajps.2022.1312099.
Mauget, S.A., Himanshuu, S., Goebel, T.S., Ale, S., Payton, P.R., Lewis, K., Baumhardt, R.L. 2022. Modeling management of continuous dryland cotton with an intervening winter wheat cover crop in a semiarid climate. Frontiers in Sustainable Food Systems. 6. https://doi.org/10.3389/fsufs.2022.1043647.
Tong, D.Q., Baklanov, A., Barker, B.M., Castillo, J., Gasso, S., Gaston, C., Gill, T.E., Huneeus, N., Kahn, R.A., Van Pelt, R.S., et. all. 2023. Health and safety effects of airborne soil dust in the Americas and beyond. Reviews of Geophysics. 61(2). https://doi.org/10.1029/2021RG000763.
Stout, J.E. 2022. Playa dynamics and salinity: A study of Yellow Lake on the High Plains of Texas. Texas Journal of Science. 74(1): Article 6. https://doi.org/10.32011/txjsci_74_1_Article6.
Laza, H., Acosta Martinez, V., Cano, A., Baker, J.T., Mahan, J.R., Gitz, D.C., Emendack, Y., Slaughter, L., Lascano, R.J., Tissue, D., Payton, P.R. 2023. Elevated [CO2] enhanced soil respiration and AMF abundance in a semiarid peanut agroecosystem. Agriculture, Ecosystems and Environment. 355. https://doi.org/10.1016/j.agee.2023.108592.
Bhandari, K., Acosta Martinez, V., Perez-Guzman, L., West, C.P. 2022. Soil health within transitions from irrigation to limited irrigation and dryland management. Agricultural & Environmental Letters. 7(1). https://doi.org/10.1002/ael2.20077.
Lascano, R.J., Payton, P.R., Mahan, J.R., Goebel, T.S., Gitz, D.C. 2022. Annual rainfall and dryland cotton lint yield - Southern High Plains of Texas. Agricultural Sciences. 13:177-200. https://doi.org/10.4236/as.2022.132014.
Himanshu, S.K., Ale, S., Bell, J., Fan, Y., Samanta, S., Bordovsky, J., Gitz, D.C., Lascano, R.J., Brauer, D.K. 2023. Evaluation of growth-stage-based variable deficit irrigation strategies for cotton production in the Texas High Plains. Agricultural Water Management. 280. https://doi.org/10.1016/j.agwat.2023.108222.
