Research Description
Background
Drylands, with arid to semi-arid climates, cover 45% of the Earth and provide homes to more than 2 billion people. The drylands of the American West are facing significant challenges caused by global change, such as drought and changing plant communities. Increases in human population and food demand have also converted many natural drylands in this region to irrigated farms. These changes in land use and climate have greatly affected the movement of water, carbon, nutrients and salt through different parts of the drylands. All of these changes impact the sustainability of natural and agricultural ecosystems.
Scientific objective
This project will investigate these important Critical Zone processes and improve our ability to predict future change. Specifically, this thematic cluster will investigate how carbonate minerals in dryland soils control and impact water, nutrients, salts, and carbon moving in and out of the Critical Zone. The overarching objective is to increase our capacity to quantify and predict dryland carbon budgets across land-use and climatic gradients by examining the role of water and nutrient availability in regulating the movement of organic and inorganic carbon.
Approach
Specifically, this project centers around the multifaceted roles of pedogenic carbonates in dictating vadose zone water dynamics, the potential recharge to deep water table, and nutrient cycling in typical dryland landscapes, piedmont, playa and irrigated agricultural fields. These in turn drive trends in evolution of Critical Zone architectures and land-atmosphere C exchange. We will tackle these problems by using a comprehensive set of tools including eddy covariance towers, deep Critical Zone drilling, hydrogeophysical surveys, soil and hydrologic sensors, isotopic analysis, synchrotron, geochemical proxies, and genetic sequencing. This project builds on the rich historical data, knowledge, and models at the Jornada LTER, the Reynolds Creek CZO, USDA-ARS Kimberly site in Idaho and irrigated agricultural sites along the Rio Grande Valley in Texas. This thematic cluster will develop an interdisciplinary framework to understand material and energy flow through dryland Critical Zones and lay the foundation for managing Critical Zone function, evolution, and services, as well as forecasting carbon budget changes with future shifts in climate and land use in drylands.
Funding
The project is funded by a $5.27 million award from the National Science Foundation (NSF) to UTEP that contains subcontracts to Boise State University, New Mexico State University, the University of Wyoming, and Insights El Paso. The project began on September 1, 2020 and runs through 2025. The project is part of the Critical Zone Collaborative Network. There are ten total funded projects in the “Critical Zone Collaborative Network.” Nine are “thematic clusters” like ours. The remaining one is the “coordinating hub” which will be run by CUAHSI.
Drylands, with arid to semi-arid climates, cover 45% of the Earth and provide homes to more than 2 billion people. The drylands of the American West are facing significant challenges caused by global change, such as drought and changing plant communities. Increases in human population and food demand have also converted many natural drylands in this region to irrigated farms. These changes in land use and climate have greatly affected the movement of water, carbon, nutrients and salt through different parts of the drylands. All of these changes impact the sustainability of natural and agricultural ecosystems.
Scientific objective
This project will investigate these important Critical Zone processes and improve our ability to predict future change. Specifically, this thematic cluster will investigate how carbonate minerals in dryland soils control and impact water, nutrients, salts, and carbon moving in and out of the Critical Zone. The overarching objective is to increase our capacity to quantify and predict dryland carbon budgets across land-use and climatic gradients by examining the role of water and nutrient availability in regulating the movement of organic and inorganic carbon.
Approach
Specifically, this project centers around the multifaceted roles of pedogenic carbonates in dictating vadose zone water dynamics, the potential recharge to deep water table, and nutrient cycling in typical dryland landscapes, piedmont, playa and irrigated agricultural fields. These in turn drive trends in evolution of Critical Zone architectures and land-atmosphere C exchange. We will tackle these problems by using a comprehensive set of tools including eddy covariance towers, deep Critical Zone drilling, hydrogeophysical surveys, soil and hydrologic sensors, isotopic analysis, synchrotron, geochemical proxies, and genetic sequencing. This project builds on the rich historical data, knowledge, and models at the Jornada LTER, the Reynolds Creek CZO, USDA-ARS Kimberly site in Idaho and irrigated agricultural sites along the Rio Grande Valley in Texas. This thematic cluster will develop an interdisciplinary framework to understand material and energy flow through dryland Critical Zones and lay the foundation for managing Critical Zone function, evolution, and services, as well as forecasting carbon budget changes with future shifts in climate and land use in drylands.
Funding
The project is funded by a $5.27 million award from the National Science Foundation (NSF) to UTEP that contains subcontracts to Boise State University, New Mexico State University, the University of Wyoming, and Insights El Paso. The project began on September 1, 2020 and runs through 2025. The project is part of the Critical Zone Collaborative Network. There are ten total funded projects in the “Critical Zone Collaborative Network.” Nine are “thematic clusters” like ours. The remaining one is the “coordinating hub” which will be run by CUAHSI.
Figure 1. Conceptual model to illustrate the water, carbon and nutrient (P) fluxes in the natural and irrigated CZ systems in drylands, that are regulated by formation of pedogenic carbonates.
Hydrogeophysics
Dryland hydrologic processes are intrinsically related to the unique subsurface architecture that features a deep water table, perched aquifers, and layers of pedogenic carbonates, salts, and clays. These characteristics pose significant challenges to applying common hydrological monitoring networks to investigate water fluxes and flow paths in drylands. |
Carbon
We will test the hypothesis that C balance in dryland critical zones is driven by soil water potential dynamics that simultaneously control calcite precipitation/dissolution dynamics and biological activity (e.g., plants, biocrusts, soil microbes), the relative contribution of which is likely to depend on different moisture threshold requirements. |
Nutrients
While multiple nutrients can be limiting in drylands, phosphorus (P) is particularly important because Ca-P complexes can form during pedogenic carbonate formation that are thought to be inaccessible to plants. The strategies of P acquisition by plants, microbes and biocrusts are poorly known in drylands. |
