Collaborative Research: SitS: Development of multiple-scale sensor and remote sensing technology to quantify abiotic carbon dioxide emission in irrigated soils of aridlands

干旱土地覆盖了40%以上的陆地表面，居住着20多亿人。为了生产更多的粮食和养活日益增长的人口，全世界都在利用集约化灌溉把干旱的土地变成农田。然而，旱地集约化灌溉带来了一些问题，包括蒸发失水、盐分积累和方解石矿床的形成，这些都会堵塞土壤孔隙，改变水分入渗模式。此外，这些方解石矿物的形成伴随着二氧化碳(CO2)的释放，这可能会改变地区和全球的碳平衡。该项目的总体目标是利用埃尔帕索地区沿格兰德河谷的一个灌溉山核桃园作为试验场，促进我们对干旱农业土壤中方解石产生的二氧化碳释放的基本理解。为了实现这一目标，研究人员提议使用一套测量工具，包括便携式二氧化碳同位素分析仪、涡流协方差塔和安装在无人驾驶飞行器上的遥感系统，量化他们的山核桃园试验场方解石产生的二氧化碳的排放量。该项目的成功完成将使社会受益，因为它收集了新的数据，并发展了新的基础知识，即当旱地变成灌溉农田时，有多少非生物二氧化碳排放到大气中。将通过学生教育和培训以及公共宣传活动进一步造福社会，包括指导4名研究生(2名博士和2名硕士)、3名UTEP本科生和1名TAMU博士后学者。越来越多的证据表明，灌溉干旱农田中成壤碳酸盐矿物的形成与向大气中释放非生物二氧化碳有关。这一提议的研究人员最近的研究已经在埃尔帕索的山核桃、紫花苜蓿和棉花田的土壤气体中发现了这种非生物二氧化碳信号。然而，灌溉干旱农业土壤中非生物二氧化碳的释放还需要进一步的研究，以评估其对区域/全球碳平衡和土壤物理化学性质的潜在影响。该项目的目标是通过详细测量位于格兰德河谷埃尔帕索地区的一个灌溉山核桃园试验田向大气排放的非生物二氧化碳通量来解决这一知识差距。为了推进这一目标，研究人员建议使用二氧化碳同位素分析仪、可调谐二极管激光吸收光谱遥感、高光谱成像和耦合涡旋协方差通量测量，以高空间和时间分辨率监测山核桃园试验田的生态系统-大气二氧化碳交换。通过这一综合测量计划，PIS希望他们能够捕捉到非生物二氧化碳通量的时空变化，并确定控制其山核桃园试验场非生物二氧化碳释放的关键参数/变量(如灌溉强度、水化学和土壤物理化学性质)。因此，这个项目的成功完成具有潜在的变革性影响，因为它提供了第一个详细的评估灌溉旱地在区域、国家甚至全球范围内改变陆地-大气二氧化碳交换的潜力。土壤中的信号(SITS)征集，国家科学基金会和美国农业部国家粮食和农业研究所(USDA NIFA)的合作伙伴关系。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Arid lands cover more than 40% of the terrestrial land surface and host more than two billion people. To produce more food and support a growing population, intensive irrigation is being utilized worldwide to convert arid lands to agricultural fields. However, intensive irrigation of arid lands causes several problems including high water loss through evaporation, salt accumulation, and the formation of calcite mineral deposits, which can clog soil pores and change water-infiltration patterns. Moreover, formation of these calcite minerals is coupled with the release of carbon dioxide (CO2) that could alter regional and global carbon balances. The overarching goal of this project is to advance our fundamental understanding of the release of calcite-derived CO2 from arid agricultural soils using an irrigated pecan orchard in the El Paso region along the Rio Grande valley as a test site. To achieve this goal, the investigators propose to quantify the emission of calcite-derived CO2 from their pecan orchard test site using a suite of measurement tools including portable CO2 isotope analyzers, eddy covariance towers and remote sensing systems mounted on an unmanned aerial vehicle. The successful completion of this project will benefit society through the collection of new data and the development of new fundamental knowledge on how much abiotic CO2 is released to the atmosphere when arid lands are converted to irrigated agricultural fields. Further benefits to society will be achieved through student education and training, and public outreach including the mentoring four graduate students (2 PhD and 2 MS), and 3 undergraduate students at UTEP and a postdoctoral scholar at TAMU.There is growing evidence that the formation of pedogenic carbonate minerals in irrigated arid agricultural lands is coupled with the release of abiotic CO2 to the atmosphere. Recent studies by the investigators of this proposal have identified such abiotic CO2 signals in soil gases from pecan, alfalfa and cotton fields in El Paso. However, the release of abiotic CO2 from irrigated arid agricultural soils needs further investigation to evaluate its potential impact on regional/global carbon balances and soil physicochemical properties. The goal of this project is to address this knowledge gap through detailed measurements of the flux of abiotic CO2 emitted to the atmosphere by an irrigated pecan orchard test field located in the El Paso region of the Rio Grande valley. To advance this goal, the investigators propose to monitor the ecosystem-atmosphere CO2 exchange in the pecan orchard test field with high spatial and temporal resolution using CO2 isotope analyzers, remote sensing with tunable diode laser absorption spectroscopy, hyperspectral imaging, and coupled eddy covariance flux measurements. Through this integrated measurement program, the PIs hope that they will be able to capture the spatiotemporal variations of the abiotic CO2 fluxes, and identify key parameters/variables (e.g. irrigation intensity, water chemistry and soil physicochemical properties) that control the release of abiotic CO2 from their pecan orchard test site. Thus, the successful completion of this project has potential for transformative impact by providing the first detailed assessment of the potential of irrigated arid lands to modify the land-atmosphere CO2 exchange at regional, national and even global scales.Signals in the Soil (SitS) solicitation, a collaborative partnership between the National Science Foundation and the United States Department of Agriculture National Institute of Food and Agriculture (USDA NIFA).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.