Towards a Better Understanding of the Soil-Plant-Atmosphere-Water Continuum

更好地理解土壤-植物-大气-水连续体

• 批准号: RTI-2017-00315
• 负责人: Madramootoo, Chandra
• 金额: $ 10.93万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Research Tools and Instruments
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=616631
• 关键词: Towards; Better; Understanding; Soil; Plant

Our NSERC supported research is aimed at designing agricultural water management systems which conserve water and energy, while at the same time enhancing crop productivity. Studies are being undertaken to define crop water stress by developing models based on measurements of various plant canopy atmosphere parameters including vapour pressure deficit, canopy temperature, relative humidity, photosynthetic rate, and CO2 fluxes. However, preliminary work from our water management field studies has shown that NO2 fluxes are more environmentally significant than CO2. Nitrous oxide (N2O) is a significant greenhouse gas, influenced by the rate and timing of fertilizer application, irrigation and drainage practices, as well as by precipitation. High water tables contribute to soil anaerobic conditions, thereby promoting denitrification. We installed static Plexiglas chambers in the field, and manually collected gas samples in syringes, which we brought back to the lab for N2O analysis, using gas chromatography. This was a very time consuming and tedious method, and resulted in a backlog of samples in the lab, which took an inordinate amount of time to analyze. Furthermore, since we sampled manually, we often missed peak emissions, and were not able to accurately capture rainfall and fertilization effects. In addition, we often did not capture emissions due to increased microbiological activity under warmer soil temperatures during the spring thaw. There are two other complications with the collection of data manually. Firstly fluxes are not linear with time, so simple linear extrapolation between data points leads to erroneous estimates of N2O. Secondly, our data showed tremendous variability in N2O fluxes within sites. This leads us to believe that there are geospatially variable soil microbiological hotspots, influencing fluxes and we need to distinguish biological sources of N2O. We propose to use a PICARRO G5131-i N2O Concentration and Isotopes Analyzer, in order to overcome the above challenges, and to generate a better understanding of crop productivity under various soil-water conditions. It continuously and rapidly measures N2O gas concentration and isotopes (eg. δ15N). Through a Distribution Manifold we can simultaneously measure N2O concentrations and isotopomer ratios in up to 16 field-based chambers. The Small Sample Isotope Module 2 (SSIM2) of the Analyzer measures gas evolution from soils, vegetation, as well as the incorporation of stable labels into living organisms, which will completely modernize our method of evaluating N reactions in microbial-soil-plant environments. We will also be able to measure dissolved N2O evolution, an under-reported source of N2O. Approximately 25 graduate students will be trained in the use of the Analyzer. Through their training, they will become Canadian leaders in advanced environmental management for sustainable agriculture.

我们的NSERC支持的研究旨在设计农业水管理系统，以节约水和能源，同时提高作物生产力。正在开展研究，通过建立基于各种植物冠层大气参数的测量模型来确定作物水分胁迫，这些参数包括水汽压差、冠层温度、相对湿度、光合作用速率和二氧化碳通量。然而，我们的水管理领域研究的初步工作表明，NO2通量比CO2更具环境意义。一氧化二氮(N2O)是一种重要的温室气体，它受到化肥施用量和时间、灌溉和排水措施以及降水的影响。高地下水位有助于土壤厌氧条件，从而促进反硝化作用。 我们在野外安装了静态有机玻璃小室，并手动收集注射器中的气体样本，然后带回实验室进行N2O分析，使用气相色谱。这是一种非常耗时和繁琐的方法，导致实验室积压了大量样品，花费了过多的时间进行分析。此外，由于我们手动采样，我们经常错过排放峰值，并且无法准确地捕捉降雨和施肥的影响。此外，在春季融化期间，由于土壤温度升高，微生物活动增加，我们经常没有捕捉到排放。手动收集数据还有另外两个复杂问题。首先，通量与时间不是线性的，因此数据点之间简单的线性外推会导致对N2O的错误估计。其次，我们的数据显示了站点内N2O通量的巨大变异性。这使得我们相信，存在着地理空间可变的土壤微生物热点，影响着通量，我们需要区分N2O的生物来源。 我们建议使用Picarro G5131-I N2O浓度和同位素分析仪，以克服上述挑战，并更好地了解不同土壤水分条件下的作物生产力。它连续、快速地测量N2O气体浓度和同位素(例如。δ15N)。通过分配歧管，我们可以同时测量多达16个现场小室中的N2O浓度和同位异构体比率。分析仪的小样本同位素模块2(SSIM2)测量土壤、植被的气体释放，以及生物体内稳定标记的结合，这将使我们在微生物-土壤-植物环境中评估氮反应的方法完全现代化。我们还将能够测量溶解的N2O的释放，这是一种被低估的N2O来源。 大约25名研究生将接受使用分析仪的培训。通过他们的培训，他们将成为加拿大可持续农业高级环境管理方面的领导者。