Hysterisis of soil hydraulic properties and critical irrigation thresholds of crops

土壤水力特性的滞后性和作物的临界灌溉阈值

• 批准号: RGPIN-2015-04947
• 负责人: Caron, Jean
• 金额: $ 1.97万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=646880
• 关键词: Hysterisis; soil; hydraulic; properties; critical

Water is crucial to crops and is facing rarefication across the world. Agriculture must improve its productivity to meet increasing demands for food in the coming years and irrigation is a key component for achieving these increases. However, the predicted growth in irrigation needs and the coming lack of qualified manpower will require more intelligence to be built to assist decision making in irrigation to conserve water and improve crop productivity. ******Prevailing approaches in irrigation management remain based largely on calculating evapotranspiration demand. However, recent work have shown that significant gain may be achieved by using approaches that incorporate an assessment of water transfers from soil to plant roots in real time (yield gains of 20-50% and water savings up to 65%) and use critical matric potential thresholds to initiate irrigation of crops. ******Critical irrigation thresholds are those soil matric potentials (soil suction) that ensure the minimum required appropriate transfers of water from the soil to the plant in real time. This is a key parameter to intelligence in irrigation management. To estimate these thresholds, soil hydraulic properties must be characterized on site. However, such properties are hysteretic, differing according to whether the soil is being wetted or dried. Due in part to hysteretic phenomena, it is necessary to estimate critical thresholds empirically through many field experiments, requiring significant efforts, time and resources. ******The proposed program aims at building the intelligence needed to better estimate these critical thresholds. It will focus on the hysteresis of the unsaturated hydraulic conductivity function, assessing its role in deriving critical irrigation thresholds. ******Year 1 of the program (Step S.1) will be devoted to the construction of instrumented containers and soil characterization (S.2), later used (S.3, year 2 and 3) for growing two crops on 3 soil types (sand, loam, clay), in a testing phase during which soil and plant parameters will be measured regularly. In S.4, different analytical and numerical approaches using the collected experimental data will be compared to estimated critical thresholds. The most accurate approaches will then be used (S.5) to evaluate the effect of hysteresis on soil water supply and to determine the range of measurements needed to quantify adequately the unsaturated hydraulic conductivity for critical irrigation threshold determination. In the last step (S.6), independent verifications of the derived critical thresholds for different soils and crops will be performed.******In the long term, the development of an automated real-time method for determination of critical thresholds will be a world breakthrough, becoming a fast track for improving irrigation performances and crop productivity for a better use of water and agricultural input resources. **

水对于农作物至关重要，在世界范围内面临稀疏。农业必须提高其生产率，以满足未来几年对食物的日益增长的需求，而灌溉是实现这些增长的关键组成部分。但是，预计灌溉需求的增长以及即将到来的合格人力将需要建立更多的智能，以帮助灌溉决策以节省水和提高作物生产率。 ******灌溉管理中的普遍方法仍然基于计算蒸散需求。但是，最近的工作表明，使用方法可以实时纳入从土壤到植物根部的水进行评估的方法（产量为20-50％，水节省高达65％）并使用关键矩阵，可以实现显着增益。启动农作物灌溉的潜在阈值。 ******关键的灌溉阈值是那些土壤矩阵电位（土壤吸力），可确保最少的水从土壤中实时转移到植物。这是灌溉管理中情报的关键参数。为了估计这些阈值，必须在现场表征土壤液压特性。但是，这种特性是滞后的，根据土壤是被润湿还是干燥的不同。部分由于滞后现象，有必要通过许多现场实验从经验上估算关键阈值，需要大量的努力，时间和资源。 ******拟议的计划旨在建立更好地估计这些关键阈值所需的情报。它将着重于不饱和液压传导率函数的滞后，评估其在得出关键灌溉阈值中的作用。 ******该计划的1年（步骤S.1）将专门用于构建仪器的容器和土壤表征（S.2），后来使用（S.3，2年和3年），用于生长两个在测试阶段，将定期测量土壤和植物参数的3种土壤类型（沙，壤土，粘土）的作物。在S.4中，将将使用收集的实验数据的不同分析和数值方法与估计的临界阈值进行比较。然后，将使用最准确的方法（S.5）来评估磁滞对土壤供水的影响，并确定充分量化不饱和液压电导率所需的测量范围，以确定关键的灌溉阈值确定。在最后一步（S.6）中，将对不同土壤和农作物的派生临界阈值进行独立的验证。阈值将是世界的突破，成为提高灌溉表现和作物生产力的快速轨道，以更好地利用水和农业投入资源。 **