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: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=681860
• 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. **

水对农作物至关重要，但世界各地都面临着水资源稀缺的问题。农业必须提高生产力，以满足未来几年日益增长的粮食需求，而灌溉是实现这些增长的关键组成部分。然而，预计灌溉需求的增长和即将到来的合格人力资源的缺乏将需要建立更多的智能来协助灌溉决策，以节约用水并提高作物生产力。 ******灌溉管理的主流方法仍然主要基于计算蒸散量需求。然而，最近的工作表明，通过使用实时评估从土壤到植物根部的水传输的方法，可以取得显着的收益（增产 20-50%，节水高达 65%）并使用关键矩阵启动农作物灌溉的潜在阈值。 ******关键灌溉阈值是确保水从土壤实时适当转移到植物所需的最低限度的土壤基质势（土壤吸力）。这是灌溉管理智能化的一个关键参数。为了估计这些阈值，必须现场表征土壤水力特性。然而，这些特性是滞后的，根据土壤是湿润还是干燥而不同。部分由于滞后现象，有必要通过许多现场实验凭经验估计临界阈值，这需要大量的努力、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。它将重点关注不饱和导水率函数的滞后现象，评估其在推导临界灌溉阈值中的作用。 ******该计划的第一年（步骤 S.1）将致力于建造仪器化容器和土壤表征（S.2），随后用于（S.3，第 2 年和第 3 年）种植两种3种土壤类型（沙土、壤土、粘土）上的农作物，处于测试阶段，在此期间将定期测量土壤和植物参数。在 S.4 中，使用收集的实验数据的不同分析和数值方法将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）来评估滞后对土壤供水的影响，并确定充分量化不饱和导水率所需的测量范围，以确定关键灌溉阈值。在最后一步（S.6）中，将对不同土壤和作物的导出临界阈值进行独立验证。******从长远来看，开发一种用于确定临界值的自动化实时方法阈值将是世界性的突破，成为提高灌溉性能和作物生产力的快车道，从而更好地利用水和农业投入资源。 **