Method for (in-situ) determining steam scatter amount of crops

Abstract

The invention discloses a method used for determining the evapotranspiration of crops on site, belonging to the field of agricultural science and technology. The method comprises the steps as follows: data on soil water potential and soil volumetric moisture content of more than 5 layers of soil layers with different depths is measured on site in real time; wherein, at least one layer is below the root layer of the crops; a plurality of data pairs on unsaturated hydraulic conductivity-volume water content of all soil layers above the zero flux plane below the root layer are obtained when the zero flux plane exists below the root layer of the crops, thus obtaining the mathematical relationship of unsaturated hydraulic conductivity-volume water content of all soil layers, therefore, the water flux of all soil layers below the root layer can be obtained, thus determining the evapotranspiration by a water balance method. The method of the invention can be used for determining the evapotranspiration of the crops on site, destroys no soils, is convenient and precise, and can work out the evapotranspiration of the crops at the time interval without observing the zero flux.

Description

technical field [0001] The invention relates to a method for determining the evapotranspiration of crops, in particular to a method for determining the actual evapotranspiration of field crops using an in-situ measurement technique, and belongs to the field of agricultural science and technology. Background technique [0002] In the soil-plant-atmosphere system (SPAC) cycle, the terrestrial water cycle composed of rainfall, water surface evaporation, soil evaporation, plant transpiration and other processes is the basic element for maintaining terrestrial ecosystems, among which soil evaporation and plant transpiration are collectively referred to as Evapotranspiration (ET) must be considered in many fields such as regional water balance, farmland irrigation, and water resource management. [0003] At present, the methods for directly measuring evapotranspiration water consumption mainly include water balance method, lysimeter method, and zero-flux surface method. [0004] ...

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Problems solved by technology

[0004] The water balance method is the most widely used, simple and not limited by meteorological conditions; however, sampling is frequent and each sampling point is different, and the error caused by sampling cannot be ignored; secondly, in the water balance method, it is difficult to determine the lower boundary of water movement. This leads to large errors due to uncertain sampling depths; third, it is difficult to accurately separate the various components in the water balance method, such as effective precipitation, groundwater recharge, and evaporation, and the errors will be concentrated in the estimation of evaporation; Fourth, the measurement time of the water balance method is relatively long, and it is difficult to observe the daily dynamic change law of evapotranspiration

[0005] The lysimeter method is a classic standard method that can be used to measure evapotranspiration within 1 hour, but it has the following disadvantages: First, the design is complicated, which destroys the original structure of the soil and cuts off the water connection between the crop growing soil and the deep soil ; second, the representativeness of the plants in the device has an impact on the evaporation measurement, and it is difficult to adjust the water in the device; third, it needs large-scale equipment, which belongs to fixed equipment, has poor mobility and is expensive

The first two deficiencies make the experimental conditions different from the real situation; the third deficiencies prevent the method from being widely used

[0006] For the traditional zero-flux surface method, most of them are only in the theoretical discussion, but the actual application is not very extensive, mainly because the application of the traditional zero-flux method has relatively harsh conditions, only when the zero-flux method This principle can only be applied when the flux surface exists, and the zero-flux surface does not exist all the time, and it is generally not used when the groundwater level is high, and it is difficult to use when the precipitation is frequent and the zero-flux surface is unstable; At the same time, the determination of the zero-flux surface requires multiple measurements. In actual operation, the measurement cycle is long, so not all zero-flux surfaces can be observed, which limits the application of the traditional zero-flux surface method.

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