Method for FDR frequency domain reflective soil moisture sensor undisturbed soil calibration

Abstract

The invention discloses a method for FDR frequency domain reflective soil moisture sensor undisturbed soil calibration, and relates to the technical field of meteorological detection. The method includes the following steps: step one, a step of undisturbed soil reflection frequency measurement sample making, namely a step of designing a penetrating type soil sampler, directly obtaining undisturbedsoil samples of large volume, wherein the samples are directly placed into cylindrical containers of an acrylic material during a soil sampling process, which can minimize the disturbance of the soilsamples, and accurately installing measurement sleeves in the center of the soil samples by a separating plate positioning method; step two, a step of undisturbed soil of large volume humidity-frequency measurement; and step three, a step of undisturbed soil samples of large volume water content accurate measurement. The method can use an EnviroSMART multi-point position adjustable soil moisturesensor to measure reflection frequency of the undisturbed soil of large volume for the undisturbed soil, accurately measure mass to invert water content of the undisturbed soil of large volume, and determine water content of soil in the field and a reflection frequency model by taking mass measurement as a standard.

Description

Technical field: [0001] The invention relates to a method for undisturbed soil calibration of an FDR frequency-domain reflective soil moisture sensor, and belongs to the technical field of meteorological detection. Background technique: [0002] Due to the complex diversity and variability of the actual soil physical and chemical structure, the soil electrical conductivity is different, and the soil electrical conductivity mainly depends on the number and size of soil pores, soil water conductivity (or pore water conductivity) and soil particles. For different soils, due to the influence of electrical conductivity, especially the influence of soil pH, the general calibration equation cannot be used, and specific soil calibration and data calibration are required to obtain the correct soil moisture content. [0003] At present, two calibration methods are generally used for soil moisture sensors: laboratory calibration is to take soil near the installed automatic soil moistu...

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Problems solved by technology

[0003] At present, two calibration methods are generally used for soil moisture sensors: laboratory calibration is to take soil near the installed automatic soil moisture station, and after the soil is ground, removed impurities, and dried, it is made by controlling the amount of water added according to the mass ratio. Samples with different volumes of water content are used to calibrate the sensor. This method can only make one sample point of humidity value at a time. To obtain multiple sample points, repeated processing and water addition are required. The procedure is cumbersome and the workload is extremely heavy; field calibration in Manual soil drying and weighing observations are carried out around the sensor of the automatic observation equipment, and the automatic observation data of the instrument are recorded at the same time to obtain a series of manual and automatic observation volume water content data, and the instrument is corrected with manual data. The site can obtain better results, and the corrected automatic soil volumetric water content data is highly available, but for complex soil environments, uneven soil distribution and large variability, or restricted by climatic conditions, the corrected comparative sample data cannot cover the low, medium and high humidity range of soil station, the obtained corrected equation is likely to be inconsistent with the actual soil moisture

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