Soil water content colorimetric-determination method

Abstract

The invention relates to a soil water content colorimetric-determination method. The soil water content colorimetric-determination method comprises the following steps of 1, carrying out extraction on a soil sample to be detected by a cobalt chloride hexahydrate organic solution having a concentration of 0.1-30g / L as a color developing agent to remove solids and to obtain a solution to be detected, and determining the absorbance of the solution to be detected at the wavelength of 380-680nm, and 2, searching the corresponding soil water content in a built absorbance-soil water content standard curve according to the absorbance obtained by the step 1, or substituting the absorbance obtained by the step 1 into the built absorbance-soil water content standard curve equation and calculating the corresponding soil water content. The soil water content colorimetric-determination method is not influenced by soil types, components, unit weight and disturbance, has an error ratio below 2% is a pervasive soil moisture content detection method, is suitable for fast determination in the field and is suitable for soil water fast-determination in the laboratory.

Description

technical field [0001] The invention relates to a method for measuring soil water content, in particular to a colorimetric method for measuring soil water content. Background technique [0002] "Building a water-saving society and developing water-saving agriculture" is a major strategic plan of the country. Monitoring changes in farmland moisture and carrying out water-saving irrigation are of great significance to ensuring food security in my country. At present, there are two types of field soil moisture detection methods: distributed embedded monitoring and portable moisture detection. Most of the frequency domain reflection or time domain reflection moisture meters adopt the dielectric principle. Its detection speed is fast and the operation is simple, but the detection accuracy is affected by soil type, composition, bulk density, soil disturbance, etc. For embedded applications, this error can be resolved by comparing it with laboratory methods. For portable applicat...

AI Technical Summary

Problems solved by technology

[0006] The colorimetric method for measuring soil moisture has high precision, a large range, and is basically not affected by soil type, bulk density, specific gravity, and chemical composition. However, it has not been effectively promoted for more than 30 years. Species and interconversion (CoCl 2 ·H 2 O(blue-purple)CoCl 2 2H 2 O(fuchsia)CoCl 2 ·6H 2 O (pink) [CoCl 4 ] 2- (blue)); the preparation process of cobalt chloride to remove crystal water needs to be dried at 220°C for 21 hours, which is troublesome to make, and it is easy to absorb moisture during storage after dehydration; the color of the colorimetric agent with different moisture content changes, and the maximum absorption The wavelength changes; the soil has an adsorption effect on the color contrast agent, and the soil moisture content is not linearly related to the absorbance of the color contrast agent; the use of decolorizer and centrifugal method also limits the application occasion and rapidity of the method, etc.

Perhaps it is due to the CoCl 2 There are too many factors affecting the color development, which is a reversible equilibrium reaction, and the technology is far from mature, resulting in few relevant research reports for more than 30 years.