In China, it was relatively late to start the development of reference materials for soils. It was only in the mid-1980s that two batches of soil reference materials had been developed. We have developed suitable primary soil types and values ​​for the country for several years from 1991. More extensive use of the six soil active state composition reference materials, and has been approved by the State Bureau of Technical Supervision as a national standard material. The sample size of the soil has great influence on the results of the development. The sample screen (60 mesh) is very effective in the sample preparation process. Add WeChat, you want to have: 3D Folding Face Mask,3D Folding Protective Mask,3D Foldable Ffp2 Respirator,3D Folding 5 Layer Disposable Respirator Henan Aklly Filter Engineering Co., Ltd , https://www.akllyfilte.com
The effect of sample size and drying temperature on the amount of available soil components and the stability of soil available composition with storage time. The six soil samples were collected except for rice fields in Huangmei County of Hubei Province. The rest were all dry farmland. The types of soil were as follows: the open source of Liaoning, the wet and leaching soil (brown), and the light-colored wet soil of Anyang, Henan (tide). Soil), Purple Moist Soil (Purple Soil) in Jianyang, Sichuan, Iron Penetration Hydroponic Artificial Soil (Hu Soil) in Hubei Huangmei, Viscous Moist Rich Iron (Red Soil) in Yujiang, Jiangxi Province, and Jiantong Moist Iron Aluminum in Guangdong Huaxian County Soil (red soil). These soil types include both the typical acidic, neutral and calcareous soils in China and the soil types in major agricultural areas in China.
In order to ensure the homogeneity of the standard material, it will not occur in the process of development, handling, particle differentiation, resulting in changes in the amount of ingredients, the development process, and more fully using the grinding method, generally required 200 mesh sieve. However, in the routine analysis of the soil's available components, in order to make its value more reflective of the objective reality of the natural state 0, the original soil particles are destroyed as little as possible, and the unified determination of the pH and the effective state components used for the determination of 10 mesh or 20 Measured soil samples; organic matter, nitrogen, and exchangeable ions, etc., were used to measure soil samples that had been used for sample preparation (60 mesh). In the process of preparing samples of soil available standard reference materials, if 10 soil samples are used, particles with different particle sizes will be separated and separated due to excessive coarse particles, and it is difficult to ensure the uniformity of reference materials. On the other hand, if the particle size of the soil sample is too small, the soil sample cannot be guaranteed to be as close to the natural state as possible.
With the exception of the individual effective component values, most of the values ​​are increased with varying degrees of sample particle size, and the cation exchange capacity decreases with the sample particle size, but the variation is relatively small. Relatively speaking, the available potassium and available iron are relatively The amplitude of change is a little larger, especially the effective iron amplitude of the light-colored damp rudimentary soil and the viscous moist iron-rich soil. The amount of available phosphorus, available iron, and available copper in the wet and lightly-colored moist forming soils, and the available phosphorus, available iron, and available copper in the viscous moist iron-rich soils are seen as 60 The magnitude of the change is much smaller than the magnitude of the 100-item sample. Therefore, in order to meet the requirements for regular analysis of the soil particle size as much as possible, the uniformity of the reference material can be ensured, and the sample preparation screen for the reference material sample is finally determined ( 60 mesh). 