Rapid measurement method of soil available potassium

Abstract

The invention relates to a rapid measurement method of soil available potassium. The method comprises the following steps: (1) extraction: weighing a certain amount of a soil sample and placing the soil sample into a container, adding phosphorus-free active carbon, adding an universal soil extractant--a NaHCO3 aqueous solution with concentration of 0.6-0.7 mol / L, oscillating for 3-5 min, and filtering; (2) turbidimetry reaction: respectively fetching a blank control solution, a standard solution and a solution to be measured, respectively adding a soil available potassium masking agent and a soil available potassium turbidity agent, and standing; and (3) nephelometry test: adjusting optical path wavelength to 420 nm, using the universal soil extractant solution as the blank control solution, respectively measuring absorbance values of a potassium standard solution and the solution to be measured at the absorbance measurement gear, or adjusting a reference scale value based on the rapidly available potassium standard solution at the concentration measurement gear, placing the solution to be measured into the optical path, and correspondingly calculating or reading the content of rapidly available potassium in the soil sample to be measured. Based on existing rapid measurement, the technology of the invention is simplified much more, costs are reduced, and stability can be raised.

Description

technical field [0001] The invention belongs to the field of agricultural testing, and in particular relates to a rapid determination method for soil available potassium suitable for neutral and calcareous soils. Background technique [0002] The abundance of soil nutrients not only directly affects the growth and production of seedlings, but also measures the effect of fertilization and determines whether it is necessary to fertilize, which is the basis for fertilization. When formulating a fertilization plan, soil nutrition diagnosis should be carried out first, and the type and quantity of fertilizer should be determined according to the soil nutrient content and supply status. [0003] Plants generally absorb water-soluble potassium directly from the soil, but exchangeable potassium can quickly reach equilibrium with water-soluble potassium, so soil available potassium includes water-soluble potassium and exchangeable potassium. The exchangeable potassium in the soil re...

AI Technical Summary

Problems solved by technology

Generally, flame photometry is commonly used in routine experiments. The results obtained by this method are more accurate, but the detection cost is relatively high.

Sodium tetraphenylborate turbidimetry is a commonly used method in soil rapid measurement, but its reaction conditions and reagents used are not unified, and there are certain shortcomings

[0005] Chinese patent document CN101271072A discloses a method for measuring potassium by sodium tetraphenylborate nephelometric method, but the extraction agent used in it has complex components and high cost, and the stability of its turbidity reaction has room for further improvement

[0006] In general, the prior art has the following problems: (1) The potassium extracted with neutral ammonium acetate needs to be extracted by flame photometry. Although the result is stable, the flame photometer can only measure potassium and sodium. , the cost is high and it is difficult to apply to the field of rapid measurement; (2) In the existing sodium tetraphenylborate turbidimetric method, the preparation process of the turbidity agent is complicated and takes a long time, and the amount of raw material reagents is large, and the cost is high (3) In the existing rapid detection method of sodium tetraphenylborate, the turbidity particles produced by the reaction are not uniform, and the stability of the turbidity is poor