Soil alkaline hydrolysis of nitrogen, also known as soil hydrolyzable nitrogen, is also commonly referred to as soil available nitrogen and is the sum of ammonium nitrogen, nitrate nitrogen, amino acids, amides, and readily hydrolyzable proteins. Because this indicator is more indicative of soil N availability in the near future than soil N, it is an important indicator of soil fertility and is therefore a must-test item for routine soil testing. However, the commonly used measurement method is the alkaline solution diffusion method. This method is cumbersome to operate, requires a long time for detection, and has low work efficiency, which is far from the requirement of rapid and accurate. Due to the design defect of the detection method, for example, sodium hydroxide with a relatively high concentration is used together with the boric acid in the absorption solution in the inner and outer chambers of a narrow space container, and the glass plate, the glass plate, and the plate are quickly covered after alkali addition. Vaseline was also painted on the chamber. During the testing process, there was a slight carelessness and contamination could easily occur. As a result, the results showed poor reproducibility of results, poor parallelism, and unreliable results after the test. The use of automatic determination of nitrogen by alkaline distillation method can be a good way to avoid these problems, the performance is simple, rapid, accurate, the results of good reproducibility, parallel parallel to the sample is good, can be used as alkaline hydrolysis of nitrogen test methods. Learn more about the technical parameters, price quotes and other information of professional soil instruments such as acremeters. Nantong Weizhuo Environmental Protection Equipment Co.,Ltd , https://www.natongcwz.com
The effect of different amounts of alkali addition on the determination results can be seen that the difference between the measurement results of the different NaOH addition amount test procedures 3 and the standard value is not significant, which is closest to the standard value, that is, 50 mL of 40% NaOH solution is the best. .
As the amount of alkali added decreases, the result of the measurement decreases, and as the amount of alkali added increases, the result also increases, and the deviation from the standard value increases.
The effect of different dilutions on the determination results showed that the addition of different dilutions had a certain influence on the determination results, but the impact was not significant. The difference between program 8 and program 9 was not significant. The result of procedure 8 and the standard value The closest. It can be seen from Tables 1 and 2 that there is no significant difference in the measurement results of the sample weight 1 to 2 g, and it is recommended that the sample size be 1 to 2 g.
Effect of Addition of Nitrogen-Containing Mixed-Reduced Tablets on the Determination Results From the results of the determination of the addition of nitrogen-reducing mixed-reducing tablets, under the same detection conditions, the results of addition of the mixed-reducing tablets were generally smaller than the standard values.
2 Comparison of the results of alkali decomposing diffusion method and alkaline solution distillation method The results of the determination of 10 ordinary soil samples and GBW07413 standard soil samples by the alkali decomposing diffusion method and the alkaline hydrolysis distillation method showed that: Compared with the standard sample GBW07413, the two methods The results are in good agreement with the actual values, but the results of the alkaline distillation method are closer to the true values.
The difference in reproducibility of the two different detection methods can be determined by the absolute value of the difference between the results of the parallel determination of each group. Alkaline-distillation method is more stable, and the deviation of alkali-diffusion method is larger, the maximum difference between parallels is more than 25mg·kg-1, and the greatest difference between alkaline hydrolysis-distillation test is only 5. 94 mg·kg-1. .
Using KJeltec 8400 automatic nitrogen determination instrument to measure soil alkalinity nitrogen, the amount of alkali added is 40% NaOH solution 50 mL is appropriate, reduce the amount of alkali, test results decreased. The amount of different diluents has a certain influence on the determination results, but the effect is not so great. The best amount is to add 60 mL of diluent. When alkaline hydrolysis of nitrogen is measured by alkaline hydrolysis, addition of a reducing agent will result in a small test result.
The results obtained by the two methods of alkaline hydrolysis and alkali diffusion method are basically consistent with the actual values, but the stability of the alkaline distillation method is better, and the deviation of the alkali solution diffusion method is larger.
Alkaline solution distillation method to measure soil alkalinity nitrogen, no need to cook, no need to add reducing agent, weighing 1 ~ 2 g soil sample directly on the machine, convenient, accurate, reliable, good stability of the results, good reproducibility, can be regarded as It is a good method to determine the alkalinity of nitrogen in soil.