I. Determination of soil nutrient tester test items:
Consider the nutritional requirements of the plant. Plants are to grow normally, of which sixteen essential elements have been confirmed. Among them, a large number of elements are carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), and potassium (K); the middle elements are calcium (Ca) and magnesium (Mg). Sulfur (S) three; trace elements are iron (Fe), boron (B), manganese (Mn), copper (Cu), zinc (Zn), molybdenum (Mo), chlorine (Cl) seven. In addition, silicon, titanium, cobalt, vanadium, nickel, etc. have a good effect on plant growth and development, and are called beneficial elements. Among them, the content of trace elements and beneficial elements in the plant body is very small. As far as the plant growth is concerned, the plant growth needs can be satisfied as long as it is available. In addition, these elements also require special tools for sampling and have poor operability. There are also test methods that require extraction that are difficult for general operators to grasp. If another test method is needed, a lot of experimentation needs to be done to track whether the investigation is related to plant growth, and the test method is only advisable if correlation is found. At the same time, it is also necessary to meet operability. Otherwise, even if the data is barely tested, it cannot explain the problem. Currently, there are many trace element fertilizers on the market, and as long as the results of the general survey of the soil, the application of trace element fertilizer can be carried out without measurement. It can also reduce test costs. Therefore, it is not necessary to require the soil nutrient tester to measure the trace elements in the soil.
Carbon, hydrogen, and oxygen in a large number of elements mainly originate from air and water. With the increase in the yield of crops, the nitrogen, phosphorus, and potassium in the soil are far from meeting the needs of crops. Therefore, tests are necessary. At the same time, the correlation between NPK data and plant growth has been confirmed. For the middle-weight element, if the test method is simple and the data is related to plant growth, the soil nutrient tester can be further developed.
In summary, the soil nutrient tester should develop its own advantages. At present, the NPK is still mainly used to complete the guidance of production and serve the mission of “agriculture, rural areas and farmersâ€. It should not be a large, comprehensive and small road. If we go to this path, the soil nutrient testing will go to a Return road.
Second, the practicality of the soil nutrient tester From the "sixth five-year" development of soil nutrient tester, its focus is practical, but different periods, its practical content is not exactly the same. At that time, testing was the mainstay, as long as data could be tested quickly, and now data applications, ie, formulas, are required. This requires manufacturers to do their own products, do a lot of tracking services from which to find the relationship between rapid measurement data and modern agricultural production put forward a fertilization program with a suitability to better guide the fertilization problem in production. Some manufacturers and individuals are stealing technology, copying and blindly keeping up with others, and some give key data to the user to design input. This is an unpaid practice. Some of them, through the trust of their work units, stole technology and did not understand the root cause. When problems arise, they do not know how to improve and solve the problem. They just spend less money on reducing sales prices. They hope that friends who engage in agricultural investment activities will choose it carefully! ! !
Third, the error of soil nutrient tester The purchase of soil nutrient tester error is a very sensitive topic; it is also the main reason restricting instrument promotion. So, how large is the error of the instrument in the end, can it become an obstacle to guide fertilization, and what is the source of error? When you understand the problem, it is naturally resolved.
First, people often say that the error is a wide range of errors; and here contains three aspects: First, the instrument itself has the error; followed by the test method error; the last is the sampling error. The instrument error is mainly the error created by the linear error and stability. Linear error belongs to systematic error can be minimized by means of calibration, zero adjustment, program compensation; stability can be solved by aging and screening of electronic components; and some manufacturers lack this step work, and even more to reduce The cost of using photosensitive resistors, the instrument must be warmed up for at least half an hour. If the instrument uses a silicon battery, the stability does not change by more than ±5% (red light) within half an hour. As for the error of the filter is a systematic error, it can be completely resolved by calibration, zero adjustment, program compensation, etc. Therefore, as long as the manufacturer, in accordance with the norms of production, instrument error for agricultural applications, is negligible, can be ignored.
Second, the test method error. There is an old saying in China that “If you want to speed up, you don’t have speed†and the speed is fast. The test accuracy can be said to be worse than the classic laboratory method. If you do not recognize this, it is really misleading sales. The soil nutrient tester (quick test method) was used to commit this problem from the day it was used. It is believed that this new thing can replace everything in the laboratory. There are various unrealistic phenomena in practical application. Can not be explained in a timely manner in theory, causing the instrument a few ups and downs, but can not complete the mission of this product in agriculture ---- directing fertilization. At present, some manufacturers are still related to the laboratory to find the coefficient, to find relevant, which is lack of confidence in the speed measurement, the lack of service tracking, the embodiment of closed-door construction is undesirable. As for the use of tap water in the rapid measurement method instead of the error introduced by distilled water, it can also be greatly reduced by adjusting the calibration of the instrument so that the guidance of fertilization will not cause any problems. Secondly, the error caused by the dropper and the drop bottle instead of the standard device is not similar to the error of about 50% that some manufacturers have said; the dropper and dropping bottle technology, which comes from the laboratory's titration test technique, will drop the dropper and drop. The bottle is calibrated first, then the size of the hole is designed to reduce the error. In addition, the volume method, the volumetric method in speed measurement is based on the capacity of the laboratory, the weight method, combined with the advantages of the two designs, we call it weight. It is the result of statistical analysis of various soil samples. After more than eight years of follow-up, it has played an important role in quickly instructing fertilization and in making it easy for the majority of agricultural workers to grasp. To sum up, the rapid measurement method should be an easy-to-master method, can guide farmers to correct fertilization to reduce waste, increase production and increase income, can be widely used to promote, over-pursuing close to the laboratory, complete test project, which is contrary to the speed measurement guidance The true meaning of fertilization.
Sampling error, the impact of the entire speed measurement process is sampling accuracy, sampling error is much greater than the test method error and instrument error. Therefore, users should base on the basic requirements of agronomy and correctly take representative soil samples according to local planting conditions in order to ensure that the data obtained are correct. That is, the laboratory must also follow this requirement.
Another point to point out is testing the problem of fresh samples. Some people think that the speed measurement technique should not test soil samples that have been air-dried, crushed, or sieved. That is to say, the speed test is to test fresh samples. This has violated the fact that the soil samples are inhomogeneous. It is not practical, not responsible. Such as: economic crops, vegetables, fruit trees fertilization is concentrated fertilization, how to obtain a representative soil sample, in the process of weighing these grams of soil samples and how to ensure its uniformity? This is the real source of fast-tracking error. Repeating the same soil sample will certainly be difficult to duplicate. It will inevitably lead to users' misgivings about speed measurement technology, dissatisfaction with the speed measurement instrument, and the possibility of re-emergence. Technology pushes into the abyss. Therefore, we call on the technical personnel, manufacturers, and managers who are engaged in this technology promotion work to proceed from the actual point of view and use a dialectical and objective perspective to view this issue. In the rapid measurement technology, if a simple balance is used, the accuracy of the balance is ±10% and the environmental requirements are relatively high. Such as the flow of air, the relatively stable visual error of personnel, etc. are all important factors in increasing the error of the balance. The use of volumetric methods can avoid the above errors.
how to choose:
1 Selecting products that have been certified for measurement is the right choice for users.
At present, similar products in the market are gradually increasing. Some have worked in the sales department of a regular factory, and then they have stolen some of the technology to counterfeit, and some of them have been copied through the purchase of products. It can be said that the products will be produced and sold after 2005. Without exception, it was not recognized by the measurement department.
2 Checking stability and repeatability Stability is the difference between the maximum and minimum values ​​of the same item within 15 minutes after adjusting the instrument. Instead of adjusting the zero of the instrument, see the difference between the maximum and minimum readings in three minutes divided by the full-scale reading. This is called zero drift. But not three minutes should be 15 minutes.
3 Should choose to be responsible for the product, responsible for the use of high integrity manufacturers, but can not choose those who disrupt the market for the purpose, there is no sales service force manufacturers.
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