1 Soil nutrient rapid measurement technology and its application characteristics
1.1 Significance of Soil Nutrient Quick Measurement The soil nutrient fastness tester is an advanced agricultural instrument based on the soil nutrient fast measurement technology. The soil nutrient fast test is a relatively quick and relatively inexpensive method compared to conventional analysis, and the test equipment is more convenient. , And the test accuracy can meet the requirements of soil testing and fertilization soil nutrient testing technology and equipment. In the previous article, a detailed description of this technology has been provided in the detailed description of soil nutrient rapid measurement technology, which should be characterized by rapidity, low cost, convenience, and accuracy. The core of speed measurement is to reduce the cost of soil testing. Due to the high cost of routine analysis (usually 30 to 50 yuan for each project), the field in China is usually very small, the fertility of the field is uneven, the area of ​​soil surveying is often only a few acres, and the input of soil testing is often much larger than that of soil testing. The output has become a limiting factor in the promotion of soil testing and fertilization in China. It is precisely because of this that fertilizer manufacturers perform agrochemical services t, ltIII4 soil input often exceeds revenue from fertilizer sales. According to China's land conditions and our practices, it can be considered that the cost of soil testing must be reduced to 4 to 5 yuan per project or below. Soil fertilization has its own internal driving force. This is the economic law. Rapid measurement technology is to adapt to this economic law and produce and develop. Vice Minister Fan Xiaojian of the Ministry of Agriculture made clear in his speech at the National Soil Testing and Fertilization Management and Technology Training Class held in April 2007 that: Farmers in some localities have requested that households conduct soil testing and formulation, although it is difficult to do so at present. However, this is an inevitable trend for future development. All localities should aim at rapidity, low cost, convenience, and accuracy to further improve soil testing methods and detection techniques, improve service efficiency and service levels, and gradually meet the individual needs of farmers. Only when it is convenient, fast, inexpensive, and accurate to meet individual needs and long-term mechanisms can it be truly established.
1.2 Application areas of soil nutrient fast measurement The soil speed measurement technology department has only been applied to the soil nutrient fastness test, and has also been applied in the soil moisture quickness tester, etc., and some portable soil moisture measuring instruments are also Speaking of the application of speed measurement technology, the application fields of speed measurement include: 1 County and township agricultural technology promotion station soil testing and fertilizing service; 2 Fertilizer plant and its distribution unit promotion agricultural chemical service; 3 Soil fertility sector soil fertility survey, guidance macro Fertilization policy; 4 Agrochemical service departments formulate indicators for soil and fertility fertility; 5 Rural grass-roots units such as villages, farms, and science and technology demonstration sites self-testing services; 6 Crop hospital nutrition diagnosis; 7 Compound fertilizer production plants to carry out fertilizer nutrient content Monitoring; 8 soil testing and fertilization scientific research soil nutrient determination; 9 identify true and false chemical fertilizers. Since speed measurement is based on the premise of economical efficiency under the premise of satisfying the test accuracy requirements for certain applications, it does not start from the technical premise of increasing the accuracy as much as possible. The accuracy test and evaluation must be based on routine analysis, so it does not have Nor can it be judged authority. This limits its application area.
Because rapid measurement is a technology developed in recent years, it has not yet had time to establish its own fertility indicators and technical data system. In some cases, it must be converted into conventional data, using conventional analysis of technical indicators and The data system guides fertilization. This is also a constraint factor in the promotion of rapid measurement technology.
2 The technical connotation of soil nutrient rapid measurement technology What technical content should be included in rapid measurement technology, and there is not a saying in the academic circles. From the point of view of the developed rapid measurement technology, there are generally the following aspects.
2.1 Rapid Soil Moisture Measurement Technology Due to the speed measurement requirements can be measured in real time on the scene, often can not wait more than one day soil sample drying time, so the speed meter must be equipped with moisture speed measurement device, it should be said that there is no moisture measurement device is not a speed meter. There are many kinds of rapid moisture determination technology, but the price is very expensive, such as time domain reflectometry (TDR) about 15,000 US dollars, neutron moisture meter about 9 000 US dollars, and the soil sample required for the measurement is larger, Mostly used for the determination of farmland soil water content. Not suitable for quick test. The commonly used method of speed measurement in the past was the alcohol burning method, which was low in cost but slow in speed, and was equipped with a small scale. Recent developments in capacitance measurement, conductivity measurement, etc. have increased the efficiency of the measurement at a price of approximately RMB 1 000
Between 2 000 yuan, the measurement range is between 6% and 22%, which is more suitable for determination of soil samples.
2.2 Soil nutrient combined extraction technology The largest workload of soil analysis is pre-treatment. To improve the test speed, simultaneous rapid extraction of multiple nutrients must be achieved. It can be said that the joint extraction technology is the basis of rapid measurement technology. The combined rapid leaching must be compatible with the rapid-analysis system and must be significantly correlated with the plant's absorption of soil nutrients. In order to share technical data using routine analysis, it also needs to be significantly related to routine analysis.
2.3 Analytical method shortcut technology There are many conventional analytical methods required equipment or expensive or unable to carry or the analysis process is cumbersome and can not be used for speed measurement, for which we must find another way. For example, alkaline hydrolysis of nitrogen has developed a simple distillation method to replace the alkali deliquescence method that requires an oven; organic matter has developed a potassium dichromate oxidation colorimetric method instead of the potassium dichromate oxidation capacity method; soil NPK indicator uses a rapid measurement technique on the soil NPK content is tested and so on.
2.4 Anti-jamming Techniques of Pharmaceutical Formulations Soil nutrient fast-analysis analysis often encounters different interference problems than conventional analysis. For example, when the potassium is measured, the conventional masking agent cannot be used because of the different pH of the extracting agent. Therefore, a new masking method must be researched and developed. And masking agents. In addition, conventional methods for the determination of trace elements usually require extraction to increase the concentration of the test solution and reduce interference. For the purpose of simplifying the operation and improving the portability, extraction is not usually performed, and it is necessary to develop a masking technology with stronger anti-interference ability. .
2.5 Storage-resistance technology of finished pharmaceuticals Supplying finished pharmaceuticals to enable users to open and use bottles is an important way to increase the speed of testing, and is also the development direction of speed measurement technology at home and abroad. The shelf life of the drug is determined firstly by the choice of analytical method and the formulation of the drug. For example, molybdenum and antimony antibiotics are commonly used for the determination of readily available phosphorus, but ascorbic acid is not easily preserved, so it should not be used. Some of the pharmaceutical ingredients are easily oxidized and need to add anti-oxidant components or other measures; the preservation period of the pharmaceutical is also related to the pharmaceutical preparation process and packaging technology.
2.6 Photoelectric colorimeter design and manufacturing technology As a special instrument and portable instrument, in order to reduce costs and reduce weight, more commonly used filter photoelectric colorimeter, but the filter monochrome poor, resulting in line error Large, many products have a linearity error of 4% to 8%, which accounts for a large proportion of the total measurement error. At present, better instruments use interferometric or thin-film filters, or use intelligent software for error correction. The error can reach within 2% ~ 3%, basically reach the level of grating type II spectrophotometer. In addition, in order to improve the sensitivity and stability of the violet-blue region, light sources and detectors should be optimized and light source stabilization techniques should be used.
2.7 Portability Technology Development of portable devices such as portable constant temperature extractors, portable digestion devices, etc. In addition, utensils, utensils, and materials are also complete to improve compatibility, miniaturization, and weight reduction. , Packaging integration to improve portability.
2.8 Relationship between speed measurement values ​​and conventional analysis values ​​Technical difficulties in this area are not significant, but in the absence of rapid measurement of their own abundance indicators, it is also an essential connotation of speed measurement technology. For example, turbidimetric potassium must be converted into potassium by flame photometric method. Diluted organic method requires conversion of organic matter into organic matter in the oil bath. There is also a conversion problem in the jointly leached available nutrients. The development unit or promotion unit of the speedometer is obligated to provide this study. Data or services. The above points are that the current speed measurement technology has been fully realized.
3 Measures to reduce the cost of pharmaceuticals by measuring the speed of soil The supply of finished pharmaceuticals can speed up the analysis and reduce the cost of testing, which is one of the main measures to ensure the reliability of the test results. At the same time, it also increases the production cost of the rapid-testing manufacturers, but the pesticide residues The speed meter can reduce the speed of the test by the following measures.
3.1 Directly measure fresh soil without drying, which can shorten the soil analysis cycle by 1 to 2 days
3.2 Study using rapid combined extraction agent The extraction time was shortened from 30 minutes to 5 to 10 minutes for each of N, P and K, and the three components of N, P and K were simultaneously extracted.
3.3 Study of the liquid formulation with a longer shelf life Study the formulation of the liquid with a longer shelf life, so that the user can open the bottle for the finished product. This will not only save the dispensing time, reduce the loss of liquid preparation, but also reduce the user's dependence on the laboratory to reduce the investment burden of grass-roots units.
3.4 Selecting a test method that is quick and easy without complicated equipment If the organic matter analysis uses dilute heat colorimetry, ammonium nitrogen is used in Nessler's colorimetric comparison, and available potassium is turbidimetrically used.
3.5 Research and development of new rapid test methods such as the conventional alkaline hydrolysis of nitrogen analysis using alkaline solution diffusion method, to be heated in the oven for 24 h, the test cycle is more than 2 days, and our newly developed alkali hydrolysis nitrogen method does not need Complex equipment, as long as 1 h.
3.6 Improve Instrument Design and Simplify Operation Steps If the calibration of the transmittance file is cancelled and the concentration calibration is performed without shifting, the test speed is increased and the shift error is reduced.
3.7 using a small volume colorimetric method. Minimize the amount of reagents such as electrode potential measurement pool needs 30 mI. The flow colorimetry requires 30 to 50 mL of the reagent each time, while the YN type soil-fertilizer colorimetric cell reagent is only 3 to 4 mL. The dosage of drug is saved by 10 times, which not only reduces the test cost but also improves the portability of the instrument.
3.8 Research and development of small portable oscillators to improve extraction efficiency and reproducibility of testing. For example, a lightweight oscillator that can process eight soil samples at the same time has a 7-times improvement in efficiency.
4 Trends and Trends of Soil Nutrient Rapid Measurement Technology
4.1 The rapid measurement project is further expanded on the basis of the further improvement of the determination of total elements and the determination of quick-acting components. The focus is on the extension of the types of rapid measurement of trace elements, many of which were previously considered technically difficult or even considered incapable. The rapid measurement of trace elements is entering the field of rapid measurement research, such as zinc and molybdenum.
4.2 The further extension of the shelf life of the finished product The ideal shelf life should be more than one year, and it should be at least half a year. It is a difficult indicator for some drugs that currently only reach three months, and is also an important research field in the future.
4.3 Fertility guidance The intelligent software such as expert system is introduced into the speed meter. The purpose is to solve the problem of how to interpret the nutrient measurement value and how to make the fertilization decision in the absence of soil and fertilizer technical personnel in the rural grassroots.
4.4 Standardization of combined extractors and rapid analysis methods for speed measurement The purpose of the standardization is to standardize the speed measurement technology so that the speed measurement data can be evaluated, communicated, and data resources can be shared and exchanged with conventional methods. At present, the drafting of this agricultural standard undertaken by Henan Agricultural University is basically completed.
4.5 Establishment of rapid nutrient measurement system for soil nutrients The establishment of rapid test own index system is to promote the speed measurement technology supporting technology, than the use of the conversion factor to use conventional abundance indicators to guide the fertilization more convenient and more accurate, which requires Soil fertilizer workers and users work together.
5 Two Misunderstandings in the Development of Soil Nutrient Rapid Measurement Technology
5.1 Over-sacrificing precision and pursuing simplicity Soil nutrient quick-measuring instrument must reduce some precision quickly, but this reduction is limited. This is at least not affecting the nutrient vacancy grading and fertilization decision-making! Any speed measurement technology Applications must be tested and tested for error before they can be promoted. At present, the management of soil and fertility industry lacks the management and supervision of rapid measurement technology, and some immature or inapplicable technologies flow freely into the market. Here are some examples: 1 Replace distilled water with tap water or deep well water, perhaps in a specific place Not too big an error? However, the test accuracy is not guaranteed in rural areas. At least our experimental well water has an error of 37% to 51% compared with distilled water. 2 Prepare the standard solution with a plastic dropper or a dropper. Due to the large error of the dropper, it can only be used for reagents that are not sensitive to reagents and cannot be used in standard solutions. Experiments show that the maximum error caused by this approach can reach 21.7% to 44.2%.
5.2 Take into account the characteristics of soil nutrient rapid measurement, blindly introduce conventional techniques. For example: 1 Volumetric method to take soil samples in the conventional analysis can increase the analysis speed of soil moisture temperature speedometer, but it requires the soil samples to be air-dried, crushed, sifted However, rapid test does not have this process. Our experiments show that the volumetric method compared with the gravimetric method, the average error for different soil types, 11.8%; for different soil sample water content (15% water content compared with air-dried soil), the average error is 2l% ~ 32 %. 2 flow colorimetry This is a technology suitable for laboratory automation analysis. The use of motorized pumps for liquids, the use of the same cuvette, automatic flushing liquid, high efficiency, small error, but the consumption of the solution is not suitable for portable instruments, And speed measurement instrument can not be equipped with motorized pumps, while manual pump, low liquid efficiency is low efficiency, error. 3 filter automatic conversion. It is generally a red light and a blue light, which is selected by pressing a key. This method is easy to operate, but the speedometer only has two wavelengths to choose from, which severely limits the test items. Some very important items cannot be measured. If the measurement is too strong, the error is very large. For example, the nitrate test method measures nitrate nitrogen ( The absorption peak was 510 nm) and the organic matter was measured by potassium dichromate oxidation (absorption peak 590 nm).
1.1 Significance of Soil Nutrient Quick Measurement The soil nutrient fastness tester is an advanced agricultural instrument based on the soil nutrient fast measurement technology. The soil nutrient fast test is a relatively quick and relatively inexpensive method compared to conventional analysis, and the test equipment is more convenient. , And the test accuracy can meet the requirements of soil testing and fertilization soil nutrient testing technology and equipment. In the previous article, a detailed description of this technology has been provided in the detailed description of soil nutrient rapid measurement technology, which should be characterized by rapidity, low cost, convenience, and accuracy. The core of speed measurement is to reduce the cost of soil testing. Due to the high cost of routine analysis (usually 30 to 50 yuan for each project), the field in China is usually very small, the fertility of the field is uneven, the area of ​​soil surveying is often only a few acres, and the input of soil testing is often much larger than that of soil testing. The output has become a limiting factor in the promotion of soil testing and fertilization in China. It is precisely because of this that fertilizer manufacturers perform agrochemical services t, ltIII4 soil input often exceeds revenue from fertilizer sales. According to China's land conditions and our practices, it can be considered that the cost of soil testing must be reduced to 4 to 5 yuan per project or below. Soil fertilization has its own internal driving force. This is the economic law. Rapid measurement technology is to adapt to this economic law and produce and develop. Vice Minister Fan Xiaojian of the Ministry of Agriculture made clear in his speech at the National Soil Testing and Fertilization Management and Technology Training Class held in April 2007 that: Farmers in some localities have requested that households conduct soil testing and formulation, although it is difficult to do so at present. However, this is an inevitable trend for future development. All localities should aim at rapidity, low cost, convenience, and accuracy to further improve soil testing methods and detection techniques, improve service efficiency and service levels, and gradually meet the individual needs of farmers. Only when it is convenient, fast, inexpensive, and accurate to meet individual needs and long-term mechanisms can it be truly established.
1.2 Application areas of soil nutrient fast measurement The soil speed measurement technology department has only been applied to the soil nutrient fastness test, and has also been applied in the soil moisture quickness tester, etc., and some portable soil moisture measuring instruments are also Speaking of the application of speed measurement technology, the application fields of speed measurement include: 1 County and township agricultural technology promotion station soil testing and fertilizing service; 2 Fertilizer plant and its distribution unit promotion agricultural chemical service; 3 Soil fertility sector soil fertility survey, guidance macro Fertilization policy; 4 Agrochemical service departments formulate indicators for soil and fertility fertility; 5 Rural grass-roots units such as villages, farms, and science and technology demonstration sites self-testing services; 6 Crop hospital nutrition diagnosis; 7 Compound fertilizer production plants to carry out fertilizer nutrient content Monitoring; 8 soil testing and fertilization scientific research soil nutrient determination; 9 identify true and false chemical fertilizers. Since speed measurement is based on the premise of economical efficiency under the premise of satisfying the test accuracy requirements for certain applications, it does not start from the technical premise of increasing the accuracy as much as possible. The accuracy test and evaluation must be based on routine analysis, so it does not have Nor can it be judged authority. This limits its application area.
Because rapid measurement is a technology developed in recent years, it has not yet had time to establish its own fertility indicators and technical data system. In some cases, it must be converted into conventional data, using conventional analysis of technical indicators and The data system guides fertilization. This is also a constraint factor in the promotion of rapid measurement technology.
2 The technical connotation of soil nutrient rapid measurement technology What technical content should be included in rapid measurement technology, and there is not a saying in the academic circles. From the point of view of the developed rapid measurement technology, there are generally the following aspects.
2.1 Rapid Soil Moisture Measurement Technology Due to the speed measurement requirements can be measured in real time on the scene, often can not wait more than one day soil sample drying time, so the speed meter must be equipped with moisture speed measurement device, it should be said that there is no moisture measurement device is not a speed meter. There are many kinds of rapid moisture determination technology, but the price is very expensive, such as time domain reflectometry (TDR) about 15,000 US dollars, neutron moisture meter about 9 000 US dollars, and the soil sample required for the measurement is larger, Mostly used for the determination of farmland soil water content. Not suitable for quick test. The commonly used method of speed measurement in the past was the alcohol burning method, which was low in cost but slow in speed, and was equipped with a small scale. Recent developments in capacitance measurement, conductivity measurement, etc. have increased the efficiency of the measurement at a price of approximately RMB 1 000
Between 2 000 yuan, the measurement range is between 6% and 22%, which is more suitable for determination of soil samples.
2.2 Soil nutrient combined extraction technology The largest workload of soil analysis is pre-treatment. To improve the test speed, simultaneous rapid extraction of multiple nutrients must be achieved. It can be said that the joint extraction technology is the basis of rapid measurement technology. The combined rapid leaching must be compatible with the rapid-analysis system and must be significantly correlated with the plant's absorption of soil nutrients. In order to share technical data using routine analysis, it also needs to be significantly related to routine analysis.
2.3 Analytical method shortcut technology There are many conventional analytical methods required equipment or expensive or unable to carry or the analysis process is cumbersome and can not be used for speed measurement, for which we must find another way. For example, alkaline hydrolysis of nitrogen has developed a simple distillation method to replace the alkali deliquescence method that requires an oven; organic matter has developed a potassium dichromate oxidation colorimetric method instead of the potassium dichromate oxidation capacity method; soil NPK indicator uses a rapid measurement technique on the soil NPK content is tested and so on.
2.4 Anti-jamming Techniques of Pharmaceutical Formulations Soil nutrient fast-analysis analysis often encounters different interference problems than conventional analysis. For example, when the potassium is measured, the conventional masking agent cannot be used because of the different pH of the extracting agent. Therefore, a new masking method must be researched and developed. And masking agents. In addition, conventional methods for the determination of trace elements usually require extraction to increase the concentration of the test solution and reduce interference. For the purpose of simplifying the operation and improving the portability, extraction is not usually performed, and it is necessary to develop a masking technology with stronger anti-interference ability. .
2.5 Storage-resistance technology of finished pharmaceuticals Supplying finished pharmaceuticals to enable users to open and use bottles is an important way to increase the speed of testing, and is also the development direction of speed measurement technology at home and abroad. The shelf life of the drug is determined firstly by the choice of analytical method and the formulation of the drug. For example, molybdenum and antimony antibiotics are commonly used for the determination of readily available phosphorus, but ascorbic acid is not easily preserved, so it should not be used. Some of the pharmaceutical ingredients are easily oxidized and need to add anti-oxidant components or other measures; the preservation period of the pharmaceutical is also related to the pharmaceutical preparation process and packaging technology.
2.6 Photoelectric colorimeter design and manufacturing technology As a special instrument and portable instrument, in order to reduce costs and reduce weight, more commonly used filter photoelectric colorimeter, but the filter monochrome poor, resulting in line error Large, many products have a linearity error of 4% to 8%, which accounts for a large proportion of the total measurement error. At present, better instruments use interferometric or thin-film filters, or use intelligent software for error correction. The error can reach within 2% ~ 3%, basically reach the level of grating type II spectrophotometer. In addition, in order to improve the sensitivity and stability of the violet-blue region, light sources and detectors should be optimized and light source stabilization techniques should be used.
2.7 Portability Technology Development of portable devices such as portable constant temperature extractors, portable digestion devices, etc. In addition, utensils, utensils, and materials are also complete to improve compatibility, miniaturization, and weight reduction. , Packaging integration to improve portability.
2.8 Relationship between speed measurement values ​​and conventional analysis values ​​Technical difficulties in this area are not significant, but in the absence of rapid measurement of their own abundance indicators, it is also an essential connotation of speed measurement technology. For example, turbidimetric potassium must be converted into potassium by flame photometric method. Diluted organic method requires conversion of organic matter into organic matter in the oil bath. There is also a conversion problem in the jointly leached available nutrients. The development unit or promotion unit of the speedometer is obligated to provide this study. Data or services. The above points are that the current speed measurement technology has been fully realized.
3 Measures to reduce the cost of pharmaceuticals by measuring the speed of soil The supply of finished pharmaceuticals can speed up the analysis and reduce the cost of testing, which is one of the main measures to ensure the reliability of the test results. At the same time, it also increases the production cost of the rapid-testing manufacturers, but the pesticide residues The speed meter can reduce the speed of the test by the following measures.
3.1 Directly measure fresh soil without drying, which can shorten the soil analysis cycle by 1 to 2 days
3.2 Study using rapid combined extraction agent The extraction time was shortened from 30 minutes to 5 to 10 minutes for each of N, P and K, and the three components of N, P and K were simultaneously extracted.
3.3 Study of the liquid formulation with a longer shelf life Study the formulation of the liquid with a longer shelf life, so that the user can open the bottle for the finished product. This will not only save the dispensing time, reduce the loss of liquid preparation, but also reduce the user's dependence on the laboratory to reduce the investment burden of grass-roots units.
3.4 Selecting a test method that is quick and easy without complicated equipment If the organic matter analysis uses dilute heat colorimetry, ammonium nitrogen is used in Nessler's colorimetric comparison, and available potassium is turbidimetrically used.
3.5 Research and development of new rapid test methods such as the conventional alkaline hydrolysis of nitrogen analysis using alkaline solution diffusion method, to be heated in the oven for 24 h, the test cycle is more than 2 days, and our newly developed alkali hydrolysis nitrogen method does not need Complex equipment, as long as 1 h.
3.6 Improve Instrument Design and Simplify Operation Steps If the calibration of the transmittance file is cancelled and the concentration calibration is performed without shifting, the test speed is increased and the shift error is reduced.
3.7 using a small volume colorimetric method. Minimize the amount of reagents such as electrode potential measurement pool needs 30 mI. The flow colorimetry requires 30 to 50 mL of the reagent each time, while the YN type soil-fertilizer colorimetric cell reagent is only 3 to 4 mL. The dosage of drug is saved by 10 times, which not only reduces the test cost but also improves the portability of the instrument.
3.8 Research and development of small portable oscillators to improve extraction efficiency and reproducibility of testing. For example, a lightweight oscillator that can process eight soil samples at the same time has a 7-times improvement in efficiency.
4 Trends and Trends of Soil Nutrient Rapid Measurement Technology
4.1 The rapid measurement project is further expanded on the basis of the further improvement of the determination of total elements and the determination of quick-acting components. The focus is on the extension of the types of rapid measurement of trace elements, many of which were previously considered technically difficult or even considered incapable. The rapid measurement of trace elements is entering the field of rapid measurement research, such as zinc and molybdenum.
4.2 The further extension of the shelf life of the finished product The ideal shelf life should be more than one year, and it should be at least half a year. It is a difficult indicator for some drugs that currently only reach three months, and is also an important research field in the future.
4.3 Fertility guidance The intelligent software such as expert system is introduced into the speed meter. The purpose is to solve the problem of how to interpret the nutrient measurement value and how to make the fertilization decision in the absence of soil and fertilizer technical personnel in the rural grassroots.
4.4 Standardization of combined extractors and rapid analysis methods for speed measurement The purpose of the standardization is to standardize the speed measurement technology so that the speed measurement data can be evaluated, communicated, and data resources can be shared and exchanged with conventional methods. At present, the drafting of this agricultural standard undertaken by Henan Agricultural University is basically completed.
4.5 Establishment of rapid nutrient measurement system for soil nutrients The establishment of rapid test own index system is to promote the speed measurement technology supporting technology, than the use of the conversion factor to use conventional abundance indicators to guide the fertilization more convenient and more accurate, which requires Soil fertilizer workers and users work together.
5 Two Misunderstandings in the Development of Soil Nutrient Rapid Measurement Technology
5.1 Over-sacrificing precision and pursuing simplicity Soil nutrient quick-measuring instrument must reduce some precision quickly, but this reduction is limited. This is at least not affecting the nutrient vacancy grading and fertilization decision-making! Any speed measurement technology Applications must be tested and tested for error before they can be promoted. At present, the management of soil and fertility industry lacks the management and supervision of rapid measurement technology, and some immature or inapplicable technologies flow freely into the market. Here are some examples: 1 Replace distilled water with tap water or deep well water, perhaps in a specific place Not too big an error? However, the test accuracy is not guaranteed in rural areas. At least our experimental well water has an error of 37% to 51% compared with distilled water. 2 Prepare the standard solution with a plastic dropper or a dropper. Due to the large error of the dropper, it can only be used for reagents that are not sensitive to reagents and cannot be used in standard solutions. Experiments show that the maximum error caused by this approach can reach 21.7% to 44.2%.
5.2 Take into account the characteristics of soil nutrient rapid measurement, blindly introduce conventional techniques. For example: 1 Volumetric method to take soil samples in the conventional analysis can increase the analysis speed of soil moisture temperature speedometer, but it requires the soil samples to be air-dried, crushed, sifted However, rapid test does not have this process. Our experiments show that the volumetric method compared with the gravimetric method, the average error for different soil types, 11.8%; for different soil sample water content (15% water content compared with air-dried soil), the average error is 2l% ~ 32 %. 2 flow colorimetry This is a technology suitable for laboratory automation analysis. The use of motorized pumps for liquids, the use of the same cuvette, automatic flushing liquid, high efficiency, small error, but the consumption of the solution is not suitable for portable instruments, And speed measurement instrument can not be equipped with motorized pumps, while manual pump, low liquid efficiency is low efficiency, error. 3 filter automatic conversion. It is generally a red light and a blue light, which is selected by pressing a key. This method is easy to operate, but the speedometer only has two wavelengths to choose from, which severely limits the test items. Some very important items cannot be measured. If the measurement is too strong, the error is very large. For example, the nitrate test method measures nitrate nitrogen ( The absorption peak was 510 nm) and the organic matter was measured by potassium dichromate oxidation (absorption peak 590 nm).
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