CN101545866B - Method for measuring content of inorganic nitrogen in soil - Google Patents
Method for measuring content of inorganic nitrogen in soil Download PDFInfo
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- CN101545866B CN101545866B CN2009100834801A CN200910083480A CN101545866B CN 101545866 B CN101545866 B CN 101545866B CN 2009100834801 A CN2009100834801 A CN 2009100834801A CN 200910083480 A CN200910083480 A CN 200910083480A CN 101545866 B CN101545866 B CN 101545866B
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Abstract
The invention discloses a method for measuring content of inorganic nitrogen in soil, which comprises the following steps: 1) leaching, namely adding leaching liquor into a soil sample to leach tric nitrogen and ammonium nitrogen in the soil, and filtering to obtain filtered fluid; 2) oxidization, namely adding an oxidizing agent into the filtered fluid obtained in step 1) to oxidize the ammonium nitrogen into tric nitrogen so as to obtain soil total tric nitrogen solution; and 3) performing colorimetric determination with double wavelength on the soil total tric nitrogen solution, and calculating the content of the inorganic nitrogen in the soil according to extinction values obtained by color comparison. The content of inorganic nitrogen in the soil measured by the measuring method has no significant difference with a result measured by a conventional component measurement addition method, and the inorganic nitrogen measured by the measuring method has the recovery rate between 98.8 and 104 percent. The measuring method has the advantages of quickness, accuracy, convenient operation and high efficiency.
Description
Technical field
The present invention relates to the determination method of inorganic nitrogen, particularly the determination method of content of inorganic nitrogen in soil.
Background technology
Nitrogen is that the crops normal growth is grown one of necessary a great number of elements, had the absorbed nitrogen amount of experiment confirm content of inorganic nitrogen in soil and crops normal growth that direct correlationship is arranged, therefore the mensuration of inorganic nitrogen in soil is one of big event of agricultural fractional analysis at present.
From component, inorganic nitrogen in soil mainly comprises ammonium nitrogen, nitrate nitrogen and nitrite nitrogen.Present assay method comprises following several:
1. disposable direct determination method
Adopt zinc-ferrous sulphate or Devardasalloy in alkaline medium, nitrate nitrogen, nitrite nitrogen to be reduced into ammonium nitrogen, finish the overall process of detection by distillation and titration.
The operation of this method is fairly simple, be suitable for controlled condition, shortcoming is to need distilling apparatus and firing equipment, need external condensation water in the still-process, if content of inorganic nitrogen in is lower than 10mg/kg in the soil, the error ratio of testing result is bigger, so this method is unwell to the detection of content of inorganic nitrogen in the general agricultural land soil.
Compound mensuration add legal
This method is to measure ammonium nitrogen and nitrate nitrogen content (content of nitrite nitrogen in soil is low generally not to be considered) respectively separately, then by adding legal calculating content of inorganic nitrogen in soil.
Ammonium nitrogen content adopts direct distillation or indophenol blue colourimetry to measure, and also has to adopt the ammonia gas-sensing electrode method to detect, and classical way is the indophenol blue colourimetry.
Nitrate nitrogen content adopts Pbenoldisulfonic Acid colourimetry, reduction distillation method, reduction ratio color method, electrode method, ultraviolet spectrophotometry to detect, and classical way is the Pbenoldisulfonic Acid colourimetry.
It is classical way and the standard method that present industry is generally acknowledged that combine measured adds legal mensuration content of inorganic nitrogen in soil.Its advantage is that method is reliable, and the data accuracy is than higher.Its shortcoming is to carry out independent compound mensuration, and experimental procedure is many, and operating process is more loaded down with trivial details, and than higher, detection efficiency is lower to the requirement of laboratory technician's detection level.
Therefore, address the above problem, realize not only carrying out the single-time measurement content of inorganic nitrogen in soil fast but also exactly, reality and theoretic double meaning are arranged.
Summary of the invention
The object of the present invention is to provide the determination method of content of inorganic nitrogen in soil.
Determination method provided by the invention may further comprise the steps:
1) lixiviate: add leaching liquor in pedotheque, lixiviate goes out nitrate nitrogen and the ammonium nitrogen in the pedotheque, obtains filtered fluid after the filtration;
2) oxidation: add oxidising agent in the filtered fluid that obtains toward step 1), ammonium nitrogen is oxidized to nitrate nitrogen, obtain the solution of oxidation;
3) solution with oxidation adopts dual-wavelength spectrophotometry to carry out colorimetric estimation, obtains content of inorganic nitrogen in soil.
Pedotheque in the described step 1) is with the sample of soil to be measured under 1.0-2.0mm sieve sieve, preferably sieves with 2.0mm.
The quality of the pedotheque in the described step 1) is 1g: 5ml with the ratio of the volume of leaching liquor; Described leaching liquor is KCl or the 1.0mol/LNaCl of 2.0mol/L.
Abundant for lixiviate, can in step 1), add leaching liquor after, in the air bath oscillator vibration 30 minutes, the rotating speed of vibration is 160～170 rev/mins.
The volume of the oxidising agent described step 2) is 10 with described filtered fluid volume ratio: (1-10).
Described step 2) oxidising agent in is a potassium persulfate solution, and described potassium persulfate solution is that 40 gram potassium persulfates, 15 gram NaOH are dissolved in the solution that is mixed with in the no ammoniacal liquor of 1L.
For the oxidation effectiveness that makes ammonium nitrogen is good, can be after adding potassium persulfate solution, at pressure 1.1～1.4kg/cm
2, disappear under 120～124 ℃ of the temperature and boil 25-35 minute, preferred 30 minutes.
In order to prevent that nitrate-nitrogen reduction from becoming ammonium nitrogen, colorimetric is to carry out under acid condition in the described step 3), is preferably pH≤3.The dual wavelength that described colorimetric is used is 220nm and 275nm.
The present invention goes out ammonium nitrogen and nitrate nitrogen in the soil with KCl or NaCl lixiviate, adds potassium persulfate solution, under hyperbaric environment ammonium nitrogen is oxidized to nitrate nitrogen, carries out the colorimetric estimation nitrate nitrogen with dual wavelength afterwards under sour environment.
The compound mensuration of content of inorganic nitrogen in soil that determination method provided by the invention is measured and routine adds the there was no significant difference as a result of legal mensuration, the result who measures inorganic nitrogen with determination method provided by the invention as two Beijing soil samples is 27.99mg/kg and 25.09mg/kg, and conventional method records the result and is 27.56mg/kg and 25.19mg/kg.And the recovery of the mensuration inorganic nitrogen of determination method provided by the invention reaches 98.8-104%.
It is more that conventional compound mensuration adds legal experimental procedure, and operating process is loaded down with trivial details, and to having relatively high expectations of laboratory technician's detection level, detection efficiency is lower; And method provided by the invention quick and precisely, can disposablely finish check, has reality and theoretic double meaning.
Embodiment
The invention will be further described below in conjunction with specific embodiment, but the present invention is not limited to following examples.
Among the following embodiment, if no special instructions, be conventional method.
Among the following embodiment, described percentage composition is the quality percentage composition if no special instructions.
Agents useful for same is as follows:
Potassium persulfate solution: 40 gram potassium persulfates, 15 gram NaOH are dissolved in no ammoniacal liquor, constant volume 1L.
Hydrochloric acid solution (v/v): 1+9 (that is: the hydrochloric acid solution of the water of the hydrochloric acid of 1 part of volume and 9 parts of volumes composition).
Nitrate nitrogen (NO3
--N) standard solution: take by weighing the KNOs of 0.7218 gram through 105 ℃ of baking 4h
3In beaker, move to the 1L volumetric flask after the dissolving, constant volume shakes up, and this liquid concentration is 100mg/L.
NO
3 --N standard is used solution: dilute 10 times of above-mentioned mark liquid, concentration is 10mg/L.
KCl solution: 2.0mol/L.
NaCl solution: 1mol/L.
The mensuration of embodiment 1, content of inorganic nitrogen in soil
One, the processing of sample
1, the lixiviate of sample
Accurately take by weighing 20.00g soil (through the 2.0mm sieve), place the 150ml triangular flask, add 100ml NaCl solution, at ambient temperature, the 30min (rotating speed is 160 rev/mins) that in oscillator, vibrates, take out the back with dried filter paper filtering in the triangular flask of dried and clean, obtain sample filtering liquid.Carry out the processing of blank simultaneously, except that not adding the pedotheque, other step is identical with sample preparation.
2, the oxidation of filtered fluid
The filtered fluid of drawing the sample filtering liquid of 1ml and 1ml blank respectively is in 25ml tool plug scale test tube, add the 10ml potassium persulfate solution, shake up, the jam-pack stopper is also used gauze, rubber band is tightened the mouth of pipe, in pressure cooker, disappear and boil, timing half an hour during boiling (also disappear and boil 30 minutes) at 120～124 ℃, pressure 1.1～1.4Kg/cm2.
3, colorimetric estimation
Take out the solution of the oxidation in the step 2, cooling adds respectively and is settled to scale behind the 1ml hydrochloric acid solution and shakes up, and places 10min then, respectively at 220nm and 275nm wavelength colorimetric, obtains A again
220And A
275, light absorption value (A (sample))=A of the solution of calculating oxidation
220-2A
275
Two, the drafting of standard working curve
Draw 10mg/L NO respectively
3 --N standard is used solution (ml) 0,0.5,1.0,3.0,5.00 7.0,10.0 in the 25ml color comparison tube, mend the scale mark to 10ml with distilled water, add the 10ml potassium persulfate solution, all the other steps are the same with sample, making concentration (mg/L) is 0,0.2,0.4,1.2,2.0,2.8,4.0 standard series, colorimetric under the condition identical with sample obtains A
220And A
275, calculate A (standard)=A
220-2A
275Normal concentration and the A (standard) corresponding with it are depicted as standard working curve.
Three, the result calculates
Computing formula is:
NO
3 --N，(mg/kg)＝C×V/M×D
C in the formula: the concentration that sample light absorption value (A (sample)) checks in standard working curve, mg/L;
V: colorimetric solution volume, ml;
M: sample takes by weighing quality, g;
D: the ratio of solution volume aspirated and lixiviate volume.
Four, the feasibility of substantive approach for example
1, the different regions pedotheque detects the control experiment result who obtains with different detection methods
The pedotheque of different regions is added the content of inorganic nitrogen in that legal and provided by the invention determination method is measured pedotheque with the compound mensuration in the conventional method respectively, the result shown in the data of table 1, the there was no significant difference as a result of the result that determination method of the present invention is measured and conventional method mensuration.
Table 1. detects inorganic nitrogen in the soil of different regions with conventional sense method and determination method of the present invention
2, the testing result behind the quantitative mark liquid of different soils sample adding ammonium nitrogen and nitrate nitrogen
With ammonium nitrogen and the nitrate nitrogen content in the conventional method detection different soils sample, draw the NH of 100mg/L then respectively
4 +-N and NO
3 --N marks liquid 3.0,2.5,2.0,1.5,1.0,0.5, and the corresponding one by one back of mixing of 0ml adds in the different soils sample, every part of pedotheque 20g, and the method that provides with present embodiment detects content of inorganic nitrogen in the soil then.
Measurement result is as shown in table 2, the there was no significant difference as a result that result that determination method of the present invention is measured and conventional method are measured.
Table 2. pedotheque adds ammonium nitrogen and nitrate nitrogen mark thing, conventional method and ultraviolet colourimetry comparison test findings
| The pedotheque numbering | The NH of soil carrier own 4 +-N measurement result mg/kg | NH 4 +-N mark liquid addition mg/kg | The NO of soil carrier own 3 --N measurement result mg/kg | NO 3 --N mark liquid addition mg/kg | Conventional method is measured inorganic nitrogen summation mg/kg | Determination method of the present invention is measured the mg/kg as a result of inorganic nitrogen |
| Sample 1 | 4.14 | 15.00 | 23.42 | 15.00 | 57.56 | 58.76 |
| Sample 2 | 3.83 | 12.50 | 21.38 | 12.50 | 50.21 | 49.91 |
| Sample 3 | 3.78 | 10.00 | 25.63 | 10.00 | 49.41 | 49.81 |
| Sample 4 | 5.40 | 7.50 | 22.11 | 7.50 | 42.51 | 42.81 |
| Sample 5 | 3.53 | 5.00 | 27.45 | 5.00 | 40.98 | 41.18 |
| Sample 6 | 2.56 | 2.50 | 24.11 | 2.50 | 31.67 | 31.17 |
| The basis sample | 4.41 | 0.00 | 26.54 | 0.00 | 30.95 | 31.10 |
3, the control experiment result of the inorganic nitrogen recovery
The data preparation of table 2 can be tried to achieve the inorganic nitrogen recovery, and the result is as shown in table 3, utilizes determination method provided by the invention, and the recovery of measuring inorganic nitrogen is 98.8-104%.
The table 3. inorganic nitrogen recovery
| Numbering | Add mark liquid theoretical amount mg/kg | Measurement result deducts this height of carrier mg/kg | Recovery % |
| Sample 1 | 30.00 | 31.20 | 104 |
| Sample 2 | 25.00 | 24.70 | 98.8 |
| Sample 3 | 20.00 | 20.40 | 102 |
| Sample 4 | 15.00 | 15.30 | 102 |
| Sample 5 | 10.00 | 10.20 | 102 |
| Sample 6 | 5.00 | 5.10 | 102 |
The mensuration of embodiment 2, content of inorganic nitrogen in soil
One, the processing of sample
1, the lixiviate of sample
Accurately take by weighing 20g soil (through the 1.5mm sieve), place the 150ml triangular flask, add 100ml KCl solution, the 30min (170 rev/mins) that in bathing oscillator, vibrates, the taking-up back in the triangular flask of dried and clean, obtains sample filtering liquid with dried filter paper filtering.Carry out the processing of blank simultaneously, except that not adding the pedotheque, other step is identical with sample preparation.
2, the oxidation of filtered fluid
The filtered fluid of drawing the sample filtering liquid of 10ml and 10ml blank respectively is in 25ml tool plug scale test tube, add the 10ml potassium persulfate solution, shake up, the jam-pack stopper is also used gauze, rubber band is tightened the mouth of pipe, in pressure cooker, disappear and boil, timing half an hour during boiling (also under 120～124 ℃, disappear under pressure 1.1～1.4Kg/cm2 and boil 25 minutes).
3, colorimetric estimation
Take out the solution of the oxidation in the step 2, cooling adds respectively and is settled to scale behind the 1ml hydrochloric acid solution and shakes up, and places 10min then, respectively at 220nm and 275nm wavelength colorimetric, obtains A again
220And A
275, light absorption value (A (sample))=A of the solution of calculating oxidation
220-2A
275
Two, standard regression equation
Draw 10mg/L NO respectively
3 --N standard is used solution (ml) 0,0.5,1.0,3.0,5.00 7.0,10.0 in the 25ml color comparison tube, mend the scale mark to 10ml with distilled water, add the 10ml potassium persulfate solution, all the other steps are the same with sample, making concentration (mg/L) is 0,0.2,0.4,1.2,2.0,2.8,4.0 standard series, colorimetric under the condition identical with sample obtains A
220And A
275, calculate A (standard)=A
220-2A
275Normal concentration and the A (standard) corresponding with it are carried out regretional analysis, and it is as follows to obtain the standard linear regression equation:
Y=0.0158+0.284x, the r=0.9992 R of this equation
2=0.998
Y in the formula: light absorption value
X:NO
3 --N concentration, mg/L
Three, the result calculates
Computing formula is:
NO
3 --N，(mg/kg)＝C×V/M×D
C in the formula: the concentration of trying to achieve in sample light absorption value (A (sample)) the substitution standard regression equation, mg/L;
V: colorimetric solution volume, ml;
M: sample takes by weighing quality, g;
D: the ratio of solution volume aspirated and lixiviate volume.
Four, the feasibility of substantive approach for example
The feasibility result of the method that embodiment 2 provides is identical with embodiment 1.
Claims (7)
1. the determination method of content of inorganic nitrogen in soil may further comprise the steps:
1) lixiviate: add leaching liquor in pedotheque, lixiviate goes out nitrate nitrogen and the ammonium nitrogen in the pedotheque, obtains filtered fluid after the filtration; Described pedotheque is with the sample of soil to be measured under 1.0～2.0mm sieve sieve; The ratio of the quality of described pedotheque and leaching liquor volume is 1g: 5ml; Described leaching liquor is the NaCl aqueous solution of 1.0mol/L; Described lixiviate is to vibrate 30 minutes in the air bath oscillator, and the rotating speed of described vibration is 160～170 rev/mins;
2) oxidation: add oxidising agent in the filtered fluid that obtains toward step 1), ammonium nitrogen is oxidized to nitrate nitrogen, obtain the solution of oxidation; The volume of described oxidising agent is 10 with described filtered fluid volume ratio: (1-10); Described oxidising agent is a potassium persulfate solution, and described potassium persulfate solution is that 40 gram potassium persulfates, 15 gram NaOH are dissolved in the solution that is mixed with in the no ammoniacal liquor of 1L;
3) solution with oxidation adopts dual-wavelength spectrophotometry to carry out colorimetric estimation, obtains content of inorganic nitrogen in soil.
2. determination method according to claim 1 is characterized in that: in the step 1), described sieve is the sieve of 2.0mm.
3. determination method according to claim 1 and 2 is characterized in that: step 2) in, the condition of described oxidation is at pressure 1.1-1.4Kg/cm
2, disappear under 120～124 ℃ of the temperature and boil 25～35 minutes.
4. determination method according to claim 3 is characterized in that: the described time of boiling that disappears is 30 minutes.
5. determination method according to claim 1 and 2 is characterized in that: colorimetric is to carry out under acid condition in the described step 3).
6. determination method according to claim 5 is characterized in that: described acid condition is pH≤3.
7. determination method according to claim 5 is characterized in that: the dual wavelength that described colorimetric is used is 220nm and 275nm.
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| CN102435560B (en) * | 2011-09-06 | 2013-11-06 | 深圳市喜耕田生物科技股份有限公司 | Method for testing nitrification inhibition rate of stabilized fertilizer |
| CN102519902B (en) * | 2011-12-30 | 2013-11-27 | 广东中烟工业有限责任公司 | Method for measuring water-soluble nitrogen content in plants and plant products |
| CN102621084B (en) * | 2012-03-14 | 2013-07-31 | 合肥工业大学 | Method for measuring soil ammonium nitrogen |
| CN103808943B (en) * | 2014-03-03 | 2016-01-20 | 南京农业大学 | A kind of detection method based on nitrogen can be utilized in the soil of fluorescin distribution proportion |
| CN104215672A (en) * | 2014-08-20 | 2014-12-17 | 北京农业信息技术研究中心 | Rapid soil nutrient detection method |
| CN104833563B (en) * | 2015-05-19 | 2018-02-13 | 中南林业科技大学 | A kind of extracting method and device of dissolved nitrogen |
| CN106885780A (en) * | 2015-12-16 | 2017-06-23 | 中国科学院沈阳应用生态研究所 | A kind of method for determining soil nitrate-N |
| CN106198425A (en) * | 2016-06-24 | 2016-12-07 | 中国林业科学研究院热带林业实验中心 | A kind of soil nitrate-N detection method |
| CN106596536B (en) * | 2016-12-15 | 2019-05-31 | 西南大学 | Soil Nitrogen stage division under a kind of natural particle size |
| CN106706540A (en) * | 2017-03-09 | 2017-05-24 | 青岛农业大学 | Method for simply measuring dissolved organic nitrogen of soil |
| CN110068648A (en) * | 2019-04-29 | 2019-07-30 | 淮阴师范学院 | Utilize the method for full-automatic Kjeldahl determination device rapid survey water body or Soil Nitrogen Content |
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