First, combined fertilizer testing method
Compound fertilizer nitrogen test:
(a) Ask the user to prepare concentrated sulfuric acid (98% analytical purity).
(B) Determination procedures:
1: Weigh and grind 1.000g of compound fertilizer and grind each into a small 50ml bottle, add 20ml of distilled water to dissolve the fertilizer, then add 3ml of concentrated sulphuric acid and heat it over low heat (shaking). The solution can be reduced to about half. Remove the flask from the flame and allow it to cool. Transfer the solution to a 100 ml volumetric flask and bring up to volume with distilled water. Aspirate 1 ml from the fixed volume solution into another 100 ml volumetric flask and reconstitute with distilled water. This solution is the test solution.
2: Pipette 5 ml of distilled water into a clean small beaker and make a blank solution.
3: Draw 5 ml of the test solution in another clean beaker.
4: Draw 5ml of 8ppm ammonium nitrogen standard solution and put it into another clean small beaker.
5: Add 5 ml of phenol solution and 10 ml of sodium hypochlorite to each of the above beakers respectively, 20 ml of distilled water, and shake and stand for 30 minutes.
6: Upper instrument colorimetric measurement: For details, see the instrument's use method in the instruction manual.
(c) Calculation of results:
Fertilizer nitrogen (%) = instrument test value × 100/1 × 100/1 × 100/106
In the formula: The first two 100--sample pretreatment dilution multiples
The first 1 - weigh the quality of the sample
After 1 - to take sample volume
100/106-ppm conversion to % content
Compound fertilizer phosphorus test:
(a) 1: Preparation of the leaching agent citric acid solution: A bag of citric acid was taken out of the box and dissolved in 200 ml of distilled water.
2: Preparation of molybdenum sulfate anti-developer: 1.5 grams of ascorbic acid is dissolved in 100 ml of molybdenum sulfate solution.
(Note: This liquid is not easy to save. It will be prepared on the day of use.)
(B) Test steps:
1: Weigh and grind 0.200 g of compound fertilizer and grind them into a flask or a plastic bottle. Add 30 ml of lixiviant solution of citric acid. Stir the stopper for 30 minutes and filter with medium-speed non-phosphorus filter paper. Pipette 1 ml of the filtrate into a 100 ml volumetric flask and add distilled water to volume. This solution is the test solution.
2: Pipette 5 ml of distilled water into a clean small beaker as a blank.
3: Pipette 5 ml of the test solution into another clean small beaker.
4: Draw 5ml of 2ppm of the effective phosphorous standard solution and put it into another clean small beaker.
5: Add 5 ml of molybdenum sulfate anti-developer to each beaker, remove the gas, add 40 ml of distilled water and shake for 30 minutes.
6: Upper instrument colorimetric measurement: For details, see the usage of the instrument in the instruction manual.
(c) Calculation of results:
Fertilizer phosphorus content (P2O5%) = measured solution content × 30/0.2 × 100/1 × 100/106 × 2.2913
Where: 30,100 - for sample pretreatment dilution multiples
0.2 - Weigh the quality of the sample
1 - Draw sample volume
100/106-ppm conversion to % content
2.2913-P conversion to P2O5 conversion factor
Compound fertilizer potassium test:
(a) Determination procedures:
1: Weigh and grind 0.500 g of compound fertilizer that has been crushed and put it into a flask or a plastic bottle. Add 30 ml of distilled water. Stir it for 30 minutes and filter it with medium-speed filter paper. Aspirate the filtrate 1 ml into a 100 ml volumetric flask and add distilled water to one-half. Add 1-2 drops of 10% sodium hydroxide solution. Heat and boil for 5 minutes. Allow to cool and dilute to volume with distilled water. This is the test solution.
2: Pipette 10 ml of distilled water into a small clean beaker for the blank solution.
3: Pipette 10 ml of the test solution into another clean beaker.
4: Draw 10ml of 20ppm of available potassium standard solution and put it into another clean small beaker.
5: Add 10 drops of disodium EDTA solution and 2 ml of formaldehyde solution to each beaker. Add 2 ml of sodium tetraphenylborate solution and 40 ml of distilled water to each beaker, and shake and stand for 5 to 10 minutes.
6: Upper instrument colorimetric measurement: For details, see the instrument's use method in the instruction manual.
(b) Calculation of results:
Fertilizer Potassium Content (K2O%) = measured solution content × 30/0.5 × 100/1 × 100/106 × 1.2046
In the formula: 30, 100-dilution times
0.5 - Weigh the sample quality
1 - draw sample volume
100/106-ppm conversion to % content
1.2046 - Coefficient of converting pure potassium to K2O
Second, the simple chemical fertilizer testing method
Nitrogen fertilizer test:
(a) Urea test:
The test method and process of urea is exactly the same as the test of nitrogen in compound fertilizer, except that 1 g is changed to 0.2 g when the sample is weighed.
(B) Tests for other simple nitrogen fertilizers:
1: Preparation of elemental nitrogen fertilizer test solution: Weigh sample 1.000 g and put it into a 100 ml volumetric flask. Add a small amount of distilled water to fully dissolve the fertilizer, and then dilute it with water to the mark. From the fixed volume, take 1 ml again and place it in another 100 ml volumetric flask. Dilution with distilled water is repeated. This solution is the test solution.
2: The following test process and result calculations are exactly the same as for the compound fertilizer nitrogen test.
Phosphate test:
The method and process for the determination of the phosphate fertilizer and the calculation of the results are exactly the same as those for the compound fertilizer phosphorus.
Potassium test:
1: Preparation of single substance potassium fertilizer test solution: Weigh sample 1.000 g, put it in a plastic bottle, add 50 ml of distilled water to fully dissolve the fertilizer, and then take 1 ml of solution. Place in a 100 ml volumetric flask and dilute to volume with distilled water. This solution is the test solution.
2: The following test process and result calculations are exactly the same as those for compound fertilizer potassium.
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