HG/T 5050-2016Alginic acid fertilizers (English PDF)

3.1 alginic acid

a polysaccharide that is formed by a linear polymerization of monouronic acid, which is a block copolymer formed by 1,4 glycosidic bonds using monomers of beta-1,4-D-mannuronic acid and

alpha-1,4-L-guluronic acid

3.2 alginic acid synergist

a fertilizer synergist containing a certain amount of alginic acid and prepared after extraction with seaweed as a main raw material

3.2.1 alginic powder

a powdered fertilizer synergist containing a certain amount of alginic acid and prepared after extraction with seaweed as a main raw material

3.2.2 alginic liquid

a liquid fertilizer synergist containing a certain amount of alginic acid and prepared after extraction with seaweed as a main raw material

3.3 alginic acid fertilizer

a fertilizer containing a certain amount of alginic acid and prepared by adding an alginic acid synergist in a fertilization process

3.4 alginic acid coated urea

a coated urea containing a certain amount of alginic acid was produced by using a low-temperature dehydration process and an alginic acid synergist as the main coating material.

Compared with conventional urea, the alginic acid coated urea has a certain slow-release effect and can reduce a volatilization loss of nitrogen

3.5

bulk blending fertilizer containing alginic acid coated urea a bulk blending fertilizer containing a certain amount of alginic acid by using alginic acid coated urea as a part of a nitrogen source and produced by drying blending with other conventional nitrogen, phosphorus, and potassium granular fertilizers

3.6 alginic acid compound fertilizer

an adding-type or coating-type compound fertilizer containing a certain amount of alginic acid produced by adding an alginic acid synergist in a compound fertilizer production process.

Compared with conventional compound fertilizers, the alginic acid compound fertilizer has an effect on reducing an ammonia volatilization loss

3.7 water-soluble fertilizer containing alginic acid

a water-soluble fertilizer containing a certain amount of alginic acid prepared by adding an alginic acid synergist in a fertilization process

3.8 ammonia volatilization inhibition rate

a functional index that characterizes alginic acid-containing fertilizers to reduce an ammonia volatilization loss. Under the action of urease and magnesium oxide, ammonia released from a decomposition of urea is absorbed by a boric acid solution. A ratio of a difference value between volumes of an alginic acid fertilizer and urea consuming sulfuric acid standard volumetric solution to the latter is expressed as a percentage

5.1 Appearance

- - When the state quality supervision agency puts forward a request for type inspection.

7.2 Batching

Products are inspected in batches. An output of one shift or one day is considered to be one batch. The maximum batch of alginic acid coated urea does not exceed 1,500 t, the maximum batch of a bulk blending fertilizer containing alginic acid coated urea and an alginic acid compound fertilizer is 1,000 t and the maximum batch of a water-soluble fertilizer containing alginic acid is 100 t. A user regards the products attached with a quality certificate or the received products as one batch.

7.3 Sampling plan

7.3.1 Alginic acid coated urea

in accordance with the sampling plan of GB/T 2440;

7.3.2 Bulk blending fertilizer containing alginic acid coated urea

in accordance with the sampling plan of GB/T 21633;

7.3.3 Alginic acid compound fertilizer

in accordance with the sampling plan of GB/T 15063;

7.3.4 Water-soluble fertilizer containing alginic acid

in accordance with the sampling plan of HG/T4365.

7.4 Sample splitting and sample preparation

7.4.1 Alginic acid coated urea

in accordance with the article of the sample splitting and sample preparation of GB/T 2440;

7.4.2 Bulk blending fertilizer containing alginic acid coated urea

in accordance with the article of the sample splitting and sample preparation of GB/T 21633;

7.4.3 Alginic acid compound fertilizer

in accordance with the article of the sample splitting and sample preparation of GB/T 15063;

7.4.4 Water-soluble fertilizer containing alginic acid

in accordance with the article of the sample splitting and sample preparation of HG/T 4365.

7.5 Result determination

7.5.1

Whether the items of the product are qualified is determined by "rounding value comparison method" of GB/T 8170.

7.5.2

When all the type inspection items meet the requirements of this standard, the batch of products is deemed to be qualified.

Appendix A (Normative Appendix)

Determination of mass fraction of alginic acid coated urea nitrogen in total nitrogen of urea-A trichloromethane flotation-nitrogen determination method

A.1 Principle

The density of urea is less than that of trichloromethane, and the density of other nitrogen fertilizers, phosphate fertilizers and potash fertilizers is higher than that of trichloromethane, so that the urea can be separated from other fertilizers. Alginic acid coated urea is significantly different from common urea in appearance, color and film characteristics.

The alginate coated urea and common urea can be separated by visual inspection, their nitrogen content can be determined separately, and the mass fraction of alginic acid coated urea nitrogen in total nitrogen of urea can be calculated.

A.2 Reagents and Solutions

Trichloromethane.

A.3 Instruments

Fume hood

A.4 Test Procedure

Weigh 50.00 g of a bulk blending fertilizer containing alginic acid coated urea, which has been split and mixed evenly and the particles have not adhered, into the 500 mL beaker, add

300 mL of the trichloromethane, shake the beaker to separate the fertilizer particles, then perform standing still for 5 min-10 min, and when there are no more particles floating, use the metal screen to collect floating urea particles in an upper layer, place the collected urea particles inside a fume hood and perform a still-standing ventilation for 10 min or more to completely volatilize the trichloromethane, after selecting alginic acid coated urea with specific color and membrane properties, measure ta mass of the alginic acid coated urea (m1) and a mass of the common urea (m2) respectively, measure the nitrogen content according to

GB/T 2441.1 and mark the nitrogen content as N1 and N2 respectively.

A.5 Expression of Test Procedure

Appendix B (Normative Appendix)

Determination of mass fraction of alginic acid-A carbazole colorimetry method

B.1 Principle

Alginic acid is hydrolyzed to uronic acid under strong acid conditions and the uronic acid can form a stable purple-red compound with carbazole. The absorbance is measured with a spectrophotometer at 520 nm and a mass fraction of the alginic acid in an alginic acid fertilizer can be calculated.

B.2 Reagents and Solutions

B.2.1 Sulfuric acid;

B.2.2 Anhydrous ethanol;

B.2.3 A sodium alginate [(C6H7NaO6)n] stock solution

10 mg/mL.

Weigh 10.00 g of sodium alginate, dissolve in water, and dilute to a constant volume of 1 L.

B.2.4 A sodium alginate standard solution

1 mg/mL.

Pipette 10.00 mL of the sodium alginate stock solution into a 100 mL volumetric flask, and dilute it to a constant volume to a scale with water.

B.2.5 A carbazole ethanol solution

2 g/L.

Weigh 0.20 g of carbazole, dissolve with the anhydrous ethanol and dilute to a constant volume of 100 mL.

B.3 Instruments

B.3.1 Spectrophotometer

an absorption cell with an optical path of 1 cm and conduct a measurement at a wavelength of 520 nm.

B.4 Test Procedure

B.4.1 Plotting of standard curve of alginic acid

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Pipette 0.00 mL, 0.20 mL, 0.40 mL, 0.60 mL, 0.80 mL, 1.00 mL and 1.20 mL of the sodium alginate standard solution to 50 mL colorimetric tubes, respectively, add 3.00 mL, 2.80 mL, 2.60 mL,

2.40 mL, 2.20 mL, 2.00 mL and 1.80 mL of water to make the volume 3.00 mL, transfer the colorimetric tubes containing the solutions to an ice-water bath, slowly add 10.00 mL of the sulfuric acid while shaking, start about one drop per second, after adding half of the acid, increase to about two drops per second, after the adding, put the colorimetric tubes containing the solutions in a boiling water bath and heat for 20 min, take the colorimetric tubes containing the solutions out and cool them to 80°C, then add 0.30 mL of a carbazole ethanol solution, shake the colorimetric tubes containing the solutions well and place them at room temperature for 45 min, use a 1 cm absorption cell for colorimetry at a wavelength of 520 nm, use a reagent blank is used as a reference, measure an absorbance, use mass (mg) of sodium alginate contained in a standard colorimetric solution of a total color development volume as an x-coordinate, use the measured absorbance as a y-coordinate, and plot a standard curve or solve a linear regression equation.

B.4.2 Determination of mass fraction of alginic acid

Weigh 15-20 g (accurate to 0.0002 g) of an alginic acid fertilizer sample that has been split and mixed evenly in a beaker, add 25 mL of water to dissolve, transfer the dissolved sample to a 50 mL volumetric flask, dilute to a constant volume, and shake it evenly (if there is a precipitate, a dry filtration is required). Accurately pipette 3.00 mL of a sample filtrate into a 50 mL colorimetric tube. The following steps are the same as the plotting of the standard curve.

B.5 Expression of Test Procedure

Obtain the mass of the alginic acid corresponding to the measured absorbance from the standard curve or the mass of the alginic acid from the regression equation.

Use formula (B.1) To calculate the content of the alginic acid X in the sample, expressed in a mass fraction (%):

..............................(B.1) in which:

m4 - - value of the mass of the sodium alginate obtained from the standard curve or the regression equation, milligram (mg);

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Appendix C (Normative Appendix)

Determination of ammonia volatilization inhibition rate-A boric acid absorption-sulfuric acid titrimetric method

C.1 Principle

Urea is hydrolyzed into ammonium nitrogen under the reaction of urease. In a presence of magnesium oxide, the ammonium nitrogen produced by a hydrolysis of amide nitrogen in alginic acid fertilizers will be converted into ammonia to release out, a boric acid solution absorbs the released ammonia, then a certain concentration of a sulfuric acid solution is used to titrate the released ammonia, a prepared sample of urea with equal amide nitrogen content is used as a control, and the ammonia volatilization inhibition rate is calculated on a basis of a volume of the consumed sulfuric acid standard solution.

C.2 Reagents and Solutions

C.2.1 Urea.

C.2.2 A sulfuric acid standard volumetric solution

=0.01 mol/L.

C.2.3 A urease solution.

Weigh 0.100 g of urease (activity about 1 U/mg), add 0.5 mL of water, grind the urease with a mortar to a paste, transfer the ground urease to a 250 mL volumetric flask, shake the urease solution well, and store the urease solution in a refrigerator at 4°C for a standby application.

C.2.4 A boric acid solution

2%.

C.2.5 A magnesium oxide suspension

30g/L.

C.2.6 A mixed indicator.

Dissolve 0.099 g of bromocresol green and 0.066 g of methyl red in 100 mL of ethanol (95%);

C.3 Instruments and Devices

C.3.1 Constant temperature water bath kettle.

C.3.2 Air pump.

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