Humic acid long-acting compound fertilizer and its preparing method

[0027] Example 1

[0028] The humic acid long-acting compound fertilizer of the present invention is composed of 25-40 parts of humic acid urea-formaldehyde complex and 7560 parts of soluble nitrogen, phosphorus and potassium fertilizers in weight ratio, wherein: the weight ratio between soluble nitrogen, phosphorus and potassium fertilizers It is 12-25:30-40:10-20; the raw materials of the humic acid urea-formaldehyde complex are 15-30 parts peat powder, 31-46 parts urea, and 1-2 parts ammonium chloride. And 36 to 42 parts of formaldehyde with a concentration of 30%.

[0029] The preparation of its humic acid nitrogen fertilizer complex:

[0030] Using peat powder, urea, ammonium chloride and formaldehyde as raw materials, firstly condense urea and formaldehyde (molecular ratio 1:2.0~2.5) in an alkaline solution (pH 7~8) at 50~95℃ for 5~ 30 minutes;

[0031] Then add ammonium chloride to adjust the pH of the solution to 4~5; continue to add urea to this solution to make the molar ratio of urea and formaldehyde be 1.3~2.0:1, keep the temperature of the solution at 65~85℃ for 0.2~1 hour, Continue to condense urea and formaldehyde;

[0032] Then, slowly add peat powder (60-80 mesh), and keep stirring, the purpose is to make urea and formaldehyde react to generate urea formaldehyde binary structure (see figure 1 ) And ternary structure (see figure 2 ) Further condense with the humic acid in the peat powder, so that the carboxyl group in the humic acid and the amine group in the urea-formaldehyde condensate are condensed to form a larger polymer compound to increase the release time of nitrogen fertilizer in the soil; at the same time, it also makes urea The remaining urea during the reaction with formaldehyde is further condensed with the carboxyl group of humic acid to form humic acid urea (see image 3 ), or complexed by other functional groups in humic acid; in addition, functional groups such as amino and hydroxyl in humic acid can further react with free formaldehyde, thus reducing the formaldehyde content in the humic acid nitrogen fertilizer complex;

[0033] The reaction time between peat powder and urea-formaldehyde solution is 0.5-2 hours, and the reaction temperature is 50-90℃. The resulting humic acid urea-formaldehyde complex is a black viscous liquid, which is air-dried, dried, and crushed into grayish white or grayish black. powder;

[0034] The nitrogen release of the humic acid urea-formaldehyde complex in the soil is the result of the combination of ammonification, enzymolysis and nitrification (see Figure 4 ); its nitrogen fertilizer release process depends on the nature of the soil, temperature and microbial activity, but also mainly depends on the degree of condensation of its own urea-formaldehyde and the degree of condensation of urea-formaldehyde, urea and humic acid, and these can be controlled by the material The ratio, reaction temperature and reaction time can be controlled.

[0035]The humic acid urea-formaldehyde complex prepared above is still porous and network polymer structure, but most of the carboxyl groups are replaced by carbonyl groups and amino groups, so it still has strong complexing and chelating ability to metal ions, so it can still be Reduce the fixation of available phosphorus. In addition, the humic acid nitrogen fertilizer complex is still acidic after being decomposed by ammoniating bacteria, so it still has a certain solubilization effect on the insoluble phosphorus and the fixed phosphorus.

[0036] Preparation of compound fertilizer:

[0037] After the humic acid urea-formaldehyde composite powder prepared above is fully mixed with the soluble nitrogen, phosphorus and potassium fertilizer powder, the polyvinyl alcohol solution is used as a binder to roll and granulate in a granulator, and then sieved and dried. , After cooling, the humic acid long-term compound fertilizer can be obtained.

[0038] The advantage of using polyvinyl alcohol solution as a binder is that polyvinyl alcohol is a polymer binder, which can be glued with the humic acid nitrogen fertilizer complex to form a network structure. On the one hand, it can increase the strength of fertilizer particles and reduce the crushing rate of fertilizer particles; on the other hand, the formed network structure can encapsulate and adsorb part of the soluble phosphorus and potassium fertilizers, so that they can be slowly released in the soil, thereby reducing the phosphorus and potassium fertilizers in the soil. Fixed ratio to increase fertilizer efficiency.

[0039] The specific operations are as follows:

[0040] In an iron box with an electric heating system and adjustable temperature, 10 kg of urea and 40 kg of 30% industrial formaldehyde (molecular ratio 1:2.4) are mixed, and then the pH of the mixed solution is adjusted with saturated NaOH solution Adjust to 8.0, keep the temperature of the solution at 50~60℃, and condense for 30 minutes; then add 1.5 kg of ammonium chloride to adjust the pH of the solution to 4~5; continue to add 27 kg of urea to this solution. The molar ratio is 1.5:1, keep the temperature of the solution at 75~85℃, and continue to condense urea and formaldehyde for 0.5 hours; then slowly add 21.5 kg of 80 mesh peat powder, and keep stirring, keep the temperature of the mixture at 50~60℃ for 2 hours , The product is a black viscous liquid, pour out the black viscous liquid, spread it flat in an open container, and dry it in a well-ventilated place for 5-7 days, then put it into a drying equipment, the drying temperature range is 85-100℃ , So that the humic acid nitrogen fertilizer complex loses free water, and then crushed, passed through a 60-mesh sieve, the product is gray-black powder.

[0041] Mix 28.7 kilograms of humic acid urea formaldehyde complex powder prepared above with 25 kilograms of urea, 30 kilograms of diammonium phosphate, and 15 kilograms of potassium sulfate that have been crushed and passed through a 60-mesh sieve, and then add them to the granulator. One kilogram of polyvinyl alcohol solution (concentration of 5%) is rolled and granulated by the binder, and fertilizer particles with a particle size of 2.8-4.0 mm are screened out, and then put into a drying box for drying; the finished product is obtained after cooling. The nutrient content of the product is as follows: N, 21.3%; P 2 O 5 , 13.5%; K 2 O, 6.8%; cold water (25°C) insoluble N, 3.6%; available phosphorus, 11.4%. After being applied to the soil, the fertilizer effect period can be as long as 150 to 180 days.

[0042] Example 2

[0043] The preparation process of the humic acid urea-formaldehyde complex is the same as in Example 1, except that first, 12 kg of urea and 42 kg of 30% industrial formaldehyde (molecular ratio 1:2.1) are mixed, and then saturated NaOH solution is used. Adjust the pH of the mixed solution to 7.5 and condense for 20 minutes at a temperature of 60-70°C; then add 2 kg of ammonium chloride to adjust the pH of the solution to 4-5; continue to add 24 kg of urea to this solution, At this time, the molar molecular ratio of urea and formaldehyde is 1.4:1. Keep the temperature of the solution at 65-75°C, and continue to condense urea and formaldehyde for 0.2 hours; then slowly add 20 kg of 60 mesh peat powder and keep stirring to keep the temperature of the mixture at For 1.5 hours at 70-80°C, the product is air-dried, dried, pulverized and passed through an 80-mesh sieve to obtain a gray-black powder humic acid urea-formaldehyde complex.

[0044] Mix 33.5 kilograms of humic acid urea formaldehyde complex powder prepared above with 12 kilograms of ammonium chloride, 35 kilograms of monoammonium phosphate, and 18 kilograms of potassium sulfate that have been crushed and passed through a 60-mesh sieve, and then added to the granulator. Use 1.5 kg of polyvinyl alcohol solution (concentration of 10%) as a binder for rolling granulation, sieving, drying, and cooling to obtain the finished product. The nutrient content of its products is as follows: N, 12.0%; P 2 O 5 , 18.2%; K 2 O, 8.1%; cold water (25°C) insoluble N, 3.7%; available phosphorus, 16.1%. After being applied to the soil, the fertilizer effect period can be as long as 110 to 130 days.

[0045] Example 3

[0046] The preparation process of the humic acid urea-formaldehyde complex is the same as in Example 1, except that first 9 kg of urea and 36 kg of 30% industrial formaldehyde (molecular ratio 1:2.4) are mixed, and then a saturated NaOH solution is used to mix Adjust the pH of the mixed solution to 7.8, and condense for 10 minutes at a temperature of 80-90°C; then add 1 kg of ammonium chloride to adjust the pH of the solution to 4 to 5; continue to add 24 kg of urea to this solution. When the molar molecular ratio of urea and formaldehyde is 1.5:1, keep the temperature of the solution at 70~80℃, and continue to condense urea and formaldehyde for 0.5 hours; then slowly add 30 kg of 60 mesh peat powder and keep stirring to keep the temperature of the mixture at 80 At ~90°C for 0.5 hours, the product is air-dried, dried, pulverized and passed through an 80-mesh sieve to obtain a gray-black powder humic acid urea-formaldehyde complex.

[0047] Mix 40 kilograms of the humic acid urea-formaldehyde complex powder prepared above with 18.5 kilograms of ammonium sulfate, 30 kilograms of diammonium phosphate, and 10 kilograms of potassium chloride that have been crushed and passed through a 60-mesh sieve, and then added to the granulator. Use 1.5 kg of polyvinyl alcohol solution (concentration of 6%) as a binder for rolling granulation, sieving, drying, and cooling to obtain the finished product. The nutrient content of its products is as follows: N, 14.9%; P 2 O 5 , 13.5%; K 2 O, 5.8%; cold water (25°C) insoluble N, 4.2%; available phosphorus, 11.4%. After being applied to the soil, the fertilizer effect period can be as long as 130 to 150 days.