IL187811A

IL187811A - Fertilizing method for agricultural irrigation

Info

Publication number: IL187811A
Application number: IL187811A
Authority: IL
Original assignee: Higheffi Tech Ltd Corp Beijing
Priority date: 2005-06-09
Filing date: 2007-12-02
Publication date: 2012-02-29
Also published as: CN1875688A; WO2006131056A1; IL187811A0; CN100407898C

Description

187811 i7'Ji I 453594 mx FERTILIZING METHOD FOR AGRICULTURAL IRRIGATION 10264/0001.000 187811/2 [Field of invention] The present invention relates to a kind of agricultural technology, specifically, to a method of agricultural fertigation.

[Background of the invention] With the rapid growth of the world population and the high speed development of the world economy, the consumption of the world water resources increases rapidly; simultaneously, the water resources are destroyed seriously day by day. According to the forecast of the Food and Agriculture Organization (FAO), the world per capita volume of the water resources was reduced by 25% during 1950-2000 year. The condition is sterner in China. The per capita possession of the fluvio current only amounts to the 1/4 of the world average. At the same time, the distribution is uneven. In the four drainage areas of the Liao River, Hai River, Yellow river and Huai River, the plantation accounts for 45.2% of the national total quantity and the population accounts for 38.4% of the national total population, while the water resource amount possessed is only 9.6% of the national water resource. Thereupon, the agricultural irrigation water and the utilization efficiency of fertilizer are the primary factors which restrict the increase in the grain production of these areas. Therefore, it is extremely vital to the persistent agriculture development by using the new irrigation technology and enhancing the utilization efficiency of water and fertilizer.

Until now, all of the methods for fertigation used in various countries need to use suitable liquid or full water-soluble solid fertilizer. For example, at present the usual nitrogenous fertilizer and the potassium fertilizer mainly are water-soluble in the agriculture. It is easy and feasible to use fertigation without serious problems. As for the phosphate fertilizer, a few of which are also full water-soluble, for example, such as the industry and food grade ammonium phosphate, monopotassium phosphate and so on. Thus, it is also feasible to use the method of fertigation. However, in the agriculture the majority of phosphate fertilizers used is partial water soluble or water-insoluble at present. For this reason, it is difficult to implement crops fertigation. Some fertilizers containing secondary nutrients and micronutrients also are water-insoluble. Therefore, it is also difficult to implement crops fertigation. Now, these l water- insoluble fertilizers are used as the base fertilizers at the most of situations. Here, the efficiency of resources including phosphorus is always very low, only to 8%-20%, especially in the alkaline soil. The defect in using base fertilizer is obvious. Therefore, in order to overcome this kind of defect, the inventor has successfully developed the fertigation of the water-insoluble fertilizers by many years of research. The present invention can fully exert the superiority in the combination of irrigation with fertilization and continuously provide phosphorus, secondary nutrients and micronutrients for the crops. It is a kind of solution for the phosphorus source in the fertigation. Up to now, any related literatures haven't been found.

[Detailed description of the invention] [Technical question to be solved] The aim of the present invention is to develop a kind of method of the agricultural fertigation. This method may not only continuously provide phosphorus for crops, which makes the water-insoluble phosphate fertilizer exert the fertilizer effect sufficiently and the using efficiency of fertilizers increased, but also provide many secondary nutrients and micronutrients and enhance the antivirus ability and lodging resistance of the crops.

[Technical plan] The persons skilled in the art know that the fertigation is a method of irrigation which can provide required nutrients for crops through the micro-irrigation system by using full water-soluble solid or solution fertilizer. By means of this method, the irrigation water can enter into fields along with fertilizer, and the yield of the irrigated crops can be increased at the least of nutrients. In this fertigation system, the very high precision can be achieved in the amount, time, and space of fertilization. This fertigation is the outcome of the combination of accurate fertilization and accurate irrigation.

In the present invention, the water-insoluble phosphate fertilizer granules and water-insoluble fertilizers containing secondary nutrients and micronutrients or mineral granule are used as raw materials. The said water-insoluble phosphate fertilizer is a fertilizer whose water-solubility is less than or equal to lOOOmg/kg, preferably less than or equal to 500mg/kg, more preferably less than or equal to 300mg/kg at the room temperature and atmospheric pressure. The water-insoluble fertilizers containing secondary nutrients and micronutrients or mineral granule is a kind of fertilizer or mineral whose water-solubility is less than or equal to lOOmg/kg, preferably less than or equal to 50mg/kg, more preferably less than or equal to 20mg/kg at the room temperature and atmospheric pressure.

The above-mentioned water-insoluble phosphate fertilizer granules are selected from the phosphate rock (PR) and phosphate fertilizer produced by the wet-process or thermal-process.

The said ground PR is a kind of phosphate fertilizer which is made by crushing PR directly. The phosphorous-containing compound in PR is mainly those fluorapatites. The ground PR is a kind of slightly soluble phosphate fertilizer containing no more than 8% citrate-soluble P205 of the total P205 , the effectiveness of which is slow and lasting.

The said wet-process phosphate fertilizer is made by disposing ground PR with sulfuric acid, nitric acid, hydrochloric acid, and so on. The precipitated calcium phosphate is included in the acidifying phosphate fertilizer. The precipitated calcium phosphate is obtained by reacting of PR with sulfuric acid, nitric acid, hydrochloric acid etc., to produce phosphorous acid, and then precipitated with milk of lime.

Take the preparation of nitric acid as an example, it reacts as follows: Ca5(P04)3-F + I OHNO3→ 3H3PO4 + 5Ca(N03)2 +HF 3H3P04+5Ca(N03)2+3Ca(OH)2→3CaHP04-2H20 + 5Ca(N03)2 It can be seen that the main component of the precipitated calcium phosphate is dicalcium phosphate, which is insoluble in water but soluble in a 2% citric acid solution. It belongs to citric-soluble phosphates fertilizer, in which the amount of dicalcium phosphate(P205) is high, generally 30%-40%.

The said thermal-processed phosphate fertilizer, which mainly includes defluorinated PR. Rhenania phosphate, calcium metaphosphate, basic slag, fused calcium magnesium phosphate, is made of thermal decomposed PR through the electric power or the fuel burning,.

The defluorinated phosphate rock is made by the reaction between the fluor-apatite with steam at the high temperature (1500°C). It reacts as follows: Ca5(P04)3-F + H20→ Ca5(OH)(P04)3 + HF 2Ca5(OH)(P04)3→ 2Ca3(P04)2 + Ca4P209 + H20 The amount of P205, which belongs to citric acid soluble phosphate fertilizer, in defluorinated PR is generally 19%-38%.

The Rhenania phosphate fertilizer is made by calcining PR, sodium carbonate and silica sand at the high temperature (1250°C). The amount of the Rhenania is about 28%-30%.

The calcium metaphosphate is made by reacting ground PR with the P205 vapor at 950°C. It reacts as follows: 2Ca5(P04)3-F + 7 P205 + H20→ 10 Ca(P03)2 +2PIF The calcium metaphosphate is in the form of glassy buff crystal. The amount of P205 may be up to 60-70%. It may dissolve in the neutral ammonium citrate solution.

The basic slag phosphate fertilizer is the byproduct of steel-making industry. It exhibits an alkaline nature and takes the form of dark brown powder. The phosphorus are in the form of tetracalcium phosphate (Ca4P209) and the composite salt (Ca^CyCaSiOs) of the tetracalcium phosphate and the calcium silicate, both of which can dissolve in the citric acid and ammonium citrate solution.

The fused calcium magnesium phosphate is made in several steps. The raw materials, i.e. PR, flux (serpentine, olivine and so on) and fuels (anthracite, coke and so on), are heated up to 1450°C and melted, then sprayed with the high-pressured current of water when the melted materials discharge, which are quenched and broken into exiguously glassy grains, dried and ground. Generally, the products thus obtained are in the form of navy-gray, celadon or bottle-green powders. They have good physical character and don't absorb moisture and agglomerate. They are alkaline reactions while without corrosiveness. The calcium magnesium phosphate is vitreous body whose principal ingredients are phosphorus, silicon, calcium and magnesium. It doesn't have specific molecular formula and molecular weight. The product contains 14%-18% of P205, which may dissolve in 2% citric acid solution. The fused calcium magnesium phosphate also contains 8%-20% of MgO, 25%-40% of CaO, 22%-32% of Si02, 0.5%-3% of FeO and so on.

According to the plant nutrition, the person skilled may know that all crops not only need nitrogen, phosphorus, potassium nutrients in their growth, but also need many secondary nutrients and micronutrients.

The said secondary nutrients and micronutrients are the calcium, magnesium, sulfur, boron, molybdenum, zinc, manganese, iron, copper, nickel, and the beneficial element silicon as well.

Calcium is a structural ingredient of the cell wall, which makes effect on the synthesis of the protein and is also an assistant factor of some enzyme reactions. Besides, it has the special efficacy on controlling physiological equilibrium of the medium. Therefore, calcium deficiency in crops leads to short plant, hypogenetic root system, calcium deficiency in the cell walls, easily invasion by virus, and even rot to death.

Magnesium is a constituent element of the chlorophyll and the activator for many enzymes. It not only can promote the synthesis of the fat, but also participate in the metabolism of the nitrogen. Magnesium deficiency in crops makes leaves' reticulum turn into yellow or white color and even brown, even rot to death. The forage grass lacking of magnesium can be able to cause livestock twitch.

The sulfur is a constituent element of protein and enzyme and exists in some certain physiologically active matter, which is also the component of the nitrogenase system. When the crops lack sulfur, its growth is seriously hindered and the leaf is infected with chlorosis or etiolation.

Although silicon is not crops' essential nutrient, the crops are easy to turn lodge and the surface cells are invaded by virus when lack the silicon. Therefore, silicon is the importantly beneficial element to many crops, especially rice, sugar cane, bamboo and so on which like the silicon.

The micronutrients in plants are often components of the enzyme or coenzyme, and they have very strong specificity. They are essential components and cannot be mutually replaced.

Therefore, in the present invention, the used fertilizer has secondary nutrients and micronutrients; either they are the mixed water-insoluble fertilizer or mineral containing secondary nutrients and micronutrients.

The above-mentioned water insoluble fertilizer or mineral containing secondary nutrients and micronutrients is one or more water insoluble fertilizer(s) or mineral(s) containing calcium, magnesium, sulfur, boron, molybdenum, zinc, manganese, iron or copper.

The above-mentioned water-insoluble fertilizer or mineral containing calcium is, for example, calcium sulfate, phosphorus gypsum and industry waste residue such as the iron and steel industry slag.

The above-mentioned water-insoluble fertilizer or mineral containing magnesium is, for example, magnesite and dolomite.

The above-mentioned water-insoluble fertilizer or mineral containing sulfur is, for example, calcium sulfate, sulfuration zinc ore, pyrites, phosphorus gypsum, sulphur.

The above-mentioned water-insoluble fertilizer or mineral containing boron is, for example, boron magnesium ore, boron putty.

The above-mentioned water-insoluble fertilizer or mineral containing molybdenum is, for example, molybdenum residue.

The above-mentioned water-insoluble fertilizer or mineral containing zinc is, for example, zinc oxide, zinc sulfide.

The above-mentioned water-insoluble fertilizer or mineral containing manganese is, for example, manganese oxide, slag including manganese.

The above-mentioned water-insoluble fertilizer or mineral containing iron is, for example, ferrous oxide, pyrites.

The above-mentioned water-insoluble fertilizer or mineral containing copper is, for example, the copper oxide, smelting copper slag.

It can be seen that the solubility of the phosphate fertilizer or mineral containing secondary nutrients and micronutrients in water is very low. In order to realize the fertigation, it can be appropriately increased in the solubility and the dissolving speed of the water-insoluble phosphate fertilizer and mineral or fertilizer containing secondary nutrients and micronutrients. Therefore, a kind of activator is added in the fertigation.

In the context of the present invention, the activator should be understood as a kind of compound which can destroy the structure of the water-insoluble phosphate fertilizer and mineral or fertilizer containing water-insoluble secondary and micronutrients, consequently release nutrients of the water- insoluble fertilizers.

The said activator is one or more compound(s) selected from the inorganic acid, organic acid, inorganic salt and amide form nitrogenous fertilizer.

The action mechanism between the activator and the water-insoluble phosphate fertilizer and water-insoluble fertilizer or mineral containing secondary and micronutrients is that the ion-exchange reaction happens between hydrogen ions or alkaline metal ions and phosphoric acid ions or ions of secondary and micronutrients, which can release the latter to the irrigation water.

The said inorganic acid is one or more inorganic acid(s) selected from the hydrochloric acid, nitric acid and sulfuric acid.

The said organic acid is one or more organic acid(s) selected from the oxalic acid, citric acid, formic acid and benzoic acid.

The said inorganic salt is one or more inorganic salt(s) selected from the sodium hydrogen sulfate, potassium hydrogen sulfate, ammonium nitrate, magnesium sulfate, potassium sulfate, ammonium sulfate, ammonium chloride, potassium chloride and potassium nitrate.

The said amide form nitrogenous fertilizer is the urea.

Based on the understanding and discovery to the water-insoluble phosphate fertilizer and water-insoluble fertilizer or mineral containing secondary and micronutrients, the inventor has made the following inventions.

The present invention involves a kind of method of agricultural fertigation. The method is characterized in that it includes following steps: (i) One of more water-insoluble phosphate fertilizer selected from the ground PR, wet process phosphate fertilizer and thermal process phosphate fertilizer is mixed with the water-insoluble fertilizer or mineral containing secondary and micronutrients. Then, the mixture is loaded in the vessel, thus prepared a kind of fertilizer granule fixed bed.

The said water-insoluble phosphate fertilizer produced by acidifying is the precipitated calcium phosphate.

The said water-insoluble phosphate fertilizer produced by thermal process is selected from defluorinated PR, Rhenania phosphate fertilizer, calcium metaphosphate, basic slag, fused calcium magnesium phosphate.

The said water-insoluble fertilizer or mineral containing secondary nutrients and micronutrients is one or more water-insoluble fertilizer(s) or mineral(s) containing calcium, magnesium, sulfur, boron, molybdenum, zinc, manganese, iron or copper. The said calcium fertilizer or mineral is, for example, calcium sulfate, phosphorus gypsum and industry waste residue like the iron and steel industry slag. The said magnesium fertilizer or mineral is, for example, magnesite and dolomite. The said sulfur fertilizer or mineral is, for example, calcium sulfate, sulfuration zinc ore, pyrites, phosphorus gypsum, sulphur. The said boron fertilizer or mineral is, for example, boron magnesium ore, boron slurry. The said molybdenum fertilizer or mineral is, for example, molybdenum residue. The said zinc fertilizer or mineral is, for example, zinc oxide, zinc sulfide. The said manganese fertilizer or mineral is, for example, manganese oxide, slag including manganese. The said iron fertilizer or mineral is, for example, ferrous oxide, pyrites. The said copper fertilizer or mineral is, for example, the copper oxide, smelting copper slag.

The size of the said ground PR, phosphate fertilizer, the mineral or fertilizer containing secondary nutrients and micronutrients is 0.5-3 millimeter, preferably 0.7-1.5 millimeter, more preferably 0.8-1.0 millimeter. If the size is smaller than 0.5 millimeter, the resistance of the bed layer is too large and the power consumption is also big. If the size is bigger than 3 millimeters, the longer contact time is needed and the extract efficiency is very low.

The mixture ratio by weight of the said water-insoluble phosphate fertilizer granule and the said mineral or fertilizer containing secondary nutrients and micronutrients is 100: 0-2, preferably 100: 0-1, most preferably 100: 0-0.3. (ii) A kind of activator aqueous solution is prepared by dissolving one or more activator(s) selected from inorganic acid, organic acid, inorganic salt and amide form nitrogenous fertilizer in water.

Among them, the said inorganic acid is one or more inorganic acid(s) selected from the hydrochloric acids, nitric acids and sulfuric acids.

The said organic acid is one or more organic acid(s) selected from the oxalic acids, citric acids, formic acids and benzoic acids.

The said amide form nitrogenous fertilizer is urea.

The mass concentration of the said activator aqueous solution is 5%-30%, preferably 5%-15%, most preferably 8%-12%.

If the mass concentration is higher than 30%, the certain inorganic salts can not be dissolved completely; if the mass concentration is lower than 5%, the volume of the activator vessel is too large. (iii) A kind of the diluted activator aqueous solution can be obtained by mixing water and the said activator aqueous solution prepared in the step (ii). Then the diluted activator aqueous solution passes through fertilizer granule fixed bed prepared in the step (i) to obtain a kind of irrigation water. This irrigation water contains phosphorus and secondary nutrients and micronutrients, and it may directly irrigate the crops.

In the solution, the mixture ratio by volume of the activator aqueous solution to water is 1 : 1000 to 1 : 100, preferably 1 :500 to 1 : 100, more preferably 1 :200.

If the mixture ratio by volume of the said activator aqueous solution to water is greater than 1 : 1000, the activation concentration is too low, which can reduce the dissolving capacity of the water-insoluble granula. If the mixture ratio is less than 1 : 100, the activation concentration is too high. Thus the dissolving speed of the water-insoluble granula is too big, which possibly causes sequent precipitation in the irrigation water and blocks up the water pipage.

The line speed with which the above-mentioned diluted activation aqueous solution passes the fertilizer granula fixed bed is 0.1-5, preferably 0.5-2, and more preferably 0.8-1.2 centimeter/second.

If the line speed is greater than 5 centimeter/seconds, the contact time is too short, thus it needs higher fixed bed and the dissolving amount is too small. If the line speed is less than 0.1 centimeter/second, the vessel of the fixed bed is too big; the investment of the equipments is high and the efficiency is low.

By choosing the said water-insoluble fertilizer and the type of activators, controlling the mixture ratio of the water to the activator aqueous solution, as well as regulating the line speed of the diluted activator aqueous solution, the mass concentration of the irrigation water thus obtained is P205 1-200 mg/kg, CaO 2-300 mg/kg, MgO 1-300 mg/kg, Si02 l-300mg/kg, Fe 1-100 mg/kg, Cu 0-5 mg/kg, Zn 0-5 mg/kg, Mn 0-5 mg/kg, B203 0-5 mg/kg, N 0-400 mg/kg, S 0-300 mg/kg and K20 0-200 mg/kg. These choosing methods will be described in detail in the examples of the description.

The vessels used to apply the present invention may be any equipment which can load the phosphate fertilizer and the fertilizer or the mineral granula containing secondary nutrients and micronutrients, and which can form the fixed bed. This kind of equipment may be, for example, a vessel chosen from the tank, pot, tower and column. The section of the said tank, pot, tower and column may be in any shape, such as circle, square, rectangle, polygon and ellipse.

Besides the fixed bed, the pulsation bed and fluid bed which are known by the person skilled in the art may be used to implement the present invention. The fixed bed and the pulsation bed are preferable, the fixed bed is more preferable.

Embodiments Example 1: In this example, firstly a kind of water-insoluble ground phosphate rock is chosen. The particle diameter of the ground PR approximately is 2mm. The ground PR consists of 20% of P205, 6% of MgO 20% of Si02, 1% of FeCK 0.2% of MnO, by the mass of the phosphate rock granula. 500kg of the ground PR and 0.25kg of the zinc oxide, 0.25kg of the boron magnesium ore are weighed ,mixed uniformly, then put into the cylindrical reactor whose dischargeable capacity is 0.5m , thus formed a fixed bed named as fertilizer fixed bed.

Next, to prepare the activator solution,20kg of the ammonium sulfate, 5kg of the 36% hydrochloric acid, 3.5kg of the potassium sulfate and 5kg of the magnesium sulfate are dissolved in the 300 kg of water at the room temperature with stirring, thus obtained a kind of the activator solution. Then, the solution is encased in the tank and ready to be used.

And then, the water is drawn out from the irrigation system with the pump at the flow of 10m /h. Sequently, the activator solution in the storage tank is added into the water with the metering pump at the speed of 50 litres/hour, thus obtained a kind of the diluted activator solution, in which the proportion of the activator solution and the water to irrigate is 1 :200. The irrigation water may be obtained when the diluted activator solution passes the fertilizer fixed bed. This kind of irrigation water contains 20 mg/kg of P205, 26mg/kg of CaO, 13mg/kg of MgO, 3mg/kg of Si02, 2 mg/kg of FeO, lmg/kg of B203, 3 mg/kg of Zn, 1 mg/kg of Mn, 70 mg/kg of N, 90 mg/kg of S and 29 mg/kg of K20, by mass.

The field experiment of cotton was made using the above-mentioned irrigation water. The results of the experiment in 66.7 hectares cotton field shows that at the same cotton output, it was saved by 60% compared with the traditional application rate.

Example 2: The fused calcium magnesium phosphate is chosen, whose particle diameter is approximately 1mm. By the mass of the fused calcium magnesium phosphate, it contains 14% of P205, 36% of CaO, 8% of MgO, 31% of Si02, 1.5% of FeO. 200 kg of fused calcium magnesium phosphate is weighed, then mixed with 3kg of the boron slurry. The mixture is put into the reactor with 0.3m of dischargeable capacity, thus formed the fixed bed.

The activator solution is formulated with the raw material according to the following proportion: 5kg of the magnesium sulfate, 20kg of the potassium nitrate, 5kg of urea and 100 kg of water. Then, the solution is loaded in the tank with 0.3m3 of the dischargeable capacity.

The water is drawn out from the irrigation system at the flow of 10m3/h. According to the proportion of 1000: 1, the water is added to the solution of the activator, thus obtained a kind of diluted activator solution. The irrigation water may be obtained when the diluted activator solution passes the above-mentioned fixed bed. By the mass, the irrigation water consists of 50mg/kg of P205, 50 mg/kg of N, 90 mg/kg of K20, lOOmg/kg of CaO, 36 mg/kg of MgO, 60 mg/kg of Si02, 5 mg/kg of FeO, 5 mg/kg of B203.

The field experiment of grape was made using the above-mentioned irrigation water. The results of the experiment in 10 hectares grape field shows that at the same grape output, it was saved by 30% compared with the traditional application rate.

Example 3: The basic slag phosphate fertilizer is chosen, whose particle diameter is approximately 1.5mm. By the mass of the basic slag phosphate fertilizer, it contains 18% of P205, 40% of CaO, 3% of MgO, 5% of Si02, 10% of FeO and 3% of MnO. 100 kg of the basic slag phosphate fertilizer is weighed out and added to the reactor with 0.2m of the dischargeable capacity, thus formed the fixed bed.

The activator solution is formulated with raw material according to the following ; 5kg of the potassium nitrate, 5kg of the 98% sulfuric acid, 25kg of the ammonium chloride and 200 kg of water. Then, the solution is loaded in the tank with 0.3m3 of the dischargeable capacity. , The water is drawn out from the irrigation system at the flow of 10m3/h. According to the proportion of 300: 1, the water is added to the solution of the activator, thus obtained a kind of diluted activator solution. The irrigation water may be obtained when the diluted activator solution passes the above-mentioned fixed bed. By mass, the irrigation water consists of 30mg/kg of P205, 100 mg/kg of N, 37 mg/kg of K20, 65mg/kg of CaO, 5 mg/kg of MgO, 8 mg/kg of Si02, 10 mg/kg of FeO, 5mg/kg of MnO, 26 mg/kg of S.

The field experiment of corn was made using the above-mentioned irrigation water. The results of the experiment in the 66.7 hectares corn field shows that at the same corn output, it was saved by 50% compared with the traditional application rate.

[Industry usability] The demands of crops for the nutrients are different due to the factors including soil, climate, kinds of crops and different growth period. Therefore, people should spread fertilizer corresponding to these changes. The contents of the nutrients in the irrigation water prepared by the method of agricultural fertigation according to the present invention may alter in a very large scale, which is exactly corresponding to these changes.

Compared with the traditional fertilization, the application rate can be saved by 30%-60% and the utilization efficiency of fertilizer can arrive at 70%-90% by using the fertigation according to the present invention. The method of fertigation according to the present invention belongs to a kind of the modern agriculture method, which has higher utilization efficiency in water and fertilizer. In addition, it is advantageous to realizing agricultural industrialization.

Claims

18781 1/2 -.-'Claims

1. A method of agriculture fertigation, characterized by comprising the following steps: (i) mixing a water-insoluble phosphate fertilizer granule with a water-insoluble fertilizer or mineral granule containing secondary nutrients and micronutrients, wherein the mixture ratio by weight of the water-insoluble phosphate fertilizer granule to the fertilizer containing secondary nutrients and micronutrients is 100:0-2, and loading the obtained mixture into a vessel to form a fertilizer granule fixed bed; (ii) preparing an activator aqueous solution by dissolving one or more activators in water, wherein the activator is selected from the group consisting of an inorganic acid, an organic acid, an inorganic salt and an amide form nitrogenous fertilizer, wherein the mass concentration of the activator aqueous solution is 5%-30%; (iii) preparing a diluted activator aqueous solution by mixing water and the activator aqueous solution of step (ii), wherein the mixture ratio by volume of the activator aqueous solution to water is 1 :1000 to 1 :100; and (iv) passing the aqueous solution of step (iii) through the fertilizer granule fixed bed of step (i) to obtain irrigation water, wherein the line speed with which the diluted activator aqueous solution passes through the fertilizer granule fixed bed is 0.1-5 centimeter/second; and wherein the irrigation water contain phosphorus and secondary nutrients and micronutrients, and may be used directly to irrigate crops; and wherein the mass concentration of the phosphorus and secondary nutrients and micronutrients in the irrigation water comprises of: Ρ20¾ 1 -200 mg/kg, CaO 2-300 mg/kg, MgO 1-300 mg/kg, Si02 l-300mg/kg, Fe 1-100 mg/kg, Cu 0-5 mg/kg, Zn 0-5 mg/kg, Mn 0-5 mg/kg, B203 0-5 mg/kg, N 0- 400 mg/kg, S 0-300 mg/kg and K20 0-200 mg/kg; and wherein the phosphorous source of the water-insoluble phosphate fertilizer granule of step (i) is selected from one or more ground phosphate rock and phosphate fertilizers produced by a wet- process or a thermal-process to produce water-insoluble phosphate fertilizer granule.

2. The method according to claim 1, characterized in that the phosphate fertilizer HIGHEFFI TECH. LTD. CORP. BEIJING produced by wet-process is the precipitated calcium phosphate; the phosphate fertilizer produced by thermal process is selected from defluorinated phosphate rock, Rhenania phosphate fertilizer, calcium metaphosphate, basic slag, fused calcium magnesium phosphate.

3. The method according to claim 1, characterized in that the said fertilizer or mineral containing secondary nutrients and micronutrients is one or more water-insoluble fertilizer(s) or mineral(s) containing calcium, magnesium, sulfur, boron, molybdenum, zinc, manganese, iron or copper.

4. The method according to any one of claims 1-3, characterized in that the particle size of the said ground phosphate rock, phosphate fertilizer, the mineral or fertilizer containing secondary nutrients and micronutrients is 0.5-3 millimeter.

5. The method according to claim 1, characterized in that the said inorganic acid is one of more inorganic acids selected from the hydrochloric acid, nitric acid and sulfuric acid.

6. The method according to claim 1, characterized in that the said organic acid is one or more organic acid(s) selected from the oxalic acids, citric acids, formic acids and benzoic acids.

7. The method according to claim 1, characterized in that the said inorganic salt is one or more inorganic salt(s) selected from the sodium hydrogen sulfate, potassium hydrogen sulfate, ammonium nitrate, magnesium sulfate, potassium sulfate, ammonium sulfate, ammonium chloride, potassium chloride or potassium nitrate.

8. The method according to claim 1, characterized in that the said amide form nitrogenous fertilizer is urea.

9. The method according to claim 1, characterized in that the mixture ratio of the activator aqueous solution to irrigation water 1 :500 to 1 : 100 by volume.

10. The method according to claim 1, characterized in that the line speed with which the said diluted activator aqueous solution passes through the said fertilizer granula fixed bed is 0.5-2 centimeter/second. 18781 1/2

11. The method according to any one of claims 1 -10, substantially as herein described with reference to the examples. Dr. Shlomo Cohen & Co. Law Offices 124 Ibn-Gvirol Street Tel-Aviv 62 038 Tel. 03 - 527 1919