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Points and considerations of fertigation with drip irrigation

The use of drip irrigation system for fertilization can provide conditions for accurate fertilization, which significantly improves the efficiency of fertilization and irrigation, reduces production costs, increases yield and quality, and ultimately improves economic benefits. Drip irrigation and fertilization techniques are widely popular all over the world.

    Fertilizing through the drip irrigation belt system, on the one hand, because soluble fertilizer is directly applied to the crop root compaction area with water, no fertilizer is wasted on the open space between the crops. On the other hand, drip irrigation infiltrates into the root zone with a small amount of drip water, which is very easy to control. There will be no deep leaching waste of water and fertilizer. With nitrogen drip irrigation, the fertilizer effect can reach 74%, while the traditional application will not exceed 30%.

    The disadvantage of using drip irrigation to fertilize is the possibility of clogging the dripper. Fertilizer must be soluble, insoluble fertilizer can quickly clog the dripper. The chemical reaction between the fertilizer materials will also cause precipitation. Over time, the sediment will block the drip irrigation system. The uniformity of fertilization depends on the uniformity of irrigation. If the uniformity of the drip irrigation system is high, the uniformity of fertilization is also high. Therefore, the uniformity of drip irrigation is a very important indicator. Every effort should be made to improve the uniformity of drip irrigation:

1.Fine design of irrigation system

2.Adopt pressure compensation dripper

3. Install a pressure regulator at the proper position of the pipeline

First, the solubility of chemical fertilizers

    For fertigation using a drip irrigation system, the solubility of the fertilizer must be carefully studied. Insoluble, low solubility or easy reaction under certain conditions, avoid the use of fertilizers that form precipitation.

Most solid fertilizers are coated. In order to prevent the coating from blocking the drip irrigation system, it is best to select a small amount of sample and stir it in the dissolution tank, and then observe the dissolution of the coating. If the coating material precipitates on the bottom of the tank after dissolving, when applying, let the fertilizer injector absorb the upper solution without disturbing the whole fertilizer solution.

    When urea, nitric acid, calcium nitrate, and potassium nitrate are dissolved, the heat in the water is absorbed, and the temperature of the water is greatly reduced. At this time, the dissolved amount may not reach the required amount. In order to fully dissolve, it is best to let the solution stand for a few hours. As the temperature rises, the remaining undissolved portion will gradually dissolve and then be injected into the system.

    Before injection, observe the test to assess the possibility of clogging the dripper. Some fertilizers need to be dissolved in the fertilizer for 1-2 hours before they can see if a precipitate has formed and how much. If the solution is still chaotic after being dissolved in water for several hours, it may block the drip irrigation system. If several fertilizers are applied at the same time, samples should be taken before injection into the system, and they should be put into the observation tank at the same time to observe the dissolution after mixing, and then decide whether to inject simultaneously.

Nitrogen application in drip irrigation system

    Nitrogen is the most applied fertilizer using a drip irrigation system. Nitrogen fertilizers are generally water-soluble and are easily applied to the root zone of crops as irrigation drips into the soil. However, if improperly controlled, leaching losses can easily occur. Because the drip irrigation flow is small (single drip head: 4-8 liters / hour), it is very easy to control the leaching damage head. If irrigation and fertilization are automatically controlled, leaching damage can be completely avoided.

    Of all nitrogen fertilizers, urea and amine nitrate are the most suitable for drip irrigation. Because the application of these two fertilizers has the lowest risk of clogging, drip irrigation is generally not recommended for ammonia, as ammonia can increase the pH of the water. An increase in pH will cause calcium, magnesium, and phosphorus to precipitate in the irrigation water and block the dripper. Ammonium sulfate and calcium nitrate are water-soluble, but there is also a risk of clogging.

    If nitrogen is continuously applied, there will still be nitrogen in the water in the irrigation system for a long time after the pump is stopped in the irrigation system. At this time, the presence of nitrogen will nourish the growth of microorganisms in the system, and eventually block the dripper.

3. Phosphorus application under drip irrigation

    Phosphorus is not as active in the soil as nitrogen. Generally, the volatilization loss of phosphorus and leaching loss are not as much as nitrogen. Most crops need phosphorus early in their growth. Therefore, phosphate fertilizer should be applied before or at the time of planting. If you find signs of phosphorus deficiency in the production stage, injecting phosphorus fertilizer into the irrigation water can also supplement the phosphorus deficiency.

    Injecting phosphate fertilizer can clog the drip irrigation system. Due to the reaction between water and phosphate fertilizer, solids tend to precipitate in the water, which can cause blockages. Most solid phosphate fertilizers cannot be injected into irrigation systems due to their low solubility, such as phosphorous ammonia. Phosphate fertilizers such as ammonium monophosphate, ammonium diphosphate, potassium triphosphate, phosphoric acid, and phosphate are soluble.

    Polyphosphate ammonia is high in calcium. Injection into irrigation water can often cause precipitation and may cause blockages. The formed precipitate is very difficult to dissolve. When phosphorus and calcium ions are in the solution, divalent or trivalent calcium phosphate is formed. The solubility of this salt is very low. Similarly, phosphorus and magnesium can form water-insoluble magnesium phosphate, which can easily block the drip irrigation system.

    Phosphoric acid is sometimes injected into drip irrigation systems. In addition to applying phosphorus to crops, it can also reduce the pH value of irrigation water. Reducing the pH value can avoid the generation of sediment. The method of reducing the PH value is to add appropriate sulfuric acid and phosphoric acid, and the PH value can be reduced to less than 4.0. However, long-term injection of phosphoric acid will lead to zinc deficiency in crops. Generally, it is injected only when the combined concentration of calcium and magnesium in water is lower than 50 ppm and the concentration of bicarbonate is lower than 150 ppm.

Fourth, drip irrigation potassium

       Potash fertilizers are soluble and injected into drip irrigation systems with great success. A possible problem is that when potassium fertilizers are mixed with other fertilizers in fertilizer tanks, it is possible to produce sediments that can block the drip irrigation system. Potassium fertilizers commonly used in drip irrigation are: potassium chloride (KCI), potassium nitrate (KNO3). Potassium phosphate should not be injected into the drip irrigation system, the solubility is low.

V. Recommended Fertilizers for Drip Irrigation

1. Ammonia nitrate solution (20-0-0) NH4NO3-H20

Citrus Drip Irrigation

2. Urea + nitramine solution (32-0-0) (NH2) 22CO-NH4NO3

Be careful not to inject the calcium nitrate in one piece, otherwise it will cause precipitation

3. Calcium nitrate (15.5-0-0-19N-P-K-Ca) 5Ca (NO3) 2-NH4-10H2O

4. Phosphoric acid (0-54-0) H3P04

Never inject phosphoric acid with any calcium-containing fertilizer, as it will form insoluble calcium phosphate and block the drip irrigation system.

5. Potassium chloride (0-0-62) KCL

Because it is cheap and easily soluble in water, it is commonly used in drip irrigation.

6. Potassium nitrate (13-0-46) KNO3

Potassium nitrate is expensive but has no waste. Both nitrogen and potassium are very beneficial to citrus production. Its solubility is not as good as potassium chloride, but it is more soluble than potassium sulfate.

7. Potassium sulfate (0-0-52) K2SO4

Drip irrigation is one of the commonly used fertilizers. In areas with high salt content, potassium sulfate is often used instead of potassium chloride. Its solubility is not as high as potassium chloride and potassium nitrate.

8.Sulfuric acid H2PO4

Sulfuric acid is not a fertilizer. Without N.P.K is mainly used to control the pH value when the water is rich in bicarbonate (can be reduced to 6.5-7.0).

9. Solid urea (46-0-0) or urea solution (23-0-0)

Note: Do not inject urea with sulfuric acid.

Six, other matters needing attention

1. Fertilizer injection will have a corrosive effect on filters, valves, etc. After each injection of fertilizer, the entire system must be flushed with sufficient time. No fertilizer solution should remain in the system. After each injection, the fertilization tank should be cleaned.

2. If a fertilizer pump is used, it is best to use a stirrer in the fertilizer tank. The fertilizer should be stirred before and during each injection to accelerate dissolution.

3. Don't add too much fertilizer at one time. Fertigation with drip irrigation is best with a small amount of multiple application. Excessive concentrations of fertilizers in the soil are not good for crop growth.

4. All fertilizers to be injected must be soluble. Also pay attention to the reaction between different fertilizers. The sediment produced by the reaction may block the drip irrigation system. Nitrogen fertilizers rarely cause blockages. Phosphate fertilizers are very likely to cause clogging, so be careful. Injecting phosphoric acid is usually the safest. Common potassium fertilizers dissolve quickly and generally do not contain clogging problems.




Phone: 18863440000

Tel: +86 0531-78778678

Email: lvchunfeng@dripirrigation.com.cn

Add: No.2 Wenhe Avenue, Laiwu District, Jinan City, Shandong Province