Double superphosphate: application in the garden, composition

By growing plants for our own needs, we deprive the earth of the necessary microelements, since nature provides for a cycle: the elements removed from the soil return to the earth again after the death of the plant. By removing dead leaves in the fall to protect the garden from pests and diseases, we deprive the soil of the elements it needs. Double superphosphate is one of the means to restore soil fertility.

“Natural” organic fertilizers alone are not enough to get a good harvest. “Clean” manure is useless without sufficient urine containing nitrogen. But manure must be “aged” for at least a year so that it rots. And do not forget to correctly arrange the collar. In the process of overheating, the urine in the pile decomposes, “producing” ammonia containing nitrogen. Ammonia escapes, and humus loses nitrogen. Nitrogen-phosphorus top dressing allows you to make up for the deficiency of nitrogen in humus. Therefore, top dressing is mixed with manure during spring work and the mixture is already introduced into the soil.

What’s this

Double Superphosphate is a fertilizer containing almost 50% calcium dihydroorthophosphate monohydrate and 7,5 to 10 percent nitrogen. The chemical formula of the first ingredient is Ca(H2PO4)2•H2O. For use as plant nutrition, the initially obtained product is converted into a substance containing up to 47% plant-available phosphorus anhydride.

Two grades of nitrogen-phosphorus fertilizers are produced in Our Country. Grade A is produced from Moroccan phosphorites or Khibiny apatite. The content of phosphoric anhydride in the finished product is 45-47%.

Grade B is obtained from the Baltic phosphorites containing 28% phosphates. After enrichment, the finished product contains 42-44% phosphorus anhydride.

The amount of nitrogen depends on the fertilizer manufacturer. The differences between superphosphate and double superphosphate are the percentage of phosphorus anhydride and the presence of ballast, which is commonly referred to as gypsum. In simple superphosphate, the amount of the desired substance is not more than 26%, so another difference is the amount of fertilizer required per unit area.

When using double superphosphate as a top dressing for plants during the vegetative period, 20-30 g of fertilizer is dissolved in 10 liters of water for irrigation.

What to choose

When deciding which is better: superphosphate or double superphosphate, you need to focus on the quality of the soil in the garden, consumption rates and prices for fertilizers. In the composition of double superphosphate, there is no ballast, which occupies the main part in simple superphosphate. But if you need to reduce the acidity of the soil, then lime will have to be added to the soil, which is replaced by superphosphate gypsum. When using simple superphosphate, the need for lime either disappears or decreases.

The price of “double” fertilizer is higher, but the consumption is half as much. As a result, this type of fertilizer is more profitable if there are no additional conditions.

This fertilizer will help bind excess calcium in the soil. Simple superphosphate, on the contrary, adds calcium to the soil.

How to apply

Previously, double superphosphate was produced only in granular form, today you can already find a powder form. The use of double superphosphate in the garden as a fertilizer is most beneficial when planting crops. After the plant has taken root, it begins to gain green mass, for which phosphorus and nitrogen are vital to it. It is these substances that are found in large quantities in a concentrated preparation. In the spring, fertilizer is applied either as top dressing for a perennial plant, or when digging up the soil for new plantings.

Double superphosphate has good solubility in water, like its “brother”. Instructions for the use of fertilizer involves the introduction of double superphosphate into the soil in the form of granules during the autumn / spring digging of the garden. Application deadlines are September or April. Fertilizer is evenly distributed over the entire depth of the dug up soil.

When planting seeds directly into the soil, the drug is poured into the wells and mixed with the soil. Later, when using double superphosphate as a fertilizer for feeding already producing plants, the drug is diluted in water and the drug is used for irrigation: 500 g of granules per bucket of water.

In a “pure” form, fertilizer is rarely added. Most often, the application and use of double superphosphate occurs in a mixture with “natural” rotted manure:

• a bucket of humus is slightly moistened;
• pour 100-150 g of fertilizer and mix well;
• defend 2 weeks;
• added to the soil.

Although the amount of industrial fertilizer is small compared to “natural organics”, due to the concentrated composition, superphosphate saturates the humus with the missing nitrogen and phosphorus.

If there is a precipitate, it is either a simple superphosphate or a fake.

Nuances of use

Different plants react differently to nitrogen-phosphorus fertilizers. Do not mix sunflower and corn seeds with superphosphates of both types. These plants are oppressed by direct contact with nitrogen-phosphorus fertilizers. For these plants, the fertilizer rate should be reduced, and the preparation itself should be separated from the seeds by a layer of soil.

Seeds of other cereals and vegetables are easier to relate to the presence of nitrogen-phosphorus fertilizer next to them. They can be mixed with granules when sowing.

On some packages of double superphosphate, instructions for using the drug are printed. There you can also find out how to dose fertilizer with improvised means: 1 tsp = 10 g; 1 st. spoon u30d 10 g. If a dose of less than XNUMX g is needed, then it will have to be measured “by eye”. In this case, top dressing is easy to overdose.

But the “universal” instruction always gives general information. When choosing the dose and method of applying fertilizer for a particular plant, its needs must be taken into account. Radishes, beets and radishes are better off underdone than overdose.

But tomatoes and carrots without phosphorus will not pick up sugar. But here lies another danger: nitrates that frighten everyone. An overdose of nitrogen-phosphorus fertilizers will lead to the accumulation of nitrates in vegetables.

Plant requirement

The minimum need for phosphorus, as already mentioned, is in radishes, radishes and beets. Insensitive to lack of phosphorus in the soil:

• pepper;
• eggplants;
• gooseberry;
• currant;
• parsley;
• bow.

Gooseberries and currants are perennial shrubs with relatively sour berries. They do not need to actively collect sugar, so they do not need to be fertilized every year.

Fruit trees and plants producing sweet fruits cannot do without phosphorus at all:

• carrot;
• cucumbers;
• tomatoes;
• cabbage;
• raspberries;
• beans;
• Apple tree;
• pumpkin;
• grapes;
• pear;
• strawberries;
• cherry.

Concentrated fertilizer is recommended to be applied to the soil every 4 years, not more often.

Deficiency of phosphorus

With symptoms of phosphorus deficiency: growth inhibition, small leaves of a dark color or with a purple tint; small fruits, carry out urgent feeding with phosphorus. To speed up the production of phosphorus by the plant, it is best to spray on the leaf:

• pour a teaspoon of fertilizer into 10 liters of boiling water;
• insist 8 hours;
• filter out the precipitate;
• pour the light fraction into a spray bottle and spray the leaves.

You can also sprinkle top dressing under the roots at the rate of 1 teaspoon per m². But this method is slower and less efficient.

Increase feed efficiency

Phosphorus in the soil is converted depending on the type of soil. In soil with an alkaline or neutral reaction, monocalcium phosphate turns into dicalcium and tricalcium phosphate. In acidic soil, iron and aluminum phosphates are formed, which plants do not absorb. For successful application of fertilizer, the acidity of the earth is first reduced with lime or ash. Deoxidation is carried out at least a month before the application of nitrogen-phosphorus fertilizer.

Other varieties

This class of nitrogen-phosphorus fertilizer can be not only with phosphorus and nitrogen, but also with other trace elements necessary for plant growth. The composition of the fertilizer can be added:

• manganese;
• boron;
• zinc;
• molybdenum.

These are the most common supplements. In the general composition of top dressing, these elements are in very small quantities. The maximum percentage of these microfertilizers is 2%. But micronutrients are also essential for plant growth. Usually, gardeners pay attention only to nitrogen, phosphorus and potassium fertilizers, forgetting about other elements of the periodic table. In the event of diseases with unclear signs, it is necessary to do a soil analysis and add those microelements that are not enough in the soil.

Reviews

Conclusion

Double superphosphate added according to the instructions will be very useful for garden soil. But with this top dressing, you can not overdo it. A large amount of nitrates in fruits can lead to food poisoning.