Content
By growing plants for our own needs, we deprive the earth of essential microelements, since nature provides for a cycle: elements removed from the soil return to the ground again after the death of the plant. By removing dead tops 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 produce a good harvest. “Clean” manure is useless without sufficient urine containing nitrogen. But the manure must be “aged” for at least a year for it to rot. And don’t forget to properly design the collar. During the process of overheating, the urine in the pile decomposes, “producing” ammonia containing nitrogen. Ammonia evaporates, and humus loses nitrogen. Nitrogen-phosphorus fertilizing allows you to compensate for the nitrogen deficiency in humus. Therefore, the fertilizer is mixed with manure during spring work and the mixture is added to the soil.
What it is
Double superphosphate is a fertilizer containing almost 50% calcium dihydrogen orthophosphate monohydrate and 7.5 to 10 percent nitrogen. The chemical formula of the first ingredient is Ca(H2PO4)2•H2O.For use as a plant feed, the initially obtained product is converted into a substance containing up to 47% phosphorus anhydride assimilated by plants.
Two brands of nitrogen-phosphorus fertilizers are produced in Russia. Grade A is produced from Moroccan phosphorites or Khibiny apatite. The content of phosphorus anhydride in the finished product is 45-47%.
Grade B is obtained from 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 usually called gypsum. In simple superphosphate, the amount of the required substance is no more than 26%, so another difference is the amount of fertilizer required per unit area.
| Superphosphate, | Double superphosphate, g/m² |
Cultivated soils for any type of plants | 40—50 g/m² | 15—20 g/m² |
Uncultivated soils for any type of plants | 60—70 g/m² | 25—30 g/m² |
Fruit trees in spring when planting | 400-600 g/seedling | 200-300 g/seedling |
Raspberries when planting | 80-100 g/bush | 40-50 g/bush |
Coniferous seedlings and shrubs during planting | 60-70 g/yam | 30-35 g/yam |
Growing trees | 40—60 g/m² trunk circle | 10-15 g/m² trunk circle |
Potato | 3-4 g/plant | 0.5-1 g/plant |
Vegetable seedlings and root crops | 20—30 g/m² | 10-20 g/m² |
Plants in a greenhouse | 40—50 g/m² | 20—25 g/m² |
When using double superphosphate as a plant feed during the growing season, 20-30 g of fertilizer is dissolved in 10 liters of water for irrigation.
What to choose
When deciding the question “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. Double superphosphate contains no ballast, which occupies the main part in simple superphosphate. But if you need to reduce the acidity of the soil, then you will have to add lime to the soil, which is replaced by superphosphate gypsum. When using simple superphosphate, the need for lime either disappears or is reduced.
The price of “double” fertilizer is higher, but the consumption is half as much. As a result, this type of fertilizer turns out to be 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 use
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 it vitally needs phosphorus and nitrogen. It is these substances that are contained in large quantities in the concentrated preparation. In the spring, fertilizer is applied either as a 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”.The instructions for using the fertilizer involve adding double superphosphate to the soil in the form of granules during the autumn/spring digging of the garden. Application deadlines are September or April. The fertilizer is evenly distributed throughout the entire depth of the dug soil.
When planting seeds directly into the soil, the drug is poured into the holes and mixed with the soil. Later, when using double superphosphate as a fertilizer to feed already producing plants, the drug is diluted in water and the drug is used when watering: 500 g of granules per bucket of water.
Fertilizer is rarely added in its “pure” form. Most often, the application and use of double superphosphate occurs in a mixture with “natural” rotted manure:
- a bucket of humus is slightly moistened;
- add 100-150 g of fertilizer and mix well;
- stand for 2 weeks;
- added to the soil.
Although the amount of industrial fertilizer is small compared to “natural organics,” due to its concentrated composition, superphosphate saturates the humus with the missing nitrogen and phosphorus.
If there is a sediment, it is either simple superphosphate or a fake.
Nuances of use
Different plants react to nitrogen-phosphorus fertilizers differently. You cannot mix sunflower and corn seeds with superphosphates of both types. These plants experience depression when in 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 on the presence of nitrogen-phosphorus fertilizer next to them. They can be mixed with granules when sowing.
Some packages of double superphosphate contain instructions for use of the drug. There you can also learn how to dose fertilizer using improvised means: 1 teaspoon = 10 g; 1 tbsp. spoon = 30 g. If a dose of less than 10 g is needed, then it will have to be measured “by eye”. In this case, it is easy to overdose the fertilizer.
But “universal” instructions always give general information. When selecting the dose and method of applying fertilizer for a particular plant, you need to take into account its needs. It is better to underdose on radishes, beets and radishes than to overdose.
But tomatoes and carrots without phosphorus will not gain sugar. But here lies another danger: nitrates frighten everyone. An overdose of nitrogen-phosphorus fertilizers will lead to the accumulation of nitrates in vegetables.
Plant needs
The minimum requirement for phosphorus, as already mentioned, is for radishes, radishes and beets. Insensitive to phosphorus deficiency in the soil:
- pepper;
- eggplant;
- gooseberry;
- currant;
- parsley;
- onion.
Gooseberries and currants are perennial shrubs with relatively sour berries. They do not need to actively gain sugar, so there is no need to fertilize them every year.
Fruit trees and plants that produce sweet fruits cannot do without phosphorus at all:
- carrot;
- cucumbers;
- tomatoes;
- cabbage;
- raspberries;
- beans;
- Apple tree;
- pumpkin;
- grape;
- pear;
- strawberries;
- cherry.
It is recommended to apply concentrated fertilizer to the soil every 4 years, not more often.
Phosphorus deficiency
With symptoms of phosphorus deficiency: growth inhibition, small leaves of a dark color or with a purple tint; small fruits, urgent feeding with phosphorus is carried out. To speed up the production of phosphorus by the plant, it is best to spray the leaves:
- pour a teaspoon of fertilizer into 10 liters of boiling water;
- leave for 8 hours;
- filter off the precipitate;
- pour the light fraction into a spray bottle and spray the leaves.
You can also sprinkle fertilizer under the roots at the rate of 1 teaspoon per m². But this method is slower and less effective.
Increase the efficiency of fertilizing
Phosphorus in the soil is transformed depending on the type of soil. In soil with an alkaline or neutral reaction, monocalcium phosphate transforms into dicalcium and tricalcium phosphate. In acidic soil, iron and aluminum phosphates are formed, which plants do not absorb. To successfully apply fertilizers, first reduce the acidity of the soil with lime or ash. Deoxidation is carried out at least a month before applying nitrogen-phosphorus fertilizer.
Other varieties
This class of nitrogen-phosphorus fertilizer can contain not only phosphorus and nitrogen, but also other microelements necessary for plant growth. The following can be added to the fertilizer:
- manganese;
- boron;
- zinc;
- molybdenum.
These are the most common additives. In the general composition of the fertilizer, these elements are found in very small quantities. The maximum percentage of these microfertilizers is 2%. But microelements are also necessary for plant growth. Typically, gardeners pay attention only to nitrogen, phosphorus and potassium fertilizers, forgetting about other elements of the periodic table.In case of diseases with unclear signs, you need to do a soil analysis and add those microelements that are not enough in the soil.
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Conclusion
Double superphosphate added according to instructions will be very useful for garden soil. But you can’t overdo it with this feeding. Large amounts of nitrates in fruits can lead to food poisoning.
