Phosphoric
Phosphorus in fertilizers is contained in a form that is difficult for plants to access. But over the winter, as a result of chemical processes, it turns into an easily accessible element.
Phosphoric flour
This is a real find for supporters of organic farming. No chemicals – completely natural product. It is obtained by fine grinding of phosphorites – sedimentary rocks. It contains 19 – 30% phosphorus.
This fertilizer is especially effective on acidic soils (1) – it alkalizes them and brings them closer to a neutral reaction.
How to use. Fertilizer is evenly scattered over the surface of the soil, and then the area is dug up onto a shovel bayonet. Consumption rate – 30 kg per hundred square meters.
Features. Phosphorite flour cannot be mixed and applied to the beds at the same time as lime, potassium carbonate.
Double superphosphate
This is the most popular phosphorus fertilizer, there is a lot of phosphorus in it – 40 – 50%. It is used for the main application to the soil and for top dressing (2).
How to use. Fertilizer is scattered over the site, and then be sure to dig up. The fact is that phosphorus in this fertilizer is in the form of phosphoric acid. And it practically does not move in the soil – where it was brought in, it is fixed there. Therefore, superphosphate must be buried in the ground to the depth of the bulk of the roots. If you just scatter it over the surface of the site, there will be no sense.
Features. It is best to apply superphosphate along with organic matter – compost or humus. Then the efficiency of the fertilizer increases markedly. But it cannot be mixed with urea, ammonium, sodium and calcium nitrate, potassium carbonate, lime, dolomite, chalk.
Potash
In principle, these fertilizers could be applied in the spring – they are well absorbed. But some of them contain chlorine, which negatively affects plants. When applied in the fall, chlorine evaporates, and by spring, top dressing becomes completely safe.
Potassium sulphate (potassium sulphate)
One of the most popular potash fertilizers, it is he who is most often recommended by agronomists. Potassium in it is 45 – 53%. In addition to it, the composition includes sulfur (18%), which improves the quality and increases the shelf life of the crop. And most importantly, it prevents nitrates from accumulating in fruits. Meanwhile, 80% of arable land in Our Country is poor in sulfur. It is especially lacking in the Belgorod, Kursk, Voronezh, Lipetsk, Tambov, Rostov, Volgograd and Pskov regions.
How to use. Scatter around the site and dig a shovel onto a bayonet.
Features. The fertilizer must not be mixed with urea, ammonium nitrate, ammonium sulfate, potassium carbonate, lime, chalk and dolomite.
And potassium sulfate acidifies the soil, so it is recommended to apply it only in neutral and alkaline areas.
Kalimagnesia (potassium-magnesium sulfate)
It contains less potassium than potassium sulfate, only 26 – 28%. But on the other hand, the composition contains magnesium (9 – 16%), which is very useful on sandy soils that are poor in this element. You can apply this fertilizer both in autumn and in spring, but at the end of the season it is more convenient – there are not so many works at this time.
How to use. Scatter evenly over the site and dig a shovel onto a bayonet. And if in the spring – then directly into the holes.
Features. Potassium magnesia must not be mixed with urea and potassium carbonate. During storage, it practically does not cake (3).
Potassium chloride
This is the most potassium-rich fertilizer – it is already 50 – 60% there. But at the same time, it is also the most harmful among potash, because it contains a lot of chlorine, which inhibits plants and salinizes the soil. Cucumbers, peppers, tomatoes and potatoes do not tolerate this element. And these are our main cultures!
How to use. It, like many other autumn fertilizers, is applied in the fall, for digging the soil (4). It is absolutely impossible to use it in the spring – it is necessary that the chlorine evaporate during the winter. However, many experts advise to completely abandon this fertilizer. Indeed, why take risks if there are other potash fertilizers?
Features. If you have already decided to make potassium chloride, feed them to beets – they love salty soils. But remember: this fertilizer should not be mixed with lime, dolomite, chalk and potassium carbonate.
Nitrogen
Many summer residents will be surprised: nitrogen fertilizers – in the fall? This is wrong! After all, everyone knows that they are easily washed out of the soil with rain and melt water, so they are introduced only in spring. In most cases, this is true. But among the nitrogen ones there are those that are fixed in the soil for a long time, even despite the abundance of precipitation. Plants also need nitrogen in the fall! In very small doses, but it is needed. For example, roots, which even in winter are active, albeit small.
Ammonium nitrate
It contains about 35% nitrogen. Fertilizer works great even in frozen soil, so it can and should be applied in the fall.
How to use. Scatter over the site and close up with a rake.
Features. Do not mix with urea, calcium nitrate, superphosphate, potassium sulfate, lime, dolomite flour, chalk, potassium carbonate. But especially with organics: peat, straw and sawdust – these mixtures can ignite spontaneously and even explode! And with this interaction, toxic nitrogen oxides are released (5).
And ammonium nitrate should not be used on acidic soils – it will acidify them even more. But for neutral and alkaline areas, it is ideal.
Ammonium sulfate (ammonium sulfate)
There is less nitrogen in it, only 20%, but there is sulfur, the benefits of which have already been mentioned above.
How to use. Scatter over the site and close up with a rake. Or dig.
Features. Ammonium sulfate can only be used in alkaline areas. For neutral, and even more acidic, it is not suitable, because it strongly acidifies the soil.
And yet this fertilizer can not be mixed with slaked lime, phosphate rock, potassium sulfate, sodium, calcium and potassium nitrate, ash, potassium carbonate.
Popular questions and answers
We talked about fertilizing in the fall with agronomist-breeder Svetlana Mikhailova.
When to Fertilize in the Fall?
But phosphorus and potash can be applied from the end of August to November, as the beds are freed. Dig up potatoes? Immediately apply fertilizer to the soil and dig the area. Carrots were removed – the same thing. Cut down the cabbage – fertilize the beds after it.
In what doses should fertilizers be applied in the fall?
What else is the use of autumn fertilizers?
Sources of
- Mineev V.G. Agrochemistry. Textbook. 2nd edition, revised and enlarged // M.: MGU Publishing House, KolosS Publishing House, 2004 – 720 p.
- GOST 16306-80 Double granulated superphosphate. Specifications. Official publication // Moscow, Standards Publishing House, 1997 – 14 p.
- Yagodin B.A., Zhukov Yu.P., Kobzarenko V.I. Agrochemistry (edited by Yagodin B.A.) // M.: Kolos, 2002 – 584 p.
- State catalog of pesticides and agrochemicals approved for use on the territory of the Federation as of July 6, 2021 // Ministry of Agriculture of the Federation https://mcx.gov.ru/ministry/departments/departament-rastenievodstva-mekhanizatsii-khimizatsii- i-zashchity-rasteniy/industry-information/info-gosudarstvennaya-usluga-po-gosudarstvennoy-registratsii-pestitsidov-i-agrokhimikatov/
- GOST 2-85. Ammonium nitrate. Specifications. Official publication // Moscow, Standards Publishing House, 1987.