Dolomite, bone and fish meal for fertilizing potatoes

Dolomite, bone and fish meal are rich in macro- and microelements necessary for potatoes. The main advantage of these fertilizers is that they can be equally successfully used both in organic farming and combined with mineral fertilizers.

Dolomite flour

Dolomite flour is a ground dolomite mineral. The finer the grinding, the more effective the fertilization. The color of the powder is usually white, but sometimes, due to the admixture of iron, it is yellowish or even brown. Also, dolomite flour can contain impurities of manganese, zinc, nickel, cobalt.

Although limestone and dolomite are different minerals, they are similar in composition (dolomite has a higher content of calcium carbonate, CaCO3). Therefore, dolomite flour is often called limestone. In addition to calcium carbonate, the fertilizer is rich in magnesium carbonate (MgCO3).

Dolomite flour is one of the three most popular soil deoxidizers. The other two fertilizers are slaked lime (fluff) and ash.

Dolomite flour

Benefits of dolomite flour for potatoes:

  • contains magnesium and calcium necessary for plants, and fluff contains only calcium;
  • slaked lime (fluff) – calcium hydroxide (Ca (OH) 2), a substance that decomposes very quickly in the soil and reduces its acidity in the shortest possible time. In case of an overdose, the fluff can burn the roots of plants. It is safer to add dolomite flour under potatoes: calcium and magnesium salts decompose more slowly than hydroxide, therefore they do not harm the tubers;
  • in flour, the concentration of nutrients is approximately 2 times higher than in ash, therefore, the consumption of dolomite powder is half as much;
  • dolomite flour improves the structure of the soil, making it looser. As a result, the tubers receive more oxygen;
  • calcium strengthens the root system of potatoes, magnesium stimulates the process of photosynthesis;
  • dolomite particles have a weak abrasive effect, they damage the chitinous shells of insect pests and the skin of slugs;
  • calcium and magnesium improve the taste of tubers, increase their starchiness and shelf life.

Application and dosage of dolomite flour

Potatoes grow best in slightly acidic soils, so do not alkalize the soil too much in the area. Before adding dolomite flour, it is necessary to determine the acidity of the soil (the optimal pH value for a potato plantation is 5,2–5,7).

Methods for determining the acidity of the soil:

  • pour a handful of earth into a bowl, sprinkle vinegar on it. If the soil is acidic, nothing will happen, if it is neutral or alkaline, foam will appear, a slight hiss will be heard;
  • toss a lump of earth into a mug of natural, sugar-free grape juice. If after a few minutes the color of the juice changes, and bubbles rise to the surface, it means that the soil is neutral or alkaline;
  • wood lice, horse sorrel, horsetail grow on acidic soils, nettles, clover, coltsfoot grow on neutral soils, quinoa and field mustard grow on alkaline soils;
  • specialty shops for gardeners sell litmus strips. A handful of earth is poured with water (for 20 g of earth – 50 g of water), stirred and allowed to settle. Then the acidity is checked with a strip: below 4,5 – acidic soil, 4,6-5,0 – moderately acidic, 5,1-6 – slightly acidic; 6-7,5 – neutral, above 7,5 – alkaline. By the color of the strip: red – acidic, violet – neutral, blue – alkaline.

Dolomite flour is used only if the soil is acidic, moderately acidic or slightly acidic.

Fertilizer dosage:

  • for acidic soil – up to 50 kg per hundred square meters (0,5 kg per 1 m²);
  • for medium acid – up to 45 kg per hundred square meters (450 g per 1 m²);
  • for weakly acidic – up to 35–40 kg per hectare (350–400 g per 1 m²);
  • for greenhouses – 100 g per 1 m².

If the soil is heavy, clayey, dolomite flour is required to be applied annually. On sandy soils, the rate is reduced by a third, and fertilization is applied no more than once every 1–2 years.

Dolomite flour is the cheapest and most readily available source of magnesium. Therefore, it is used even on light alkaline soils, which further reduce their acidity. In such conditions, potatoes are more likely to get sick with scab, they absorb boron and manganese worse, so they have to be added.

Dr. Mittlider recommended mixing dolomite powder with boric acid in the proportion: 1 kg of flour – 7 g of boric acid. If the soil is heavy, then 1 g of the mixture is required to fertilize 200 running meter of the garden bed, on light soils – 100 g. Another option for introducing microelements – in the phase of closing the tops, foliar feeding is carried out: for 1 hundred square meters – 10 g of boric acid is dissolved in 30 liters of water, 20 g of manganese sulfate and 20 g of copper sulfate.

Dolomite flour can be applied both in spring and autumn, but it is most convenient to do this after harvest, before autumn plowing. The fact is that manure and nitrogen fertilizers increase the acidity of the soil, so they cannot be mixed with dolomite powder. Likewise, you cannot apply flour and phosphate fertilizers at the same time.

If dolomite flour is applied in the fall, then all other fertilizers are applied in the spring. If you have to use flour and other fertilizers in one season, then: first, the earth is evenly sprinkled with dolomite powder, and after 10-14 days, the rest of the fertilizer is added and the plot is dug up or plowed. To save time in the spring, some gardeners even sprinkle dolomite powder over the melting snow. However, this can only be done if the area is relatively flat, and the snow is loose and the thickness of the snow cover is no more than 5–7 cm.

Bone flour

Bone meal is made from the ground bones or horns and hooves of cattle. Manufacturers usually mix horn and hoof powder with bone meal. Horns and hooves are rich in nitrogen and calcium. When bones are digested, the amount of nitrogen in them decreases, but a lot of phosphorus and calcium remain. The finished flour, which is a light yellow powder, contains 15–35% calcium and phosphorus. In small amounts, the powder contains iron, iodine, manganese, copper and cobalt.

Bone meal for potatoes can be applied both before planting and throughout the growing season. Flour completely decomposes in 6-8 months, providing the plants with constant nutrition. In addition, it gently alkalizes the soil, so it is used even on neutral soils. Bone meal successfully replaces phosphate rock.

photo of bone meal for fertilizing potatoesBone flour

The rate of application of bone meal is 10 kg per one hundred square meters (100 g per 1 m²). If the soil is light and loose, then the powder is simply poured evenly onto its surface and dug up. If the soil is heavy, then the bone meal is poured with boiling water at the rate of 1 kg of powder per 20 liters of water and mixed. After 10 days, the beds are watered with a solution (2 liters per 1 m²).

It is best to add bone meal before planting potatoes. Many gardeners prefer not to scatter the powder on the ground, but to add 1 tablespoon to each hole. Bone meal is allowed to be used together with ash or nitroammophos (the rate of mineral fertilizers should be halved).

Bone meal contains fat, which decomposes at high temperatures to form toxic substances. Therefore, the powder should be stored in a cool dry place, no longer than indicated on the package.

Fish flour

Fish, or fish bone meal serves as a substitute for bone meal, it decomposes in the same way in 6-8 months. Dried fish powder is rich in phosphorus, nitrogen and calcium.

There are 2 ways to make fishmeal:

  • commercial – fish that cannot be frozen is ground directly on the seiner;
  • coastal – flour is made at the factory.

For those who practice organic farming, flour produced on a seiner is more suitable, since it is often mixed with various chemical additives in factories. Before buying, you must carefully read everything that is written on the package.

The color of the powder depends on the technology of drying the fish: if it is dried over a fire, the flour turns out to be dark, if it is treated with steam, then it is light. Light flour is rich in protein.

photo of fish meal for fertilizing potatoesFish flour

The rate of application of fishmeal for potatoes is 100 g per 1 m² (10 kg per hundred square meters), it is allowed to add a tablespoon of powder to each hole during planting. The use of fertilizer with nitroammophos or ash is allowed.

It is advisable to store fishmeal in a dry place, at a temperature not higher than +20 ° C, no more than a month from the moment the package is opened.

Anna Evans

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