Rock flour and agriculture

More and more people are becoming interested in small-scale farming, in growing their own produce for self-sufficiency, at least at certain times of the year. Today we want to answer a question that many of these amateur farmers are asking: What is rock flour and how can it help me?

What is rock flour

Rock flour is a global resource that allows soil remineralisation and is increasingly used as a substitute for chemical fertilisers, mainly in organic farming.

Rock flour is obtained by grinding natural rocks into powder, a method that was already used in ancient times. The result is the creation of an environmentally friendly fertiliser that avoids the damage caused by chemicals to the ecosystem.


Rock flour does not pollute soil, air or crop water. This alone makes it an important option to consider.

It also retains soil moisture, improving its structure and stabilising its pH. It also reduces erosion, increases organic matter and neutralises any toxins it may contain.

This natural fertiliser improves the nutritional status of plants and makes them more resistant to insects, diseases, low temperatures and drought. The nutrients it provides (macro and micro) promote a nutritional balance between the soil and the plants, and this also affects other living beings: it increases the activity of earthworms and micro-organisms.

Rock flour helps to increase yields. In fruit and vegetable crops, it is estimated to increase by up to 25%, but it also increases the vitamin C concentration of some fruits.

In short, rock flour restores nature’s conditions to allow crops to grow more optimally. Chemical fertilisers and chemical fertilisers, on the other hand, are only an artificial and temporary aid that ends up affecting the entire ecosystem.

As we all know, minerals are essential not only for the growth, development and good condition of plants, but they are also necessary for the living beings that consume them. A healthy diet based on nutritionally rich foods directly benefits us.

Mancha de polvo negro micronizado
Black micronised sand

How rock flour is obtained

Rock flour is commercially available and affordable. If you buy it, make sure it is organic and not supplemented.

We can also make it ourselves, but we should be aware that, depending on the type of soil, a certain type of rock will be needed.

Igneous rocks, such as basalt and granite, are recommended. Metamorphic rocks, such as slate, marble and quartz, and sedimentary rocks such as calcite and sandstone.

The flour is obtained by breaking the stones with a mallet or a hammer. Afterwards, it is passed through a sieve to obtain a fine powder like flour. At Canteras el Cerro we are dedicated to the production of exclusive varieties of rock flour, among which we highlight the properties of our Igea black rock flour.

How rock flour is applied

Obviously it will depend on the type of crop and the user’s preferences.

Broadly speaking, rock flour can be spread manually or it can be introduced into the soil with a shovel, plough or heavy machinery. It can also be spread mixed with a liquid using a knapsack sprayer.

Depending on the humidity, soil type, etc., it will be necessary to use more or less flour. It is important that it is of various colours, to ensure the use of different minerals and thus the best possible development of the plants.

Soils remineralised with rock flour provide us with healthy plants, which makes organic production possible.