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Study of agricultural soils. Complete guide

Study of agricultural soils

What is the ground? Meaning of Fertile Soil

The soil is the thinnest layer of the Earth’s surface and its fertility is due to the action of the atmosphere, the water and the microorganisms that live in it. This surface layer is the one that concentrates all the agronomic interest, since its high organic matter allows the farmer to develop crops. Knowing its behavior will favor the production of biomass thanks to a balanced fertilization.

What is the composition of the soil?

It is composed of a solid phase (minerals and organic matter), a liquid phase (water) and a gas phase (air between the particles). The interaction of the three phases gives the soil certain physical, chemical and biological characteristics.

The solid phase , which is mainly composed of particles of inorganic origin , acts as a reservoir of macronutrients and micronutrients such as potassium, calcium, magnesium and iron. To a lesser extent, it is also composed of a part of organic origin , composed mainly of nitrogen, phosphorus and sulfur. The organic origin of the soil comes from the decomposition by microorganisms of plant and animal material. This phase is closely related to the soil being fertile and suitable for agriculture.

The liquid phase of the soil is where the macronutrients and micronutrients that are essential for plant nutrition are found in solution.

And the gas phase, it consists of the spaces between the soil particles, which allow the exchange of nitrogen, oxygen and carbon dioxide.

How does the composition of the soil influence the development of the crop?

The variation of the three phases explained above will influence the physical characteristics of the soil type suitable for agriculture. Soil texture , structure , temperature and color determine the quality of a soil. In short, it is essential to study and analyze the soil where our future crop will grow in order to obtain optimal production performance.

Texture refers to the size of the particle and the presence of clay gives rise to the classification of three types of soil.

Types of soil according to its texture:

  • Sandy soil , when the clay represents less than 10%.
  • Loam soil , when the clay represents between 10% and 30%.
  • Clay soil , when the clay represents more than 30%.

Texture is an important part that will determine if the soil is suitable for agriculture, since it can directly influence its capacity to retain water , nutrients and the amount of air . This, which many farmers and agricultural technicians intuit from their experience, should be done with a soil study that is reflected in the Soil Analysis report. In this way, the type of fertile land will be determined in order to act accordingly.

For example, a clay soil will be characterized by a smaller particle size, and due to the little space that exists between particles, it will favor a greater retention of water and nutrients, but there will be less air flow between the particles, which will increase the probability of waterlogging ground.

On the other hand, in a sandy soil, the size of the particle will be greater, so the retention of water and nutrients will be less, therefore, there will be a loss of two essential components for the development of a crop.

It is essential that for the correct development of the crop there is an adequate structure of the soil, so that there are different particle sizes that allow the retention of water and nutrients, avoiding waterlogging, and there is also a correct oxygenation of the roots of the crop.

In addition, the color of the soil can help classify the soil where we want to plant our crop. A white soil is indicative of the high presence of carbonates and sulfates, while a dark soil will be indicative of a high concentration of organic matter. A greenish soil implies that clay predominates in its structure, therefore, it is a soil that tends to waterlogging and lack of aeration.

What factor influences soil fertility?

The decomposition of organic remains gives rise to a soil acidification process , mainly caused by the organic acids released into the environment which, in solution with the liquid phase, release a large quantity of H + ions, causing the organic particles to acquire a negative charge. This process gives rise to cation exchange capacity (CEC) , where positively charged mineral cations such as potassium, calcium, and ammonium bind to the surface of these particles.

That is why the analysis of agricultural soils to find out their CEC will give us a better understanding of whether the soil is fertile or not, that is, if our soil is suitable for agriculture. A soil containing a high CEC will provide more nutrients to the root of the plant.

The water, pH and salinity in the soil

The availability of water is essential for the proper development of the crop and is a great challenge facing humanity. But very especially the peninsular southeast since the new conditions generated by climate change that we are facing are causing it to be a scarce commodity. That is why the importance of a correct use of this precious resource to save water and nutrients.

We must know the water with which we irrigate our crops, that is, we have to analyze the irrigation water to interpret and know what nutrients are present in it to efficiently fertilize our soil.

A greater use of solid fertilizers implies a greater use of water to be able to dissolve them, which can lead to a loss of essential nutrients for the development of the crop towards the deeper layers of the soil through the leaching process.

The pH of soil and water are closely related to the availability of nutrients by the plant. In the soil, the texture of a soil will determine the power of regulation of the pH level, since the size of the particle will influence the retention capacity of ions and cations in the CEC.

As we have seen in the section on soil fertility, a higher concentration of organic particles released a large quantity of H + ions into the medium, generating an acidification of the liquid phase which in turn allows the binding of cations to these particles.

Finally, the salinity of a soil is due to the use of saline water during irrigation and the type of fertilizers we use. The excess of salts negatively influences the intake of water through the root of the plant, which will cause stress since it will have to use more energy for its absorption.

This is a serious problem in arid areas, where the lack of rainfall prevents the leaching of salts and this leads to an increase in the amount of water to wash the agricultural land of salts.

The continuous loss of organic matter and soil texture are related to a major erosion process, making it unusable for cultivation.

Solutions that we propose from our company

From Industrias Químicas Fervalle we can provide solutions to our farmers so that the agricultural soil presents optimal conditions for the development of the crop.

Although we have previously explained that the organic part gives rise to a fertile soil, we propose that MAORVALLE be added to the irrigation water. Its formulation rich in organic matter will contribute to increasing the particles of organic origin in the soil, favoring soil acidification, which will contribute to increasing the soil’s cation exchange capacity.

On the other hand, the addition of HUMIVALLE , from American leonardite, will favor the union of the existing particles in the soil, helping to strengthen its texture. Both products are essential to apply to types of soil that need to increase the conditions to make it suitable for agriculture.

Once we have measured the pH of the soil and the irrigation water, we must make decisions. Most of the soils in the Iberian Peninsula are basic in nature, that is, they have a high pH and a white soil due to the high concentration of calcium carbonate, preventing the binding of micronutrients and other essential cations to the complex of change.

As a method to lower the pH of the soil, it is necessary to regulate the pH of the water with which we irrigate. For this we must add an acidifying solution such as the products PH VALLE and/or PH COLOR . In this way, it will help favor the acidification of the liquid phase of the soil and thus increase the use of the nutrients provided during irrigation by the root of the plant.

For greater control of the salinity of our soil, as we have explained previously, it implies that a solution rich in calcium is added to the agricultural soil, such as the one provided by the DESALVALLE product , so that it competes with the sodium bound to the exchange complex . The release of sodium will cause it to be dragged in the successive stages of irrigation towards the deepest layers of the soil, freeing the rhizosphere from the presence of salts that are harmful to plant growth.

Now that we have seen what is the most important thing in the study of agricultural soils and why it is so important to do a soil analysis or soil analysis, the next step is to carry out a soil report on your farm to know all these parameters and act as soon as possible.