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Precautions in the use of fertilisers. Guidance and advice.

Fertiliser’s use and precautions to avoid risks

Today, the use of fertilisers is widespread throughout the world. Fertilisers, also called manures, provide plants with the nutrients they need to grow. They can be organic, such as manure, slurry or peat, or inorganic, such as nitrogen, phosphate or potash fertilisers, among others..

The use of fertilisers brings multiple benefits. However, it is important to take certain precautions when applying them.

Recommendations prior to the use of fertilisers

Before applying any fertiliser it is important to consider:

The general state of the plants: age, productivity, foliar analysis, etc. to know the amount of nutrients they need.

– It should be taken into account whether the plantations are not yet in production or already in production as nutritional needs vary.

To determine the amount of nitrogen that crops need, soil analyses must be carried out and factors such as soil moisture must be considered.

Soil and/or foliar analyses, as well as knowledge of past fertilisations, are necessary to determine the dosage of phosphorus, potassium and magnesium to be applied. It is advisable to control, at least every 2 years, the requirements of these elements by means of this type of analysis.

– It is necessary to know the amount of manure and other organic amendments to be applied in order to avoid detrimental effects on organic production.

Climatic conditions are important as excess water and humidity, excessive transpiration, intense cold, lack of light or other conditions can profoundly alter the condition of the crop.

Risks arising from the use of fertilisers

As already mentioned, fertilisers can be natural substances, known as organic fertilisers, or chemical substances, called chemical fertilisers, inorganic fertilisers, mineral fertilisers or synthetic fertilisers.

The risks arising from the use and handling of fertilisers depend on the type of fertiliser:

Use of organic fertilizers: danger related to the emission of certain toxic and flammable gases (ammonia, carbon dioxide, methane and hydrogen sulfide). Also with the risk of infection for containing pathogenic organisms for human health. To a large extent they can be used in organic farming (treatment of organic products)

Use of chemical fertilizers: risks related to their physical-chemical characteristics and their degree of toxicity due to the use of chemical products.

Precautions in the use of natural or organic fertilizers

The raw materials used to make organic fertilizers can be harvest waste (fruits and vegetables), eggshells, animal manure, etc.

When using these natural resources, or organic waste as fertilizer, certain precautions must be taken:

– Organic fertilizers must be previously treated before being applied, to prevent crops from becoming contaminated with pathogenic organisms that are harmful to human health.

– Manure application should not be done in high quantities or at times close to harvest. It is preferable to mix it with other organic waste such as fruit and vegetable or garden waste.

– It is important to take into account the acidity of the soil.

Use of inorganic fertilizers and their environmental effects

In the agricultural sector, a multitude of chemical substances with different ranges of danger are used, among which are inorganic fertilizers.

The main risks derived from the misuse of fertilizers are:

– Theintrinsic properties of the chemical agent, such as the ease of the substance to be absorbed by the body and its ability to cause damage.

– Conditions that facilitate contact between chemicals and the person applying them, such as diffusion in the air, handling, frequency of skin contact, temperature, etc.

– The individual or personal characteristics of the applicator, such as age, sex, health status, etc. that may lead to greater susceptibility to damage.

– The incorrect handling of these substances, such as smoking while applying the products or not using the appropriate protective equipment.

The environmental effects that this type of fertilizers can cause are:

Soil infertility

Agricultural soilscan become saturated with the high levels of nutrients that some chemical fertilizers contain, also negating the effectiveness of other essential nutrients.

Soil infertility can also be caused by increased soil acidity, since many fertilizers contain sulfuric and hydrochloric acid, negatively affecting plant growth.

Increasing in microorganisms

There are many chemical fertilizers rich in nitrogen and an excess of this element can generate an increase in the population of microorganisms. This would be detrimental to the plants as they could consume all the organic matter and nutrients from the surrounding soil.

Underground water pollution

Plants are capable of absorbing only a certain amount of nutrients, so if they are applied in excess, they will not be assimilated correctly and will filter into the soil. Later, they could move with the rain and contaminate streams, rivers, lakes, reservoirs and oceans.

Salt burns

Chemical fertilisers are often very salty. An excess of salt in the plants could cause the dehydration of certain areas or their death.

Excess growth

The application of chemical fertilizers can cause plants to overgrow. A considerable increase in weight can affect the roots of the plant.

Effects of fertilisers on human health

The use of fertilisers can trigger health problems for humans. The main risks are:

– When handling organic fertilizers, you come into contact with biological matter and parasites that can be harmful.

– Some manures and fertilizers, when they decompose, emit toxic gases, such as ammonium nitrate, which irritate the respiratory tract and mucous membranes. Be very careful with toxic fertilisers

– The incorrect handling of certain fertilizers, such as calcium cyanamide, can cause skin burns.

– Improper storage of large amounts of fertiliser in pressurized tanks can cause explosions.

Is some type of certification needed for the handling of fertilizers?

The agrochemical industry distinguishes different types of phytosanitary products:

Pesticides: control biotic stress.

Fertilisers: provide nutrients to plants and stimulate their growth.

Biostimulants: increase crop yields.

In Spain, all those who carry out activities related to the use or handling of plant protection products must have a phytosanitary product handler card. With this card, it is ensured that they have been adequately trained to apply phytosanitary products correctly and that they comply with current regulations in this regard.

Phytosanitary products are those that appear on the list of products authorized by the Ministry. For its application, the phytosanitary product handler card is required.


It should be noted that there are four types of phytosanitary product applicator card according to the level of responsibility of the applicator:

– Basic

– Skilled

– Fumigator

– Applicator pilot