Slurry and manure, the best due to the lack of nitrogenous fertilizers

Agricultural production with the use of organic manure and manure fertilizers is the best solution, given the current shortage of nitrogenous fertilizers caused by the conflicts in Russia and Ukraine.

What is purin?

The slurry of animals is the excrement of pigs, cows, sheep, horses and birds stored in closed enclosures and in liquid form, that is, dissolved with the urine and water that normally comes from the cleaning of livestock farms.

Vegetable manure is the result of the fermentation of certain plants and can have fungicidal or soil-activating effects.

Purines are therefore natural organic fertilizers that serve as nutrients for plants without the need to use chemical products.

The «Council Directive 91/676/CEE of 12 December 1991 relative to the protection of waters against contamination caused by nitrates of agricultural origin« is the regulation that governs the use of manure.

The minerals that make up slurry are fundamentally nitrogen, phosphorus, potassium and calcium.

Manure discharges are prohibited by the Spanish Water Law. Therefore, the use of slurry should be as a nutrient for agricultural areas and for gardening.

In addition, the distribution must not exceed 15 km from the farm, except with 20m3 tanks. The definitive regulations depend on the Autonomous Communities and the City Councils.

What is manure?

It is the mixture of excrement with straw or broom that is normally used by the farmer for animal bedding. The plants ferment with the solid and liquid depositions and form a compact organic fertilizer.

It is the perfect component to nourish the soil and is especially advantageous for crops of beet, rapeseed, barley, vegetables, trees, etc... It is spread in the furrows and covered before planting or at the same time as the crop is sown. It should not be outdoors much to avoid the evaporation of ammonia and odorous gases.

The tillage of the land causes the manure to mix with other plant remains, so that we obtain a fertilized soil in an ecological and renewable way.

What are fertilizers?

Fertilizer: is any substance that contains one or more nitrogenous compounds and is applied on the ground to increase the growth of vegetation, including manure, waste from fish farms and sewage sludge.

Chemical fertilizer: produced by an industrial process.

Eutrophication: the increase in the concentration of nitrogen compounds, which causes an accelerated growth of algae and higher plant species, and causes negative disturbances in the balance of the organisms present in the water and in its own quality.

Pollution: the introduction of nitrogenous compounds of agricultural origin into the aquatic environment, directly or indirectly, which has consequences that may endanger human health, harm living resources and the aquatic ecosystem, cause damage to places of recreation or cause inconvenience for other legitimate uses of the waters.

Nutrient cycle with slurry and manure
Nutrient cycle with slurry and manure

Slurry storage

When the farmer has a considerable number of animals, farm or macro-farm, he must have a tank to store the manure, with a channel that collects all the excrement, liquid and solid. These mixed with the water to clean the stables or without water and accumulate in the deposit.

We must avoid carrying soaps. For this reason, the milking parlor, in the case of a dairy animal farm, is usually isolated and with cleaning waste channeled apart from slurry.

To avoid the volatility of ammonia, the pits must be covered, which is mandatory in new installations and protected with enclosures, sometimes buried for the convenience of the installation and thus avoid the emission of gases.

Why does the purine contaminate?

Within the slurry we find ammonia (NH4) in equilibrium between an ionic form soluble in water and ammonia in gaseous state (NH3). As the formula indicates, it is a mixture of nitrogen and hydrogen and the gaseous form volatilizes with the contact of the slurry surface and the intermittent air, resulting in contamination.

Ammonia nitrogen comes from the urea contained in the urine of cattle and from the intake of forage. Pig slurry releases the most ammonia (75%), followed by beef (40%).

To avoid contamination in stables it is very important that they remain clean. Currently, automatic cleaning systems can be installed that transfer the excrement to the tanks. These cleaners are installed between the beds (in this case sand) and the feeders.

The distribution of the slurry is done with tanks that can launch the mixture onto the ground with a plate, fan or cannon, also with direct injectors into the furrows.

It is important to control and regulate all waste for reuse while avoiding pollution.

Video of the automatic cleaning of a dairy cow farm in Galicia

Disadvantages of the use of manure

We have already commented that one of the problems is its storage. The other is its distribution.

Less polluting procedures are being studied. Some Communities already have proposals for decrees that prohibit aerial spreading in some types of plots and crops.

The aim is to implement the obligation to distribute the slurry with injection systems if the moisture level is greater than 65% and buried like manure if the percentage is lower.

In addition to having a control of the application of fertilizers or purines by means of an accredited technician.

When we want to move it to more distant areas, more problems arise, because in liquid form it is quite difficult. The solid form of manure or solid waste from poultry and sheep is easier.

Possible solutions, some under study:

  • Systems capable of removing liquid ammonia from slurry reservoirs.
  • Extract ammonia in the environment of farms, especially in the case of poultry.
  • Eliminate water and convert it into solid manure that is easier to transport and distribute.
  • Pits with capacity adapted to the number of animals to avoid spills. In case of surplus, have alternative deposits and that are located near the livestock areas.

All this requires economic aid from the Administration, to create storage, transformation and means of transport points.

Advantages of using slurry

The main advantage is that slurry and manure are organic fertilizers. If we avoid contamination in its storage and distribution, it is much better than the use of chemical fertilizers. At the same time that the nutrient cycle is closed. It is the ideal fertilizer for crops close to livestock farms.

Its application is recommended to farmland:

  • On days before the rainy ones that help them to get into the ground.
  • Better not be a windy day.
  • Low temperatures.
  • Soils tilled or with vegetation.

We must complement this fertilizer with green manures:

  • The stubble from the farms or green manures that we get from the weeds that serve as both a nutrient and a support.
  • Pruning remains.
  • Postharvest straw.
  • Non-operational waste: peat, compost, fresh population garbage, composted urban garbage.

In gardening it is common to mix green fertilizers with sludge from EDAR (Wastewater Treatment Plants).

If we also control the needs of our soil, depending on the type of crop, we can better manage waste and at the same time collaborate with the environment.

It is very important to understand the accounting of the land, that is, through the analysis of the land we can know what its balances are and design a reserve consumption strategy, which is very possible that we have them.

According to the CAP regulations :

"The data on the nitrogen content in the soil obtained by means of in situ meters, suction probes or lysimeters, installed in the edaphic zone and, where appropriate, in the vadose zone, will be carried out on the areas especially affected".

And, of course, we relate everything to the water balance of our soil. Since in order for nutrition to occur, the plant must be able to hydrate itself, so having the moisture content of our soil controlled is vital to be able to know if there is nutrient extraction.

Fundamentally, with all this we avoid the manufacture of fertilizers that require high fuel consumption and release a high content of CO2 into the atmosphere.

Regulations for spreading slurry and manure

According to the PAC 2022 slurry must be spread with a certain regulation that each Autonomous Community can adapt according to its needs by the Royal Decree 1078/2014.

  • Slurry cannot be applied with plates or fans, especially in transitory intensive farms, that is, crops that are sown or planted after each harvest.
  • Manure distribution cannot be applied at temperatures above 30ºC.
  • Do not fertilize surfaces with average slopes greater than 20% with slurry.
  • The manure must be buried within a maximum of five days after being spread, except for a major cause.
  • Avoid urban areas.

The following are exempt from the regulations:

  • Cultivos de cobertera que se siembran con la finalidad de fertilizar el suelo o que retengan el agua. Favorecen la biodiversidad..
  • Applications in pastures and permanent crops, that is, they live for more than two years, such as vineyards, olive groves, pistachios, almond trees and others.
  • Plots that are cultivated with direct sowing techniques, so that after sowing the soil cannot be disturbed.


Vacas con alimento ecológico
Typical Galician cow with organic food
Reciclaje-Agricultura sostenible
Sustainable agriculture

The objective is to ensure that manure, slurry and fertilizers in general, are applied to the soil using procedures or methods that do not endanger human health and do not harm the environment.

It will be taken into account when spreading a certain amount of slurry: the type of soil and the type of crop.

Also: the slope of the land, the climatic conditions, the type of irrigation. and crop rotation.

Finally, the amount of nitrogen in the soil.

In addition we must bring:

«The parcel register of the areas of application of manure, slurry and other materials containing nitrogen, such as sewage sludge».

«The georeferenced record of the places where manure and slurry are generated, including the amounts generated, their management and the manure storage tanks and slurry ponds».


Importance of Plantae sensors in fertilizer management

All crops need fertilizers to get the minerals that the plant needs. But the control of soil moisture is the basis of the absorption of nutrients by the plant.

The New Moisture Sensors - Production Begins at Madritonic controlan el grado de agua necesario y suficiente para que la planta tenga cubiertas sus necesidades sin sufrir estrés hídrico y el aporte de nutrientes sea equilibrado y el necesario en cada momento de su estado fenológico.

Humidity control ensures that the plant gets the nutrients it needs when it needs them. The excess of water causes the components of the fertilizers to dissolve in excess and contaminate the soil because the plant is not able to absorb them.

Los sensores de temperatura del suelo nos controlan el estado del sistema radicular y con ello podemos evitar enfermedades de la planta.

Conductivity probes prevent the accumulation of salts that makes the plant absorb nutrients less well.

Todo lo expuesto nos lleva a las tres claves de la agricultura circular y sostenible: reducir, reciclar y reutilizar.



Plantae AGRO


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