Available Technical Improvements in Slurry Management

When evaluating a pig farm project, the administration (and society as a whole) always put the spotlight on the management of manure, since they are responsible for the greatest impacts on the environment. In the basic projects for the request of a Integrated Environmental Authorization (AAI) of a new farm or because of a modification of an already created one, it is crucial to detail the best available techniques (MTDs) that will be carried out in the management of slurry or manure. This is a key aspect that can make a difference when it comes to getting the green light on our project.

What the Law Says

La Act 16/2002, of July 1, on integrated pollution prevention and control, replaced all the environmental authorizations that existed at the time. More recently the RD 1/2016 integrated this law with others that had emerged that regulated industrial emissions. Are all pig farms subject to the Integrated Environmental Authorization (AAI) procedure? The answer is no. Let us know if this Royal Decree is applicable or not, we must read its Annex I. This Annex (which all environmental consultants have framed) reads as follows:

“9.3 Facilities for intensive farming [...] of pigs that have more than:
[...]
b) 2,000 places for bait pigs weighing more than 30 kg.
c) 750 places for breeding sows.”

Thus, if we exceed 2,000 places for fattening pigs, our project will have to request an AAI and will also be subject to an ordinary Environmental Assessment in accordance with Annex I of the Law 21/2013 (which hangs on the same wall as the previous one).

And how many pigs can I have on the same farm? Well, according to RD 306/2020 that we analyzed In this other post, the maximum is 720 Major Livestock Units (UGM). If, for example, we were talking about bait pigs, these 720 UGM would be equivalent to 5,142 pigs and, if authorized by the Autonomous Community, it would be possible to extend this maximum capacity by an additional 20%.

Pork sector and sustainability

In our country, there are already examples of this type of intensive “macro farms” that concentrate thousands of pigs in a small space. In some cases, these projects have generated social alarm and have even been dismissed. What is the reason for this rejection? There is no single reason, but besides ethical issues related to animal welfare, the common factor is always sustainability.

Despite the importance of emissions from this livestock sector, the main criticisms are usually directed at possible contamination of inland water bodies by manure. The economic importance of this activity, which helps to settle the population in rural areas, has not been enough to prevent some peoples from mobilizing against them.

Are all farms the same? Can I differentiate myself?

A pig will always be a pig and associated with its diet there will always be a consumption of water and feed, a production of manure and polluting emissions to the atmosphere. The greater the number of pigs, the greater the consumption of resources, the generation of waste and emissions. So far so good (or bad) but how can my farm be more environmentally friendly? Then introducing improvements that will help reduce their derivative impacts, especially those related to slurry management.

A pig will always be a pig and associated with its diet there will always be a consumption of water and feed, a production of manure and polluting emissions to the atmosphere.

These best available techniques (MTDs) are compiled by the European Commission, which in 2017 published the Decision (EU) 2017/302 with regard to intensive pig farming. Here are some highlights:

1. To reduce ammonia emissions, the installations must be properly designed (total floor grilling, V-pits...), reducing the agitation of the slurry and covering the tank or pond.
2. To avoid emissions to soil and water, we must waterproof all buildings that are in contact with the slurry, periodically check their integrity (these types of tasks must be included in the general maintenance plan and why not? in the Environmental Management System of our farm) and install leak detection systems.
3. To reduce these same emissions, we can treat manure by performing anaerobic digestion. This process generates methane-rich biogas that can be used in cogeneration engines to obtain electricity from renewable sources and thermal energy for self-consumption in the plant itself. On the other hand, a liquid digestate is obtained that can be used as fertilizer in the fields. In this link you can see an example of a technical data sheet for a plant in Torregrossa (Lleida).
4. If we choose to apply manure directly to the field, there are numerous good practices that can be done. We will mention deep injection in a closed groove, since it is a technique with high environmental efficiency that can reduce ammonia emissions by up to 70%. In this way, not only will we value waste, with the consequent saving of fertilizers and reducing costs for farmers, but we will also be able to alleviate the discomfort derived from the odors of slurry.

So I throw the slurry into the field and that's it?

Spain is the 4th largest pig producer in the world (behind only China, the United States and Germany). There are already more pigs than people and that means a large production of faeces. If we take as an example a farm of 5,000 bait pigs, it is estimated that 7,500 tons of manure will be produced each year. Faced with such magnitude, we must be very clear about when, how much and where to apply the slurry to the field:

• When: Meteorology plays a role. We cannot apply slurry on icy or water-saturated soil, for example.
• How much: the amount of slurry determines the nitrogen content and this must be in balance with the needs of the crop.
  
• Where: the necessary area must be calculated based on the types of cultivation of each plot and whether it is a vulnerable area or not.

All of this must be perfectly documented in your Slurry Production and Management Plan. If you have any questions at Environmental Ideas we can help you prepare any environmental documentation and improve the environmental performance of your farm.