slurry
Slurry is a naturally accruing manure , mainly from urine and feces consists of farm animals. Depending on the addition of litter and water, one speaks of thick or thin manure, alluvial manure or liquid manure or liquid manure (see manure ). High levels of combined nitrogen , phosphorus , potassium and other nutrients to make slurry a major fertilizer whose presence in agricultural plants the need for zuzukaufenden synthetic fertilizers can be reduced and used for the purposes of the circulatory thought on the farm accordance with good practice again. This keeps water (the main component of manure) and nutrients on the farm.
The word "manure" originally comes from Low German and means something like "puddle" or "pool". In the Alemannic areas of the German-speaking area (southwest Germany, Switzerland), liquid manure is also used as a synonym for liquid manure . In technical terms, however, Jauche refers to a farm manure that mainly consists of liquid excrement.
With professional application of farm and mineral fertilizers, the nutrients are completely absorbed by the plants. If there is excessive fertilization, soluble, superfluous substances such as nitrate are washed out and end up in the groundwater and the receiving waters . This is another reason why the application of fertilizer in Germany is strictly regulated. The requirements of the federal government regulate the Fertilizer Act and the Fertilizer Ordinance . In 2017 and again in 2020, the national fertilizer law changed fundamentally. It should lead to a reduction of environmental pollution and thus ensure the implementation of the EC nitrate directive .
In Europe, liquid manure plays a major role in the formation of fine dust in the atmosphere.
Slurry types
Liquid manure occurs particularly in pig and cattle farming . In poultry farming, on the other hand, solid manure is usually produced .
The nutrient salt content in the manure depends, among other things, on the type of animal, the feeding, the water content and the type and duration of storage. Liquid manure contains u as a mixture. a. the plant nutrients nitrogen , phosphate , potash and magnesia and is therefore a compound fertilizer .
Pig manure with a dry matter content of 7% per m³ contains an average of 4.9 kg total nitrogen, of which around 3.3 kg are readily available as ammonium nitrogen, 2.5 kg phosphate (calculated as P 2 O 5 ), 4 , 3 kg of potash and 1.2 kg of magnesia. Dairy and cattle manure contains about 3.9 kg total nitrogen per m³ with a dry matter content of 8%, of which about 2.2 kg readily available ammonium nitrogen, 1.7 kg phosphate (calculated as P 2 O 5 ), 4.6 kg of potash and 1.0 kg of magnesia.
Depending on the pH value and composition of the manure, ammonia can outgas, especially if it is not applied properly, which is not only a nuisance due to a pungent smell, but also a breath poison and a threat to the climate. When handling liquid manure, it should be noted that other dangerous gases can be released, such as hydrogen sulfide (smell of rotten eggs, breath poison), methane gas ("swampy" smell, explosive in certain proportions with the air) and carbon dioxide (odorless, leads to higher Concentration to fall asleep and to death from suffocation).
amounts
26.1 million pigs and 11.6 million cattle produce urine and faeces in Germany. Every year the farmers distribute more than 200 million tons of liquid farm manure on German fields and meadows, around half of which is cattle manure and a third is biogas digestate.
storage
Since liquid manure is constantly accumulating, but with a few exceptions, it can only be recycled with a delay, intermediate storage of large quantities of liquid manure is necessary. For economic and legal reasons, storage capacities of several months are often required.
Storage takes place in open or closed systems of various types ( slurry silos ), in which settling processes can create clumped floating and sinking layers. These impair the pumping and flowability of the liquid manure, which is why liquid manure mixers and liquid manure agitators are regularly used for stirring .
Use and recovery
Slurry drying is basically possible, for example to increase the transportability . Mixing it with dry matter (e.g. chopped straw) helps to reduce unpleasant odors.
Farm manure
The traditional and conventional liquid manure recycling way, the application as economic own fertilizer on fields and grassland with a manure spreader , which distributes the slurry on the surface or inoculating directly into the ground.
Possible effects on the environment must be taken into account. If liquid manure is applied in excess or at times of the year when the vegetation cannot absorb the nutrients it contains (in Central Europe: winter), the risk of nutrients being leached into deeper soil layers and seepage or runoff ( erosion ) in groundwater and surface water increases . Ammonium (NH 4 + ), nitrate (NO 3 - ) and other liquid manure constituents can be caused by eutrophication in water and the like. a. Cause algal blooms and kill fish . Manure fertilization is generally forbidden for vegetable and fruit growing, since dangerous pathogens (such as EHEC bacterial strains ) can get into the soil through animal excrement .
Spreading liquid manure on the surface of the soil - especially when using wide spreaders - is associated with nutrient losses, since volatile nitrogen compounds , especially ammonium, are lost. The Fertilizer Ordinance therefore prescribes immediate incorporation into the soil in Section 6. Corresponding technical devices for exact distribution are u. a. Drag hose and slotted shoe distributor on slurry tanks. These reduce emissions and thereby also nutrient losses and unpleasant odors.
In the 1970s and 1980s, a significant increase in nitrate levels in groundwater was noted in Germany and other countries. The water management authorities identified the manure management as the main cause. Stricter regulations on application with application bans outside of the growing season as well as the obligation of farmers to keep sufficient storage capacity available, could partially limit the problem. The introduction of additional measures as part of the European Water Framework Directive in 2000 did not result in a significant reduction in the nitrate content in groundwater .
The application of liquid manure on agricultural land is subject to legal restrictions. In Germany, application has been regulated since 1996 by the Fertilizer Ordinance (DüV), which is accompanied by supplementary ordinances of the federal states. There it is precisely defined what liquid manure is and at what times it is permitted to spread. Application bans exist in principle in flooded, water-saturated, deep-frozen and snow-covered soils as well as in the winter closed period (November 1st or 15th to January 31st).
Liquid manure can contain residues from veterinary drugs . Especially in intensive animal husbandry , in which antibiotics are used on a large scale, the animals excrete a large part of the substances in the faeces and urine unchanged. Spreading such manure also releases the pharmaceuticals into the environment. To a contamination of groundwater by preventing drug residues, the Federal Environment Agency, which advises for pesticides apply applicable limits for veterinary medicinal products.
In 2015, 55% of all farms in Germany applied liquid manure, i.e. liquid manure, liquid manure or liquid digestate from the biogas plant. A total of 204 million cubic meters of liquid farm manure was applied to 7.5 million hectares of agricultural land (45%). Around two thirds of the liquid manure was spread on arable land and around one third on permanent grassland. With a share of around 52%, cattle manure was most often used. Pig manure (15%) and liquid digestate from biogas plants (31%) were also often used. The remaining 2% was made up of liquid manure and other liquid manure.
Biogas production
| material | Biogas yield in m 3 per ton of fresh mass |
Methane content |
|---|---|---|
| Corn silage | 202 | 52% |
| Grass silage | 172 | 54% |
| Rye GPS | 163 | 52% |
| Pressed sugar beet pulp ensiled |
125 | 52% |
| Fodder beet | 111 | 51% |
| Biowaste | 100 | 61% |
| Chicken litter | 80 | 60% |
| Pig manure | 60 | 60% |
| Cattle manure | 45 | 60% |
| Grain Meat | 40 | 61% |
| Pig manure | 28 | 65% |
| Cattle manure | 25th | 60% |
Before being used as fertilizer, the organic compounds contained in the manure and not digested by the animals can also be used for energy. For this purpose, the liquid manure is broken down as a substrate in the fermenter of a biogas plant by microorganisms , generating methane-rich biogas that is burned to generate bioenergy .
After fermentation, all of the important plant nutrients in liquid manure can also be found in the digestate , which can be applied using the same technology as liquid manure. The plant availability of nitrogen is increased. The flow properties of the digestate are better because the organic compounds contained have been broken down. The digestate therefore drips off the plants more easily . The escape of hydrogen sulfide and the conversion to elemental sulfur during fermentation also reduce the odor nuisance during application.
Composting can be carried out after fermentation .
Full processing
After a six-year planning and construction phase, a processing plant was put into operation in Velen in the Munsterland region in 2019 , which extracts technically usable and marketable raw materials from overhang manure, primarily nitrogen and phosphorus compounds. The pilot plant has a capacity of 200,000 tons per year and is intended to cover 90% of the company's own energy requirements by generating biogas from the liquid manure supplied. Agricultural businesses in the area are involved with around five million euros in the investment of around 17 million euros; further funding came from funds from the federal special-purpose funds at the Landwirtschaftliche Rentenbank . Scientific support is provided by the Board of Trustees for Technology and Construction in Agriculture .
trade
At manure banks or manure exchanges traded with manure. In demand are, for example, farmers who do not keep animals themselves, but want to fertilize with liquid manure. Suppliers are, for example, farmers who have more liquid manure than they can use themselves.
Liquid manure is also traded across borders (liquid manure tourism ). Due to a decree issued by the NRW Ministry for Climate Protection, Environment, Agriculture, Nature and Consumer Protection on November 8, 2010, manure imports from the Netherlands and Belgium fell significantly. According to the decree, in order to minimize the risk of epidemics, only manure that had been pressure-sterilized could be imported (at 133 ° C and 3 bar for 20 minutes). In 2010 there were very few pressure sterilization facilities in the Netherlands. In 2011, the import of processed slurry (heat-inactivated at 70 ° C for 60 minutes) was permitted in North Rhine-Westphalia without a permit. In North Rhine-Westphalia , more controls against illegal manure imports were required in 2018.
Web links
- Liquid manure fertilization - fertilizer effect, application technology, legal requirements (Chamber of Agriculture North Rhine-Westphalia)
Individual evidence
- ↑ What is in the manure? Chamber of Agriculture NRW, April 16, 2019, accessed on April 16, 2019 .
- ↑ What is slurry? Chamber of Agriculture NRW, April 16, 2019, accessed on April 16, 2019 .
- ↑ University of Augsburg : What does our food really cost? In: Wissen.de , October 8, 2018, accessed October 8, 2018.
- ↑ fertilization. Federal Ministry of Food and Agriculture, April 16, 2019, accessed on April 16, 2019 .
- ↑ IASS fact sheet 1/2016: Agriculture, ammonia and air pollution ( Memento from August 12, 2007 in the Internet Archive )
- ↑ Bavarian State Research Center for Agriculture: nutrient content, nutrient effect, volume, application ( memento of August 12, 2007 in the Internet Archive ).
- ↑ Average nutrient content of organic fertilizers (guide values, as of January 2014). (pdf) Chamber of Agriculture North Rhine-Westphalia, accessed on May 8, 2020 .
- ↑ The four gases in manure. Agricultural Social Insurance, accessed May 2, 2018 .
- ↑ Federal Statistical Office: Animals and Animal Production , online at www.destatis.de, May 8, 2020
- ↑ Federal Statistical Office: Half of the farmers fertilize with liquid manure , online at www.destatis.de, May 8, 2020
- ↑ Methane and nitrous oxide - the forgotten greenhouse gases. WWF Germany, November 2007, accessed on September 22, 2019 . P. 19.
- ↑ Veterinary medicinal products - a new problem for groundwater? Federal Environment Agency, March 21, 2014, accessed on March 8, 2015 .
- ↑ Current fertilization on Destatis.
- ↑ Fachagentur Nachwachsende Rohstoffe e. V. (FNR): Biogas basic data Germany. (PDF; as of October 2008). Source for all information except for pressed pulp.
- ↑ Biogas yields of different substrates, division potatoes / beets lfl.bayern.de, see pressed pulp ensiled .
- ↑ Angelika Gördes-Giesen: When manure is turned into gold. WDR5, July 26, 2019, accessed July 26, 2019 .
- ↑ Diethard Rolink: NDM wants to relieve Westphalia of 200,000 t of manure per year. July 30, 2015, accessed July 26, 2019 .
- ↑ Environmental technologies for the full processing and sanitization of liquid manure. Retrieved July 26, 2019 .
- ^ Rheinische Post, May 23, 2011
- ↑ Policy: Import of Dutch manure newly regulated. In: topagrar.com. October 20, 2018, accessed November 19, 2019 .
- ↑ Alfons Deter: More control should curb illegal manure imports In: topagrar.com , October 13, 2018, accessed on October 13, 2018.