In conventional agriculture, fields are often fertilized with the excrement of cows and other farm animals. But there is another way, as a new study shows. Accordingly, organic and green waste compost can also be used as fertilizer. The quality of this compost has increased significantly in recent years. It can now help to improve the soils in fields and fields. This is a good option, especially for organic farmers who practice organic farming, according to the researchers.
Large amounts of green waste and organic waste are generated in Germany every year. These can be fermented and composted in large plants and processed into fertilizer. This currently produces around 2.5 million tons of fresh compost every year. For a long time, however, this organic compost was considered inferior compared to the excrement of animals that is otherwise usually spread on fields. But is that still true?
How good is organic compost?
Researchers and entrepreneurs have now examined this in a joint joint project. As part of the “ProBio” project, they carried out practical tests at different locations over several years. They fertilized the fields with different compost mixtures, planted them with different crop rotations and then evaluated measurement data on soil quality.
This showed that fertilization exclusively with compost made from green waste and organic waste is completely sufficient to maintain the areas and even improves them. This gave the soil more phosphorus and potassium. The nitrogen content of the soil could also be increased. This was particularly true for organic compost made from organic residues from private households, as the team announced. The biological activity also increased in the test fields where this organic compost was spread over several years. This means that more microorganisms and animals lived in the soil, which is crucial for the fertility and health of the field. In addition, more humus accumulated. This applied to both types of compost, but green waste composts had a slower but longer-term effect than compost made from organic waste.
High quality, low demand
The tests also show that the quality of such organic compost has steadily and significantly improved between 2015 and 2024. Today they also contain significantly fewer heavy metals and foreign substances. Around 70 percent of the composts examined proved to be suitable for organic farming, where stricter limit values apply than in conventional agriculture. According to the researchers, organic fertilizers could make an important contribution to nutrient supply, humus build-up and improving soil fertility in agriculture, especially in organic farming and for farmers without their own livestock. This would not only be less harmful to the climate than animal husbandry and the use of animal manure, but would actually be good for the climate, the team emphasizes. The newly created humus binds the greenhouse gas CO2.
But despite the progress and great potential, only a few organic farms are currently using this organic compost in their fields. Less than ten percent of the available compost is used, a survey of farmers has shown. Instead, they usually use other organic fertilizers. However, almost 80 percent of the companies surveyed could imagine using organic compost in the future. Calculations showed that this could also be economically worthwhile for most companies.
“There were concerns and reservations [bei den Landwirten] regarding logistics, especially the accessibility of the composting plants, the high transport costs, the lack of storage options,” says the project’s final report. In order for the switch to be successful and generate profits, farmers should now be better networked with the compost manufacturers and have better access to organic and green waste composts. A newly developed system should also help Information system.
Source: Federal Agency for Agriculture and Food (BLE); Final report “ProBio”