In the right form and in the right place, the manure of domesticated animals is a valuable source of nutrients.
For many, however, manure is a burden. More efficient processing and utilisation of manure could make it a source of income, helping to bind nutrients in crops instead of the environment. Why, then, is manure not recycled?
“In Finland, animal husbandry and crop farms are concentrated in different parts of the country”, says Juha Grönroos, Principal Research Scientist at the Finnish Environmental Institute (SYKE).
“In some parts of the country, too many nutrients are accumulated, while in other parts of the country, nutrient needs are supplemented by purchasing fertilisers. Manure should be spread over a larger area, but transporting manure in itself is not sensible.”
The bulk of manure ends up where it in principle should – in an unprocessed form in the field.
However, producers need to restrict the use of manure and increase the area over which manure is spread due to regulation becoming more stringent and on account of the fact that the phosphate levels of the soil are high following large volumes of manure having been spread in large volumes in the past”, says Sari Luostarinen, Principal Research Scientist at the Natural Resources Institute Finland (Luke).
According to Grönroos, there is a need for processing.
“The proportion of nutrients contained in manure is not optimal from the perspective of plants. This challenge is coupled with the fact that the nitrogen in manure easily evaporates in the form of ammonia”, Grönroos says.
“Only a fraction of all the manure produced by the domesticated animals in Finland is delivered to plants”, Luostarinen says.
“This is the situation, although there is a lot of talk about biogas, for example”, she says.
The producers are interested in the subject, and would be more than happy to obtain a new source of income from the processing of manure.
“The problem lies in substantial investments and in the uncertainty of the methods that would be suitable for a particular farm”, Luostarinen remarks.
According to researchers, an individual producer should not necessarily invest in manure processing but, rather, develop processing in collaboration with other producers in the same area.
“The profitability of processing greatly depends on the characteristics of manure. For example, when testing the flinging of liquid swine manure, we noticed that the method is only cost-effective with concentrated liquid manure”.
Processing is not necessarily the best solution.
“For example, when planning a biogas plant, one of the issues to take into account are the questions of how and where nutrients could be used most efficiently”, Luostarinen says.
“The spreading of manure in fields can also be made more effective”, Grönroos says.
“If animal husbandry and crop farms could collaborate more closely and if solutions could be found for sensible transport of manure”, Grönroos says.
Every link in the chain of manure handling – with or without processing – must be thoroughly thought out. All the pieces of the jigsaw must fit together in order to ensure that the whole will be functional and sustainable, both from the perspective of the environment and the economy.
“The producer should not be left alone to deal with these questions. For this reason, for example, under our ’Teholanta’ (’Power manure’), we are in a process of creating uniform instructions for poultry producers for the utilisation of manure”, Luostarinen says.
Text. Anna Toppari, Luke
Published in Finnish in Maaseudun Tulevaisuus on 3 October 2016.