Till now, the cow has been regarded as a killer of the climate, because, with their digestion, the animals produce methane, which is expelled continuously.
Now, the German and Czech team have concluded that when bovines don't spend the cold season exclusively in the cowshed, and are kept out on winter pastures, they have the potential to produce methane.
The study, carried out on a Czech farm, proved that two factors are vital for this process to take place: the amount and quality of organic material from the excrement and the strong compaction of the soil by the weight of the cattle.
These changes facilitate methane-producing microorganisms from the gastro-intestinal tract of the animals can be established in the soil while, simultaneously, the process of methane oxidation is restrained.
"The over-wintering of bovine animals is quite widespread at least in the ecological agriculture of Central Europe as a whole," Dr. Michael Schloter, lead author of the study, said.
"The reasoning is that the animals are less susceptible to infectious disease, thanks to the movement outside and, therefore, fewer antibiotics need to be used. However, this connection has not been proved," he added.
The investigation was carried out on a farm in South Bohemia.
The area in question comprises approximately four hectares and has been used since 1995 for the over-wintering of about 90 cows from October till the beginning of May.
According to Schloter, "At the end of this season, we could clearly see the consequences of the over-wintering, on the soil."
Unlike typical summer grazing, where the animals spread out evenly, the animals on the winter pastures prefer to stay near the feed house.
As a result, no vegetation was visible any more in this area, and the ground was strongly compressed. In addition, this area was marked by a very high incidence of organic matter from the excrement of the animals. In more distant areas, the consequences were far less drastic.
The intensive grazing in the areas close to the cowshed led to a clear increase of methane emissions throughout the whole winter. These showed 1,000 times more than the control areas, where no bovine animals were kept.
Methane oxidation is the metabolic way that can lead to the breaking down of the methane.
The scientists were able to show further that methane producing micro-organisms from the gastro-intestinal tract of the cattle could survive in the soil and suppress parts of the autotchtone microflora.
"We shall continue the project, because we also suspect consequences for the nitrogen cycle," adds Schloter.
"All in all, it can be said that just about every agricultural measure has its positive and negative consequences. What weighs more in each case, however, is a social, rather than a scientific question," he said.