Swiss Federal Research Station for Agroecology and Agriculture, Zurich-Reckenholz

Ammonia exchange with grasslands

As it is generally known, plants can exchange ammonia (NH3) with the atmosphere. Yet, the actual NH3 exchange potential of crops, especially of grassland, has hardly been studied so far. The European project GRAMINAE focused on the influence of climate and management on NH3 exchange between grassland and the atmosphere on different sites throughout Europe. At the Swiss site, located in an intensively managed agricultural area, research emphasised on NH3 exchange potential of the individual grass species of a grass/clover mixture. The research was based on plant physiological processes at N application levels of 80 and 160 kg N per hectar and year. In contrast to annual crops no NH3 emission was measured from the grass/clover crop during the entire regrowth periods. NH3 emission was restricted to periods after the cut and especially after fertilization. A higher clover fraction and a higher N2 fixation rate at the lower N application resulted not only in an equal N yield but also in an equal NH3 uptake potential of the plants for both treatments. The fact, that grass and clover acted as a NH3 sink during regrowth periods points out the buffer capacity of rough fodder cultures in intensively managed agricultural areas.

To the archive