Browsing by Subject "managed grassland"

Enhancement of soil carbon sink has large potential to mitigate climate change. Earlier studies have suggested that improved management practices could promote climate change mitigation and improve soil fertility. To find out if the carbon sink of a clay soil under improved grassland management in Southern Finland can be enhanced by increasing mowing height at harvest, an experiment was set up with two different mowing heights (6 and 15 cm). Net ecosystem carbon exchange, based on total ecosystem respiration and photosynthetic capacity were monitored with chamber methods during three growing seasons from 2019 to 2021. Also, plant biomass, leaf area index, soil temperature, soil pH, soil water retention capacity, and soil grain size distribution were studied at both mowing height treatments. In this study, negative value is the CO2 flux from the atmosphere to the ecosystem and positive value is the CO2 flux from the ecosystem to the atmosphere. Negative NEE means that the ecosystem gains C when the absolute value of GPP is greater than TER and vice versa. The higher mowing height increased CO2 uptake by plants and caused more negative NEE for the higher mowing height after the grass was harvested. These results indicate that higher mowing height might be better for mitigating climate change. However, mowing height did not have a significant effect on biomass, LAI, TER or soil properties in the experiment. Short lasting and non-existent differences between mowing heights are probably explained by more pronounced compensation growth reaction at the lower mowing height as growth conditions were otherwise similar except for mowing height treatment at both treatments. More frequent measurements, especially after the harvest, could better reveal the dynamics of grass height differences and its effects on GHGs. Better detection of the effect of mowing height on the carbon balance would require even more regular and continuous measurements after harvesting and fertilization in different soil types with experimental setups such as applied in this study.