Environmental impacts of grazed clover/grass pastures
Year: 2009
Type: article
Abstract: Grazed clover/grass pastures are important for animal production systems and the clover component is critical for its contribution to N inputs via biological fixation of atmospher-ic N2. The resource efficiency and environmental emissions for clover/grass pastures can differ from that of N-fertilised grass-only pastures. Fixation of N2 by clover uses pho-tosynthetically-fixed carbon, whereas fertiliser N production consumes fossil fuels and has net greenhouse gas (GHG) emissions. Clover has a higher phosphorus (P) require-ment than grass and where extra P fertiliser is used for clover/grass pastures the risk of P loss to waterways is greater than for grass-only pastures. Nitrogen leaching from grazed pasture increases exponentially with increased N inputs and urinary-N contrib-utes 70 to 90 % of total N leaching. However, the few studies comparing clover/grass and N-fertilised grass-only pastures at similar total N inputs indicated similar N leaching losses. Nitrous oxide emissions from grazed pastures due to N-cycling of excreta are similar for clover/grass and N-fertilised grass-only pastures at similar total N inputs. However, grass-only pasture requires the application of N fertiliser, which will result in additional specific losses that don’t occur from clover-fixed N. Thus, total N2O emissions
Institution: AgResearch
Language: English
Subfield: Agronomy and Crop Science
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2101599688