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3篇 您的检索式:作者名="Stewart LEDGARD"
    题名 作者 年代 出处 被引量
1Uncertainty of global warming potential for milk production on a New Zealand farm and implications for decision making显示文摘Claudine Basset-Mens Francis M. Kelliher Stewart Ledgard Neil Cox 2009The International Journal of Life Cycle Assessment2009,,7:1
2Nitrogen cycling in low input legume-based agriculture, with emphasis on legume/grass pastures显示文摘Stewart F. Ledgard 2001Plant and Soil2001,,1:1
3NEW ZEALAND DAIRY FARM SYSTEMS AND KEY ENVIRONMENTAL EFFECTS显示文摘This paper provides an overview of the range of dairy pasture grazing systems used in New Zealand(NZ),the changes with increased inputs over time and associated key environmental effects including nitrogen(N)leaching and greenhouse gas(GHG)emissions.NZ dairy farming systems are based on year-round grazing and seasonal milk production on perennial ryegrass/clover pasture where cows are rotationally grazed in paddocks.There was an increase in stocking rate on NZ dairy farms from 2.62 cows ha−1 in 2000/2001 to 2.84 cows ha−1 in 2015/2016.During the same period annual milk solids production increased from 315 to 378 kg·yr−1 per cow.This performance has coincided with an increase in N fertilizer use(by~30%)and a twofold increase in externally-sourced feeds.Externally-sourced feeds with a low protein concentration(e.g.,maize silage)can increase the efficiency of N utilization and potentially reduce N losses per unit of production.Off-paddock facilities(such as standoff or feed pads)are often used to restrict grazing during very wet winter conditions.A systems analysis of contrasting dairy farms in Waikato(largest NZ dairying region)indicates that the increased input would result in an increase in per-cow milk production but little change in efficiency of milk production from a total land use perspective.This analysis also shows that the increased inputs caused an 11%decrease in N footprint(i.e.,N emissions per unit of milk production)and a 2%increase in C footprint(i.e.,greenhouse gas(GHG)emissions per unit of milk production).Jiafa LUO Stewart LEDGARD 2021Frontiers of Agricultural Science and Engineering2021,8,1:0
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