The intensification of modern pastoral agriculture
has increased the risk of environmental degradation.
The use of nitrification inhibitor technology has been
shown to reduce nitrate (NO₃
⁻) leaching losses and
nitrous oxide (N₂O) emissions from New Zealand
dairy pasture systems. However, published data on
inhibitor usage to reduce these losses from intensive
sheep winter grazing systems is also needed. A trial
was conducted at Lincoln University using lysimeters
in a Templeton silt loam soil. Four treatments (control,
control + DCD, urine, urine + DCD) were applied in
May 2009, with urine applied in patches at an N loading
rate of 300 kg/ha with dicyandiamide (DCD) at 10 kg/
ha. Water (simulating rainfall) was applied in spring to
supplement natural rainfall. Nitrous oxide gas sampling
and leachate collections were made for 4 months.
Application of DCD reduced the N₂O emissions by
up to 72% (4.55 kg N₂O-N/ha without DCD to 1.32 kg
N₂O-N/ha with DCD) from late autumn applied sheep
urine and also reduced the amount of NO₃
⁻-N leached
by up to 70% (147 kg NO₃
⁻-N/ha to 44 kg NO₃
⁻-N/
ha). These results indicate that the use of DCD may
be a useful technology to mitigate N losses from sheep
break-fed pasture over winter. The need for further
research in this area is discussed.[Show full abstract]
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