The potential of L. scoparium, K. robusta and P. radiata to mitigate N-losses in silvopastural systems.
Silvopastoral systems aim to enhance economic, cultural and social principles by sustainably combining forest management with agriculture. In these typically high-nitrogen (N) environments, plant species selection can profoundly influence N fluxes. For grazed pastures, plants may be exposed to urine patches that have received the equivalent of up to 1000 kg N ha-1. We aimed to determine the growth and N fluxes in three potential trees that may be used in silvopastoral systems: L. scoparium, K. robusta and P. radiata. Plants were grown in a greenhouse lysimeter experiment, with controlled irrigation and temperature and exposed to N at rates of 200 kg ha-1equiv. for 15 weeks, followed by the addition of 800 kg ha-1N equiv, to simulate a urine patch. Urea produced a positive growth response of all plant species. Treatments containing L. scoparium and K. robusta leached lower amounts of nitrate (NO3-) (2 kg ha-1NO3-) compared to P. radiata (53 kg ha-1). Measurements of N2O over 20 days after the application of 800 kg N ha-1indicated an inhibitory effect of L. scoparium and K. robusta on denitrification, hence loss of N via N2O. Both L. scoparium and K. robusta demonstrated that they have potential to reduce N-losses in silvopastural systems, while producing valuable biomass.
Lincoln University, Faculty of Agriculture and Life Sciences, Department of Soil and Physical Sciences, P O Box 84, Lincoln 7647, New Zealand.
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J
Esperschuetz
Lincoln University, Faculty of Agriculture and Life Sciences, Department of Soil and Physical Sciences, P O Box 84, Lincoln 7647, New Zealand.
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N
Balaine
Lincoln University, Faculty of Agriculture and Life Sciences, Department of Soil and Physical Sciences, P O Box 84, Lincoln 7647, New Zealand.
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T
Clough
Plant and Food Research, Microbiology Division, Canterbury Agriculture and Science Centre, Gerald St, Lincoln 7608, New Zealand.
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S
Bulman
Lincoln University, Faculty of Agriculture and Life Sciences, Department of Ecology, P O Box 84, Lincoln 7647, New Zealand.
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NM
Dickinson
The Institute of Environmental Science and Research Limited, Kenepuru Science Centre, PO Box 50-348, Porirua 5240, New Zealand.
J
J
Horswell
Lincoln University, Faculty of Agriculture and Life Sciences, Department of Soil and Physical Sciences, P O Box 84, Lincoln 7647, New Zealand. Electronic address: brett.robinson@lincoln.ac.nz.
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Robinson
D000383:Agriculture / Q000379:methods*; D058440:Denitrification; D005308:Fertilizers / Q000032:analysis; D016468:Forestry / Q000379:methods*; D065928:Forests; D009566:Nitrates; D009584:Nitrogen / Q000032:analysis*; D014197:Trees
D005308:Fertilizers; D009566:Nitrates; D009584:Nitrogen
Kānuka; Leaching; Mānuka; Nitrous oxide; Pine; Urea