Lincoln University, Faculty of Agriculture and Life Sciences, Department of Soil and Physical Sciences, P O Box 84, Lincoln 7647, New Zealand.
Plant and Food Research, Microbiology Division, Canterbury Agriculture and Science Centre, Gerald St, Lincoln 7608, New Zealand.
Environ Pollut. 2017 Jun;225:12-19. doi: 10.1016/j.envpol.2017.03.042. Epub 2017 Mar 23.
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. 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 equiv. for 15 weeks, followed by the addition of 800 kg ha N 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 (NO) (2 kg ha NO) compared to P. radiata (53 kg ha). Measurements of NO over 20 days after the application of 800 kg N ha indicated an inhibitory effect of L. scoparium and K. robusta on denitrification, hence loss of N via NO. Both L. scoparium and K. robusta demonstrated that they have potential to reduce N-losses in silvopastural systems, while producing valuable biomass.
林牧系统旨在通过可持续地将森林管理与农业相结合，增强经济、文化和社会原则。在这些通常具有高氮（N）环境中，植物物种的选择可以深刻影响 N 通量。对于放牧牧场，植物可能会暴露于尿液斑块中，这些斑块已经接收了相当于高达 1000kgNha 的 N。我们旨在确定三种可能用于林牧系统的潜在树木的生长和 N 通量：L. scoparium、K. robusta 和 P. radiata。植物在温室淋溶实验中生长，受控制的灌溉和温度影响，并以 200kgNha 当量的速率暴露于 N，持续 15 周，然后再添加 800kgNha 的 N 当量，以模拟尿液斑块。尿素使所有植物物种都产生了积极的生长反应。与 P. radiata（53kgNha）相比，含有 L. scoparium 和 K. robusta 的处理中硝态氮（NO）的淋溶量较低（2kgNha）。在应用 800kgNha 后 20 天内对 NO 的测量表明，L. scoparium 和 K. robusta 对反硝化作用具有抑制作用，因此通过 NO 损失了 N。L. scoparium 和 K. robusta 都表明它们有潜力减少林牧系统中的 N 损失，同时产生有价值的生物量。
