Response of Leptospermum scoparium, Kunzea robusta and Pinus radiata to contrasting biowastes

Abstract

The myrtaceae family has a cosmopolitan distribution and includes the Australasian native species Leptospermum scoparium (mānuka) and Kunzea robusta (kānuka), which are of economic interest for the production of high-value honey and essential oils. Potentially, these species could be established on low-fertility or degraded soils that have been amended with biowastes, including biosolids and sawdust. We aimed to determine the effect of these biowastes on nitrate leaching and the growth and chemical composition of these plant species compared to Pinus radiata (pine), a common forestry species. The addition of biosolids (1250 kg N ha⁻¹ equiv.) increased the total dry biomass of mānuka, kānuka, and pine by 117, 90, and 86% respectively. Mixing sawdust with biosolids stimulated growth of mānuka (52%), kānuka (121%) but not pine. Biosolids increased plant uptake of N, P, and trace elements, but not to levels of concern. Nitrate leaching from all treatments was negligible (<2 kg ha⁻¹).