Inspired by New Zealand Trade and Enterprise’s focus on native products as a key sector, Lincoln University Soil Science PhD student, Salome Seyedalikhani, is carrying out a study to determine the effects of bio-wastes on the quantity and quality of essential oils produced from manuka and kanuka plants.

Associate Professor Brett Robinson says Seyedalikhani’s research is linked with a number of other studies and field trials being carried out. "Salome's work is part of a larger progamme that seeks to divert biowastes from landfills or waterways onto land where the nutrients that they contain can provide economic value. Lincoln University is working with the Centre for Integrated Biowaste Research (CIBR) on field trials around New Zealand to elucidate the benefits of NZ native vegetation on soil that has been improved using biowastes."

Bio-wastes are organic materials of biological origin, such as bio-solids, dairy shed effluent and sawdust. While these materials may contain contaminants such as heavy metals and pathogens, they are also rich in plant nutrients, and a cheap and plentiful resource for rebuilding degraded or low-fertility soils where food is not produced.

One such place is former forestry soils, where rebuilding the soils with bio-waste may be a more viable economic alternative than replanting in pines. Bio-wastes would increase the soil’s nutrient and water holding capacity, and provide essential elements to accelerate plant growth. Bio-wastes would also change the quality of essential oils produced by these plants. The nature of these changes is the subject of Salome’s research.

In a series of greenhouse experiments, manuka and kanuka were grown in low fertility soils, and soils amended with either biosolids, biosolids and sawdust, or dairy shed effluent. The addition of biosolids increased the growth of both species by up to sixty percent. In turn, manuka and kanuka have an effect on the soil, producing antiseptic chemicals and affecting soil microbes involved in nutrient cycling.

The most important components of the essential oils were unaffected by the addition of bio-wastes. Ultimately there is potential for some bio-wastes to be diverted from landfills to degraded land, where they can boost the production of essential oils made with manuka and kanuka.

Fields trials are now being carried out to explore the ecological variables and production economies.  While the bio-waste concepts can be applied internationally, manuka and kanuka production can’t be replicated elsewhere, giving New Zealand a unique industry opportunity and a competitive edge.

After winning the Lincoln Postgraduate Conference Prize for top presenter in her Faculty, Seyedalikhani will be presenting her findings at an international soils conference in Queenstown from 12-16 December, http://www.nzsssconference.co.nz/. The biennial joint conference of the New Zealand Society of Soil Science and Soil Science Australia is expected to attract over 400 delegates from Australasia and overseas.

Source: Lincoln University