Pflanze-Boden-Mikroben-Interaktionen in Agrarsystemen: Einfluss von Cadmium und Stickstoff auf mikrobielle Gemeinschaften in der Rhizosphäre sowie auf das Wachstum einheimischer Pflanzenspezies in Landwirtschaftssystemen
Ökologie der Landnutzung
Zusammenfassung der Projektergebnisse
The disposal of biosolids is a global environmental issue. Currently most biosolids are placed in landfills. Biosolids represent a low-cost source of nitrogen (N) and phosphorous (P), and depending on their provenance and level of treatment, they may contain high concentrations metals, macro- and micro-nutrients, organic compounds. Therefore, on the one hand biosolids addition to soil can result in contaminant accumulation in both soils and plants, but on the other hand can lead to high yields of plant growth and plant products when contaminants do not accumulate in certain plant parts that are interested for a certain industrial purpose. A lysimeter experiment under controlled conditions was set up with aim to continuously measure leachate and gas exchange rates throughout the experimental period. European and New Zealand native plant species (manuka, pine, kanuka, sorghum, ryegrass and rapeseed) were grown in different soil treatments (control, biosolids, biosolids + sawdust, elevated N) for observation, measurement and analyses with respect to C and N, plant and soil metal chemistry, and plant substances. A destructive harvest at the end of the experimental period allowed comparing microbial biomass, microbial activity as well as the microbial community structure in the plants rhizosphere with respect to different soil treatments. Urea fertilization provided insufficient nutrients to promote rapeseed growth and seed production on low fertility soil. Biowaste application enhanced plant quality by increasing element concentrations, especially Zn, in the plant biomass, while potentially toxic elements (Cd, Cr, Ni) did not exceed food safety standards. Biosolids application increased seed biomass as well as seed and crop quality, by enhancing the concentration of important elements, especially Zn and P. Biowaste application increased available P and S concentrations in the rhizosphere, and had a smaller effect on soil microbial communities compared to mineral fertilizer. An application of 50 t ha-1 of biosolids, equivalent to 1250 kg N ha-1, did not exceed current soil limits of Cu, Zn and Cd. Maintaining the soil with biosolids applications equivalent to 200 kg N ha-1 every two years after the initial biosolids application would be a safe alternative compared to mineral fertilizer for 40 years, before reaching threshold concentrations. Results from blending biosolids with fresh sawdust varied strongly depending on plant species, and therefore the use of sawdust in these scenarios must be decided on a case-by-case basis depending on the required outcome. Sawdust can immobilize available N for plant growth. However, sawdust can also enhance plant quality with respect to individual nutrients in biomass and seeds, including P, Cu, Zn, Mn, Fe, S or Na, and can stimulate biomass and activity of the soil microbiota. Biosolids application did result in lower N leaching compared to urea, irrespective plants species, and N leaching was unaffected by mixing the biosolids with sawdust. Further investigation of biosolids application rates in combination with sawdust and different plant species could maximise the plant quality benefits derived from sawdust, hence improving its value for recycling in combination with biosolids on land, instead of increasing landfill deposition. Leaf metal chemistry was altered by different treatment application, and influenced the soil microbial community structure via exudation and rhizodeposition. There was an indication of certain plant species and plant compounds interfering with the N cycle. Specifically, results indicated biological nitrification inhibition in the rhizosphere of sorghum, and the potential of manuka and kanuka to reduce N2O emissions from soil. To further investigate N processes and biological nitrification inhibition, stable isotope experiments could identify different sources of NO3-, and further identify the effect of plant exudates on N transformation processes in combination with biowastes. TV Rural Delivery, s10-e11 (2014) Effects of New Zealand native plants on reducing leaching, http://www.kiwiscience.com/research.html -> valuable ecosystem
Projektbezogene Publikationen (Auswahl)
- (2013) Special interest article – the phytomanagement of biowastes. Putting waste to work - A centre for integrated biowaste research publication 6, 8
Robinson B.
- (2014): Phytomanagement of biosolids-amended soil (20th World Concress of Soil Science, Jeju / Korea)
Esperschütz J, Lense O, Dickinson N, Anderson C, Bulman S, Hofmann R, Paramashivam D, Balaine N, Clough T, Horswell J, Robinson B
- (2015) Cashing in on biowastes for environmental benfits. Putting waste to work - A centre for integrated biowaste research publication 10, 2
Esperschuetz J. & Robinson B.
- (2015): Benefits from biowaste application on low fertility soil – Influence of biosolids on plant quality, soil health and microbial communities (SETAC Australasia, Nelson / New Zealand)
Esperschütz J, Lense O, Dickinson N, Anderson C, Bulman S, Horswell J, Hofmann R, Robinson B
- (2016): Biowaste mixtures affecting the growth and elemental composition of Italian ryegrass (Lolium multiflorum). Journal of Environmental Quality, Vol. 45 No. 3, p. 1054-1061
Esperschütz J, Lense O, Anderson C, Bulman S, Horswell J, Dickinson N, Robinson BH
(Siehe online unter https://doi.org/10.2134/jeq2015.09.0459)
