At the Annual UK – China CZO programme meeting in Guiyang the Peri-urban project presented an update of how work was going with in each work package to that point in time, 18 months into the project. The bullet points below summaries this presentation.
Using Critical Zone Science to Enhance Soil Fertility and Improve Ecosystem Services for Peri-Urban agriculture in China – Prof Steven Banwart and Prof Yongguan Zhu
- Work Package 1:
- Field mesocosm experiments have been set up to test the effects on wheat and vegetable production on 1) 100% chemical fertiliser, 2) 100% sewage sludge, 3) 100% pig manure, and 4) 50% chemical fertiliser and 50% pig manure.
- The experiments are being monitored to assess the impact of these treatments on biogeochemical cycles, water flow and transport of agrichemicals to surface and groundwater, and to assess the occurrence and transport of antibiotic resistance genes (ARGs) in the organic fertilisers, soils, water and crops.
- Carbon-14 labelled antibiotic compounds are currently being synthesised for use in fate and transport studies in the field mesocosm experiments.
- Work Package 2:
- Manure-derived antibiotic compounds significantly reduced rates of microbial denitrification and anaerobic ammonia oxidation.
- A meta-analysis of 141 studies worldwide showed that replace some or all of mineral fertilisers with organic fertilisers generally improved crop yields, reduced N- and C- greenhouse gas emissions and reduced soluble and particulate N loss in drainage waters.
- Work Package 3:
- The biogeography of ARG occurrence within 4 sub-catchments of the Critical Zone Observatory demonstrated correlation of ARG numbers with land use including relation to agricultural land and sewage discharge areas and showed dynamic seasonal behaviour.
- Laboratory studies of soil-plant-water interactions showed that application of manure significantly increased the occurrence of ARGs in soil and plant leaves.
- Work Package 4:
- The land use history and change in land area of characteristic land uses has been re-constructed for the past 40 years.
- The geospatial distribution of metals contamination in soil, the occurrence of antibiotics and of ARGs has been mapped across the site.
- Process modelling of coupled C-N dynamics in the watershed, rainfall-run off-soil water dynamics in land uses is ongoing and a new modelling research fellow is appointed to quantify the mechanistic interactions of soil processes with the full Critical Zone, i.e. with the atmosphere, vegetation, soil, surface waters and aquifers.