Using Critical Zone Science to Enhance Soil Fertility and Improve Ecosystem Services for Periurban Agriculture in China

The research programme

This work is funded through the NERC and the National Natural Science Foundation of China (NSFC) programme “Using Critical Zone Science to Understand Sustaining the Ecosystem Service of Soil & Water (CZO)”

About the project

This research project focuses on sustainable intensification of agriculture in highly productive peri-urban farming areas in China. This agricultural base is essential to meet China’s increasing food production demands but is under pressure from urban pollution inputs, soil and water pollution from farming practices – particularly extensive use of mineral fertilisers and pesticides, and urbanisation. We will quantify the benefits and risks of a substantial step-increase in organic fertilizer application as a means to reduce the use of mineral fertiliser.

Our approach is to study the role of soil as a central control point in Earth’s Critical Zone (CZ), the thin outer layer of our planet that determines most life-sustaining resources. Our Critical Zone Observatory (CZO) site is the Zhangxi catchment within Ningbo city, a pilot city of rapid urbanization in the Yangtze delta. We have identified 3 detailed scientific hypotheses.

  1. Replacement of mineral fertiliser use by organic fertiliser will shift the soil food web for N/C cycling from one dominated by bacterial heterotrophic decomposition of soil organic matter (SOM) to one dominated by heterotrophic fungal decomposition that will increase SOM content and improve soil structure through soil aggregate formation;
  2. Increased use of organic fertiliser from pig slurry (PS), and wastewater sludge (WS) will, however, lead to increased environmental occurrence of emerging contaminants, particularly antibiotics and growth hormones. Environmental transport, fate and exposure must be determined to quantify environmental and food safety risks, including the development of microbial antibiotic resistance, develop soil and water management practices for risk mitigation;
  3. Decreased use of mineral fertilisers and increased use of organic fertilisers will reduce environmental and food safety risks from metal contamination; this is due to lower metal mobility and bioavailability from redox transformations, reduced soil acidification and increased metal complexation on soil organic matter.

We will conduct the manipulation experiments across nested scales of observation with idealized laboratory microcosm systems, controlled manipulation experiments in field mesocosms, pilot testing of grass buffer strips to reduce the transport of emerging contaminants from the soil to surface waters, and field (~1ha) manipulation

experiments.  Mechanistic soil process models will be applied to quantify fluxes at the catchment scale, indicating ecosystem service flows. These results will allow us to evaluate scenarios for how these measures of ecosystem services will change with the widespread of organic fertilisers through the farming area of the catchment.

The team

Principal Investigators: Steve Banwart (UK) & Yongguan Zhu (China)

Co-Investigators: David Beerling, Tim Daniell, Les Firbank, Joe Holden, Visakan Kadirkamanathan, Paul Kay, Andy Meharg, Caroline Meharg, Manoj Menon, Paul Millner, Donatella Zona