Summary

The withdrawal of nitrogen-based fertiliser applications [at Wytham, following the introduction of organic farming] resulted in an immediate reduction in grassland productivity, while species richness increased by 300%. These are the key points made in the 2016 special issue paper.
  • Understanding the impact of changing farming practices on vegetation diversity and productivity is a key issue in the development of food security policy. Farming at the Wytham ECN site switched from conventional to organic mid-way through the ECN monitoring period, allowing the response of grasslands to reduced fertiliser inputs to be evaluated.
  • The withdrawal of nitrogen-based fertiliser applications resulted in an immediate reduction in grassland productivity, while species richness increased by 300%.
  • The study illustrates a clear trade-off, whereby the increase in biodiversity occurs at the expense of productivity, as a consequence of high-yielding nitrogen loving grass species being replaced by a more diverse mix of less productive grasses and forbs.
  • The study brings into clear focus the challenges of meeting potentially conflicting policy agendas.

 

Reference: Pallett, DW., Pescott, OL. and Schafer, SM. (2016). Changes in plant species richness and productivity in response to decreased nitrogen inputs in grassland in southern England. Ecological Indicators, 68, 73-81. DOI: 10.1016/j.ecolind.2015.12.024.