Tuesday, 17 May 2011

UK Soil Nutrient Balances

The National Farmers' Union (NFU) has recently reported that Defra (Department for the Environment, Food and Rural Affairs) has released  information on  changes in N and P soil balances between 1990 and 2009.

According to the report, soil nutrient balances have been calculated by Defra for England and the UK for the years 1990, 1995 and 2000-2009.  Soil surface balances have also been calculated.  These care the difference between inputs (inorganic fertiliser, manure, N fixation etc.) and offtakes (crop uptake, grass and fodder eaten).  The key findings are:

  • Nitrogen soil surface balances fell from ~140 kg/ha in 1990 to ~80 kg/ha in 2009.  This was not due to a fall in agricultural area since this was only reduced by 0.2% for the same period.
  • Nitrogen soil surface balance fell by 22% in the UK between 2000 and 2009, and 20% in England for the same period.
  • The steady decrease in nitrogen soil surface balance has been driven by reduced applications of inorganic fertiliser and livestock manures.  However, a reduction in the removal of N via forage harvesting somewhat offset the decrease.
  • Nitrogen use efficiency is showing a positive (upwards) trend i.e. efficiency of N use in agriculture is increasing.
  • Phosphorus soil surface balance fell by 54% in the UK between 2000 and 2009, and 64% in England for the same period.
  • Most of the reduction in phosphorus soil surface balance has taken place since 2007 and is a result of a reduction in inorganic fertiliser applications (in 2009) and increased off-take in harvested crops since the removal of set-aside.

Read the full report and an explanation of the methodology by visiting the Defra Statistics page.