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.