Keywords:fertilisation, nutrient, phosphorus, potassium, nutrient removal, nutrient balance, soil analysis database.
Amounts of nutrients phosphorus and potassium applied as mineral fertilisers have decreased by 70% in France in the last twenty-five years, without any compensation by more organic fertilisers. UNIFA, the French fertiliser industry association, produces official delivery statistics on mineral fertilisers and estimates for organic inputs. UNIFA has calculated nutrient balances in 21 regions of France to show the trend in the phosphorus and potassium balance since 1988/1989.
The nutrient balance has been calculated from the difference between the total input to soils and the total nutrient removal in crops and grass, calculated according to the annual statistics of the Ministry of Agriculture.
The difference between the total input and output has reduced considerably since 1988 in all regions. This is the logical result of reduced nutrient inputs during this period. Although the recycling of urban and industrial bio waste and the importation of organic fertilisers has increased since 2005, this does not compensate for the decrease in both mineral fertilisers and of animal excreta, due to reduced numbers of livestock.
The balance has been negative for phosphorus for the last ten years, especially in the cereal producing northern and central part of France. The consequence of this is a decrease of extractable Olsen phosphorus in soil analyses, which can be assessed from a large database of more than two million soil analyses covering the 25 years since 1990.
The trend for exchangeable potassium is less significant in the data from both intensive cattle rearing regions and cereal growing regions. This French National Soil Test FNST database (BDAT in French) is operated by the National Agronomic Research Institute INRA under the auspices of the French Soils Scientific Interest Group (Gis Sol).
P Eveillard, UNIFA Union des Industries de la Fertilisation, France.
N P A Saby and L Gouny, INRA Infosol, US 1106 Orléans, France.
P Denoroy, ISPA, Bordeaux Science Agro, INRA, 33140 Villenave d’Ornon, France.
B Lemercier, UMR SAS, AGROCAMPUS OUEST, INRA, 35000 Rennes, France.
23 pages, 11 figures, 1 table, 7 reference