agreste

Agreste cahiers n° 46 - décembre 1999

Multiplying the cultivated area by the average quantity of mineral nitrogen spread per hectare provides an estimation of the volume of mineral nitrogen which is consumed at the regional level.

Multiplying the cultivated area by the average quantity of mineral nitrogen spread per hectare provides an estimation of the volume of mineral nitrogen which is consumed at the regional level. This very simple model is sustained by surveys on cropping practices, which furnish the average amounts of nitrogen per hectare. These data can be updated in order to integrate changes in fertilisation practices. The model is applicable at the level of the département. The results can be compared to the estimates coming from direct local enquiries of farmers about fertilisation. Brittany did in fact take advantage of the 1997 national survey on farm structure to insert a regional rubric on mineral fertilisation into the questionnaire. Using both the model and surveys, the consumption of mineral nitrogen is estimated at around 145,000 tons in Breton agriculture. Temporary meadows absorb one-third of the total.