How significant is the transfer of mineral elements from conventional to organic farming?

Mineral management is a key aspect of organic farming systems. The European regulations for organic farming strictly prohibit the use of synthetic fertilisers. However, they do permit the use of certain products derived from conventional farming. In this study, we quantified the intensity of nitrogen (N), phosphorus (P) and potassium (K) from conventional agriculture for 63 organic farms spread across three French agricultural regions defined by their production focus (arable, livestock or mixed). Inputs from conventional agriculture account for 23 per cent, 73 per cent and 53 per cent of N, P and K inputs respectively. These inputs are mainly explained by the farms’ production systems and are positively correlated with their demand for fertilisers.