Acknowledgements
We thank David Sherlock for his help with developing the method, the University of York Technology Facility for sequencing, Asger Bachmann and Terry Mun for preliminary data analysis and script development, SEGES and the farmers for access to the organic fields, and DLF for access to their clover field trials. This work was funded by grant no. 4105-00007A from Innovation Fund Denmark (S.U.A.). Initial development of the method was funded by the EU FP7-KBBE project LEGATO (J.P.W.Y).