1) This indicator is suitable only for longer-term projects where you can measure not only whether farmers have tried the practice you promote but have also adopted it (i.e. use it for the minimum required period of time).
2) If you promote a larger number of practices, consider changing the indicator to “% / number of farmers who for the past [specify the time period] followed at least X out of X promoted agronomic practices on their farms” (for example, 2 out of 4).
3) Decide whether you want to collect the data only from those farmers who were trained in the promoted practice or also from other local farmers. If you implement a longer-term project and you expect that farmers who were not trained might replicate the practice from those who were, the latter option will give you a more accurate picture of the project’s outcomes (alternatively, you can also segregate the data by those farmers which were and those which were not trained).
4) Also consider including a question about where farmers learned the agronomic practice – this might help you assess to what extent the production of the given crop can be attributed to your intervention.
5) Even if a farmer follows the promoted practice, s/he might do so on a tiny portion of her/his land. Therefore, consider assessing also the extent to which the practices were applied – for example, on how many hectares of land.
6) European Commission's DEVCO recommends to use two similar indicators: "Land managed using a) improved technologies and b) improved management practices (in hectares)" and "Number of hectares of where land management practices have been introduced with EU support".