Agronomist's concern (4)
I believe the answer is:
soil
'agronomist's concern' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for soil that I've seen before include "In which plants grow" , "Earth for growing" , "Earth; make dirty" , "Sully with earth" , "Top layer of the surface of the earth" .)