[Low risk] Good rotation [High risk] Crop monoculture [Factor] 
Cropping system
C r o p p i n g s y s t e m
C u l t i v a t i o n s y s t e m
W e e d c o n t r o l
H e r b i c i d e u s e
C o n t r o l i n p r e v i o u s y e a r s
W e e d i n f e s t a t i o n
R e s i s t a n c e i n v i c i n i t y