It really depends on climate, soil type and level of agrotechnology. It could be (in the case of wrong agrotechnology): water deficiency at early stage of seedlings development due to separation of loose upper soil from more dense wet level below, accumulation of weeds, pests, and diseases (especially Fusarium) , residuals herbicides and fungicides in upper layer of soil. , slower decomposition of crop residuals.
In the Brazilian cerrado No-tillage crop residues left on the soil surface can create favorable conditions for the survival and proliferation of some pathogens of diseases such as white mold (Sclerotinia sclerotiorum). The pathogen can attack plants of economic importance mainly soy, beans. To minimize this problem crop rotation, seed treatment practices should be required in SPD...