The aim of this project is to develop sustainable methods to improve the soil resistance of soils compared to soil pathogens such as R. solani. From previous research has shown that soils can vary greatly in their disease suppressing capacity at opzichtvan R. solani. Moreover, research in the laboratory has shown that Phytopathology R. solani scleroten parasitized and killed off are, after the incorporation in the soil of pure lignin or lignin by-products. The mechanism of action is based on the stimulation of specific microbial populations in the ground and is dependent on the soil type. Understanding soil abiotic and biotic factors that determine soil resistance to R. solani in natural soils and after administration of lignin material is necessary to develop appropriate control strategies.