I am concerned about my garden soil for next year. My tomaotoes had early...
Tomatoes can be susceptible to several foliar diseases such as early blight and septoria. All produce spots or lesions on leaves, start at the bottom of the plant and progress through the season if conditions are right, to defoliate tomato plants (spotting, yellowing, dying.) Be sure to remove badly infected plants and remove infected plant debris at the end of the season.
Next season if your garden is large, rotate your tomatoes to another section but In many small gardens this is not possible.
You can remove the lower leaves to slow the upward spread of the disease, keep plants well mulched to minimize soil splashing, water at the base of the plants, provide adequate spacing and spray with a copper fungicide (early in the season) to lessen spread of the disease, Fungicide treatments can help to protect new or un-infected foliage they are not curatives. See our link for more information and management http://extension.umd.edu/learn/early-blight-tomato