We used to soot our garden regularly back home. We put a lot of chikcen manure into the soil, and so to counter the acidic effect of organic decay, the ash from our fireplace (we burned about 10 cords a year) was added to it for years. Our biggest problem was too much nitrogen, which would make the spinach, radishes and lettuce bolt. I recall taking armfuls of spinach around the neighborhood to give away, stalks about an inch around at the time. Just like too much zucchini, you can overdo it on spinach in the garden too. Bolting radishes means no bulbs.