Linda. I do not have any hands on experience with black walnut, but I took a tree science class in college and was told that the leaves of black walnut are high in acid or another toxin I don't exactly remember witch. But they tend to kill grass and other plant life including sprouting walnut trees when they decompose. So it would most likely help if you rake any leaves that fall from your Black Walnut tree and not use them in your compost if you are trying to grow anything underneath them
Linda. I do not have any hands on experience with black walnut, but I took a tree science class in college and was told that the leaves of black walnut are high in acid or another toxin I don't exactly remember witch. But they tend to kill grass and other plant life including sprouting walnut trees when they decompose. So it would most likely help if you rake any leaves that fall from your Black Walnut tree and not use them in your compost if you are trying to grow anything underneath them