Hello, I grow vegetables in my backyard. I do not use any chemicals in my garden soil including any fertilizers, I just use old chicken manure and the compost I make. Although I recycle everything by composting vegetable leftovers, sometime I have to trash them. For example when my tomatoes get the blite or when Beans are infested by viruses I have to dispose all the plants. Can I burn these -using a simple outdoor fireplace- and then use the ash in the garden? Is the ash beneficial to the soil? How/How much/When do I add the ash to the soil? What about half burned plants that look like charcoal, can these be used too? Thanks.
Yes, you can use the ash of plants, including diseased plants. See page 7 of this pub: https://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/hgic/HGIC_Pubs/Soil_Amendment...
As long as infected/infested plants are burned/scorched and do not show green, they should be safe to compost or recycle. in your garden.
Hi- that's correct, ashes do not improve soil structure. They add a small amount of nutrients and can potentially increase soil pH. Adding ash to the compost pile will not improve compost quality. Since the compost is presumably going to be applied to the garden soil it really doesn't matter where you apply it (soil or compost pile), especially since it's a relatively small amount.