Dry leaves should be crushed or shredded to speed decom-position and to prevent blowing and matting. Leaves can be used as a mulch without first composting. You may wish to add a nitrogen supplement before mulching to avoid a deficiency. Oak leaves make an especially good mulch or compost for acid-loving plants such as azaleas and blueberries. Avoid the use of black walnut leaves because of the presence of juglone, a substance which hinders crop plant growth.
Lawns can absorb nutrients from decomposing grass clippings that are left on the lawn after mowing.
Because of their abundance and high percentage of nitrogen, clippings can also be put to good use on more heavily cropped plots. It is nitrogen which provides the heat source to activate a compost pile. To prevent compaction, mix the grass with a large amount of dry material, or first allow the grass to dry before adding it. Sticks and twigs are best used as a mulch after chipping, or as aeration layers in compost heaps. They can provide an absorption layer and structural strength to the heap.