If soil test recommendations include adding limestone to reduce soil acidity, it will take some time for the limestone to bring about pH adjustment. A thorough incorporation of limestone achieved by tilling is preferred over broadcasting the limestone on the soil surface. Surface application of limestone brings about a much slower modification of pH level and may not affect the level in the critical root zone of many plants. Organic matter added in the fall and worked into the soil will be acted upon by microorganisms and beneficial insects and broken down to improve soil fertility in the spring. Fall tilling enables the home gardener to take advantage of a plentiful source of organic matter - leaves.
Leaves are an excellent soil amendment.
To hasten breakdown of leaves, simply place them on a pile, moisten lightly to reduce dust and run over them several times with a lawn mower. Exercise care to avoid striking rocks or other debris that might be contained in the leaves. Keep others away when running over the leaves and wear safety glasses. After shredding the leaves, till them into the soil. Fall tilling aids in insect control by exposing insects to harsh conditions so that many will not survive the winter.