Tree Leaves as an Organic Fertilizing Agent

Mulching

• In natural settings such as forests and meadows, leaves fall from trees and carpet the ground. With other organic matter, such as twigs, grasses and weeds, the leaves evolve into a self fertilizer for the trees. They mat together and mulch the trees, conserving moisture, then decay to nourish tree roots and other plants. In cultivated landscapes, leaves benefit from shredding or chopping into mulch material. The chopped leaves decompose more quickly, whether they are mowed in place under trees or chopped and bagged for other mulching.

Amending

• Shredded or chopped tree leaves mix easily in soil. In autumn, the falling leaves in urban areas must be raked, gathered and removed to prevent gutters clogging, leaves drifting and other hazards. When these leaves are chopped or shredded, they are reduced in bulk to about one-tenth their original size. These leaf pieces, worked into landscapes or garden soil, aerate soil and rot in the wet, cold winter. When grass clippings or vegetable garden debris are mixed in the soil with the leaves, the green plants provide nitrogen that speeds leaf decay. By spring, the amended soil contains nutrients for the growing season.

Composting

• Because of their carbon content, tree leaves are an incomplete fertilizing agent. Most plants benefit from both nitrogen and carbon. When organic materials such as tree leaves, grass clippings and plants are chopped and combined with water and air, the carbon, nitrogen and other nutrients decay into rich compost suitable for fertilizing perennial or annuals. The compost, due to its aging and decomposition, is a stable mixture and provides balanced nutrition for garden and landscape plants.

Tips

• Shred or chop tree leaves with a mower or mulcher, which reduces volume so that leaves take less room in a waste management leaf bin or home reuse program. Tree leaves are organic matter that, used as covering mulch around shrubs or trees, conserve water and reduce weed growth. Mow leaves and grass at the same time, and dump the combined organic matter in a bin or heap for an informal compost heap. Turn it periodically, blending and aerating the organic materials. Do not be overly concerned about the precise leaf to plant or carbon to nitrogen ratios. In the natural environment, they all rot and return to the soil.