Enriching Soil With Fall Leaves

"The falling leaves drift past my window. The falling leaves of red and gold." How can such beautiful, romantic leaves cause such serious disposal problems in the fall. Leaves are an excellent material to improve the soil. They fulfill all of the basic criteria of acceptable soil amendments. Price is always a consideration and leaves cost nothing except the time to rake them from your own yard or haul them from the neighbors. The task is even easier because they are often already bagged. In most instances you only need to pick them up from the curb and take them home. Abundance is another key and abundant leaves are blanketing the valley with thick layers of wonderful organic matter. An almost unlimited supply is available to enrich garden soils of all kinds. There is no limit on the amount that is available. Weed-free is another important criteria. Many soil amendments that fulfill the first two don’t make this one. Leaves have almost no seeds at this time of year and are not likely to promote the growth of any unwanted plants in the garden. Even those that drop pods right now are not likely to cause serious problems. The importance of this criterion is not fully appreciated until you make the mistake of putting millions of weed seeds into the garden by using contaminated soil amendments. The next consideration is that leaves are not likely to burn your plants because they are too hot. Some amendments are rich in nitrogen and can burn plants because they have excess soluble nutrients. Leaves are mostly cellulose and usually need nutrients added to make them decompose so they are not likely to burn your plants. Unlike some other amendments leaves are never high in soluble salt so they will not burn or cause a salt buildup in the soil. Inexpensive, abundant, weed-free, and free of any potential toxins describes a near-perfect amendment. Since nothing in life is perfect, there must be some drawbacks to even leaves. One potential drawback is that leaves are not a rich source of nutrients as is sometimes supposed. They are high in carbon but low in most other nutrients, so the fertilizer value is limited. Nutrients in the leaves are not available until they decompose. High carbon materials usually require additional nitrogen to break them down. Fortunately this is an easy and inexpensive process. Add one pound of ammonium sulfate [21-0-0] or its equivalent for every inch of matted leaves per one hundred square feet. This provides sufficient nitrogen to feed the microorganisms that are decomposing the material. Providing extra nitrogen is important because the soil organism don’t rob the plants of nutrients that they need to grow. Adding more fertilizer counteracts supposed toxicity from leaves or sawdust.