In autumn when a thick layer of leaves builds up on the ground beneath trees, homeowners spend countless hours managing lawn waste. At one time, leaves were raked and disposed of. In recent years, homeowners have turned to green lawn care practices that benefit the lawn as well as the Earth.
Autumn Leaf Build Up
A thick layer of leaves left undisturbed on a lawn over the course of an autumn or winter may have long-term detrimental effects on the health and appearance of the grass. Leaves block sunlight, smothering the grass and preventing moisture from evaporating on the lawn. This may cause fungal problems and grass death, resulting in a patchy or dead lawn the following spring. Under dry conditions, these leaves are a fire hazard that may result in property damage.
Leaf Mulching
Mulching lawn mowers are used to shred leaf litter into tiny bits. This natural mulch will eventually turn into a compost rich in nutrients such as nitrogen. Although some leaf mulch may be beneficial to your lawn, mulching should be done early in the autumn and with frequency, to prevent a thick layer of leaves from building up on the lawn. Leaves left to build up on the grass over the course of a season will do damage to the lawn and will be hard on the mower when it’s finally mulch. In addition, leaves will decompose more quickly early in the autumn when temperatures are warmer. Leaf mulch should be used sparingly because microbes in uncomposted leaves may compete with grass for nitrogen during the decomposition process, lessening the beneficial effects of the mulch. Once 1-inch layer of mulch has built up on the lawn, alternative methods of dealing with the leaves should be considered.
Composting
Composting the leaves before adding them back to the lawn will prevent competition for nitrogen. In addition, composted leaves will have more immediate benefits than uncomposted leaves, adding potassium and phosphorous to the soil, while increasing water-holding capacity, soil drainage and tilth. Leaves may be composted in a pile on the lawn, but compost drums decrease the time it takes for the leaves to compost. Compost drums are filled two-thirds full with leaves and 1/4 cup of nitrogen-rich fertilizer. Then the mixture is moistened, and the composter is turned every few days. Within a few months, compost has been produced.
Other Considerations
A recent study conducted by a Purdue University professor shows that some trees under stress from drought conditions may produce leaves with a higher than normal tannin content. With tannin levels elevated to twice the normal amount, these leaves may slow down crucial processes in the soil, including decomposition and nutrient cycling. This study was conducted in 2011 with leaves from red maple trees. The long-term effects of elevated tannin levels in the soil is uncertain.
Source: https://homeguides.sfgate.com/impact-leaves-grass-40416.html