Adding compost to your garden imitates what Mother Nature does naturally—recycle organic material.
It is beneficial to your garden, the landfill and the environment to compost your kitchen and yard waste. However, if composting is not for you, there is nothing wrong with buying the finished product. Many gardeners buy compost to supplement what they make. Adding compost to your garden is the best way to build healthy biologically active soil. Our soil needs regular servings of compost to replenish the nutrients plants have used, as well as what has been lost into the atmosphere and in runoff.
A healthy garden is a complex soil-food web. It is a community of organisms that live in the soil and interact with plants. The organisms include bacteria, fungi, protozoa, nematodes, arthropods and earthworms. As they cycle organic material through the soil, they make nutrients available to plants. Compost contains the organic matter that fuels the microorganisms that build this active symbiotic ecosystem.
Beneficial organisms live around plant roots where they mine the soil for nutrients and convert them into a form plants can use. Some microorganisms help prevent plant disease by protecting roots from pathogens; others help plants through insect attacks. Plants depend on this soil food web.
Plants need a large amount of nitrogen, phosphorus and potassium; however, they require more than that to thrive. Nutrient-rich compost adds not only a measure of the macronutrients to the soil, but also secondary and micro nutrients that are not often available in chemical fertilizers.
If you use chemical fertilizer be aware that it dissolves more quickly in water than organic amendments. Chemical fertilizer therefore readily leaches out of the soil and runs off into our steams and waterways. Compost, however, increases soil’s ability to retain water and holds nutrients so they don’t so easily leach out. When soil is rich in organic content it decreases nutrient run off. That means less pollution in our waterways.
Most gardeners avoid adding pesticide and herbicide treated plant material to their compost bin. Most lawn and garden chemicals should completely degrade during the composting process, but not all of them do. Temperature and moisture, among other variables, affect the rate at which garden chemicals degrade. Moreover, some persistent chemicals in herbicides have a longer life span and do not break down in the composting process. These chemicals can severely harm plant growth.
Microorganisms break down many of the toxic chemicals in the soil. Unfortunately some lawn and garden chemicals are harmful to these very same beneficial soil organisms. They can kill the microorganisms that are working to improve the soil. This is one of the numerous reasons to avoid unnecessary pesticide and herbicide use in your garden.
Compost tends to neutralize acidic and alkaline pH. A case in point is my hydrangeas. The only nutrients they received came from compost during the 16 years they have grown in our side yard. Originally the flowers were bright blue, a reflection of acidic soil. I’ve watched the flower color evolve to blue-purple and to what is now purple-pink. The color change is an indicator that is soil has become less acidic.
Mulch in a garden acts as leaf litter does in the forest. It decomposes, thereby adding organic material to the soil. The type of mulch you use can help improve your garden soil. Organic mulches made from hardwoods are preferable because they are higher in nutrients than other common materials. Non organic mulches add no value to soil.
Amending your garden with compost is the surest way to improve your soil. Any time of year is good. However, a fall serving of compost will work into the soil over the winter. Then, in the spring you can top dress your plants with more. You can’t add too much compost to your garden.
Reach Debbie Menchek, a Clemson Master Gardener, at firstname.lastname@example.org.