Digging into organic, inorganic mulch options
Mulch is a material used to reduce water loss from soil. Lately, it has not been unusual to question whether mulch is useful on dry soil. That may be an issue in the short term if the mulch is insulating the dry soil from the limited amount of rainfall rather than insulating the moisture in the soil from evaporation. If there is no moisture in the soil, mulch is not preserving the moisture. Once the plants use the available water in the soil, they must wait until more moisture can enter through the bare ground and even the protective mulch. In the long term, however, mulch is recognized as a valuable ingredient of efficient water use.
Mulch is also a layer of material that prevents or reduces weed germination and growth.
We usually think of mulch as being an organic material. Among the most useful materials for mulch are compost, leaves and wood chips. Inorganic materials, however, can also be a useful mulch. Among the materials used as inorganic mulch are various sizes of rocks or pebbles, path materials like flagstone or brick, or a colorful plastic material.
Compost
Compost is decomposed organic material. It has limited nutrients, but when incorporated into the soil, it improves drainage, water holding capabilities and nutrient efficiency. If it is layered on the garden soil, it serves as a mulch as it continues to decompose. The decomposition is a fast process, and it is not the most effective material to use for a water retention or weed control mulch, but you get its extra dividends. It works especially well if replenished at 2-3 inches deep every year or two.
Leaves
If you have trees that drop their leaves in the fall, such as ash, pecan, red oak and sycamore,
or in the late winter, like live oak, you can resupply your mulch layer twice. The large leaves can be mowed before they are placed as a mulch layer on garden areas, or they can be collected as whole leaves. I like the live oaks best because they work well for paths and don’t decompose as fast as the other species.
Quite often, you can work out a deal with a neighbor who bags his or her leaves to use in your landscape. They never have to be wasted in the landfill.
Wood chips
Wood chips are the organic material that takes the longest to decompose. Obtain them from ground-up tree trimmings from your arborist. Wood chips and sawdust make a useful mulch in some situations, but the long decomposition time can be an asset or an issue, if you must provide extra nitrogen to feed the decomposition process. Pecan shells are hard to find now, but they make an attractive mulch if you can tolerate rodents, fire ants and deer interest.
If you are most interested in a relatively permanent mulch with
effective impact on weed prevention and water conservation, using some of the inorganic mulches may work well.
Flagstone or brick
For a patio or path, flagstone or brick without mortar allows the water to penetrate between the materials. It is effective in saving water and preventing weeds. The patios and paths are also especially functional as part
of the landscape. Decomposed granite is also an effective option.
Stones and rocks
Stones and rocks can be used as a landscape stream feature that efficiently absorbs and channels water. Smaller pebbles also work and make a path material that is almost as functional for the purpose as decomposed granite.
Plastic materials
The pebbles can be colorful, but for even more color in a mulched area, plastic mulch materials are also available and can be arranged to be especially decorative and colorful. It may be best to limit to this type of material to be placed on landscape fabric to make it easier to collect at the end of its use.
For more ideas for mulch options, visit plantanswers.com and the San Antonio Water System landscape website.