Reducing soil water loss means more water is available to plants and less water needs to be provided. Mulch also reduces the number of weeds in a water-wise landscape by preventing light-induced germination of weed seeds. With fewer weeds, less cultivation is required, which can prevent damage to plant roots, soil structure, and soil organisms. In addition, mulch moderates soil temperature and protects plant roots.
In winter, moderation of soil temperature can prevent plants from heaving out of the ground due to freezing and thawing. Mulch also can be an important visual design element in a water-wise landscape, and it is used along walkways, in plant borders, and for color and structure in a landscape or garden.
Organic mulches include materials such as wood or bark chips, shredded bark, nut shells, pine needles, or other discarded plant parts. These materials have the potential to enhance soil structure, increase soil fertility, prevent compaction, and increase soil organic matter as they break down and are incorporated into the soil.
Mulch is a great way to recycle yard waste, such as pruned woody plant materials, fallen leaves and needles, and even grass clippings. To ensure adequate water infiltration and aeration and to slow decomposition, make sure mulch particles are larger than the underlying soil particles (usually larger than a half inch in diameter).
Recycled plant materials must be free from weed seeds, disease-causing organisms, and pesticide and herbicide residues. You can either use disease-free plant parts that have not been chemically treated, or you can compost your mulch before use.
Composting results in controlled decomposition of organic materials through the activity of microorganisms and generates enough heat to kill weed seeds and disease organisms. Composting also may break down some pesticides that can injure growing plants.
In most cases, use of organic mulch increases the nutrient fertility of the underlying soil and decreases the need for fertilizer application to mulched plants. However, the use of fresh wood or bark as mulch may lead to temporary nitrogen deficiency because microorganisms that decompose these high carbon content materials use up nitrogen that otherwise would have been available to the plant.
This is mainly a problem if the mulch is incorporated into the soil. Nitrogen loss can be avoided by using composted mulch or by adding nitrogen at a rate of 1-2 lbs actual N per 1000 ft2.
Over time, organic mulches break down and will need to be replenished. Replenishment can be accomplished simply by adding more mulch over the top of the decomposed mulch material. Before adding new mulch, roughen up the old mulch layer to prevent formation of a water-impervious surface between old and new mulch.
Decomposition of organic mulches sometimes can lead to nitrogen deficiency. Watch plants for telltale signs of nitrogen deficiency. If you notice yellowing that starts in older leaves, as well as decreased vigor, replace lost nitrogen using the fertilizer rate listed above.
Inorganic mulches consist of non-plant materials and may include a variety of different kinds of rock or gravel. Different sizes and colors of inorganic mulches are available. The decision about which to use will depend upon the kind of landscape, the reason for its use, and its availability.
Examples include gravel or crushed stone, lava rock, recycled tumbled glass, and cobblestones of different sizes, shapes, and colors. The size of inorganic mulch particles should complement the scale of the landscape. For example, cobblestones work great in an expansive formal or naturalized setting or in a rock garden, but would be overwhelming in a small flower bed.
Inorganic mulches provide the same benefits as organic mulches, including moisture retention, temperature moderation, and prevention of compaction. In addition, inorganic mulches provide excellent drainage that is often required of drought-adapted plants. Inorganic mulches do not decompose and need to be replaced infrequently.
The disadvantage of inorganic mulch is that it does not add to soil fertility or organic matter, and plants will need to be monitored for signs of nutrient deficiency and fertilized accordingly.
Apply organic mulch to a depth of 3 to 4 inches, and inorganic mulch to a depth of 2 to 3 inches. A 2-inch thick layer of mulch requires about 6 cubic yards of material per 1000 square feet of area.
A weed barrier may be placed on the soil surface before using either organic or inorganic mulch material. The best choices are landscape fabrics of various types that allow air exchange and water infiltration.
Plastic sheeting should be avoided because it tears easily, may generate excessively high root-zone temperatures in direct sun, and interferes with water and air exchange with the soil.
Apply landscape fabric in strips over the soil, overlapping strips about 4 inches. Place mulch material over the weed barrier. Decomposed organic mulch will favor the growth of weeds on top of the weed barrier and should be replaced rather than replenished as needed.
In Utah, urban landscape irrigation accounts for 50-65% of the annual municipal water use, and much of it is applied in excess of the plant's needs. Scheduling irrigation according to landscape plant water needs can reduce excess water use. In addition to conserving water, proper irrigation can encourage deeper root growth and healthier, more drought tolerant landscapes.
HereAn important component of water-efficient landscaping is creating hydrozones for your irrigation needs. To provide adequate water to all plants without over or under-watering some, group plants with similar irrigation needs in one zone.
Once your plants are grouped into zero, low, medium and high water groups, you should plan your irrigation schedule to apply the appropriate amount of water to each zone. You can learn a great deal about plant-water requirements simply by observation.
Signs, such as wilting, will let you know when many landscape plants require watering, but be careful not to overdo it. Plant roots need just as much air as water and you don’t want to drown them. If you are using an automatic irrigation timer, be sure to adjust it seasonally as the weather changes.
A great deal of water is wasted when automatic irrigation systems are continually programmed for the hottest part of the summer without adjusting for times when temperatures are cooler and more natural precipitation is occurring.
Another important aspect of irrigation planning includes routine maintenance of the system. Monthly examination of the irrigation system, while in use, will help you to find and repair any broken, misaligned, or clogged sprinkler heads and keep your system running efficiently.
Drip Irrigation systems consists of plastic pipes with emitters that deliver water directly to plants. These types of systems are great for water-efficient landscapes as water goes directly to the plants roots and is not wasted on areas that do not need to be watered.
Turfgrass has shallower roots than other landscape plants and therefore should be irrigated more frequently, but not as deeply as other landscape plants. Consider using turfgrasses with lower water requirements to reduce water use even further.
Plan and design irrigation systems so that turfgrass areas are irrigated separately from other landscape plants. There are several resources available to determine the appropriate watering schedule for turf areas in Utah.
Trees and shrubs have much deeper and more extensive root systems than turfgrass so they should be watered less frequently but for longer periods of time. The optimum time to water is just before you can observe any water stress. Therefore, it is important to determine sub-surface soil moisture. Soil moisture can be determined using a soil moisture probe.
Sandy soils absorb water the fastest (about 2" per hour), followed by loam soils (3/4" per hour). Clay soils have the slowest absorption rate (1/2"per hour). By allowing water to penetrate deeper into the soil profile, you are encouraging deeper rooting and a more drought tolerant plant.
Frequent, light irrigation will lead to plants that have a shallow root system and that are more prone to water stress. When using sprinkler systems about 1/2 -1 inch of water may be required weekly for shrubs and smaller trees (<4" trunk diameter). For drip irrigation about 5-50 gallons of water may be required.
These amounts would be higher in southern Utah and lower in northern Utah and would also depend on plant size. Large trees (>4" trunk diameter), depending on the size of the tree, may require hundreds of gallons of water per week. Water newly planted trees and shrubs more frequently until the root system is established.
Irrigation system maintenance is necessary to ensure the most efficient use of water that is being applied. Irrigation controllers should be checked at the beginning of each growing season before running sprinklers for the first time.
Programming: Set-up an irrigation schedule. The following basic irrigation schedule is recommended for use in Utah. Consult USU county extension offices for irrigation schedules that are directly applicable to your county
Inspect Sprinkler System: Once the irrigation schedule is programmed, inspect the sprinkler system by checking the valves,sprinkler heads, and emitters. Before running the system, remove the last sprinkler head in each line and let the water run for a few minutes to flush out any dirt and debris. Replace the sprinkler head and turn the system on, running one valve at a time.
Inspect Drip System: As with sprinkler systems, flush the drip system before running it by removing the emitters and letting water run through the tubing for a few minutes to flush out any dirt and debris. Replace emitters and run the system, one valve at a time, to check for problems.