Soil is the most important component of the landscape. Many well-designed landscapes have failed because of inadequate soil preparation before planting, and/or soil management after. Incorporating organic matter is important because drainage is improved, and the soil is able to retain moisture and nutrients longer in the root zone.
Proper soil preparation and management also improves landscape water conservation by increasing plant rooting depth and soil water holding capacity and reducing water runoff and evaporation. Soils high in clay absorb water very slowly and cause water waste and loss when unabsorbed water runs off. Sandy soils can direct water below and out of reach of thirsty plants. Soils compacted by construction or foot traffic can be difficult to penetrate by either water or plant roots. A good soil is one that is high in organic matter. Many of our soils in the intermountain west will have 1-3% organic matter, but gardens that have been in use for any period of time will have less than 1% organic matter. (Most of the soils tested in this area have come back with less than 1%.) Improve the soil in your landscape by adding amendments the soil.
An organic amendment that gives the best result is usually some type of compost. Peat moss is usually not recommended due to the fact that with high summer heat. A fine textured material like peat moss will dissipate quickly—sometimes within less than a year. Make sure that the compost you use has varied sized particles which aid in a slower break down and help to fluff up the soil to allow for air movement. As you add compost, remember, that if it has not been stabilized by the addition of nitrogen, you will need to add a nitrogen fertilizer. This additional nitrogen is to stop the depletion that occurs as organisms in the soil break down the organic matter.
It is also important to remember that when adding amendments to the soil, make sure you add enough to change the structure of your soil. A little bit of material won’t provide any benefit. Apply about 3 inches to the top and mix it into the soil to a depth of 6-8 inches.
Fall is the ideal time to make the addition of soil amendments. The fall weather allows the composted soil to absorb water, increases water infiltration and increases the water holding capacity. This water then becomes available for next year’s growth of plants.