JoAnne Skelly: Prepare garden soil now
Successful Nevada gardeners know that Nevada soils are worth the toil to ensure a great garden. Our native soils are low in organic matter due to low rainfall amounts. In addition, they are more alkaline than soils rich in organic matter. The alkalinity of a soil often interferes with micronutrient availability causing nutrient deficiencies in plants. The good news is that by adding organic matter, our soils can support healthy plants and yield good harvests.
In addition to improving nutrient availability, organic matter (OM) increases soil moisture retention, improves soil structure and decreases compaction. It also improves drainage and the workability of the soil (Utah State University Extension). OM supplies some essential nutrients and improves the habitat for soil organisms that enhance a soil’s health.
OM is a term that describes carbon-containing materials. This can include leaves, manure, grass clippings, non-animal kitchen scraps and paper. Compost is OM that has decomposed to that lovely smelling stuff that no longer looks anything like whatever it was originally. Gardeners refer to compost as “black gold.” Mulch, on the other hand, is a material that is applied on the surface of the soil to reduce soil moisture evaporation, limit weed development and protect trees and shrubs. Mulch may be organic, or it may be inorganic such as rocks or pea gravel.
One thing to know is that just adding OM might not supply adequate plant nutrition. Sometimes, if we add OM that is not sufficiently broken down, it initially will deplete and tie up the nitrogen in the soil as microorganisms “eat” the soil nitrogen as part of the decomposition process. The addition of a nitrogen fertilizer with the OM will help deter a drop in soil nitrogen availability that could cause plants to suffer. Utah State University Extension (https://extension.usu.edu/yardandgarden/soils/) recommends one pound of 21-0-0 (ammonium sulfate) per each 1 inch of organic matter per 100 square feet. Or, add an organic nitrogen source if you prefer.
Work OM into a soil annually. Two to 4 inches of OM per year will build the soil and benefit your plants. However, do not exceed 2 to 3 inches of manure in order to avoid salt buildup problems. Do not use cat, dog, pig or meat-eating animal manures to avoid disease contamination. Dig in the OM by hand to a depth of 8 inches or more. A tiller works but might not get the material deep enough into the soil. Also, avoid overtilling a soil, which can turn it into a powder.
JoAnne Skelly is associate professor and Extension educator, Emerita at University of Nevada Cooperative Extension. She can be reached at firstname.lastname@example.org.