JoAnne Skelly: Soil is key to garden success
February 12, 2018
Often, gardeners focus on the plants in their landscape. However, successful plants rely on healthy soils to support them. In Northern Nevada, soils are extremely variable and can provide challenges for the gardener. Before any planting comes soil preparation.
When I was young, the tradition was to dig soil a few times a year. Now we know too much tilling or digging can have undesirable side effects such as soil compaction and soil structure breakdown. Soil structure is how the particles clump together. Big clumps don't allow for good seed/soil contact. They can also block root development. Soil without clumps is like a powder and becomes impermeable to water. Ideally, we want crumb-like granules that hold water and air and are easy to dig. Too much digging can also unbalance soil microorganism populations (Rodale "Successful Organic Gardening — Improving the Soil").
Turning the soil once a year is enough, and sometimes even that isn't needed on beds with no foot or equipment traffic. When a soil is worked or turned, put in organic matter, fertilizer and soil amendments. Anything that needs to be added after this one-time dig will be spread on the surface and gently raked in later.
Organic matter helps increase the ability of a soil to absorb and store water. In porous, sandy soils, the addition of organic matter slows water movement through the soil, increasing the soil's water-holding capacity. In clay-rich soils, the addition of organic matter helps loosen the soil, improving or increasing water infiltration and drainage. Organic material also acts as a holding station for plant nutrients, keeping the nutrients in the soil where they're needed by plants. It further reduces the potential for nutrient pollution to groundwater and surface water.
Is it too early to work soil? Soil that's worked while it's too wet compacts easily and its structure can be spoiled for the whole season. This is especially true if equipment is used to till the soil. Soil that's ready to be worked falls apart fairly easily when you poke it with your finger after squeezing it into a ball in your hand. Clay soil that's too wet sticks together and you can rub it into a ribbon or "worm" between your fingers or hands. Sandy soil, on the other hand, rarely sticks together and can be turned earlier than other soils.
I hope this goes without saying, don't try to dig soils that are frozen!
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JoAnne Skelly is Associate Professor & Extension Educator, Emerita at University of Nevada Cooperative Extension. She can be reached at firstname.lastname@example.org.