- Author: Linda Lewis Griffith
- Editor: Noni Todd
By Linda Lewis Griffith UCCE Master Gardener
Soil is vital to the success of any garden. So it's worthwhile to understand the key factors that impact its productivity:
- Texture is the relative proportions of sand, silt and clay particles in any soil. It determines a soil's fitness for growing plants, or its tilth, as well as its nutrient and water-holding capacities. Soils with coarse-grained sand are referred to as light. Soils with fine particles of clay are considered heavy. The ideal soil, loam, is a combination of all three.
Soil structure. Soil particles form into groups called aggregates. Soil structure refers to the way these aggregates are arranged into various sized crumbs and clods. A soil with good structure will have adequate water infiltration, drainage, aeration and overall tilth.
Soil pH. The pH of garden soil is its relative acidity or alkalinity. A soil's pH influences numerous chemical reactions, including the availability of nutrients considered essential for plant growth. Most crops do best when the soil is slightly acidic to neutral (pH 5.5 to 7.5). Your soil pH can be measured with a soil test kit that is readily available at nurseries and garden centers.
- Soluble mineral salts dissolve easily in water and can accumulate in soil. They're usually washed away by winter rainstorms. But they build up in semi-arid Mediterranean climates where rainfall is scant. To make matters worse, drought, fertilizers and irrigation all contribute to excessive salt in the soil. Many plants, such as ornamentals, fruits and vegetables are damaged by too much salt. The solution is to flush away the salt with excessive water. However, that may prove impractical in areas with severe water restrictions.
Fertilizers and Amendments. Fertilizers add nutrients to the soil. Amendments improve the soil's physical or chemical properties. It's sometimes tricky to distinguish between the two; animal manure, for instance, can be a source of readily available nutrients as well as supplying organic matter.
To learn more about soil, attend our Advice To Grow By Workshop this Saturday, April 21, from 10 am -12 pm, at the UCCE Auditorium, 2156 Sierra Way, San Luis Obispo.