by Matt Drummond, North Coast Community Garden Collaborative
Many gardeners make the tragic mistake of neglecting their soil year after year. Often this results from planting veggies season after season without adding amendments (manure, compost, organic fertilizers, mulch) or from not allowing garden beds to rest between plantings. Over time this will result in low harvests, more pests, and an increased need for expensive chemical fertilizers that only provide fleeting boosts to your plants. Building rich, fluffy, and healthy soil is the key to garden success and it really isn’t that hard. Understanding the basics of soil science and soil maintenance will give you the tools you need to start building dreamy soil at home.
Soil is a mix of sand, silt, clay, water and air. Soil is categorized into sand, clay, silt, and loam types based on the dominating size of the particles within a soil. The presence of these is controlled by the geology of your region or watershed. For example, the Eel River floodplain is composed of a silty soil due to movement of silt onto the banks during flooding.
The main soil types and the benefits and limitations of each are as follows:
- Sandy Soil (25% sand or more) – Benefits: great drainage, light, easy to work, warms quickly in the spring. Limitations: low water and nutrient retention.
- Clay Soil (25% clay or more) – Benefits: high in nutrients, holds water. Limitations: poor drainage, may crack in summer.
- Silt Soil – (80% silt or more) Benefits: light, high moisture and nutrient retention, high fertility. Limitations: easily eroded or washed away by rain.
- Loam Soil (composed of sand, clay and silt, providing the benefits of each) – Benefits: fertile, easy to work with, great drainage. Limitations: needs additional organic matter (compost, manure, etc.) for continued fertility.
Most healthy garden soils are composed of sandy loam or clay loam. Much of Humboldt County is composed of loamy soil due to thousands of years of sand, clay and silt deposition from waterways and the accumulation of organic matter from plants and animals. These soils are extremely fertile and will produce bountiful gardens only if you give back to the soil.
Gardening isn’t all about harvesting. It’s about a deep relationship with the soil that supports us all. Here are a few simple practices to build soil fertility year after year.
- Cover Crops – planting cover crops protects the soil from erosion, brings atmospheric nitrogen into the soil, and provides beneficial bulky organic matter for soils when cut down.
- Compost – adding a layer of compost to your beds provides organic materials, trace minerals, and food for beneficial bacteria, fungi, and insects.
- Chop and Drop – chop down dead or bolting plants, allowing them to be returned to the soil. Leave the roots in the ground and they will also break down and nourish the soil.
- Mulch – adding thick layers of mulch (manure, grass, leaves) in the fall protects top soil from heavy winter rains, keeps down weeds, and provides organic matter as it breaks down.
- Be creative! – compost tea, cardboard, cat hair, grass clippings, and animal bedding (straw, shavings) can all be used in your garden, and all are available locally for free. Talk to your friends, neighbors, and local farmers to find soil-building supplies in your neighborhood. Shifting your focus toward soil health will give you a closer relationship with your garden, neighborhood, and environment.