"Feed the soil, not the plant" is a statement Master Gardeners hear often during their training with University of Nevada Cooperative Extension. Worn-out soils with reduced productivity result from insufficient organic matter, lack of a diverse and thriving population of soil organisms and compaction. Instead of reacting to these symptoms by adding fertilizer, more irrigation or ripping a soil open, a good gardener needs to focus on general soil health.
A first step is to employ practices that promote good soil organic matter management. Soil organic matter is the basis for soils that grow healthy and productive plants. This requires:
- Using a number of practices that add organic materials to the soil
- Using a diverse source of organic material
- Conserving native soil organic matter
- Protecting the soil surface
- Developing and maintaining good soil structure
- Managing soil fertility (Magdoff and van Es. "Building Soils for Better Crops").
Organic matter consists of fresh organic residues, well-decomposed plant residues and living organisms such as bacteria, fungi, protozoa and insects. The living portion makes up about 15 percent of the organic matter content. These "critters" break down plant residues and manures into usable components for plants. Their by-products can help bind soil aggregates together to create good soil structure. Earthworms leave behind channels for air and water infiltration and root penetration.
The well-decomposed portion is called humus. Humus holds onto essential plant nutrients slowly releasing them for plant use. Humus reduces drainage problems and compaction issues. It increases a soil's water-holding capacity.
Tips to great soil include not working it when it is too wet in the spring, planting cover crops in the fall to prevent erosion, and building up and maintaining high levels of organic matter. Increasing organic material requires crop rotation in vegetable gardens, using manures (not human, dog, cat or pig), plant residues, mulches and composts. Plant residues include leaves, grass clippings (without herbicides), chips, some leftover garden matter, aged sawdust and straw. Raising organic matter in sandy soils is more challenging than on clay soils because it decomposes quickly in a loose soil.
Adding compost is essential. Making compost at home isn't difficult, but does require some time and effort. Take plant residues, non-animal kitchen wastes, soil and water. Mix them all together. Stir the mix and water regularly and soon you will have compost. It is important to add things in the right proportion, but I will write on that next week.
- JoAnne Skelly is the Carson City/Storey County Extension educator for University of Nevada Cooperative Extension. Contact her at 887-2252 or skellyj@unce. unr.edu, at your local University of Nevada Cooperative Extension office or at www.unce.unr.edu. "Ask a Master Gardener" at mastergardeners@unce.unr.edu