Many problems with home vegetable gardens, fruit trees, shrubs and flower gardens are not caused by pests, diseases, or a lack of nutrients, but by poor soil physical conditions. Growing plants in soils that have too much clay, too many rocks or are just plain too sandy can be a real challenge.
Symptoms of poor soil quality include:
- Soil that is dried and cracked in summer.
- Digging holes in the soil is difficult, whether it is wet or dry.
- Rhododendrons, hydrangeas, and other shrubs wilt in hot weather, even with added water.
- Leaves on shrubs turn yellow and have brown, dead sections on them, particularly on the south side of the plant.
- Tomatoes and peppers get blossom end rot, even if fertilized with calcium.
- Water tends to pool on the soil surface and to drain slowly, or it runs off the surface.
The same types of problems occur with lawns; they include:
- On heavy clay soils, grass is just not as vigorous and thick as it should be.
- The poorer the soil, the shallower the turf grass root system and consequently, the turf is less able to deal with drought or weeds.
- When we get into our hot, dry summer months, lawns on poor soils are the first to turn brown or the first to get infested with weeds and moss.
The majority of plants grow best in well-drained, well-aerated, fertile soils. Plants do best when soils provide a nice even moisture supply, but they also require an open, well-aerated soil for good root penetration and to allow roots to breathe. A tight clay soil limits root growth because of the lack of air available in the soil, and simply by the resistance of the soil to root penetration. Resilience in plants and their ability to withstand stress is directly related to the size and health of their root system. Plants may struggle for years in poor soils, performing poorly, and disappointing the homeowner because they fail to live up to expectations.
One of the best ways to improve soil quality is through the addition of organic matter. Annual applications of compost, animal manure, cover crops, or organic mulch materials will help to improve even the worst soils. It may take several years, but eventually soil structure will be improved.
There are several ways to mix organic matter into garden soil. The most common methods involve digging or rototilling. Rototillers are effective, but hand-operated machines usually are capable of working only the top 4 to 6 inches of soil. Excessive rototilling, however, has very detrimental effects on soil structure, particularly if done when the soil is wet. Rototilling can compact soil just below the tillage depth, reduce the volume of pore spaces in soil for air and water and kill earthworms, which are essential for maintaining soil quality. Although digging amendments into the soil is laborious, it will enable you to incorporate organic matter as deeply as you choose to dig, up to 12 inches. To minimize the impact of digging on soil structure, consider using a spading fork.
Cover crops provide a relatively easy way to add organic matter to soil. The mat of roots formed by the cover crop often is more valuable in building soil structure than the above ground biomass. Both winter and summer cover crops can be used. You can dig in the cover crop before planting your garden, or you can remove the above ground plant material and compost it.
Another option is to apply a layer of organic amendment to the soil surface and simply plant into it. This method has the advantage of not requiring any disturbance of the soil structure. Also, the amendment will serve as a mulch and help preserve soil moisture and suppress weeds.
One of the most important reasons for adding organic matter is to improve the ability of the soil to accept and store water. Amending your soil may mean that you can reduce the amount of water that a newly planted garden requires. Adding organic matter also increases the activity and number of soil organisms. Over time, a well-amended soil will supply more of the nutrients your plants require, which will reduce fertilizer requirements.