If the results of your soil test indicate a lack of certain nutrients, you should follow the recommendations made by the testing company for supplementing the soil. If the imbalance is slight, organic fertilizers can be used.
© 2006 Publications International, Ltd.
The fruit of your labors --
a tiny seedling grows.
Because they generally contain a low percentage of nutrients that are slowly released into the soil, organic fertilizers are inadequate when fast results are needed or if the imbalance of nutrients is great. In these situations, inorganic fertilizers are the better choice.
A combination of both kinds may be a good compromise: Use the quick-to-feed commercial plant foods first, then
follow up in subsequent years with the slow-feeding organic fertilizers.
Chemical fertilizer is commonly formulated in some combination of the three major nutrients: nitrogen, phosphorous, and potassium -- N, P, K. The numbers featured on each bag represent the percentage of each of these nutrients in the mix. For example, 5-10-5 contains 5 percent nitrogen (N), 10 percent phosphorous (P), and 5 percent potassium (K).
The NPK formula is also listed on each container of organic fertilizer. The percentages of each nutrient are lower in organic fertilizers than in inorganic fertilizers. Therefore, larger amounts of organic plant food are required to achieve the same results.
It's also possible to purchase fertilizers separately rather than in a three-nutrient mix. These are useful when there's a deficiency in a single nutrient. Consult with your Cooperative Extension office or garden center staff if you feel uncertain about solving nutrient deficiency problems.
Other Ways to Improve Soil
While fertilizers are pretty fool-proof -- and definitely convenient -- there are other ways to make your soil the best it can be. Read the following tips to find out more.
- Get local compost from your city or town hall service department. Made from leaves and grass clippings collected as a public service, the compost may be free or at least reasonably priced for local residents.
To find other large-scale composters, check with the nearest Cooperative Extension Service; they are up-to-date on these matters. Or try landscapers and nurseries, who may compost fall leaves or stable leftovers for their customers, and bulk soil dealers, who may sell straight compost or premium topsoil blended with compost. Don't give up. Yard scraps are discouraged or banned in many American landfills, so someone near you may be composting them.
- Plan ahead for bulky organic soil amendments -- compost, manure, and leaves -- that may be added by the wheelbarrow-load to improve the soil. This will raise the soil level, at least temporarily. As the organic
matter decays, the soil level will lower.
- If soils rich in organic matter drop to expose the top of
a newly planted shrub or tree roots, add more soil or organic matter to keep the roots under cover.
- If your garden is beside a house or fence, keep the soil level low enough so it won't come in contact with wooden siding or fencing that isn't rot-resistant.
- When planting around existing trees, shrubs, and perennial flowers, avoid covering the crown -- where stems emerge from the ground -- with organic material. This helps prevent disease problems.
- Till or spade a thick layer of compost into lightly moist (never wet) soil to bring it to life before planting a new garden. If you are starting with hard, compacted soil, it's necessary to spade the soil first to break it up. Go over the area, removing weed roots and other unwanted vegetation as you go. Then go over the soil with a rototiller. After the first pass, go over it again crosswise until you break the soil into reasonably small pieces.
Your well-tilled soil, like screened topsoil, may look great at first, but silt or clay soils are likely to get stiff, crusty, and hard after a few heavy downpours. The best way to keep soil loose and light is to add organic matter.
Add a 4- to 6-inch-deep layer (more if soil is very poor) of compost to the soil and work it down until it's 10 to 12 inches deep. The soil will become darker, moister, and spongier -- a dramatic conversion right before your eyes. As long as the organic matter remains in the soil, the soil is likely to stay loose. But since it slowly decays, you will have to continue to add organic matter -- compost, mulch, or shredded leaves -- to maintain the desired texture.
- Try spading or no-till systems to preserve the texture and organic content of thriving garden soils. Once the soil is loose, light, and rich, minimal disturbance helps preserve the levels of organic matter. Avoid repeated tilling, which breaks healthy soil clumps and speeds up decay.Instead of tilling, loosen rich soil before planting by turning the surface shallowly with a shovel and breaking it apart with a smack from the shovel backside. Very loose soil can be made ready for direct seeding by combing it with a hoe or cultivator.
© 2006 Publications International, Ltd.
To check your soil texture quickly, squeeze some lightly moist soil in your hand.
Most important, be sure to test your soil by feel before and after it is amended to judge the extent of the change. Take a small handful of lightly moist soil from several inches below the soil surface. Squeeze it into a ball in your hand and watch the results when you extend your fingers.
Sandy soils, which can have a scratchy feel, will fall apart. To enrich a sandy soil, apply and incorporate a several-inch layer of compost and even an inch or two of clay, then try again. When the soil is improved, the ball will cling together better.
Clay soils, which have a slick feel, will form a tight ball that's not easily broken up. To lighten clay soil, add extra compost and coarse sand. When the soil is light enough, the ball will break up with a tap of a finger.