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Fertility Facts for Home Gardeners
| Agdex #: 530 |
| Author: |
| History: Revised February 3, 2000 |
| Plant Nutrient Requirements: |
| Plant growth is dependent on as many as sixteen chemical elements all of which have one or several special functions in growth and development. These elements are grouped into major elements and micro (trace) elements. The majors (those required in relatively large amounts) include: carbon, hydrogen and oxygen (supplied by air and water) as well as nitrogen, phosphorus, potassium, calcium, magnesium and sulfur (which come from the soil). Micros include iron, manganese, copper, zinc, boron, molybdenum, and chlorine (which also come from the soil). Of all the elements listed, the only ones found in regular garden fertilizers are nitrogen, phosphorus and potassium (potash). All others, except calcium and magnesium, are normally in sufficient quantities for plant growth either in the soil naturally or as by-products applied in fertilizers, compost or manures. Calcium and magnesium are supplied by the addition of limestone. Soil testing should be done on a regular basis to determine the nutrient status of the soil and thus the amount of fertilizer which must be applied to grow a successful garden or lawn. Soil pH is also determined from a soil analysis. Island soils are naturally acidic and require limestone to correct this condition before plants can grow successfully. Soil Test Reports indicate the relative levels of nutrients in the soil. On the basis of these levels, the amount of Nitrogen (N), Phosphorus (P205) and Potash(K20) will be indicated in the‘Required Applications’ section of the report. The amount of limestone and fertilizer which will supply the recommended nutrients is provided on a sheet attached to the report. |
| Fertilizers and Limestone: |
| The composition of commercial fertilizer is always shown on the bag or container and appears as a series of three numbers, for example 10-20-20. This means that the fertilizer contains 10% total nitrogen expressed as N, 20% available phosphorus expressed as P205 and 20% soluble potash expressed as K20. The order of N, P205, and K20 will always be the same on all bags and containers. For example, soil test results indicate that 45 Kg/ha of N, 45 Kg/ha of P205, and 45 Kg/ha of K20 need to be applied. The fertilizer application could be: 9 lb/1000 sq.ft. of 10-10-10 fertilizer or 6 lb/1000 sq.ft. of 15-15-15 fertilizer; what you use will depend on cost and availability. The soil test report will usually suggest one commonly used fertilizer formulation. Agricultural lime is usually used to correct soil acidity. There two types of lime normally available; dolomitic lime which contains mainly calcium and magnesium carbonates and calcitic lime which contains only calcium carbonate. Both types are equally effective and cost approximately the same. Dolomitic lime does, however, supply magnesium as well as calcium. Magnesium is often deficient in our soils so the use of dolomitic lime is usually recommended. |
| Moss Control: |
| Moss is a common weed in neglected turf in areas of high rainfall. Moss cannot compete in healthy vigorous lawns and is therefore easily kept under control. Chemical treatments are only a temporary control. The growing conditions of the soil must be improved to prevent the re-establishment of unwanted moss. |
| Conditions that favour moss include: |
| - poor soil aeration - poor soil drainage - low fertility - high acidity (low pH), and - heavy shade |
| Commercial moss killers are available through garden centres however, you may wish to use the following products which will eliminate moss at a fraction of the cost: |
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| After chemically treating the unwanted moss, leave it for two weeks. Remove the dead moss by raking. Then apply fertilizer, if recommended and lime if the soil pH is below 6.0. If the grass is thin and bare patches are present, overseed the area with a recommended grass mixture. |
| For more information on soil sampling, soil sample interpretation, or fertility facts, contact: |
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PEI Analytical Laboratries
P.E.I. Department of Agriculture 440 University Ave., Charlottetown, PEI, C1A 7N3, Tel:(902) 368-5628 or Fax: (902) 368-6299. |
