Harnett County Center
BECOME AN EXPERT GARDENER BY FOLLOWING THESE FERTILIZER TIPS, 5/22/98
Giving plants the proper type and amount of fertilizer is one of the most important steps to success in the garden. This is true whether you are growing shrubbery, flowers, fruits, or vegetables.
As I've mentioned here before, the three numbers on a fertilizer bag (e.g. 10-10-10) stand for the percentages of nitrogen (N), phosphate (P), and potash (K), respectively. But to truly give plants what they need, it's important to understand some specifics about each nutrient.
NITROGEN
The first number indicates the percentage of nitrogen . The nitrogen in your average bag of 10-10-10 or 8-8-8 dissolves very rapidly. Therefore, if excess nitrogen is applied, it can runoff the soil surface or leach into the groundwater. Excess nitrogen in our lakes and rivers is a real concern these days. It can also get into drinking wells, creating health concerns, especially for young children.
Therefore, there is a real advantage to using slow release fertilizers. Slow release forms of nitrogen dissolve very slowly. There is less of a chance that it will contaminate our water supply. Plus, the plant benefits by having a more level and constant source of this nutrient.
PHOSPHATE
The percentage of phosphate is indicated by the second number on the bag. Unlike nitrogen, phosphate tends to stay in the soil instead of running-off or leaching. When applied to the soil surface, it takes a long time before it reaches the root zone where it is needed.
Therefore, if you are planting a new flower bed, vegetable garden, lawn, etc., and the soil test report indicates that phosphate is needed, it is a good idea to mix the phosphate into the top 4 to 6 inches of the soil.
Many soil test reports for home lawns and gardens recommend a fertilizer that contains no phosphate, for example a 15-0-14 or an 8-0-24. This is because many homegardeners have been using 8- 8-8 or 10-10-10 for several years. Since phosphate tends to stay in the soil for a long time, they have built up some reserves. If they continue to apply phosphate, they may actually harm the plants by applying too much.
POTASH
Potash is the last number. Potash behaves more like nitrogen, in that it dissolves rapidly. When applied to the soil surface, potash will move fairly quickly into the root zone.
Thus, advanced gardening involves understanding the individual components of fertilizer and managing them separately. At times it may be better to apply a fertilizer that contains only one of the three nutrients (some examples are in the table).
From a nutrient standpoint, organic fertilizers such as manure are no better or worse than a 10-10-10 or 8-8-8. The plant doesn't care if the nitrogen comes from the garden center or the horse stall. There are many organic fertilizers available commercially. Just as with 10-10-10, the bag will have three numbers indicating the percentages of each nutrient.
Help your plants AND the environment by taking your fertilizer routine to the next level. If you'd like to know more, please give me a call.
Nutrient Percentages for Common Fertilizers
| Fertilizer | Nitrogen | Phosphate | Potash |
| 10-10-10 | 10 | 10 | 10 |
| Ammonium nitrate | 34 | 0 | 0 |
| Nitrate of soda | 16 | 0 | 0.2 |
| Triple super phosphate | 0 | 45 | 0 |
| Muriate of potash | 0 | 0 | 60 |
| Bone meal | 3 | 25 | 0 |
| Chicken litter (estimate) | 36 | 80 | 34 |
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