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For the best results in growing plants and vegetables they need nutrients from the soil. When there is an inadequate supply of these nutrients in the soil you need to add fertilizer.

Have your soil tested to determine the amount of nutrients that are currently in the soil. Recommendations on what type of fertilizer and how much you need will be in the soil test report.

What Do Your Plants Need?

The most abundantly available nutrients come from the air and water. These nutrients are oxygen, hydrogen and carbon. The next major nutrient requirements, or primary nutrients, are nitrogen, phosphorus and potassium. These are found in the fertilizers we buy and are referred to as NPK which shows the amounts of nitrogen, phosphorus and potassium in the fertilizer. Next are the secondary nutrients your plants require. Calcium, magnesium and sulfur are needed in smaller quantities than the NPK but are still important for healthy plant growth. The micro nutrients are the least amount required by plants and consist of boron, chlorine, copper, iron, manganese, molybdenum, and zinc. The availability of the micronutrients to your plants may be controlled by the pH of your soil.

Organic and Inorganic Fertilizer

Organic fertilizers come from living plant or animal sources where as inorganic or chemical fertilizers are manufactured. The most common inorganic fertilizers are made up mostly of the 3 primary nutrients, nitrogen, potassium, and phosphorus. Organic fertilizers on the other hand will normally contain both micronutrients and macronutrients. Since the nitrogen in an organic fertilizer relies on micro organisms to reduce it to a form useable by the plants it is slower to be available than the nitrogen from inorganic fertilizers. So in comparison, inorganic fertilizers are considered fast and the organic fertilizers are slower or time-released. Most organic fertilizers are only effective when soil organisms are active enough to break down the fertilizer and release the nutrients. This usually means the soil needs to be moist and warm. The pH of the soil will also affect the activity of these organisms.

The soil’s physical structure is improved and organic matter content is increased through the use of organic fertilizers.

Care needs to be taken when using inorganic fertilizers to protect ground water from pollution due to leaching. Also, chemical fertilizers should be washed off of foliage to prevent damage to the plants. Since sandy soil types tend to leach it is wise to use slow release fertilizers which tend to leach less than the faster fertilizers.

Some common organic fertilizers are:

  • Cottonseed meal – for fertilizing acid-loving plants.
  • Blood meal – is dried, powdered blood with a high nitrogen concentration. Sometimes used to increase activity in a compost bin.
  • Fish emulsion – Very well rounded fertilizer with an unpleasant odor lasting a couple days after application
  • Manure – Chicken and cow manure are two common manures used in a complete fertilizer.

Since the amount of nutrients available in manures is limited, they are better used as soil conditioners or additives.

Fertilizers are purchased as “complete”, “balanced”, “specialty” or “slow release” types.

  • Complete – Contains all three of the primary nutrients, nitrogen, phosphorous and potassium.
  • Balanced – Contains equal amounts of the three primary nutrients and is indicated by a label with all 3 numbers being equal such as, 10-10-10 or 3-3-3.
  • Specialty – These fertilizers are prepared for specific plants or plant types.
  • Slow Release – Release their nutrients at a slower rate and don’t need to be applied as often as other types of fertilizers.

Fertilizers come in various forms including powders, pellets, spikes, liquids, tablets and granular.

How often you have to apply fertilizers depends on several factors:

When planning your garden or landscape you should group plants based on their fertilizer and watering needs. This will help reduce over or under application of fertilizer and water.

Remember to follow the recommendations from your soil test to decide which fertilizers to use and also follow the manufacturer’s recommendations for applying.

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