Soil Test

• When it comes to fertilizer, there is such a thing as too much of a good thing. Although plants need certain nutrients to thrive, not all plant need the same amounts or types of fertilizer. If a plant receives too much of a nutrient, it can harm the plant as much as if the plant receives none of the nutrient at all. For example, all plants that receive too much nitrogen will appear burned. This is because too much nitrogen pulls water from the plants. A soil test can help determine which nutrients are deficient in the soil. This can aid in the selection of a fertilizer with the right blend of nutrients.
  
  

Macronutrients

• The macronutrient content is typically listed as three numbers on the front of a package of fertilizer. Each of these number represents the ratio of fertilizer in the package. The numbers are known as N-P-K numbers. N stands for nitrogen, P stands for phosphate and K stands for potassium. Nitrogen in fertilizer helps with growth and the development of green foliage. Phosphorous helps with the transfer of energy during photosynthesis. This stimulates plant development and hastens plant maturity. Potassium helps with the movement of nutrients through a plant. When there is not enough potassium in soil, plant growth is typically stunted and low in yield.
  
  

Micronutrients

• Plants do not absorb micronutrients at the same rate as they do macronutrients. Additionally, not all plants use all micronutrients. Because of this, many fertilizers do not even contain micronutrients. Despite this, many plants do need micronutrients to thrive. For example, plants that do not receive enough iron often display yellow leaves with dark green veins. This condition is known as iron chlorosis. The eight major micronutrients are iron, zinc, manganese, copper, boron, molybdenum, chlorine and nickel. Chlorine and nickel are not often added to fertilizer because plants can absorb enough from the soil.
  
  

pH

• A plant's ability to absorb fertilizers or nutrients from the soil may be compromised by the pH of soil. pH is a measure of how alkaline or acidic soil is. All plants can absorb certain nutrients within a pH specific to that individual plant. Additionally, certain nutrients are absorbed better at a certain pH range. Most plants absorb nutrients better in slightly acidic soil. Alkaline soil often "ties up" nutrients. The soil pH can also be indicative of the levels of certain nutrients in soil. For example, low pH soil is often low in calcium and magnesium.