In Arizona, fertilizing your plants can mean the difference between a lush green landscape and a bland collection of half-dead trees and shrubs.  But don’t just grab the first bag of fertilizer you find at the home improvement store; understanding what fertilizers are is just as important and fertilizing.

What are fertilizers?

Fertilizers are any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of the plant.

Fertilizers typically provide, in varying proportions;

• six macronutrients: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S);
• seven micronutrients: boron (B), chlorine (Cl), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), and zinc (Zn).

Only three other macronutrients are needed by all plants: carbon, hydrogen, and oxygen. These nutrients are supplied by water and carbon dioxide.

Forms of Fertilizers

Fertilizers come in various forms, divided into organic or inorganic. Plants can only absorb their required nutrients if they are present in easily dissolved chemical compounds. Both organic and inorganic fertilizers provide the same needed chemical compounds. Organic fertilizers provided other macro and micro plant nutrients and are released as the organic matter decays.

The most common solid fertilizer is a granulated or powdered form. The second most common form is liquid fertilizer; some advantages of liquid fertilizer are its immediate effect and wide coverage.

Slow Release forms

Slow-release fertilizers reduce the problem of “burning” the plants due to excess nitrogen. Polymer coating of fertilizer ingredients gives tablets and spikes a ‘true time-release’ or ‘staged nutrient release’ (SNR) of fertilizer nutrients.

Can you over-fertilize your plants in Arizona?

Yes! You can over use plant fertilizer. Over-fertilization of a vital nutrient can be as detrimental as not fertilizing at all. Over-fertilizing or “Fertilizer burn” can dry out of the leaves and damage or even kill the plant. So if you are going to fertilize make sure you read all the directions before starting the process.

Organic fertilizers and their benefits

Organic fertilizers include naturally occurring organic materials, (e.g. chicken litter, manure, worm castings, compost, seaweed, guano) or naturally occurring mineral deposits. Poultry litter and cattle manure often create environmental and disposal problems, making their use as fertilizers very beneficial. Organic fertilizers have been known to help soil life and long-term productivity of soil.

Comparison with inorganic fertilizer

Organic fertilizer nutrient content, solubility, and nutrient release rates are typically all lower than inorganic fertilizers. In general, the nutrients in organic fertilizer are both more dilute and also much less readily available to plants. Nevertheless they are at least as effective as inorganic (chemical) fertilizers over longer periods of use.

More recently, organic fertilizers are on the rise as people are trying to use environmental friendly products. Although organic fertilizers usually contain a lower concentration of nutrients, this lower concentration avoids complication of nitrogen burn harming the plants. In addition, organic fertilizers such as compost and worm castings break down slowly into complex organic structures which build the soil’s structure and moisture- and nutrient-retaining capabilities.

Inorganic fertilizers almost always readily dissolve and unless added have few other macro and micro plant nutrients. You see results faster when the inorganic fertilizers are used.  

When it comes to fertilizing plants in Arizona,