The scoop on fertilizers: Is organic better than chemical versions?

If you don't have a worm bin, you'll want one!

You might tend to think that organic fertilizers are better for your plants. However, the fact is plants can't tell the difference between organic and synthetic (chemical) fertilizers. They are both used by the plant in the same way. There are basically 3 components in fertilizers. Macronutrients are Nitrogen (N), Phosphorus (P) and Potassium (K). All 3 are usually found in commercial fertilizer in varying proportions. With organic fertilizers you typically need 3 different materials to add all 3 macronutrients. In the Tucson and surrounding communities, soils high in alkalinity (pH) can be a problem, as it binds nutrients from becoming available to the plant. This makes it even harder to deliver necessary nutrients to your plants.

Aside from the 3 macronutrients, plants also need micronutrients, which are much more difficult to find in chemical fertilizers. Micronutrient deficiencies in the soil are one of the reasons food grown today is not as nutritious as it used to be. This is where the use of organic fertilizers shine. They provide much more than the basic 3 nutrients. Organic fertilizers also improve soil structure and lower pH, which increases the availability of all nutrients.

Because each type of organic matter offers different nutritional support, you will need to add as many different kinds as you can.

Types of organic fertilizers include:

Nitrogen boosters: animal manures, plant matter (such as leaves), compost, fish meal, bat guano, worm castings and blood meal.

Phosphorus boosters: bone meal, rock phosphate

Potassium boosters: kelp meal, greensand, wood ash (depending on wood type)

Micronutrient suppliers: compost (which also contains beneficial microorganisms), gypsum (which helps break up hard alkaline soils), kelp meal and worm castings.

A new addition to the world of organic soil additives are Humates. They are touted to improve alkaline soils, but are pricey.

Sulfur can be added to soil to also correct high alkalinity, but the jury is out as to how effective this is.

While plants don't know the difference between chemical and organic fertilizers, it is important to understand that organic fertilizers last longer in the soil, and, especially when using manures and compost, create a good soil structure that retains water and encourages healthy soil organisms such as earthworms. Chemical fertilizers do not amend the soil. Period.