What is Organic Fertilizer?

All traditional organic fertilizers need to be broken down by microorganisms in order to be made plant available. After an application of an organic fertilizer, it can take up to 8 weeks before nutrients are made available and plant response is seen. Organic fertilizer nitrogen has to be transformed into ammonium or nitrate by microorganisms in order to be made plant available. This takes time and can be frustrating as it is also temperature dependent, meaning that microorganism mineralization and immobilization start to happen at soil temperatures above 60F, then it can take 8 weeks for any visual impact is noticed.

Therefore, timing of applications is essential and should be done for the summer months only. Most traditional organic fertilizers have a nitrogen content between 2% – 10% with the exception of poultry manure being 15% and dried blood at 13%. As a consequence, they have a relatively higher cost per lb compared to synthetic fertilizers but are beneficial for you soil profile as they provide a carbon source for microorganism health and development, which directly benefits your soil through improved structure and providing a beneficial environment for turfgrass health.

Traditional Organic Fertilizer Sources are:

Animal Byproducts like bone meal, dried blood, dried fish wastes etc.

Plant Residues like soybean extracts, tobacco stems, rapeseed meal, cottonseed meal, kelp, molasses etc.

Biosolids processed from humans, cattle, poultry, pigs, horses’ sewage/manure etc.

Newer Blended Organic Fertilizers for Spring and Fall

Naturally occurring nitrogen sources are being blended with other organic sources in order to provide a fertilizer for applications that desire a faster response during times when temperatures are low. These blended fertilizers in part do not require microbial breakdown and are still naturally found instead of being harvested. You will see a greening effect and growth spurt from an application with a blended organic fertilizer which will carry the fertilizer through to the time when the other ingredients can be available.

Blended organic fertilizer sources contain Chilean Nitrate, Sodium Nitrate which in nitrate form are readily available to the plant. This means now you can truly create a year-round fertilizer program just with organics and you can do away with synthetics, if that’s your goal. Again, cost is up versus synthetic fertilizers, and they are a little bit harder to understand when it comes to nutrient release.