Ag 101 Week 11

Fertilizers and Pajamas 

have something in common

 One size does NOT fit all  


Now that I have every serious farmers' attention with a title like that I am going to explain myself.

At some point in time, most people have bought an article of clothing that claims one size fits all. Everything from gloves to pajamas come that way. I'm here to tell you that the tag on the pajamas is a lie. If I get them to fit one place they inevitably don't fit somewhere else.

Fertilizer blends are no different. 

What I have come to realize is that soil fertility cannot always pigeonhole into a pre-formulated blend. Not that fertilizer blends like a 10-10-10, a 5-3-7, or a 4-8-4 don't have their place, just not every place.  You may get the NPK (nitrogen, phosphorus, potassium) to fit but, the other components or ingredients, if you will, may not be the best fit for the rest of your fertility program. 

I will also be the first to say that if I can get a blend to work for a farmer, I will gladly recommend it. But it must fit all the criteria I've established for that farmers' needs based on soil tests, crops, individual components, their chemistries, and price. 

I use this example in a presentation I've given about understanding fertilizers and amendments.

Let's look at a 50 lb bag of 8-0-24 (N-P-K)

1.To calculate the pounds of Nitrogen: 50×.08 = 4 lbs N

2.To calculate the pounds of Potassium: 50×.24 = 12 lbs K

There are a total of 16 lbs of nutrients

in a 50 lbs bag of 8-0-24

This leaves you with 34 lbs of filler material


That is 68% filler material

That's 68% of the pajama that doesn't fit me! I don't know about you but I want my pj's to fit 100% of me not just 32%.  

Filler materials are added to fertilizer blends for several reasons. In the case of organic fertilizers, they are made with naturally mined materials and animal by-products leading to variables such as moisture and consistency. Liming materials or dried clays may need to be added to help the fertilizer flow better through the processing equipment or a farmers’ spreader. It also helps with distribution in the field when being spread.

Usually, fillers are inexpensive materials, such as granular limestone, clays, and aragonite. Not that these are necessarily bad for your soil. What I want farmers to realize is that just like the materials used in the blend to achieve the NPK amounts, the fillers are chemistries that change the soil as well.

Remember the farmer I mentioned in Week 9, that had a challenge with pH? We traced it back to filler material in the fertilizer he had been years consistently over several years. It was aragonite. Aragonite is one of my favorites for calcium. However, due to its pH being around 8.0, but variable depending on where it is mined,  it has a liming effect that needs to be taken into consideration. Not only is aragonite a readily available calcium source, but it also makes a great filler because it is relatively inexpensive and when dried helps blended fertilizers flow better.

This is an example of a material that can accomplish several things. Keep in mind your soil might not need all it can do. Just as the pajamas fit in one place and not another,  a fertilizer blend might fit one criteria, but not all. Educate yourself as to what is in the blend and how each component can potentially alter the fertility of your soil. 

Not only is there an impact on soil fertility, and even though fillers are relatively inexpensive, there is a financial impact even if nominal. It costs money for the manufacturer to purchase, and that cost is passed on to the farmer.  Being naturally mined means, they are not always sourced geographically close to where they are needed leading to greater transportation distances. Most clay materials are only available in the central and western part of the country or even further away, necessitating the need for them to be imported. Last but not least there is the potential for a greater environmental impact as well. 

Get a soil test to see if a blend will work or a single input.

You might be surprised at what you can do with one input or even thinking beyond and using different management strategies.

Trust me; you really don't know till you try the pajamas on.