So, What IS Your Fertilizer Doing For You?

Our friend Mace Bower made a powerful post on Crop Talk.  One of my mentors called and said it's the best piece he has read on there.  My friends and I are discussing this mind tingling post.  It's more than worth discussing today.

"I kind of had an AH HA moment recently. I add this to contribute based on the recent discussions on adding Fungi of some name brand as a root growth promoter or for whatever reasons they are sold, and apparently have quite a following lately. As you learn, it is important to understand that there is more to science than just buying cleverly marketed inputs.


Well in January, one of the funniest things at National No-till Conference was Gabe Brown picking on Dave Brandt that he needed to "take out the pacifier" if he wanted to get his soil biological system working correctly. The scenario is that Brandt uses 60 lbs of Nitrogen to grow his corn crops that are otherwise grown with legumes/cover crops/organic fertilizer etc, and that he obviously sees a positive net return to this (60 lbs) input. Gabe is saying, that he has learned, the addition of this fertilizer is really holding back the biological soil/plant/microbial system from its potential. Or that the "cost" is greater than the nitrogen alone. So, lots of people don't "see" or believe what Gabe is saying, that is fine. It is what he has been taught/believes/is selling/whatever.

More recently, I am currently in a Soil Microbiology class (PhD). We had a guest lecturer, who specializes in mychorrhizal fungi (those that operate as root extensions, they use the plant for Carbon, and contribute other nutrients to the plant). I took some bullet notes and will share those, they are something that is definitely worth thinking about. Much of this is economically irrelevant in times of high grain prices, or low fertilizer prices, as profit trumps science every time. But if you are interested in the soil as a biological system, some good points.

-Phosphate critical for living cells. ATP

-Mychorrhizal associations contribute 20-80% of P needs.

-Plants without mychorrhizal association explore 1-2 cm3 of soil around roots.

-Plants w/ myc ass. explore 12-15 cm3 of soil around roots.

-When P or N is limiting, plants support mychorrizal association.

-High concentration of P or N in plants create more demand for Carbon. Then plants reduce C contribution to mychorhriza or eliminate association.

-Plants spend less energy in the mycorrhizal association than producing root mass for nutrient uptake.

-Hyphae (structure) reach up to 10 cm from roots.

-Phosphorus is largest nutrient uptake by mychorrhizae fungi to host.

-Other nutrients taken up N, K, Mg, Ca, Mn, Zn, Cu

-Increase plant tolerance to water stress. Hyphae extract water from small pores.

-Suppress root disease, improve plant health, mechanical resistance.

-Produce Glomalin to bind soil particles.

-Excess fertilizer leads to less myc association. 45 lb/A/Yr reduced colonization by 50%

-Negative correlation to high P

-Plants depend on myc to different level. Flax 90%, Corn 80%, Sorghum 60%, Wheat 30%.

-Brassica's are non-host of mychorrhiazal fungi.

The speaker's belief or prediction also included that political tensions will build over phosphate rock. The world would move from an oil economy to a phosphate economy. That is worth a whole discussion itself, as I have seen several scientists present that same view with hard data."

So the question is, when a friend produced 300 bushels of corn this year on 80-90 pounds of purchased nitrogen, how much were the above factors working in his soil?  I am thinking greatly but don't know how you would ever quantify it.

As I build my soil with more air and carbon from crop and cover crop root mass, I can see I am on the right path.  This strays from current adopted agricultural practices so it must produce beautiful crops that are efficient and profitable to get notice.

"Speak With Your Fields."

Ed