Nitrogen is Nitrogen is Nitrogen...or is it?

I watched a video recently by Graeme Sait, a guy from the Australian permaculture scene, and he mentions that not all nitrogen is created equal. He claims in the video below (which is super info dense) at around minute 7 that current agricultural practices with nitrate ( NO3−) fertilizer means that our food crops contain 75% nitrate and only 25% (roughly) ammonium nitrogen (NH4+).

He claims that studies have demonstrated carcinogenic activity and toxicity from high concentrations of nitrates in food (and, therefore in the bloodstream).

This lit review suggests that NH4+ (ammonium) is widely shown to be toxic to both plants and animals.

As I understand it, Ammonium is primarily a waste product of animal metabolism and comes out as some kind of pee (urea). Frankia bacteria (leguminous root nodule fame) fix yet another form of N in the form of NH3 (ammonia).

Are there any soil chemistry or straight chemistry pros that could help to explain what Graeme might be getting at?

Thank you in advance to everyone.

Excellent overview of NH4+ ecology with nuggets of pertinent info


Graeme Sait Video:



So we have:

Ammonium: NH4+ (in urea)
Ammonia: NH3 (from Frankia in nodules)
Nitrate: NO3− (several million kgs per year used as fertilizer)
Nitrite: NO2- (what NO3- becomes when ingested)

At the moment I find it quite difficult to understand, but I am interrested.

Our crops should contain more NH4+ and 25% is too little... and at the same time NH4+ is said to be toxic?
I scratch my head...

What I can see right now is that N with H is better than N with O?
Great, so it has always been good to use animal manure and green manure.
And the modern habit of delivering a N form with O is not the right way...
Though plants seem to to absorb very well this stuff!

And what is the form of N in rain?
Also (I cannot open the video) does he say something about mineral and organic forms?
I have understood, if right, that all humic reserve of nutrients in the soil are linked to C, carbon.
But this form is not available to plants, they need some help to brake it and mineralize it.
The advantage of the organic form, = with carbon, is that it will be delivered little by little to the plants, and will not be washed away.

The problem with fertilizer is thus that the form is available to plants, but too much at a time, and can be lixiviated.
Same as our digestion, we need FIBER, that is to say a form of CARBON, so that we do not get all our nutrients all at once!

I found this wikki article about nitrogen assimilation in plants which has a few pointers.

Here's a snippet...

Plants absorb nitrogen from the soil in the form of nitrate (NO3-) and ammonia (NH3). In aerobic soils where nitrification can occur, nitrate is usually the predominant form of available nitrogen that is absorbed. However this need not always be the case as ammonia can predominate in grasslands and in flooded, anaerobic soils like rice paddies Plant roots themselves can affect the abundance of various forms of nitrogen by changing the pH and secreting organic compounds or oxygen. This influences microbial activities like the inter-conversion of various nitrogen species, the release of ammonia from organic matter in the soil and the fixation of nitrogen by non-nodule-forming bacteria.

Then diluted urine commonly used is useless or even bad? What happens to it in the soil?

Xisca Nicolas wrote:
And what is the form of N in rain?

It's NO3 from atmospheric N2

From what I've found in digging a little deeper, early succession systems tend to work with N03- and NH3 as the primary Nitrogen sources. NH4+ has been shown to be toxic to early succession plants in too high of a NH4:NO3 soil ratio. So pioneer species, and most annual veggies and fruits seem to do well with NO3- and NH3. Legume-Frankia teams are the ones fixing NH3.

Late succession plants (typically trees and forest cover plants) seem to be very tolerant of NH4+ as the primary source of N.

So maybe this suggests that urea harvesting is better used on late-succession plants, more food forest fertilizer.



But this still doesn't answer the original question...can an early succession plant like spinach realistically be grown with 75% NH4+? Is anyone actually growing leafy greens with 75% NH4+, or do they display toxicity symptoms?

Then diluted urine commonly used is useless or even bad? What happens to it in the soil?

From what I've read the "dominant" plant-available sources of N seem to be NH4+ (from urea reaction) and NO3-, with NH3 being from N-fixers, with various bacteria switching Nitrogen compounds from one form to another. What happens to urine N in soil probably depends on the soil type, as Burra quoted from the wikipedia article. Different soil conditions (aerobic or anaeorobic) will have different bacterial mixes; different bacteria are going to produce different products.

Many soil bacteria possess the enzyme urease, which catalyzes the conversion of the urea to ammonia or ammonium ion and bicarbonate ion, thus urea fertilizers are very rapidly transformed to the ammonium form in soils. Among soil bacteria known to carry urease, some ammonia-oxidizing bacteria (AOB), such as species of Nitrosomonas, are also able to assimilate the carbon dioxide released by the reaction to make biomass via the Calvin Cycle, and harvest energy by oxidizing ammonia (the other product of urease) to nitrite, a process termed nitrification.[40] Nitrite-oxidizing bacteria, especially Nitrobacter, oxidize nitrite to nitrate, which is extremely mobile in soils because of its negative charge and is a major cause of water pollution from agriculture. Ammonium and nitrate are readily absorbed by plants, and are the dominant sources of nitrogen for plant growth.

SOURCE

Very interesting video. I've reposted it and commented on it at my blog.

So, because we were on the subject of NH4+ and urea ( CO(NH2)2), I thought I'd link this entertaining jewel of a table into the conversation. I don't have a book money budget yet, but when I do, mister Crawford's book is high on the list. In his table in the pdf below, he takes the average N content of urine and calculates the number of "pees" for trees based on their N requirements. Half pees are not easy.


LINK: See page six for the pee table :)


Please note that this is only a book preview and that the full book can be purchased here.


On a related note, John mentioned that Nitrates, because they're so soluble, tend to be easily washed out of soils. I've seen lots of permaculture methods for fixing and catching and passing and retaining and enriching as far as nutrients go. I found the following "half-permaculture" thinking (working from a industrial ag starting point but implementing permaculturesque approaches to failing systems):



This could at least decrease world energy costs associated with synthetic phosphate production. It's a decent bandaid.

John Elliott wrote:Very interesting video...

You'll definitely enjoy the others on their Vimeo channel here.

I really enjoy Graeme's style, he doesn't try to dumb stuff down, very info dense stuff. I recommend his "getting the good bugs back vid." Very interesting, systemic perspective of the digestion-immune system.

This question has been bugging me and I finally caved in and bought a kindle copy of Teaming with Nutrients

If you search for 'ammonia' and go the first result, you'll read this.

Nitrogen is assimilated into plants in two forms, as ammonium (NH4+) and nitrate (NO3-). When a plant takes in NH4+ and it enters the cytoplasm of a cell, one of the H+ in its ionic structure quickly combines with an OH+ typically floating around due to the relatively high pH. The result is a water molecule and an ammonia molecule (NH3). This reaction changes the pH of the cytoplasm by decreasing the OH+ concentration (that is, increasing the H+), which can quickly create toxic conditions and mess with the transport of electrons needed for photosynthesis and respiration. In order not to have this happen, ammonia is either converted into organic molecules or transported to a vacuole, where the conditions are acidic, meaning there are plenty of H+ to return it to ammonium and thus a non-toxic state.

Nitrate is also converted into organic molecules. At first, this typically occurs in the roots, but as more and more nitrate accumulates, it is moved to shoot cells for assimilation. The conversion to organic molecules or assimilation causes NO3- to become nitrite (NO2-), which is toxic to plant cells.

Does that help any?

My brain's switching off for the evening...

for what its worth my take

from and overall view,
plants are adapted to grow in certain conditions (wet, dry, hot , cold, acidic, basic, sun, shade, etc)
the inner workings of the plants are set-up to function under those conditions
and expect to see nutrients in certain forms
most plants also evolved with the problem of deficiency rather than excess
so regulation of excess isn't there
if it is freely there, the plant will suck it up
for most chemical fertilizer what's calculated to be needed for the crop is applied all at once
so it's sucked up too fast or lost
if the type of excess (NH4+ rather than NO3-)
additional problems occur
NH4+ is a positive (anion)
NO3- is a negative (cation)
excess NH4+ suppresses uptake of other anions (Fe, Ca, Mn, K, etc)
an excess of either can cause an imbalance in pH
which forces the plant to expend energy to correct
neither should be floating around for long without being used

so the application of instantly soluble fertilizer, chemical or organic , especially in the form its not designed to handle,
can cause a plant problems

feed the soil

Besides limiting the non-ammonium types of nitrogen you put into your soil, the addition of mycelium in the form of oyster mushroom spawn, will help with remediation of soil nitrogen uptake. There are several others that are beneficial such as some of the puff balls that will help in the control of how much of which type of nitrogen available is taken in by your crop plantings. I don't use any artificial additions to my gardens, just completely finished compost and leaf mold are used. calcium, boron, and essential minerals come from composed bones, the remains of fish cleaning and green sand/dried seaweed.