what is the difference between chemical and organic nitrogen?

What is the difference between chemical and organic nitrogen for composting carbon rich materials? Of course, I know that organic nitrogen sources tend to be less soluble, which is important in some circumstances. Also, I know that the addition of chemical nitrogen will speed the decay of soil organic matter, eventually destroying it without frequent additions of organic matter. Other then that, what is the difference?

Hey Gilbert,

As I understand it, chemical nitrogen needs to be processed into a format that can be used by plants. One of the ways this is accomplished is by the use of what are referred to here as "nitrogen-fixers." Simply put, these plants, or some of them, anyway, host one of two different types of bacteria that live in nodules in their root zones, which convert chemical nitrogen to a form that can be used by plants. Otherwise, the nitrogen simply isn't in a form that can be used. It's like you trying to drink water through a straw, except that the water is in the form of ice cubes. It is in the wrong form to fit up the straw, which in this scenario is your only method of getting the water. You have to wait until something converts it into a useable form.

There is also the issue of burning live plants with too much nitrogen. That is one reason why so-called "hot" manures must be composted.

There are better explanations of this all over this site. For your purposes, I would suggest threads on composting and nitrogen fixers.

-CK

That's a complicated question, as simple as it seems. I'll try to help explain with what little I know, hopefully not confusing anyone or leaving the question unanswered. Plants readily use certain forms of nitrogen: Ammonium (NH4+) and nitrate (NO3-). There's also nitrite (NO2-) and urea (CO(NH2)2), which nitrite is toxic to plants and urea isn't available until it meets a water molecule and forms ammonium carbonate (NH4)2CO3) which is unstable and readily falls apart into NH3 and CO2 and in the presence of water the NH3 reacts and grabs the hydrogen ion off a water molecule and forms NH4, ammonium. Another manufactured nitrogen fertilizer is ammonium nitrate (NH4NO3) and readily dissolve in water and the molecules separate into readily available ammonium and nitrate.

Downsides to manufactured forms of nitrogen are aplenty, being sourced from petroleum (like methane in particular to make urea), then requiring lots of energy to make the chemical reactions happen. Other downsides are death to soil life from a rapid influx of nitrogens, and  the high doses of nitrogen like nitrate can flush other molecules (like boron) out of a plants xylem. Sure the plants all of a sudden look a rich green color and may appear to be healthy and beautiful, but it's nothing other than "plastic surgery" or "lipstick" for plants, prettifying the appearance but not much more.

So some nitrogens aren't chemically different whether man made or organic. Nitrate is nitrate, and ammonium is ammonium, the molecule being the same whether man made or made by nitrogen fixing bacteria. Conventional farmers, Ag industry & the petroleum industry make that argument and they are indeed identical molecules, therefore synthetics are safe. Ag & Petro industries have a symbiotic relationship, both needing each other to make money (and big oil is bolstering their relationship with big Ag as they see the future of oil in automobiles on the way out and electric vehicles on the way in over the next 50 years). They don't want the notion or thought being mainstream that successful, higher yielding, healthier crops can be grown without their products. Remember, they don't care about you and me or the planet. They care about money.

The real difference is the bacteria slowly make nitrogen compounds from the nitrogen in our atmosphere (N2), providing a steady supply. When an influx of nitrogen is added in the form of synthetic fertilizers, nitrogen fixing bacteria (and other soil biota) will either die, or go dormant and quit doing their job, cause there's plenty of nitrogen available and there's no need to make more for the plant. Synthetic fertilizers wreck havoc on soil life.

There's more to it that this, and I hope some others chime in.

*I paraphrased information in the first paragraph sourced from lancaster.unl.edu* (I don't have that sort of stuff memorized) :)

Well that's a much more complete and detailed answer than I thought to give. Thanks James.

Not to hijack the thread, but I am still unclear on the specific mechanics of burning plants with too much nitrogen. If anyone could break that down, I think it might be relevant to the OP's question.

-CK

From what I understand as to how nitrogen "burns" plants is thru desiccation. It starts to dry things out, even if there's plenty of water available. I don't know the chemistry or mechanics of how water for the plant becomes unavailable in the presence of excessive nitrogen.

I'd like to expound on Gilberts note that chemical nitrogen speeds decay of organic matter, because the soil microbes responsible for the breakdown of carbonaceous materials require nitrogen (and oxygen) to do their job. With a boost of nitrogen, they get hyper active and rapidly munch through carbon materials. There is, as with everything in nature, a balance. Adding too much carbonaceous materials to soil, like burying dead leaves in the fall, ties up nitrogen and plants can't get to it. Aside from using most the available nitrogen, they take a lot of oxygen in the soil too. Roots need oxygen. The microbes in the soil are all of a sudden given a bunch of food to munch on, and they will take the surplus nitrogen in the soil to go to their job at the expense of plant growth and performance. This is why composting is good, to let this process take place in a controlled area, above ground with lots of oxygen around, instead of in the soil where we are trying to grow food. This is also important why to gain the full benefit of compost, it really needs to be fully finished compost. Adding partially broken down compost that still has a lot of carbon materials to soil doesn't reap much benefit, at least immediately.

This really is a tough question, and honestly a tough one for me to deal with in a real world situation on my farm.

Like everything, there is a balance and one great thing about having too many acres for my sheep is that they are healthier because worms are a non-issue on my farm simply because the sheep are getting 2 acres per head. I can sustainably handle 10 sheep per acre here. Unfortunately that also means I do not have enough manure (natural nitrogen) for the acreage that I pasture and crop off from. In years past I have been able to add liquid dairy cow manure to get my crops to grow, but years of that have resulted in insane high levels of iron, zinc, magnesium and copper. Equally these farms have realized their manure is about as valuable as the milk they produce, so its not easy to get anymore. Drat!

Unfortunately, as great as manure is in having nitrogen, it is less potent in phosphorous and potassium. (the P and K of the NPK amounts). I can get that in wood ash, but wood ash has a composition of 0-1-3 so its not too potent. On some of my fields getting the N and P up is significant, my latest field being 210 pounds to the acre (80-70-210 NPK). I got wood I can burn to get that, but to get the phosphorous right would require 156 cords of wood to be burned just for the ash. Yikes. I don't mind diverting that much wood if it was a one time application, but every few years it would require that much more. That is a lot of logging so I am currently seeking alternative sources.

For the first time this spring I added chemical fertilizer, but I had to, not because I wanted to. I got a grant from the USDA and part of that grant was getting the NPK and PH levels to optimum conditions. When you get money from the Government, you must play by the rules, so that meant chemical fertilizers. As I stated, and others have stated, everything has to be in balance, so even if I had the sheep manure to do the field in question, I would have had to apply so much of it to get the phosphorus high enough, I would have been over applying nitrogen, which with manure is not just a waste, but a flagrant violation of the law.

I am in no way advocating chemical fertilizers here, it is just that I do not have the answer. Years of manure applications have maxed me out on the micro-nutrients and on organic matter...yes you can have too much, but yet crops require nitrogen so I need to provide that to my plants. I can no longer use seaweed fertilizer because those also contain lots of micro-nutrients; something I am maxed out on. This leaves me with the problem of NPK primarily. Part of me says screw it, just buy chemical fertilizer and throw it on my fields; because custom blends are easy to mix, I can get the exact requirements with what I need in a mere phone call and subsequent check. I saw this year the yields that idyllic soil amendments bring, but it is the quick and easy way out, and I am don't like throwing in the towel when I know its not right.

While the original question was based on nitrogen alone, really the whole equation is very tough to deal with in a real situation. No one ever said farming was easy though.

One thing I try to keep in mind with "chemical" versus "organic" is the other stuff included in the fertilizer. Travis' example makes for a good one — manure is a good source of nitrogen, but along with it comes micronutrients, organic matter, and a whole host of living organisms. What's the other stuff in a chemical nitrogen fertilizer? We may be able to say the nitrogen component of the two are similar, but in no way are the fertilizers themselves similar.

I think in terms of your question (composting), the most important difference is that "chemical" nitrogen supplies food for plants, but harms the living organisms that make compost compost, while "organic" nitrogen supplies food for your composting organisms. At the end of the day, it's those composting organisms that do the work. Feed them, don't harm them.

Thanks for the thoughts everyone.

I think in terms of your question (composting), the most important difference is that "chemical" nitrogen supplies food for plants, but harms the living organisms that make compost compost, while "organic" nitrogen supplies food for your composting organisms. At the end of the day, it's those composting organisms that do the work. Feed them, don't harm them.

I thought that chemical or organic nitrogen didn't make much of a difference to microorganisms, so long as they were provided with plenty of carbon, as they would be in an active compost pile?

After reading all the responses, the drawbacks of chemical nitrogen seem to be: lack of other elements which may be present in organic nitrogen fertilizer (though this may be a benefit as Travis points out,) unbalancing of the soil nutrients (which wouldn't be a concern in a compost pile,) damage to the soil from a quick flux in the nitrogen level, (which would not be a problem in a compost pile), and nitrogen fertilizer's ultimate lack of sustainability, due to its energy consumption.

I wonder how it would be if fossil fuels were only used to produce chemical nitrogen. How long would they last?

Anyway, it looks like chemical nitrogen added to a compost pile would have few if any drawbacks so long as it was used sensibly (not over added, which could lead to damage to nearby water bodies.) The chemical nitrogen would definitely all be organic once the finished pile was spread on the soil.

Gilbert Fritz wrote:

Anyway, it looks like chemical nitrogen added to a compost pile would have few if any drawbacks so long as it was used sensibly (not over added, which could lead to damage to nearby water bodies.) The chemical nitrogen would definitely all be organic once the finished pile was spread on the soil.

I don't feel qualified to say if that is true or not, but even if it is, is there a benefit?  I don't know how you would tell if you had the "right" amount.  If you just throw in some green matter, you accomplish the same thing for free, and it seems with much less chance of getting too much so that it leeches out into your water supply somewhere.  Not bashing your decision to use fertilizer for this if you want to, I'm just curious what the benefit would be?  Green material is everywhere.

I thought that chemical or organic nitrogen didn't make much of a difference to microorganisms, so long as they were provided with plenty of carbon, as they would be in an active compost pile?

I think the two big differences are the types of nitrogen (chemical fertilizers are already processed into plant-available forms, composting organisms usually create those plant-available forms), and the potency. Kind of like the difference between throwing a big log of oak on your fire vs. pouring a gallon of gasoline on the fire. Sure, they're both fuel… but they create tremendously different fires. The gasoline might even make it hot enough to burn out any wood you had left in the fire, leaving nothing left when it's done.

Yeah green material is a great source of nitrogen. I sweep lawn mower clippings and mix them in my compost, not every time I mow but when I have the time I do. There's a decent amount of nitrogen in pee. If I'm outside working in the garden and gotta take a leak, I waltz over and pee in my compost pile.

Kyle Neath wrote:One thing I try to keep in mind with "chemical" versus "organic" is the other stuff included in the fertilizer.

I've wondered myself of the other stuff, or "inert ingredients" on the label. It seems like one of those umbrella terms that could include a myriad of crap we don't want in the soil.

Anyway, it looks like chemical nitrogen added to a compost pile would have few if any drawbacks so long as it was used sensibly (not over added, which could lead to damage to nearby water bodies.) The chemical nitrogen would definitely all be organic once the finished pile was spread on the soil.

In another thread you mentioned maybe selling compost/potting soil?  I think that would be one downside for customers who wanted to know the ingredients used?  Many of us are following at least certified organic standards and more, so would not want a chemical nitrogen (or any other additives like that) in the mix.  

In another thread you mentioned maybe selling compost/potting soil?  I think that would be one downside for customers who wanted to know the ingredients used?  Many of us are following at least certified organic standards and more, so would not want a chemical nitrogen (or any other additives like that) in the mix.

I wouldn't do this for any compost material I would be selling, or would note such components. Though if it came to that, my potting soils will not be certified, and there for may not be usable for anyone seeking certification; I do not know about that.

I don't feel qualified to say if that is true or not, but even if it is, is there a benefit?

That is a good question. Green materials are more likely to be contaminated then brown ones. I've stopped importing manure and grass clippings to my property due to contamination risks. It is interesting to note the stringent requirements of manure composting in organic farming systems.  Most green materials also are unable to be stored up to make a big hot pile. Size matters for a hot compost pile, particularly in this climate. My property does not produce enough green material in a single week to heat up a pile. In fact, green materials sitting around here (weeds, dead plants) rapidly turn into brown materials that will not heat up.

I think the two big differences are the types of nitrogen (chemical fertilizers are already processed into plant-available forms, composting organisms usually create those plant-available forms), and the potency. Kind of like the difference between throwing a big log of oak on your fire vs. pouring a gallon of gasoline on the fire. Sure, they're both fuel… but they create tremendously different fires. The gasoline might even make it hot enough to burn out any wood you had left in the fire, leaving nothing left when it's done.

To heat up this pile, I decided in the end to use blood meal, which worked well. Blood meal is an interesting case. It definitely has the gasoline type effect, and is in fact very similar to the chemical nitrogen fertilizers in potency and effect. If I used too much, I'd expect to lose a lot of carbon I could have kept in the compost pile, just as would happen with chemical nitrogen. But organic systems allow the use of blood meal despite this, even though it comes from (non organic ) slaughterhouse operations. I'd rather not use it due to opposition to slaughterhouses and expense compared to chemical nitrogen.

I guess that is a different way to put the same thing; is there any advantage to blood meal over chemical nitrogen?

This is an important topic and one that deserves better treatment than I am going to give it... Anyhow:

Nitrogen has it's own cycle. All the PK and microminerals either exist where the plants are or don't. Nitrogen can be made. I think this is the underpinning of Travis' decision to use artificial nitrates and ammonium. If you have a surplus of the other nutrients, the nitrogen is limiting the effective healthy growth. I am not Travis, so I am not going to defend or attack his decision, but it is something that is helpful to understand- imbalance is it's own issue.

Species by climate zone is a good reference. Don't miss out on the vines and trees! Bryant has addressed some of the variables in other threads, not all legumes are equal. Green beans are basically a break-even, they consume most of the nitrogen they fix. But most of them produce 50-100 lbs per acre as a monocrop. Other than alfalfa farmers, probably no one is growing monocrops of legumes in the US, mostly it is a rotation with other crops. So the efficiency is not that high. Lets say my field is 10% clover at 100lbs/acre. That is the equivalent of 10# ammonium nitrate fertilizer per acre. There is wide variance in the numbers, depending on how efficient the plants are at making nitrogen. I suspect it is a good deal lower than that in my field. So I have planted nitrogen fixing trees and vines. They all add into it. So for optimal field performance, Travis may need 100# of nitrogen per acre just to get the nitrogen into a level that will allow his fields to most efficiently utilize the rain and available sunlight, even with clover in his field. I suspect he still has nodulation occurring even adding artificial nitrogen because the clover actually can't extract the applied fertilizer as readily as the grass.

I would agree in principle that I would prefer to add organic nitrogen sources, but sometime look at the N % on a bag of black kow. It is 0.5%!!! So applying that and expecting a rise in N would require ludicrous amounts. Compost is probably about 0.5%, that is why it doesn't burn. Urine on the other hand is maybe 10% and can burn. So you have to work in your system. Mine is expected to run without applied N, but I don't have Travis' constraints. I remember the first few videos of Permaculture stuff I saw were from Lawton, and he goes crazy on the nitrogen fixers. There is a reason- you need a whole lot of them to keep nitrogen from limiting your production and plant health.

So as Travis says, if you don't test its just a guess. I think depending on your scale you can get away with compost. It is robust for soil health for sure. But I suspect Gabe Brown (who is awesome) gets a lot of nitrogen from lightning (wicked storms up there) that Travis may not. Otherwise you have to have a high percentage of your crop area in nitrogen fixers. I am targeting 20% at least initially. Each year when I see my soil sample results I will be able to tailor it to maximize my effective biomass. I have at least 12 nitrogen fixers so far and always looking for more.

All the other elements except carbon (carbon is kind of similar to nitrogen in cycle) can be amended only be reapplying. Maybe some can be brought up by deep-rooted plants, but serious deficiencies are likely to manifest without artificial application. It takes fossil fuels for me to get my minerals decent. Without calcium the nitrogen from the legumes will leach into the rivers. I put down wood chips from anyone who will give them to me to get more carbon per square foot than I could grow. That takes fossil fuels.

I think the mindfulness of the process is important. If I could do it without fossil fuels and rapidly repair my fields I would do so. I mow 2 acres with a scythe and can't do much beyond that, so it gets the bushhog. Soon I hope to have herbivores, and that may lead to the same issues Travis faces. All of it is geared toward a healthier ecosystem, and with the lowest inputs I can do while still rapidly regenerating the land.

You bring up a very good point TJ and that is zones play a huge role with nitrogen fixers.

My fields are North facing, and in my micro-climate of being North Facing, and high on a hill they get slammed with wind. That means even here in Maine, most of my fields get little snow cover...it blows right off. Because of the deep cold and no snow cover, legumes which are prone to winter, often die off. I experienced that this year. No snow, coupled with intense cold, killed off a huge portion of my alfalfa and clover, so much so that an agronomist figured the loss around 40%. No wonder my yield was low. That is why I cannot plant my fields in 100% alfalfa or clover, I must mix it up with other grass mixtures like orchard grass, timothy, and rye. Granted there are a few well protected fields that have 90% alfalfa in them, but they tend to be very small, very protected fields. So for farms in the northern climates, winter-kill for legumes has to be accountedfor when it is first sown down, then monitored.

Another thing that you touched on, and I did as well, is the topic of organic matter. Years of liquid dairy cow manure applications, crop rotations, and generally loamy ground anyway shows that I am actually above optimum on many fields, and at optimum levels on the rest. They range between 4.8% organic matter, to as high as 6.1% organic matter. While I do not have any immediate plans to stop using manure because of this reason, it does mean I am less motivated to use compost since it is not something I need. I need the nitrogen from the manure, but do not necessarily have to go through composting to get it. Interestingly I still do, using my bulldozer to push my manure piles into piles at various times so that it really cooks.

And while this is not addressed to TJ just to be clear, I am in NO WAY advocating the use of commercial fertilizers. In my case this spring I had to bring my field quickly up to ideal NPK and PH levels or I would not get paid. Since every bag of fertilizer had to have the tag presented, there was no lying about what was applied and what was not. I took the government's money, and thus had to play by government rules.

One other clarification; the rules regarding manure dispersal on farms is not limited to organic farms, it applies to all farms. That is because manure is a byproduct of farming, but can be toxic when applied wrong. Because it is "free", the real cost is in moving it. If the government did not have rules in place, manure would be applied heavily in the closer fields, and not so heavily in other fields. To give you an idea of what I mean, on our dairy farm we once had a field that was 33 miles away from the farm. Fields here can be long distances from the farm. One farm I know has a field 55 miles away! And these rules limit manure applications from water bodies and wells too. They are not always a bad thing. Now chemical fertilizers can pollute too, and they are regulated as well.

Travis, I've been meaning to ask you- how do you get alfalfa to even grow at your pH? Does it dictate your lime application rate? I would love alfalfa, it is the only deep-rooted cloverish plant I know of and a great all-purpose plant, but the lime rates we would need are astronomical. But it does really drill down for years in a way I don't think sweet "clover" does. I am struggling to find drillers other than radishes. So far chicory has been a bust. And I am liming to get my soil in the mid-6 range!

Oh yes, corn and any fields with alfalfa dictate how much lime they get. You have to keep in mind that fields here get crop rotated; about every 7 years because our soil is prone to compaction. Another reason is because while we plant good mixtures of grass, other plants inevitable creep in like dandelion. Since we don't spray to kill that stuff, crop rotation takes care of that instead. To give you an idea of what that looks like, we will have a field in grass for 7 years, and by that time is up, its getting encroached with dandelion and other less desirable grasses, and is rather compacted from tractors and trucks. We'll rip that open, break up the compaction by sub-soiling, then leave it in corn or small grains for 7 years, cover cropping in the winter with winter rye. Then because other grass fields are getting compacted and weeded up, we will rotate them into corn or small grains, and then convert our corn fields back into grass fields. Overall our grass/corn fields are a 50/50 mix acreage wise.

Another thing to keep in mind is that we have some cheap lime alternatives here; mill lime coming off the paper mills at $22.50 a ton, and seaweed that is a lime equivalent of $1.90 a ton. As stated earlier due to the extra micro-nutrients of seaweed I can no longer use that, but it was cheap. Just realize that it takes 10 tons of seaweed to equal 1 ton of quarried lime, so its cost is actually $19.00 a lime-ton; still both mill lime and seaweed are not that expensive even at 3000 pounds to the acre. Neither have magnesium, but our fields seldom require that so we are okay there.

We like alfalfa here because it is such good feed, and does help with compaction to some degree. Obviously it fixes nitrogen well. While we do use lots of clover too, alfalfa is really good at driving down its roots. We have lots of shaley ledge and it somehow will jam a root down 20 feet into it, but I have no idea how. Considering some of our fields have soil only a few inches deep due to ledge, we like that trait.

But lest you think my farm somehow has it altogether I assure you it does not. It is a constant battle, and I got a pasture that needs some major help. I am thinking about driving a yeoman plow through it and seeing if that will help as it has the right grass growing, just not vigorously. Phosphorous and potash this year smartened it up some, but it needs other help. Sadly I do not have one and will have to buy one; a purchase on a trial not being something I like to do. I am a minimalist farmer after all.