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I'm always surprised when I read someone arguing that fertilizers depend on fossil fuels. That's like saying that electricity depends on fossil fuels, confusing a production method with the thing produced. There are lots of ways to make electricity and lots of ways to make fertilizer, but that doesn't seem to be well understood.
Fertilizers can be very good news, of course, but if they’re based on fossil fuels then a priori they are not likely to be sustainable. There has to be an overall move towards boosting soil fertility in other ways, making use of nitrogen fixing crops, green manures, bio-char, animal wastes and so on.Fertilizers are not based on fossil fuels. Fossil fuels are often used to make them, but that's because they are, in this era, cheap and abundant. When that is no longer the case then other feedstocks will be used, again, as they have been in the past, and will be in future.
Methane, natural gas, is one feedstock often used today. It's a good one since it has a lot of hydrogen, CH4, that can be stripped off and used to make ammonia, NH3. Nitrogen, the main ingredient, makes up the vast majority of our atmosphere, so it's readily available to the process.
But ammonia isn't really the end objective. Ammonium, NH4, and nitrate NO3, are what plants eat. Soil bacteria convert ammonia to ammonium, and then to nitrate, the gold standard for plant food.
Other forms of nitrogen, such as urea, are even further from the desired state, but soil bacteria can convert it to ammonia and as above be converted in turn.
These bacteria are ubiquitous since they do the same sort of conversions on compounds that contain organic nitrogen. Plants need mineral nitrogen. Organic nitrogen (such as urea - urine) is useless to plants.
There are also denitrifying bacteria that eat nitrates and in the end release dinitrogen N2 back to the atmosphere as a stable gas. That's why no soil contains nitrogen unless it has been recently added except in rare cases where it is locked up in a way that neither plants nor bacteria can get at it. This happens with biochar through a combination of chemical and mechanical properties of charcoal. Nitrogen locked in this way can be released by certain enzymes secreted by bacteria that associate with plant root hairs.
Fertilizer manufacture without fossil fuels can be done many ways. For example, methane is created by bacteria too. It's even a problem since it is a powerful GHG that leaks from manure lagoons, wetlands, landfills and the like - organic matter in anaerobic conditions. But it's just a source of hydrogen for fertilizer synthesis, and hydrogen can be gotten in many ways, not least from water, H20.
Nitrogen and oxygen, the elements needed to make nitrate, make up most of our atmosphere. Nitrates are synthesized in the air by lightning, and falls to ground in rain. That's an energy intensive way to make nitrate, slamming the bits together so hard that they break and recombine. All of the industrial methods used to make nitrate or its precursors are attempts to do it in a more energy efficient way, using multiple chemical steps and catalysts.
There will never be a shortage of fertilizer due to exhausted feedstocks. If there were no fossil fuels it would still be made. The issue is only cost and in the end, since the base components are free in the air, it is the cost of energy that is the limit. But there are many sources of abundant energy. They just aren't near population centers or in a portable form such as a liquid fuel.
The clearest example of this is geothermal power released at plate boundaries, such as in Iceland. They have energy but no market since they are remote. There are efforts underway to make hydrogen using that energy and sea water. It's a good fuel but it is also a feedstock for regular, old fashioned ammonia synthesis. That would be a good product since it is far more easily transported to markets and the infrastructure for ammonia handling already exists. Every ship on the seas and port on land has ammonia facilities since it is the common refrigerant used in shipping, and is a commodity currently traded around the world.
Anti-fertilizer foo makes no sense. Tales about dependence on fossil fuels are peeing in the pool, polluting the social mind with misinformation. What should be criticized is bad farming practices that use fertilizer poorly, unbalanced or in excess, and so harms land and water and increases costs. Too much manure - green or brown - does this too. It isn't just a problem with manufactured fertilizer. Redirecting the human energy wasted on fertilizer opposition to wise fertilizer use is constructive rather than destructive.
The problem is that it's easy to oppose and hard to construct, and people are lazy. It's much easier to march around with your metaphorical fist in the air than to do something constructive. Indeed, those opposed to fertilizers seldom show any awareness or understanding of the issues at all. They have political talking points, but no useful grasp of the subject.
Worse, I think, they have no true concern for either the environment or people. They aren't trying to understand the system and champion smart behaviors, they are grinding axes, posing and relishing a fashionably transgressive stance though it is of no actual value. It's status seeking in certain circles, being cool in school, even when the posers are gray beards.
We would do well to help develop a higher fashion, a passion for truth and a sincere desire to improve systems.
On pg 50 of "Feeding the World", Vaclav Smil writes:
"Depending on the quality of diet we would be willing to accept, our numbers would have to shrink by two or three billion in a world devoid of synthetic nitrogenous fertilizers."
While recognizing the benefits, particularly to soils, from many of the "organic" compared to conventional practices, doesn't this call into question the fundamental principle (nothing synthetic) of "organic" agriculture? It appears that observations of the negative impact of synthetic fertilizers on soil was the major impetus for the development of the philosophy and principles of organic agriculture (Lotter, DW, 2003. Organic Agriculture (J Sust Agric)).
Is Smil's statement true (he's written a book on the subject)? If so, then for sustainability at even our current population organic agriculture and conventional agriculture have to meet somewhere in the middle, organic having to allow the use of synthetics and conventional having to reduce energy inputs.
Posted by: noname at July 18, 2008 06:35 AMI think that the current fashion for reducing energy use is the new "organic" - an idea that has some surface plausibility but doesn't bear close scrutiny.
It isn't reducing energy use, or any other input, that is a reasonable goal, it is reducing cost that is always the goal. Cost is an indicator of a host of factors and information. It is the considered view of society as a whole, a clue from the social mind to help make good decisions.
Energy costs are rising today. That's a clue. Energy has not always been dear, and probably will not always be so. It's cyclical as old energy systems cease to be adequate and newer ones develop.
We have some long term perspectives to help us place this in context. Klaus Lackner, director of the Center for Sustainable Energy at the Earth Institute, grounds this subject: "Technology in general and energy at its base ultimately define the carrying capacity of the Earth for humans".
It is an old idea that energy use is the true measure of civilization. If we consider the embedded energy in even common artifacts it seems obvious that human progress will require ever greater energy use.
The task then is to develop better energy systems to provide it in abundance without unintended harms. We will become more efficient in energy use, less wasteful, but still have a monotonic increase in energy use.
Posted by: back40 at July 18, 2008 08:04 AMYou're absolutely right Gary; I was being lazy. I agree absolutely that synthetic fertilisers at their current prices (albeit tripled from a couple of years ago) depend on fossil fuels. As you point out, what they really depend on is cheap energy. That underpins making them and moving them around, today and for the foreseeable future.
In the end, I think this too comes down to a question of scale. For the past, what?, century or so, it has generally been a good idea to get big and then to transport whatever it is you are making. I think the future is going to see things happen on a smaller scale. For nitrogen, the smallest scale is the nodules on legumes. Forget about engineering nitrogen-fixing into cereals etc. They've been trying that for 30 years now and have made very little progress. A rotation that includes a well-inoculated legume is going to help boost soil fertility, for nitrogen, and I don't think it is silly to hope that this will once again become good practise.
Other macro-elements such as phosphate may be harder to supply, especially when soils are very depleted. But perhaps small bio-reactors fed with bones could make a difference. Or get the bonemeal back from animal feed.
The main reason to talk vaguely about general soil fertility rather than specific elements is not because of some organic foo, as you put it, but as a recognition that there is often one limiting nutrient. and as you say, bad use of fertilisers (of any origin) is the real problem. So sticking on extra nitrogen, when what you really need is phosphorus or potassium or something else, is not only a waste of money but also unnecessarily damaging. The "feed the soil" approach encapsulates that idea of a microbe-rich soil decomposing everything that's thrown at it in a more comprehensive manner and thus helping to boost the limiting nutrients while not over-supplying those that are plentiful.
I know that sounds like holistic nonsense, but it does seem to be pretty effective.
Hi Jeremy,
It isn't that fertilizers depend on cheap energy, or cheap anything, it's that the cost of things is information that helps us make management decisions that are coordinated with social and physical reality.
We will use fertilizers, or starve, but fertilizer isn't all there is to an agronomic system. Those other inputs and tasks have costs too. Sometimes there are tradeoffs where one or another part of the system can be maximized or minimized in pursuit of a good cost benefit ratio.
Are rhizobia cheaper than manufactured fertilizers? Not usually. They don't work for free, they charge plants for the nitrogen they fix. They trade the nitrates to plants in return for carbohydrates, sugars. Plants will only pay this price when they can't get nitrates a cheaper way since it diminishes them, leaves less resources for building roots, leaves, stems, flowers and seed.
Knowledgeable growers intervene in this system by adding variable amounts of a variety of fertilizers, in various forms, in the attempt to produce the most product - biomass in the end but perhaps with a focus on fruit or seed - for the least cost. Actually, it's a bit more complicated than that since a grower could choose to have less product if that can be done for a proportionately greater reduction in cost, improving the net benefit even when the gross revenue is down.
For example, a mature dairy quality pasture is a polyculture of various grasses and forbs that is fertilized in various ways. Since it is mature it has high quality living soil that makes the most of available nutrients. Nitrogen can be supplied in various ways: rhizobia, manures or top dressed nitrates.
The legumes, often clovers, that rhizobia need do not produce as much forage on a dry matter basis as grasses. The more clover you have the lower the total sward productivity. But, with no other nitrogen source the growth of grasses is stunted and clovers can compete better. Their lower production is less of an issue when the production of grasses is lower as well. Add nitrogen and grasses grow better. So do clovers since they don't need to buy so much nitrogen from rhizobia, but not as well as grasses. A well fertilized sward will gradually crowd out clovers since they are weak competitors in those conditions. A poorly fertilized sward will gradually crowd out grasses since they are weak under those conditions.
Pasture managers usually seek some intermediate state that gives the most forage for the least cost. A target often used is 30% clover. This supplies perhaps half of the nitrogen needed for good productivity at the cost of some reduced dry matter production. The amount of nitrogen added by the manager depends on the cost of that fertilizer relative to the value of increased forage production.
How to decide? What are the land costs? Water? The market prices of meat and dairy? Debt service, fuel, labor, insurance, opportunity cost? Government interference? Maybe he should just plow it up and grow maize for the ethanol plant?
That's holistic thinking. No system that is not grounded in social and physical reality is holistic. You can't care for the land if you are bankrupt or starved to death. There is no safety net, not in the long run and large scale. Not in a world scale system. You can have Potemkin villages, little pockets of subsidized fantasy where reality has been suspended, subsidized by the rest of the system, but not everyone can live there.
Plants are inefficient. They don't get much bang for the solar buck. The amount of nitrogen legumes can buy from rhizobia is limited by their ability to pay, and that is a meager amount compared to need. To produce at a level required to provision burgeoning humanity requires outside energy input to make up the shortfall. The alternative is bankruptcy. Death in the end.
Non-holistic thinkers charmed by the Potemkin romance actually find the idea somewhat attractive. Frustrated by reality, melancholic and depressed, they come to long for a great crash, a die off, a massive reduction in human population that would make it possible for their romantic notions to be sufficient to need. It wouldn't work that way of course. Humanity will not go gently. By the time the crash was over everything would have been wrecked by the thrashing of the hungry victims. Think Haiti. The land would have been picked clean and the environment destroyed.
We need real holistic thinking rather than a new-agey pretend version. The subset of best practices embraced by the pretenders must be completed by many of the practices they scorn. It isn't that the feed the soil approach is wrong, it is that it is insufficient. It's a good start, but can't go the distance.
Posted by: back40 at July 19, 2008 06:22 AM