As we hear more and more about agriculture’s contributions to climate change, a lot of people are wondering why farmers can’t just stop using fertilizer. Some link the need for fertilizer to “industrial” agriculture, or “corporate” farming, or worst of them all, “factory farming”. Many people seem to believe the use of fertilizer strip-mines the soil, rendering it an inhospitable, dried up hunk of dirt that can’t support any life at all without it. Some even think it’s somehow tied to the infamous Roundup that, supposedly, our crops depend on multiple applications of to survive. So, what’s the real story here?
This week, our air drills will go to the fields to plant our 2022 crop. Over the next few weeks, we will apply hundreds, or even thousands, of metric tonnes of fertilizer of various types. The reality is, farmers need fertilizer to be sustainable, to look after their land. Fertilizer replaces the nutrients we take from the soil when we harvest a crop. If we don’t replace the nutrients, the soil slowly gets mined to exhaustion. Somehow, we have to replace what we take. Nutrients don’t come out of thin air (well, except nitrogen – but we’ll get to that later).
Think about it this way. When you eat your bread, you consume nutrients. If your bread was made from whole wheat flour, it contains a wealth of nutrients, including fibre, vitamins, minerals, and of course, carbohydrates. Where did these nutrients come from? The soil, the sun, and the air; plants like wheat consume carbon dioxide, solar energy, water, and a list of elements from your high school chemistry class, like nitrogen, phosphorus, potassium, sulphur, magnesium, and so on. Wheat depends on these nutrients to develop a seed (hopefully, lots of them!) that gets ground up to produce your flour. These nutrients can’t be created from nothing. They must come from somewhere.
The major nutrients wheat needs (called macronutrients) include several elements, such as carbon, oxygen, nitrogen, and a few more (read more here). These macronutrients don’t differ a whole lot in most of our major crops. Whether you’re growing corn, wheat, canola, or lentils, you need all of these nutrients to produce a healthy plant with nutritious seeds.
In this post, I’ll address the elephant in the room: nitrogen, the nutrient we apply in by far the largest volumes in much of the world.
You might know that nearly 80% of the air we breathe is nitrogen. So, why can’t our crops just use that? Well, it’s not “available” to them. The N in our atmosphere is tightly bound up as N2 and cannot easily be broken up. This unfortunate paradox, that the most important nutrient most plants need is abundant, but not actually available, has been a tremendous challenge for all of humanity’s history in agriculture. It was recognized as the primary reason why famine would overtake the exponentially growing human population a hundred years ago. Enter Fritz Haber and Carl Bosch.
These two men developed a method for breaking the bond between N2 in the atmosphere and developing it into a source available for plants. This ammonium nitrate they developed was a godsend for agriculture, saving the lives of untold billions of people over the last hundred or so years. Without this innovation, our world would be very, very different. In fact, every second person alive right now exists only because of this discovery.
The downside, of course, is the energy required for the so-called Haber-Bosch reaction is substantial, making it a significant contribution to greenhouse gases. But, I would submit that the lives of 4 billion people outweigh that.
But wait – don’t some plants not need nitrogen fertilizer at all? Why can’t we just grow them?
Yes, some of our crops don’t need nitrogen (at least, no nitrogen fertilizer). Our legumes, like soybeans, lentils, peas, and others work symbiotically with soil bacteria, giving the bacteria carbon and getting “fixed” atmospheric nitrogen in return. Unfortunately, legumes don’t have the ability to produce the calories required, or the nutrient mix necessary, to provide for all of humanity’s diet. They also tend to have greater disease risk in the field and all sorts of other production challenges. They work as a great rotation with cereal crops like wheat, but not as a whole farm crop. We need cereals, and oilseeds, too.
Why can’t wheat, canola, and all these other crops produce their own N, like the legumes? Well, scientists have been working to crack that biological mystery for decades. Someday they will. Even today, new products are emerging that may allow us to reduce N requirements for these crops, so there is reason for optimism here. But for now, and for the foreseeable future, we still need nitrogen.
But wait – can’t organic agriculture get us out of using all that toxic nitrogen fertilizer?
No, it can’t.
Organic agriculture has often been touted as the saviour of modern agriculture. As the way out of using all these toxic fertilizers and pesticides and monocrops. Well, here’s the truth – organic agriculture is a marketing play. Nothing more.
Organic farmers use pesticides and practice monocropping (which there is nothing at all wrong with, by the way). They till up their soils to kill weeds and generate nutrient release from it. Yes, tillage, the dirty word we left behind in the 1980’s after a legacy of dust storms and dead soils. Organic farming is not more sustainable than conventional farming is. Don’t get me wrong – there are great organic farmers out there, who really do look after their soils well. Many organic farmers are excellent producers and I am not criticizing their decision to be organic farmers. But even they will admit their production just cannot match conventional agriculture.
And then there’s regenerative agriculture. It has also been touted as an improvement on conventional agriculture. The problem with this system is nobody knows what it is. It has a thousand definitions and practices. Until regenerative agriculture settles itself out, its flurry of definitions and practices leaves me cold. In any case, regenerative crops need fertilizer too, and that is not likely going to change.
Nitrogen, along with all the other major nutrients our crops need, is a key component of good soil fertility and healthy crops. Too much of it is no good for anyone, least of all us farmers who pay the bill for it. This year (and most years), our nitrogen fertilizer bill is the single largest expense on our farm. It is truly a costly nutrient, so farmers are already incentivized to minimize the use of it. We have reams of research on application guidelines, nitrogen requirement information for all of our crops split out by region, and incredible access to researchers, agronomists, and other advisors to help apply the right amount of nitrogen, in the right place in the soil, at the right time.
Until there’s a better option, farmers need nitrogen fertilizer, and lots of it. If we want to continue to feed a planet that seems to be lurching from one crisis to the next, with food security becoming a clear and present danger for hundreds of millions of people, we need unrestricted access to nitrogen. Someday, technology may develop that allows us to replace nitrogen fertilizer with bacteria, but that’s not today. Some may consider synthetic nitrogen fertilizer a necessary evil; I consider it one of the greatest achievements in human history.