Fertiliser (a quick analysis)

TL;DR

The countries with the most access to fertiliser see the lowest gain from its use over time. This can even be negative.

Over 800 million people across the globe live on less than 1200 calories a day (starving by UN standards). Fertiliser usage (synthetic or natural) is essential to feeding those in need.

Better Land Management can provide higher yields than misusing fertiliser

Getting Going

Everything you know about fertiliser is wrong... well maybe not everything. Fertiliser is the backbone of modern society. Crops grown with fertiliser feed about half of the worlds population.

Here you'll learn how fertiliser impacts crop yield at the global level. Or as a question, how does fertiliser usage affect crop yields across the globe?

Our World in Data accumulates and analyses much of the world's development data. It's an awesome resource, with the information required to dive into crop yields and fertiliser usage (and a lot more).

Fertiliser is essential to the current agriculture industry. Plants need Nitrogen to grow and fertiliser is like a plant supplement. Nitrogen makes up 80 percent of the air you’re breathing. Alone it's useless, but when combined into a molecule with another element. When combined with hydrogen or oxygen, it becomes something that can react with other chemicals. In this “fixed” state, plants can use it to build proteins. Those proteins are the building blocks of life. From the food you eat to... you, proteins are everything.

Our population growth has exploded on the back of fertiliser... but it also presents massive issues. When we apply too much to crops, we create N2O and NOx gases that directly and indirectly increase atmospheric warming and climate change. A unit of N2O has over 200x the warming effect of CO2.

Looking at the Data

Check out the spreadsheet if you want to see the numbers. This analysis aims to be directionally correct as opposed to definitive.

What do these points mean? First we see that fertiliser usage has increased around the world over the last 30 years. Particularly in Asia. In tandem with this data we see massive increases in yields, most notably in Maize. You can assume that these increases are due to fertiliser usage.

When you look at the correlation between the change in Nitrogen / Hectare and the individual yields we see something... strange. It suggests that the nations with the largest change in fertiliser usage aren't the ones with the highest yields.

Dumping more fertiliser on crops and expect better yields. There is a point of diminishing returns on the impact of fertiliser on crop yields.

Individual crops react differently to higher nitrogen fertiliser usage. It seems to affect a nation's maize output more than its rice output. This is in part because Phosphorus is more important for rice nutrition. However, one can assume that fertiliser usage would grow as one unit as opposed to in smaller bits. Rice is grown in nations with lower access to financing. This means that farmers are less likely to have meaningful access to the tools that could help them advance.

Segmented by Continent

When segmenting data by continent, you can make some interesting observations. In Europe and North America there is a negative correlation between fertiliser usage and crop yield.

This means that They have reached the point, where a one more unit of fertiliser is not equal to a one more unit of output. It is less efficient for North American and European farmers to use as much fertiliser as they do.

However, developing parts of the world like Africa and Asia (I know this isn't necessarily correct, but bear with me) do see higher output in fertiliser usage.

Improving the analysis

This cannot speak to individual farms, because it was done at the country level. Since the goal was to get a basic understanding of how fertiliser usage could affect crop yields at a macro level, it serves its purpose.

In a perfect world, this would aggregate farm level data and have more segments based on farm type. Farm level data is difficult to come by and would add levels of complexity that go beyond the intent of this analysis.

Adding a nations economic development status would have allowed for a dive into agricultural efficiency and GDP. As we saw North America and Europe have negative correlations between fertiliser use and yield. GDP might follow a linear correlation with crop yields.

Additionally, adding more specific geographic locations would have made the analysis more rigorous. For example, segmenting Asia further into South, South East, North, East, Middle East and Central would have led to a more precise analysis. Since geography is a determinant of destiny, this could have allowed for a more nuanced look into how the agricultural economy works.

Combined with GDP data, this would have allowed for a deeper dive into agricultural efficiency.

What we learned

From this you should understand; the countries with the most access to fertiliser have seen the least gain in their yield over time. You see this when you look at the correlation coefficient between Wheat and Nitrogen use in North America.

Next, the areas of the world with the least access to fertiliser are the ones that need it the most. In the developed world we talk about moving away from fertiliser. Much of the developing world can't afford that luxury, yet. Over 800 million people across the globe subsist on less than 1200 calories a day (starving by UN standards).

The first priority must be to either better distribute existing food supplies, or improve crop yields where it can affect the most people (This is a this year problem). Then, farmers in those parts of the world need to be given the tools to manage their land sustainably. In the ideal case, you could cover both bases, which you'll see soon ;).

Some More Articles on Fertiliser

How orange peels revived a Costa Rican forest

In 1997 2 scientists convinced Del Oro to dump 12,000 metric tons of orange peels in the rainforest. 16 years later, in 2013, researchers came back and saw a thriving ecosystem. What had happened here?

The area fertilised by orange waste had richer soil, more tree biomass, greater tree-species richness and greater forest canopy closure. This was done without monitoring, which means that Methane was released during the composting process. Fortunately, this can be avoided with a bit of management. This could be a key to reforesting areas, and building natural fertilisers.

A fun story about composting

Just a little anecdote about how complex these things really are. Author struggles to set up a home composting kit. Compost can be excellent as fertiliser!