Nostalgia for a world without fertilizer

We live in an exciting time. A time in which current agricultural practices are looked at with suspicion for solutions in relation to all kinds of social issues. By renewing the agricultural system, we can restore biodiversity, mitigate the effects of climate change, improve soil quality and ensure a good quality of ground and surface water. Fertilizer functions as a scapegoat.

After all, with the invention of the Haber-Bosch process to convert nitrogen from the air into ammonia, all the major problems of the current agricultural system started, right? 

In the past year I have had several thorough conversations with Joost Visser, the author of the book Down to Earth† Very inspiring. Based on thorough historical research, he shows that in the past 100 years (conscious) choices have been made to industrialize agriculture and make it dependent on 'artificial' nutrients. Given the availability of fertilizers, fundamental research into natural processes was no longer considered relevant. Agricultural research into natural processes that facilitate crop growth was sometimes halted and often counteracted. As a result, the current fertilization recommendations as well as the 'Good Agricultural Practice' established by experts are strongly biased by a focus on chemistry. 

A personal reflection
As a soil scientist and agronomist, I am uncomfortable with this conclusion. First of all, because this story gnaws at the foundations of our agricultural insights and advice. Is it really true that all agricultural trials conducted in recent years have been analyzed incorrectly, due to a focus on fertilizer use? I haven't come across that myself in the last 15 years and think we've learned from the mistakes of the 60s and 70s too.

Today I often experience the opposite. In many studies into biostimulants, compost preparations and similar substances, as well as studies that want to demonstrate the role of soil life. Many of them are really substandard. But does the same also apply to agricultural experiments, because natural processes are underexposed due to the experimental design and measurement methods used? A good question.

Secondly, as an independent researcher, it forces me to look critically at the underlying assumptions of my own concepts: how well-founded are these? Is it indeed possible to be blind to scientific facts because of a colored education (based on insights from the past 50 years, with a blind spot for the insights from the years before)?

Blind for alternatives
Looking at actual measurements in the field, the conclusion emerges almost consistently that fertilizer increases crop production substantially. As well as that the environmental impact is substantially lower than that of organic manure. Am I blind to alternative explanations or why don't I see them? I seriously want to be convinced of the opposite, but so far I have not come across that research. Is the cause my own or are those facts not there in 2020 either?

Thirdly, in my own research, as well as in current scientific research, I do not experience any active direction from the fertilizer industry to ignore natural processes. Rather, it is quite the opposite: the industry is looking for opportunities to design fertilization in such a way that it matches the natural (ecological) carrying capacity of the living environment. 

A hypothesis
While reflecting, I arrive at a possible explanation, a hypothesis might be a better word. Much historical research conducted in the years before the invention of fertilizers took place in relatively 'natural systems' already used for agriculture. These are originally also the plots/areas with a higher natural fertility. At that time, no crops were grown on infertile soils, such as the dry, poor sandy soils in the Netherlands.

Nitrogen-fixing bacteria
At the same time, environmental factors had a greater influence, plants grew more slowly (not necessarily also a lower yield) and soil life played a major role in making nutrients available for crop uptake. Through symbiosis with nitrogen-fixing bacteria, many crops were able to absorb some of the nitrogen from the air and the agricultural system was less dependent on external input of nutrients. It is unclear whether the losses to the environment were lower. 

In 2020, however, these kinds of situations hardly occur in the Netherlands, simply because agricultural use has changed the situation in recent decades. Agricultural plots have been 'enriched' with nutrients and organic matter, poor sandy soils have been made fertile with animal manure, cultivation plans have been simplified, crop yields have been increased, diseases and pests are suppressed and the number of crop varieties is limited.

Natural processes still play a role, but their relative contribution to crop growth is much less than in the past. This may explain why much recent research into the role of organic nutrient uptake - or the influence of benthic life - shows strong effects in arctic regions or nature reserves, but not in agricultural plots. It is precisely these natural systems that are comparable to the agricultural systems of 100 years ago. It also explains why the impact of natural processes is smaller in highly productive agricultural areas.

And what does that mean for now?
This raises an interesting question: could we have achieved the current increase in crop production without artificial fertilizers? And in 2020 can we also return to the situation where natural processes are used to the maximum to facilitate crop growth? Many examples from organic agriculture, as well as all kinds of initiatives on regenerative agriculture in the Netherlands, show that it is possible to produce sufficient food on soils that are already rich by nature, or on soils that have been enriched in recent decades.

This is precisely where the potential lies to explore new routes to enhance the contribution of the soil and soil life without major risks of loss of yield or damage to the environment. Whether that ultimately also leads to a better environmental quality is still an open question for me. The practice of many organic farms shows that the soil surpluses are high (i.e. the supply of nutrients via organic manure, residual flows, clippings and compost is many times higher than the crop intake) and thus the risk of losses to air and water increases. .

Meaning agricultural research
Worldwide, it also calls for a more nuanced picture: in areas with poor soils and a growing population, the use of artificial fertilizers is crucial to facilitate life. What does this mean for agricultural research? First of all, that we use the knowledge we have gained from soil processes to ensure that agricultural practice is as close as possible to the carrying capacity of the soil.

In concrete terms, this means that it is unnecessary to add a lot of organic matter to the soil if more than 2 to 3% organic matter is already present. This also means that soils with a high P availability (which is a large part of the Netherlands) require less animal manure than soils with a low P availability. This also means that variation in the crop plan, crop diversification and the use of natural pest control has priority over standardization and the use of chemical crop protection products.

In order for agriculture to take more and better account of natural soil fertility, innovative fundamental research is needed into the natural processes in the soil and the options for influencing them through concrete measures and thus increasing resilience. More insight into the role of soil life will certainly help.

This also means that in Dutch soils (which are rich in nitrogen and phosphate) it is better to get more fertilizer than (processed) animal manure, because it allows better control of lower emissions. At the same time, this also means that we have to make more and more customization possible. Fertilization recommendations are well substantiated, but do reflect a multi-year average situation for an average soil. And from the figures we know that every company and every soil is different. There is potential for further fine-tuning here. With an eye for the quality of the soil, with an eye for sufficient crop production as well as the quality of the living environment.

Homesick or not?
Has this changed my view on fertilizer? I hesitate. I share the nostalgia for an agricultural system, where local cycles are closed. Crop production is geared to the quality of the living environment. At the same time, I support the desire for further (technical) optimization in order to maximize food production while preserving the living environment.

In an earlier article I have shown about the usefulness and necessity of fertilizers that current visions of the future of agriculture vary from the nostalgic image of Ot and Sien on the one hand and modern precision agriculture with sensors and robots on the other. In the high-tech form of agriculture, the use of fertilizer is crucial, while the more ecological form of agriculture of Ot and Sien traditionally has a great reluctance to use fertilizer.

I argue in favor of not simplifying reality to one of these 2 visions of the future: the challenges are simply too complex to be solved with one comprehensive approach. On the contrary, there is potential in smart integration and linking of technological solutions and traditional sustainable agricultural practice. In my opinion, the debate about the role of fertilizers benefits from this interplay of both visions of the future. 

But 'Down to Earth' has even more surprises in store. I'm curious...

Gerard Rose

Senior project manager in soil, water and agriculture at the Nutrient Management Institute (NMI).

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