Soy's Water Footprint II: A Complex Picture

In the previous article I introduced some of the issue related to water consumption as a result of soybean mass production at a local scale as well as the regional impacts that such water footprint would have on the environment. However, the more I read about this issue, the more I began to grasp the complexity of such implications. 

I concluded that soybean agriculture was indeed "bad" for the environment in terms of local freshwater withdrawal, but many more questions arose as a result: 

how does soybean compare to other major crops on a global, rather than local, scale? Should we abandon this crop or is this the "least bad" of our options? 

Let's first take a step back and consider why water footprint is an issue that I should be considering when evaluating the environmental impacts of agricultural crops. 

The water footprint calamity

Global freshwater use has increased by 600% in the 20th century, leading to the belief that by 2025, at least 2billion people will have experience the direct effect of water scarcity. Moreover, a UNESCO report in 2006 exposed the dangers of freshwater exploitation: 

studies found that up to 80% of the world population will suffer from water scarcity in the near future and the situation will only get worse as current trends in food and energy demand inevitably increase.

The current global water footprint (as an average of values between 1996 and 2005) is 9087 GM3/year, with cereal, meat and dairy products being the major contributors. 

So does agriculture play this big of a role? 

The answer is YES Studies estimated that between 85% and 92% of all water consumed at  global scale is for agricultural purposes, with irrigation alone accounting for 70% of total yearly freshwater usage.  

It is important to highlight that water scarcity and stress do not automatically or necessarily match high levels of water demand. In fact, water footprint considers both the amount of water readily available and the amount that is being demanded. Moreover, not all water consumption is the same, and in order to manage and control water footprint, it is necessary to distinguish between different types of usage. 

Firstly, blue water is the water that can be directly extracted from rivers and reservoirs, whereas green water is the one enclosed in the vegetation or within the unsaturated soil layer. 

Recently, the concept of gray water was added to the former two to highlight the critical importance of pollution in freshwater consumption. Gray water is essentially the amount of water that is required to assimilate pollution from a certain source - usually it is composed of washed off water from crop fields containing fertilizers and pesticides. 

Freshwater demand is inevitably going to increase over the future decades due to increasing global population and economic development. However, as freshwater demand increases, there is a risk for supply to decrease as a result of climate change leading to even less security. Climate models predict that precipitation patterns will change and droughts will become a much more prominent issue as the global temperatures rise, leading to even more complexity in the distribution of this fragile resource. 

The global picture

As mentioned above, cereal take up a vast majority of the water footprint on the global scale. In fact, wheat alone requires 1087 Gm3/year. Other crops the require high inputs of water are rice and maize, with values of respectively 992 Gm3/year and 770 Gm3/year. The figure below illustrates rather effectively the distribution of total water footprint amongst crops. 

Global contribution to water footprint by different crops

This image immediately sparks up an interesting point: soybean may be causing dramatic impacts at a local scale but on a global one there are crops we should be more concerned with. The water footprint associated with soybeans only make up 5% of the global picture, so really it's not that bad...

But HOLD ON A SECOND: these percentages account for the total footprint of the crops, and cannot be directly compared because some of them are more popular than others. If I produce 100kg of wheat and 1kg of soybeans then it is most likely that the wheat production will have a higher water footprint. 

We should further investigate how soybean agriculture impacts water footprint PER TON of crop produced, as well as analysing whether the water footprint is green, blue or grey. The table below provides much more detailed information: 

Broken down water footprint for major crops 

  

With a global footprint of 2145 m3 per ton of crop, soybeans have a much higher environmental impact than rice, maize and wheat!

In simple terms, if soybean agriculture were to expand to the same amount of wheat produced on a global scale (estimated to be around 16.68m tons in 2015), its water footprint would be almost 20% more of what is currently caused by wheat. 

On the other hand, it is also important to remember that most crops have much higher gray footprint impact than soybeans so this could be a safer option in terms of pollution. 

Is soy's water footprint Sweet or Sour?

There is no simple answer to the complex issue of water footprint: an hierarchy of scale across a highly heterogenous range of crops creates a complex scene that makes it difficult to come to a conclusion as to wether soybean is destructing or could potentially save our planet. In terms of global footprint, an increase in soybean agriculture would lead to exceptional increase in water withdrawals, but at the same time could potentially benefit the environment through reducing water pollution levels. 

Let me know what you think in the comment section below! 

Soy: a water footprint calamity

Land use change is majorly driven by the expansion of cropland and intensification of agricultural activities, with the soybean being the most important agricultural output in the Brazilian landscape. Demand for food products and energy sources is ever rising and soybean plantations have rapidly taken over the natural environment in parts of the Amazon forest. 

This process clearly has a number of environmental consequences that will later on be discussed and considered in this blog, but I will start from taking into consideration the impact that land use intensification connected to soybean cropland has in terms of water footprint.

I will explore the changes in water quality, quantity and catchment hydrology that are connected to the new land use patterns due to soybean expansion. Moreover, I will place my discussion the framework of the freshwater planetary boundaries and the relative consequences of soybean mass production on the regional as well as global ecosystems. 

Will Steffen

Water Quality

Firstly, the soybean, just like other legumes, requires great quantities of nutrients in order to flourish, regardless of the local climate conditions. The introduction of chemical fertilizers is bound to cause local contamination of water sources and lead to changes in the regional aquatic ecosystems. In fact, a rapid flash rise in nutrients can be devastating for habitats as it causes eutrophication and it accelerates the growth of algae and consequently a decline in light available to the living organisms. 

Moreover, the washed off chemicals can lead to declining levels in groundwater quality. Chemicals contained in the fertilizers, such as lead and cadmium, can have negative consequences for the local flora and fauna.

Water Quantity

Secondly, the tropical forests and local climate patterns pivots around evapotranspiration. If vast amounts of canopy are destroyed, then naturally less precipitation will take place. 

Studies have found that rainfall in the tropical forests in Brazil will decline by 20% by 2050 purely as a result of recent and predicted deforestation rates.  

As less moisture is reintroduced into the water cycle and deforestation drives a decline in precipitation, the ecosystems will begin a slow and dangerous drying process. Land use change will also lead to higher surface temperatures and in turn this could cause higher evaporation rates and -unfortunately- even worse water balance levels.

The Tapajos river basin

Let’s take a step back and look at an example of the direct consequences that soybean agriculture can cause on a region’s water cycle. A very recent review of the water footprint of soybean agriculture in the Amazon has opened my eyes to the extent of the danger of such rapid land use intensification. The study considers both water use and pollution around and within the cropland area as well as in the entire water catchment. 

As expected, the water footprint will rise considerably by 2050, but by how much?

Water scarcity and water pollution estimates for 2050

The study finds that 1.8% of the study area will face threat posing or unsustainable water scarcity levels, with a 15% increase in the locations that are just about within the limit of sustainability. 

Moreover, for what regards water quality, over 10% of sites in the study area will present unsustainable or threat posing levels of pollution within the next 40 years. These values did not strike as particularly worrying until I consulted the planetary boundaries recently discussed by Will Steffen.

Planetary Boundaries 

The current freshwater boundary level for sustainable use at basin scale is expressed as the ratio between water withdrawal and the mean river flow – and is set at 55%. 

Similarly, in the Tapajos river basin study, water scarcity is calculated as the ratio of water footprint (or more simply the amount of water withdrawn to be used in the soybean production) and water availability in the catchment.

A simple cross reference of these two papers confirms that only in the Tapajos river basin, an area equivalent of 147,730 football fields (!) will have surpassed the local freshwater planetary boundary by 2050.

Before you panic…

When talking about planetary boundaries I believe it is necessary to begin a self-critical discussion on the hierarchy of scales. 

If like in this case one boundary is overcome at a local scale, I shouldn't necessarily assume there will be "sour" global implications. And at the same time a global variation in freshwater use or even climate change may not have local repercussions. 

Different planetary boundaries are applied at the same time over a variety of spatial and temporal scale and leading to a very complex picture of how we make sense of resilience. There are clear limitations to this framework but it is widely accepted that at a local scale it is a solid starting point for the development of management strategies to support sustainability goals.

We have established that soybean agriculture is a remarkable water footprint calamity, but is it worse or possibly not as bad as other crops? 

In the next article I will explore the global changes in freshwater use and water footprint associated with agriculture and further investigate the hierarchy of local-global scales.

In the meantime feel free to leave a comment below or tweet me!

Soybean Agriculture: Sweet or Sour Implications?

Over the centuries, soybean production has expanded globally leading to environmental and social concerns over its exponential growth. Before WWII soybeans were mainly grown in Asia, especially in China, as it is a popular a source of protein in eastern diets. The green revolution and the associated technology leap after the war lead to the introduction of soybean plantations in the global market, especially in the US.

Brief History

Soybeans are known to be very effective at fixing nitrogen in soils and, if planted in combination with other popular crops, they allow for soil recovery and support the local nitrogen cycle. This legume crop is not difficult to harvest and benefits crops like wheat and corn. Despite not being especially popular as part of the western diet, the soybean popularity exponentially grew as it became one of the main sources of animal feed thanks to its exceptional content of protein. 

As a result, soybean crops became virtually monopolized by the US, which produced over 85% of this commodity in the world market.

The end of the 20th century represents a turning point for soybean production. As asian countries underwent a rapid economic growth, meat was introduced to their population’s diet. In order to respond to such fast-paced demand not only in China, but South Korea, India and the Philippines, the asian meat industry had to cede to importing large quantities of soy. The European Union is no exception: soybeans were seen as a safe solution to the mad cow issue, which is caused by cattle being fed animal protein.

The global rise of demand of soybean meant that new countries started to cultivate and export this commodity, including: Brazil, Bolivia, Argentina,Paraguay and Mexico. It was at this point that environmental as well as social concerns started to rise as such mass production began to take place in countries that include some of the most diverse landscapes in the world. 

In fact, Brazil has recently overtaken the US as the top soybean exporter, mainly thanks to the advantage of having cheaper agricultural land. Moreover, Latin America provides a much better suited environment for the legume to flourish thanks to warmer and wetter conditions with longer growing seasons.

Soybean production in Brazil in the south of Brazil 
and over the dry savannah (cerrado)

There is a very wide range of “sweet” benefits and advantages as well as more “sour” issues and concerns that need to be discussed regarding the recent global expansion soybean mass production. I hope that this blog will allow for conversation to spark over scientific facts as well as personal experience. I cannot wait to find out how everyone feels about different issues that are connected to soybean agriculture.

The main question I am looking to answer is: 

Is soybean mass production saving or destroying our planet?  

How will I go about answering this question?

As explained by Will Steffen:

 "The planetary boundaries framework defines a safe operating space for humanity based on the intrinsic biophysical processes that regulate the stability of the Earth System"

In this blog I will attempt to use these boundaries as a starting point to discuss the impact of soybean mass production on the environment and the extent to which it is pushing our planet closer to the edge of instability. 

The nine planetary boundaries proposed by Will Steffen 

Stay tuned!