Jul 08 2021

Are Hydroponics Coming?

I have been hearing about hydroponics – the growing of plants in water without the use of soil – for my whole life. Epcot showcased them decades ago as the farming of the future. Hydroponic farming exists. I can buy hydroponic lettuce at the supermarket. But despite the hype, it remains a small percentage of global agriculture. Hydroponics appears to be experiencing some rapid growth, however. In 2020 the global market was estimated to be $9.3 billion, and projected to almost double by 2026.

Modern hydroponics can be traced to botanist Julius von Sachs who in 1860 published the nutrient mixture necessary to add to water, demonstrating for the first time exactly which nutrients plants needed to grow. Since then several hydroponic systems have been developed and today modern hydroponics is very sophisticated, with precise nutritional and environmental control to optimize growing.

The potential advantages of hydroponics sound very impressive, with the only real downside is that startup costs can be high and overall price of produce is higher than conventional farming. The reason hydroponics remains niche is that it may not be as economically viable, but as systems improve this is changing. The other clear downside is that hydroponics uses much more energy. Conventional farming is mostly powered by the sun, where hydroponic farming relies heavily on grow lights. A 2015 estimate found that hydroponics used 11 times the energy of conventional farming. Here are the advantages:

Hydroponic farming allows for vertical farming, because it is not dependent on the soil. This allows for greater plant yield per unit of land, which is becoming farming’s most precious resource. Estimates of the land advantage depend on the crop and the height of the vertical farm, so there is no one figure, but it varies from several times to hundreds of times the yield of soil-based farming. Vertical hydroponic farms can be designed for optimal land use if desired, easily resulting in hundreds of times the yield of soil-based farming.

This high yield per unit of land also allows hydroponic farming to exist in urban areas. This could mean a portion of fresh produce is grown locally, and does not have to be shipped at all. This further allows for crop varieties to be optimized for nutrition and taste, rather than the ability to survive transport.

Water use is also much lower, because hydroponic farms can recycle 98% of the water they use. Conservative estimates are that hydroponics uses <10% of the water as conventional farming, but with properly designed systems can be even better. Fresh water is also becoming an increasingly precious resource, with farming using 70% of global fresh water. A shift to significant hydroponics could dramatically reduce our fresh water demand.

Hydroponic farming also uses an indoor controlled environment. This has multiple advantages. First – no pesticides. There are no weeds to deal with, and insects can be much more easily controlled. Air quality can also be micromanaged, as well as temperature, humidity, and light. Growers have total control over the timing, intensity, and frequency of light, optimizing growth and using light frequency as a biological trigger when necessary. This also means that hydroponic farming can occur year-round, and in any environment, even in the desert.

Because it is a closed system, there is no nutrient run-off  – no algal blooms from nitrogen getting into the waterways. Also, risk of food contamination is much lower. There are no pathogens from soil or fertilizer.

What about the crops themselves? As the technology has been tweaked over the years, adjusting nutrients and growing conditions, the final products have improved. Again, this is crop-dependent, but in many cases hydroponic plants have superior qualities of nutrition and taste. This will only further improve as crops are bred or engineered to be optimized for hydroponic farming.

The high energy demand is a downside that can be mitigated. The availability of increasingly cheap and efficient solar panels, for example, can power a hydroponic farm. Systems to take maximal advantage of natural lighting can also help. But it will likely always remain the case that hydroponic farming is more energy intense – energy is the substitute for soil, water, and sunshine. Over time, however, soil and water are becoming more limited resources while energy is becoming cheaper. As these lines cross, hydroponic farming will likely take off.

As is almost always the case, economics will determine the future of hydroponic farming, but it does appear that we have reached a tipping point. The next couple of decades will tell. But the environmental benefits can be huge, and as these concerns grow the motivation for hydroponic farming will also grow.

With all of the environmental advantages you might think that organic growers would be enthusiastic – dramatically reduced water use, no pesticides, no pathogens, no nitrogen run-off. But organic farmers are not happy and they are pushing back. Why? It appears to be naked brand protection. First they are trying to deny hydroponics the “organic” label, even though it can meet all of their requirements. They argue this is because organic farming is all about nurturing the soil, and without soil how can you have organic farming. They pretend there is something magical and unknown about how soil feeds crops, and hydroponics cannot capture the magic – despite the fact that the produce is as good or better.

But we knew this about organic farming. They use more land than conventional farming for the same output, with significant negative environmental effects, but they don’t care. Now they would push back against the clear benefits of vertical hydroponic farming in order to protect their “magic soil” brand.

I don’t anticipate that hydroponics will replace all soil farming anytime soon. But it can make an important addition to our agricultural infrastructure, and help us feed a growing population without increasing the amount of land needed. In fact, it may decrease our dependence on land, and create the ability to return some farmland to natural ecosystems. Like all parts of agriculture, whichever method of farming is optimal for the location and crop should be used, regardless of philosophy. We no longer have the luxury of farming philosophy – we need science-based farming optimized for efficiency and reduced environmental impact.

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