Farming Dumps All the World’s Fertility into the Ocean


Or does it?

In traditional soil grown farming systems, minerals are routinely added to the soil to fertilize plants. But as much as 85% of these minerals get leached beyond the root zone, traveling deeper into the soil to eventually reach water tables, rivers, lakes, and oceans. These minerals often get a bad name because they can potentially damage ecosystems and denude soil health.

However, what I’ve experienced with mineral fertilizers, especially hydroponic fertilizers, is that they cause all sorts of microbes and organisms to grow rapidly and thrive. When you fertilize plants, you’re not just giving plants valuable minerals to grow, but also bacteria, fungi, insects, worms, algae, and many other microorganisms. It’s not just the minerals that are causing all this life to grow, it’s also water, carbon, oxygen, sunlight, and heat.

When you bring all of the basic elements needed for life, it begins to flourish. However, there can be too much of a good thing.  

Mineral fertilizer is a collection of different kinds of salts. Table salt (NaCl) or sodium chloride, is one type of salt used in cooking, but there are 90 other kinds of naturally occurring salts that are known on the periodic table. If you have the right amount of salt (not too much or too little), you can expect life to flourish. If you don’t have enough of a certain kind of salt, that is a deficiency. If you have too much salt, that is a toxicity.  For minerals used to fertilize plants, these salts can leach away from farms where they may enter aquatic ecosystems.

When this happens, life begins to flourish (known as eutrophication), and this initially is a good thing.  However, if minerals continue to leach into a pond, organisms like algae will start to grow so rapidly that they end up creating high levels of organic matter in the water.  As organic matter builds, (algae growing/dying/growing again) other decomposing organisms start to grow and use up oxygen in the water.

Eventually, oxygen levels become reduced or depleted, creating what is known as a “dead zone.”  Fish and other aquatic life must then try to leave these areas in search of more oxygenated waters, but in many cases, they’re trapped or unable to escape in time. This results in fish-kills, where many thousands of dead fish can be seen floating on the surface of bodies of water.  

The excessive use of mineral fertilizer is what causes this, but I don’t think this means that mineral fertilizers are to blame. Poor land management (bad farming practices) are to blame for these mistakes.

One of the modern ways to prevent eutrophication is with hydroponics. Within a circulating hydroponic system, minerals tumble around in a closed-system until plant roots take them in. The minerals are unable to leach out because they are in a container. For example, a grower could pump water from mineral-rich lake water into a hydroponic system, grow a huge biomass of water hyacinth or duckweed, and 99% of those minerals would eventually be removed from the water, now accumulated in the leaves of the plants. The cleaned water could then be discharged back into the lake.

Another way to prevent the loss of nutrients in soils is to keep them vegetated with perennials, such as trees and shrubs that will hold onto the soil.

Alice Lin