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Hydroponics is a method of growing plants using mineral nutrient solutions, in water, without soil. In a recent Mingpao article titled “Farming can make money”, the purveyors of hydroponically grown produce tout many of its impressive benefits. Chief among them was food safety. 

They rightly point out that much of China’s land is contaminated and its fresh water is polluted. This jeopardises our food safety since most of our food comes from China. They go on to suggest that hydroponic produce, grown in clean water without any soil, is a solution to our food safety problems. What they fail to note is that hydroponic production would in fact exacerbate the food safety problem. To understand why, we need to look at the source of the minerals used in a hydroponic system.

17 elements have been identified as essential for plant growth, 3 of which come from the air and water. The remainder come from the soil or fertilisers. In a hydroponic system, these nutrients are extracted from the earth and chemically processed to feed plants. The materials used to produce the nutrient solutions are either mined or synthesised via energy intensive industrial processesCommon chemicals used in hydroponic systems include:

Calcium nitrates, Potassium nitrates, Magnesium nitrates, Ammonium nitrates, Monopotassium phosphates, Monoammonium phosphates; Potassium sulphates, Magnesium sulphates, Ammonium sulphates, Potassium chlorideMagnesium sulphate heptahydrate; Manganese sulfate monohydrate; Zinc sulfate dihydrate; Boric acid; Sodium molybdate; Copper sulfate pentahydrate and Iron EDTA

Mining is one of if not the single most environmentally devastating activities carried out by mankind. According to the Australian government, these impacts include heavy metal contamination and leaching; the spilling and leaking of chemical agents from the minesite into nearby water bodies and erosion of cleared land surfaces. Thus, the production of minerals for hydroponic systems causes the pollution that it kindly offers to protect us from.

In contrast, organic farming relies on biological (instead of chemical) processes to accomplish the same thing. The primary nutrients are derived from composted animal manures or recycled food processing waste such as bone, peanut and soya meal. Plants with the help of microorganisms (bacteria, fungus) living in the soil extract most of the secondary elements they require for growth directly from the soil. Organic farming mimics nature to create a virtuous cycle in which nutrients are recycled to produce more food. 

Hydroponics creates another type of “virtuous” cycle – a purely profit driven one. The more we contribute to damaging the environment by buying hydroponic produce, the more we are compelled to buy hydroponic produce to protect ourselves from the damage. A great business model indeed.