What Makes Plants Grow

By Alexis Madrigal

To understand why fertilizer works, we need to get some basic plant biology out of the way. Plants need large amounts of three nutrients: nitrogen, phosphorous, and potassium. Combine those with water and sunlight and plants will grow.

In a natural ecosystem, nutrients are naturally cycled. Plants grow, using these substances, then they die. Microbes decompose them and new plants use the same nutrients to grow again. You know, the whole circle of life thing.

Agriculture gives us civilization exactly because it disrupts this balance. Humans use plants to mine nutrients out of the soil and then eat them. We can even measure the amount of nutrients that a crop can mine for us. For example, a hectare of maize in the US needs about 22 kilograms pounds of nitrogen per tonne of yield. We call this the plant’s mineral uptake. Problem is, the corn on the cob you’re eating is full of the nutrients that the next generation of plants would have used. We’ve taken nutrients out of the cycle, so we’ve got to replace them or the soil will be depleted.

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What Makes Plants Grow

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