View “How Plants Turn Back into Soil”

Photography by Christopher D. Cook
Written by Christopher D. Cook

After food crops have been harvested, their vines are brought to a pile near Kaiser’s barn. This compost is covered with a thick blanket to keep it warm so it can decompose, then eventually be used as fertilizer for more crops.

Kaiser uses a thick acrylic blanket to keep both soil and compost piles covered (this follows the second of his three rules for soil health). Most farmers, if they cover soil at all, use immense plastic sheets, which end up each year in the landfill. “These blankets,” Kaiser says, “last me 10 years!”

As old crops and weeds get eaten by worms and other bugs (millions of which are too small to see), the refuse slowly decomposes. Within a few weeks, it begins to resemble dirt.

In a few more weeks, compost’s resemblance to dirt is almost complete. It’s now ready to be spread on his fields.

When Kaiser’s compost is first applied to his fields, it doesn’t contain all the minerals and other nutrients in real dirt. So it often feels a bit lightweight, like potting mix. Many farmers use manure to add substance to their compost. Kaiser has been reluctant to use manure, fearing the agrochemicals that a lot of manure contains. But he’s now experimenting with it.

Once the compost has had a chance to fully mature into soil—thanks to help from the worms, other soil microbes, and nutrient exchanges with the roots of new crops—it finally becomes real dirt. When this process is done properly, with all the nutrient support possible, the result is like this pile in Kaiser’s hands: dark, rich and dense, what farmers call “chocolate cake.”

Christopher D. Cook is the author of "Diet for a Dead Planet: Big Business and the Coming Food Crisis," an investigation of the food industry’s impacts on consumers, the environment, workers, and farmers.

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