The Omnivore's Dilemma: A Natural History of Four Meals

by Michael Pollan

“The important thing to know about any grass is that its growth follows a sigmoid, or S, curve,” Joel explained. He grabbed my pen and notebook and began drawing a graph, based on one that appears in Voisin’s book. “This vertical axis here is the height of our grass plant, okay? And the horizontal axis is time: the number of days since this paddock was last grazed.” He started tracing a big S on the page, beginning in the lower left-hand corner where the two axes met. “See, the growth starts out real slow like this, but then after a few days it begins to zoom. That’s called ‘the blaze of growth,’ when the grass has recovered from the first bite, rebuilt its reserves and root mass, and really taken off. But after a while”—the curve leveled out at around day fourteen or so—“it slows down again, as the grass gets ready to flower and seed. It’s entering its period of senescence, when the grass begins to lignify [get woody] and becomes less palatable to the cow. “What you want to do is graze a pasture right at this point here”—he tapped my pad sharply—“at the very top of the blaze of growth. But what you never, ever want to do is violate the law of the second bite. You can’t let your cows take a second bite of a grass before it has had a chance to fully recover.”