The World Without Us

It is also the only one that has required no management. In 1882, it occurred to Lawes and Gilbert to fence off a half-acre of Broadbalk—the winter-wheat field that had variously received inorganic phosphate, nitrogen, potassium, magnesium, and sodium—and leave the grain unharvested, just to see what would happen. The following year, a new crop of self-seeded wheat appeared. The year after that, the same thing occurred, though by now invading hogweed and creeping woundwort were competing for the soil.

By 1886, only three stunted, barely recognizable wheat stalks germinated. A serious incursion of bentgrass had also appeared, as well as a scattering of yellow wildflowers, including orchid-like meadow peas. The next year, wheat—that robust Middle Eastern cereal grown here even before the Romans arrived—had been entirely vanquished by these returning natives.

Around that time, Lawes and Gilbert abandoned Geescroft, a parcel about half a mile away, consisting of slightly more than three acres. From the 1840s to the 1870s, it had been planted in beans, but after 30 years, it was clear that even with chemical boosts, growing beans continuously without rotation was a failure. For a few seasons, Geescroft was seeded in red clover. Then, like Broadbalk, it was fenced off to fend for itself.

For at least two centuries before Rothamsted’s experiments began, Broadbalk had received dressings of local chalk, but low-lying Geescroft, hard to cultivate without digging drainage, apparently hadn’t. In the decades following abandonment, Geesecroft turned increasingly acidic. At Broadbalk, which was buffered by years of heavy liming, pH had barely lowered. Complex plants like chickweed and stinging nettle were showing up there, and within 10 years filbert, hawthorn, ash, and oak seedlings were establishing themselves.

Geescroft, however, remained mainly a prairie of cocksfoot, red and meadow fescue, bentgrass, and tufted hair grass. Thirty years would pass before woody species began shading its open spaces. Broadbalk, meanwhile, grew tall and dense. By 1915 it added 10 more tree types, including field maple and elm, plus thickets of blackberry and a dark green carpet of English ivy.

As the 20th century progressed, the two parcels continued their separate metamorphoses from farmland to woodland, the differences between them amplifying as they matured, echoing their distinct agricultural histories. They became known as the Broadbalk and Geescroft Wildernesses—a seemingly pretentious term for land totaling less than four acres, yet perhaps fitting in a country with less than 1 percent of its original forests remaining.

In 1938, willows sprouted around Broadbalk, but later they were replaced by gooseberry and English yew. “Here in Geescroft;” says Paul Poulton, unsnagging his rain parka from a bush bright with berries, “there was none of this. Suddenly, 40 years ago, holly started coming in. Now we’re overgrown. No idea why.”

Some of the holly bushes are the size of trees. Unlike Broadbalk, where ivy swirls up the trunk of every hawthorn and flows over the forest floor, there is no ground cover, save for brambles. The grasses and herbaceous weeds that first colonized Geescroft’s fallowed field are completely gone, shaded out by oaks, which prefer acidic soil. Due to overplanting of nitrogen-fixing legumes, and also to nitrogen fertilizers and decades of acid rain, Geesecroft is a classic example of exhausted soil, acidified and leached, with only a few species predominating.

Even so, a forest of mainly oak, brambles, and holly is not a barren place. It is life that, in time, will beget more.

^{Broadbalk Wheatfield and “Wilderness.” (Trees, upper left.)}

^{© ROTHAMSTED RESEARCH LTD 2003.}

The difference at Broadbalk—which has just one oak—is two centuries of chalk lime, which retains phosphates. “But eventually,” says Poulton, “it will wash out.” When it does, there will be no recovery, because once the calcium buffer is gone, it can’t return naturally unless men with shovels return to spread it. “Someday,” he says, almost in a whisper, his thin face scanning his life’s work, “all this farmland will go back to woody scrub. All the grass will disappear.”

Without us, it will take no more than a century. Rinsed of its lime, Broadbalk Wilderness will be Geescroft revisited. Like arboreal Adams and Eves, their seeds will cross on the winds until these two remnant woodlands merge and spread, taking all the former fields of Rothamsted back to their unfarmed origins.