For the first time, farmers could easily slice through the tough roots of prairie grasses to expose the rich topsoil. America was set on its path towards becoming the world's breadbasket. Now the 150-year era of the great steel plough is coming to an end as an astonishing revolution sweeps through those same plains. Its central tenet is retiring the old moldboard plough, which lays the earth open to wind and water erosion. Instead, farmers leave residue from the previous year's crops in place to hold soil and moisture, then scratch or chisel-in seeds, which sprout through the decomposing residue.
Crop rotation is used to break insect cycles.
The techniques were, in fact, known a half-century ago but not widely adopted because of stubbornness and lack of economic urgency. Now environmental concerns, politics and economic necessity have fortuitously converged to drive this farm revolution. Many farmers long ago sensed the damage the traditional ploughing cycle was doing to their land, heaving it up yearly, exposed and crumbling, to be ravaged by the elements. According to an old saying you could stand on the bridge over the Mississippi River in the town of Vicksburg and every hour you could watch an Iowa farm go by in the current below. You can give a rating to this scheme overall.