A top-of-the-line farm tractor stands taller than an African elephant. And fully loaded with grain, a combine harvester weighs up to 36 tons—as much as a small herd of pachyderms. As these mechanical beasts lumber across fields, their extreme heft can slowly crush the soil and make it harder for plant roots to grow. Such effects, a new study suggests, could diminish harvests across 20% of global cropland in the coming decades.
>> read more …