Field and Garden: Should I be using 'biologicals'?

In 1893, William P. Brooks conducted a classical experiment at the Massachusetts Agriculture Experiment Station.

Brooks filled pots with soil that had never been exposed to soybeans. To one group of pots, he sprinkled a pinch of dust collected from the floor where soybeans had been threshed. The remaining pots were left untouched.

The outcome was remarkable: Soybean plants in pots with added dust...