Millions of earthworms per acre perforate the soil so rain can quickly penetrate, and a high level of organic matter from the Thompsons' careful management of livestock manure and crop residue gives the soil outstanding moisture-holding capacity. As a result, the ditches between the Thompsons' fields and the road are virtually free of silt. In contrast, their neighbors' ditches must be dug out nearly every year. In their fields, insecticides kill most of the earthworms, and the soil surface is crusty. Rain puddles and forms gullies, washing the sickened soil away in a torrent of runoff water, filling the ditches with silt and swelling the already overflowing creeks and rivers.
Healthy soil is the key to healthy crops and health-enhancing foods.
Conventional tomato growers never plant tomatoes in the same soil two years in a row because the accumulated disease pathogens will destroy the roots of the second crop. Consequently, less profitable crops must be grown for two to five years before tomatoes are reintroduced to the field. After each tomato crop is finished, he removes and composts the tomato vines, applies last year's finished compost to the soil, and plants a cover crop of sesbania, a fast- growing tropical legume. When the cover crop is five to six feet tall, he flail-chops it and turns it under the soil surface as a green manure. Later, when he transplants the new tomato crop, he also plants an onion, leek, or garlic plant next to each tomato.