But by the continuous growing of crops like wheat

But by the continuous growing of crops like wheat

But by the continuous growing of crops like wheat

But we must add humus, or vegetable matter, to the soil. You remember that the virgin soils contained a great deal of vegetable matter and plant food, but by the continuous growing of crops like wheat, corn, and cotton, and by constant shallow tillage, both humus and plant food have been used up. Consequently much of our cultivated soil to-day is hard and dead.