“The farmer for centuries was simply a ‘tiller of the ground.’ Guano, though formed, according to some eminent authorities, long ages before the creation of man, was not then known. The coprolites lay undisturbed in countless numbers in the lias, the greensand, and the Suffolk crag. Charleston phosphates were unknown. Superphosphate, sulphate of ammonia, nitrate of soda, and kainit were not dreamed of. Nothing was said about the mineral manure theory, or the exhaustion of the soil. There were no frauds in artificial fertilizers; no Experiment Stations. The earth, fresh from the hands of its Creator, needed only to be ‘tickled with a hoe to laugh with a harvest.’ Nothing was said about the value of the manure obtained from the consumption of a ton of oil-cake, or malt-combs, or bran, or clover-hay. For many centuries, the hoe, the spade, and the rake constituted Adam’s whole stock in trade. “At length,” continued the Doctor, “a great discovery was made. A Roman farmer--probably a prominent Granger--stumbled on a mighty truth. Manuring the land--that is, hoeing and cultivating it--increased its fertility. This was well known--had been known for ages, and acted upon; but this Roman farmer, Stercutius, who was a close observer, discovered that the _droppings of animals_ had the same effect as hoeing. No wonder these idolatrous people voted him a god. They thought there would be no more old-fashioned manuring; no more hoeing. “Of course they were mistaken,” continued the Doctor, “our arable land will always need plowing and cultivating to kill weeds. Manure, in the sense in which we now use the term, is only a partial substitute for tillage, and tillage is only a partial substitute for manure; but it is well to bear in mind that the words mean the same thing, and the effects of both are, to a certain extent, identical. Tillage is manure, and manure is tillage.” CHAPTER VIII. SUMMER-FALLOWING.