BOOK XVII. iii. 39-iv. 42
quality. This is the kind of earth usually found in land newly ploughed where an old forest has been felled, earth that is unanimously spoken highly of. And in the matter of bearing cereals the same earth is understood to be more fertile the more often cultivation has been suspended and it has lain fallow; but this is not done in the case of vineyards, and consequently the greater care must be exercised in the selection of their site, so as not to justify the opinion of those who have formed the view that the land of Italy has by this time been exhausted. In other kinds of soil, it is true, ease of cultivation depends also on the weather, and some land cannot be ploughed after rain, as owing to excessive richness it becomes sticky; but on the other hand in the African district of Byzacium, that fertile plain which yields an increase of one hundred and fifty fold, land which in dry weather no bulls can plough, after a spell of rain we have seen being broken by a plough drawn by a wretched little donkey and an old woman at the other end of the yoke. The plan of improving one soil by means of another, as some prescribe, throwing a rich earth on the top of a poor one or a light porous soil on one that is moist and too lush, is an insane procedure: what can a man possibly hope for who farms land of that sort?
Use of marls for manure.IV. There is another method, discovered by the provinces of Britain and those of Gaul, the method of feeding the earth by means of itself, and the kind of soil called marl: this is understood to contain a more closely packed quality of richness and a kind of earthy fatness, and growths corresponding to the glands in the body, in which a kernel of fat solidifies. This also has not been overlooked by the Greeks—indeed what have they left untested? They give