Pliny: Natural History, Vol. V

it also acted where it had not established certainty of quality: for this reason we shall first speak of the faults.
33 I would designate a bitter soil by its black, undergrown plants; a cold soil by the shrivelled growth produced; likewise a damp soil by its drooping crops; red earth and damp clay are noted by the eye, being very difficult to work and prone to burdening the rakes or ploughshares with huge clods, although what is an obstacle to working is not also a handicap to productivity; likewise, the opposite can be discerned by the eye, namely ash-coloured soil and white sand; for a barren soil with its thick, hard surface is easily detected by even a single stroke of a prong.
34 Catooriginal: "Cato" (referring to Cato the Elder, author of De Agri Cultura On Agriculture) defines the faults of soil briefly and in his customary style:

‘Take care when the soil is rotten original: "cariosam" not to dent it either with a waggon or by driving cattle over it.’
What do we infer from this designation to have been the thing that so much alarmed him that he almost prohibits even setting foot on it? Let us compare it to the rot in wood, and we shall find that the faults of soil which he holds in such aversion consist in being dry, porous, rough, white, full of holes, and like pumice-stone.
35 He has said more by one striking word than could be fully recounted by any quantity of talk. For some soil exists which analysis of its vices shows to be not old in age, a term which conveys no meaning in the case of earth, but old in its own nature, and consequently infertile
36 for every purpose and powerless. The same authority judges the best land to be that extending in a level plain from the base of a mountain range in a southerly direction, which is the conformation of the whole of Italy, and the soil known as ‘dark’ original: "pulla" to be ‘tender’; consequently this will be the best land.

information as to the good points; and accordingly we will first speak about soil defects.
Varieties of soil.

A bitter soil is indicated by its black undergrown plants; shrivelled shoots indicate a cold soil, and drooping growths show a damp soil; red earth and damp clay are noted by the eye—they are very difficult to work, and liable to burden the rakes or ploughshares with huge clods—although what is an obstacle to working the soil is not also a handicap to its productivity; and similarly the eye can discern the opposite, an ash-coloured soil and a white sand; while a barren soil with its hard surface is easily detected by even a single stroke of a prong. Cato defines defects of soil briefly and in his customary style:

‘Take care when the soil is rotten not to dent it either with a waggon or by driving cattle over it’.
What do we infer from this designation to have been the thing that so much alarmed him that he almost prohibits even setting foot on it? Let us compare it with rottenness in wood, and we shall find that the faults of soil which he holds in such aversion consist in being dry, porous, rough, white, full of holes and like pumice-stone. He has said more by one striking word than could be fully recounted by any quantity of talk. For some soil exists which analysis of its vices shows to be not old in age, a term which conveys no meaning in the case of earth, but old in its own nature, and consequently infertile and powerless for every purpose. The same authority gives the view that the best land is that extending in a level plain from the base of a mountain range in a southerly direction, this being the conformation of the whole of Italy, and that the soil called ‘dark’ is ‘tender’; consequently this will be the best land both for working and for the crops.