HKB
Of manuring
XXXVIII. As part of this same operation should be considered what places in a field need manure and what kind of manure you can use to the greatest advantage, for the several kinds have different qualities. Cassius says that the best manure is that of birds, except swamp and sea birds,[89] but the best of all is, he claims, the manure of pigeons because it is the hottest and causes the land to ferment. This ought to be sown on the land like seed, not distributed in heaps like the dung of cattle. I myself think the best manure is that from aviaries in which thrushes and blackbirds are kept, because it is not only good for the land but serves as a fattening food for cattle and hogs: for which reason those who farm aviaries pay less rent when the owner stipulates that the manure is to be used on the farm, than those to whom it is a perquisite. Cassius advises that the manure next in value to that of doves is human feces, and third that of goats and sheep and asses. The manure of horses is of the least value on corn land, but on meadows it is the best, because, like the manure of other draught animals fed on barley, it brings a heavy stand of grass. The manure pit should be near the barn in order that it may be available with the least labour. If you plant a stake of oak wood in the manure pit it will not harbour serpents.
2° PLANTING TIME
Of the four methods of propagating plants
XXXIX. The second operation, namely that of propagating, must be considered in relation to the proper time for sowing each kind of seed, for this concerns the aspect of the field you are to sow and the season fitting for what you are to plant. Do we not see some things grow best in the spring, others in summer, some in autumn, and others again in winter? For each plant is sowed or propagated or harvested in season according to its nature: so while most trees are grafted most successfully in spring, rather than the autumn, yet figs may be grafted at the summer solstice, and cherries even in winter.
And since there are four methods of propagation of plants, by nature and by the several processes of art, namely: transplanting from one place to another, as is done in layering vines, what is called cuttage or propagating quick sets cut from trees, and graftage, which consists in transferring scions from one tree to another, let us consider at what season and in what locality you should do each of these things.
a. Seeding, and here of seed selection
XL. In the first place, the seed, which is the principle of all germination, is of two kinds, that which is not appreciable by our senses and that which is. Seed is hidden from us when it is disseminated in the air, as the physicist Anaxagoras holds, or is distributed over the land by the surface water, as Theophrastus maintains. The seeds which the farmer can see should be studied with the greatest care. There are some varieties, like that of the cypress, which are so small as to be almost invisible, for those nuts which the cypress bears, that look like little balls covered with bark, are not the seed but contain it. Nature gave the principle of germination to seed, the rest of agriculture was left for the experience of man to discover, for in the beginning before the interference of man plants were generated before they were sown, afterwards those seeds which were collected by man from the original plants did not generate until after they had been sown.