two thousand six hundred and forty cubic inches per acre of available soil, with its mineral ingredients, and constantly increasing capacity of gathering, retaining, and supplying plant food. The conditions of quality of soil and climate being the same, the productiveness of soils must be in proportion to its mass. Sir J. B. Lawes found five thousand seven hundred pounds of nitrogen per acre in the first nine inches of his soil. The Russian black lands, which are held to be the richest in the world, have, according to Prof. Schmidt, within three feet of the surface, from forty thousand to forty-four thousand pounds of nitrogen. Several analyses of Boussingault showed from twenty-five thousand to thirty-two thousand pounds per acre beneath the surface, and a soil analyzed by Prof. Volcker, in 1868, showed eight thousand four hundred and twenty-five pounds per acre. The practice of deep plowing will depend upon circumstances; a good, though shallow mould, or other soil, resting upon a sticky, clay subsoil, would not be benefited by being at once broken up deeply, bringing large, hard lumps of unfertile clay to the surface, and deteriorating the physical quality of the top-soil.

DRAINAGE.

Drainage, more especially underdrainage, renders a clay subsoil, when moved by the plow, more susceptible to pulverization, and in such case a thorough drainage would have to precede deep plowing. Underdrainage prevents the drowning out of crops after heavy rainfalls. It increases the fertility and pulverization of the soil by admitting air. It keeps the ground moister in a dry season. It prevents the washing away of the soil and its fertilizing materials. It permits the farmer to work his land sooner after heavy rain, and earlier in the spring, and it prevents the land from becoming sour

in wet seasons. The total absence of water would be destructive to vegetation, for it is itself necessary to plant life; but undrained land is not merely wet, it becomes water-logged, and through absence of air, the plants are drowned out. When, however, water passes through, and away from the land, air takes its place, and also passes through the drains, and finds its way into the overlying soil, increasing its fertility and pulverizing it. The reason why drained land gains heat, and the temperature of water-logged land decreases, is the lack of heat-conducting power in water, or the fact that air can not be transmitted downwards through water. When land is saturated with water, the heat is expended in evaporating the moisture, instead of warming the land, and during this evaporation the temperature is reduced. Undrained land becomes sour in wet weather, and the formation of substances injurious to vegetation is encouraged. The absorbing power of soil is so great that ammonia and other fertilizing agents of water and air are arrested in their passage through it, thus enriching the soil; while the water on undrained land washes over the surface, carrying off into the water courses the fertility that might be saved. In undrained land, the passage of moisture, encouraged by evaporation from the surface, is upwards, whereas in drained land, the current is downwards to the level of the drains, supplying the roots with aërated moisture in condition to be taken up by them. An excess of water in the soil produces such a saturated state of the atmosphere, as to prevent a healthy perspiratory action of the leaves of plants growing upon it, and growth is retarded.

PREPARING THE SOIL.

Efficient drainage being provided, the land should be broken up and pulverized as deeply as possible. A mass

of sticky clay will absorb a slight amount of moisture, but when it is reduced to a powdered condition, its absorbing power will be very much increased. One hundred grains of fine clay left for twelve hours in contact with a solution of caustic potash, the latter not filtered through it, absorbed one thousand and fifty grains of potash.

Soils have the power of separating ammonia, and other bases from their solutions, and of separating alkaline bases from the acids with which they were combined.

Soils possessing the greatest amount of capillary porosity, most friable and mellow, or, in other words, such as are in the best agricultural condition, will condense the greatest amount of fertilizing material; and the more they are pulverized, the better will they resist the leaching action of water. Soil in an improper physical condition may hold fertilizing materials in sufficient quantities for a full crop. It will, however, yield only a small percentage to the vegetation upon it, until it is made friable, and so becomes conducive to growth. Carbonic acid is one of the chief agents in this process; and in order that this acid may be formed, the carbonaceous matter in the soil must be brought in direct contact with the atmosphere. As long as the soil is in a compact condition, or is saturated with water, carbonic acid is not formed. During the recent severe drouths it has been observed that crops growing on deeply-plowed land have suffered the least, for the reason that the greater the mass of fine soil, the greater must have been the amount of moisture absorbed. Heat is evolved during the decomposition of vegetable matter; and the darker the soil is from decomposing vegetable matter, the warmer will it become. The warmth of light-colored sands is attributable to their conductive power. Half the crop depends sometimes upon the previous preparation of the land. Owing to the absence of a covering of snow and of successive freezings and thawings, fall plowing, so useful at

the North, is destructive of fertility at the South and is not advisable.

CULTIVATION.

The land having been properly prepared by plowing, and sufficiently manured, and the crop planted with regard to the capacity of the soil, the most important matter to the farmer is, thorough culturë, or keeping the earth fine and mellow among the plants. Stirring the soil can scarcely be repeated too often during the earlier periods of growth, or until there is danger of injury to the roots or to the tops of growing plants by the cultivator. The ground may be too wet, but never too dry, for stirring; because the more frequently it is broken up, fined and aërated, the more moisture will the soil absorb from the atmosphere. This is an operation that should be performed after every rain, sufficient to cause incrustation or baking, which would prevent a free admission of air into the soil. The most obvious benefit of stirring the soil is, the destruction of weeds; for no crop can become remunerative, if crowded by weeds which deprive it of air, light, moisture, and even a part of the fertility of the soil. A war of extermination should be waged against weeds, although at times they become a necessary evil to the farmer who only cultivates the soil between the rows. Breaking the lumps gives free scope to the finer roots to secure all the available nutriment within the extent of their ramifications, as these finer roots are not capable of penetrating large clods, and thus may be debarred from reaching a large part of the food contained in the soil. Thorough and frequent culture of the soil admits air to the rootlets of the growing plant; it increases the capillary attraction of the soil, by which its humidity is rendered more uniform; by presenting a larger number of points of radia

tion, the deposit of dew, so beneficial in dry weather, is augmented; the temperature of the soil is increased by the freer admission of warm rain and air, and by the chemical processes thereby facilitated; and finally the fertility of the soil is augmented through the ammonia, nitric acid, etc., which are introduced with the air. The plow, horse-hoe, and cultivator are to be used, whenever available; but the hand-hoe must always be relied on for the finer and more careful work, when, particularly in the later stages of the crop, only superficial stirring is advisable. When plants are grown in a crowded state, darkness and want of air elongate the stems and leaves, at the expense of the roots and of a general healthy condition. The operations of thinning and hand-weeding are performed in connection with hoeing, to admit a free circulation of air around the remaining plants, and the sun is permitted to have an immediate influence upon each, developing the desired form, bulk, and other qualities.

CHAPTER III.

MANURES, THEIR KINDS AND USES.

Almost any soil may be so altered in its character by judicious and plentiful manuring, as to be made fertile. enough to produce good and remunerative crops. Manure is the most indispensable factor for success in marketgardening, and must be applied in much larger quantities than in any other branch of agriculture. The gardener should never be restricted by a short supply to an inadequate application of manure, as the superior quality and quantity of his crops will generally justify an apparently lavish use. Knowledge of his soil, the peculiar requisites