« AnteriorContinuar »
being mixed with wood or coal. When screened and free from excessive moisture, the analysis is not liable to be much below the average stated. The fact that skillful Connecticut valley tobacco farmers continue to purchase this article in increasing quantities year after year, at from $25 to $35 a ton, is good evidence that a fair equivalent for the money is received.
A better idea of the peculiar composition of cottonhull ashes can be obtained by comparing them with the analysis of wood ashes, given in the next line above it (Table IV, Page 112). Average cottonhull ash contains nearly 25 per cent of potash and about 8 per cent of lime. In wood ashes this condition is nearly reversed, the lime being 33 per cent, while the potash is 5 per cent. To furnish as much potash in the form of wood ashes as is obtained in an average ton of cottonhull ash, five tons of wood ashes would be necessary, which, at $11 to $15 per ton, makes a total cost of $60 to $75, or double the cost of cottonhull ash. The quantity of phosphoric acid obtained from cottonhull ash is also four times as much as from wood ashes—as lime is a very cheap article, costing about $12 per ton, it is economy to purchase the cottonhull ash and supply the deficiency of lime, than to use wood ashes. These facts have been determined by experience as well as analysis, and the custom of applying cottonhull ash and lime to tobacco lands is quite general wherever this ash is extensively used, oyster shell lime being preferred.
Another Objection to Wood Ashes is the great bulk of matter that must be handled if they alone are used as a potash supply. There is, however, some compensation in the large quantity of lime obtained, and wood ashes can be used in part on tobacco lands. . The reasonable price of cottonhull ash has prevented any extensive use of wood ashes, and the latter can only be regarded by the tobacco grower as a source of lime so long as cottonhull ash can be obtained in the present quantities. Cottonhull ash is applied broadcast in the spring at the time of first harrowing, at the rate of 750 to 1000 pounds per acre. As the ash is generally considered to contain about 25 per cent of potash, 750 pounds gives about 187 pounds of potash, and 1000 pounds of ash about 250 pounds of potash.
As the fine quality of the present sulphate of potash salts becomes more generally appreciated, there is a tendency to use them instead of cottonhull ash, the only reason for the abandonment of the latter being the uncertainty of composition. This ash, however, is yet the most popular potash supply, and it will long continue to be so because the potash in it exists as the carbonate of potash, which is by far the best form. Carbonate of potash exerts a powerful influence on the soil through its caustic properties, and this gives it a greater value than an equal amount in the form of sulphate of potash. Another important point is the entire absence of chlorine in cottonhull ash.
OTHER MANUR1AL SUBSTANCES.
Tobacco Stems supply both nitrogen and potash. These systems must not be confused with tobacco stalks. Stems are the midribs of the leaf that are discarded when the leaf is cut into wrappers, or stemmed for the English markets. They are largely employed in fertilizing tobacco fields, and at one time the demand for this purpose was very strong. Stems vary considerably in analysis, according to the quantity of sand and water present; but they are usually a good purchase at $10 per ton, but during the boom, prior to the panic of '73, they sold as high as $35 a ton. Kentucky stems contain about 25 per cent water, organic and volatile matter 62 per cent (including nitrogen 1.8 percent), and mineral matter 13 per cent, of wnich about 8 per cent is potash and 1 per cent phosphoric acid. Seedleaf stems are usually drier, containing about the same quantity of nitrogen and phosphoric acid, but one-fourth less potash. As with all coarse material, stems should be applied very early in the spring, and the better plan is to plow them under in the fall. They supply both nitrogen and potash, and are well suited to the tobacco crop. They are so popular in the Connecticut valley that all the systems available have been used, and before the season for selling closed (about June 10), each year has found the dealers with their stocks exhausted and their late orders unfilled, from 3000 to 5000 tons of stems being used annually.
Lime is used to a considerable extent upon tobacco lands in the seedleaf districts, and its effect is somewhat peculiar and not wholly in the way of a food element. Tobacco ash contains a large percentage of lime, but on some lands sufficient is present in the soil to meet the demands of the crop. But the opinion is growing that a sufficiency of lime is more often lacking in the soil used for tobacco than is usually supposed. Lime is constantly leaching from the upper layers into the lower strata of soil. All saline manures make it leach further. Tobacco, as well as other plants, possesses the power of substitution, and where lime is abundantly present and potash is'lacking, a larger quantity of lime is consumed than would otherwise be the case. It is, therefore, well to have a fair quantity of lime present, more, even, than is usually found in the soil.
The most important action of lime, however, is not that of a plant food, but rather that of a mechanical agent. It promotes nitrification, or the conversion of crude animal and vegetable matter into nitrates. It destroys woody tissue, and when used in excess, burns out the vegetable matter present in the soil, impairing its future value. A little of this burning effect is valuable, since by it latent plant food is made available, but lime should not be used on light lands unless plenty of vegetable matter also is present. Lime corrects the acidity of soils by combining with any excess of acids that may be present. It also, to some extent, acts upon the mineral elements and sets free potash that would not otherwise be available.
Another characteristic of lime is that it improves the texture of both light and heavy soil, but in entirely different ways. It binds together the loose particles of light soils, making them more compact, increasing their capacity to absorb and retain moisture, thus correcting the waste features of such land. On heavy, especially on clay, soils, it has an entirely different effect, as it overcomes the tenacious nature of the land, causing the particles to fall apart, thus promoting ease of cultivation and the better development of plant roots. On cold, wet lands it improves the mechanical condition of the soil by making it lighter. It also corrects the acidity usually present in wet soils, promotes nitrification, and gives it life and energy. Almost any soil that becomes hard and compact can be improved by a moderate use of lime. On tobacco lands it is not used now as much as in former years, although it is resorted to whenever the mechanical condition of the soil requires it.
How to Apply Lime.—The power of lime to liberate dormant plant food is very great and fully understood, and where land has been heavily dressed with manures for a number of years, an application of lime produces very favorable results. On this account it was formerly the custom to make quite a heavy application at intervals of three or four years, but it is now believed that small, annual applications are better. On the general run of lands, 500 pounds is ample, and more often one cask per acre is used. Nova Scotia lime, such as is used for building purposes, is the best. Some advocate the use of air-slaked lime only, while others prefer to apply it in a more caustic state.
A favorite way is to dump the contents of a cask on the plowed field, leaving it a few days to shake by the influence of the moisture of the air and the soil; if then it is lumpy, sufficient water is added to reduce it to a fine, dry powder, care being taken that it does not become pasty. It is then scattered broadcast over the field, after the manure has been applied.
As in the case of manure, the best time to apply it is in the fall, or if not done then, very early in the spring. It absorbs the excessive water in the land, and also assists in reducing coarse manure to the more congenial form of vegetable mold. Lime exists in large quantities in wood ashes, and to a smaller extent in cottonhull ash, and some of the beneficial action of wood ashes results from the lime. In leached ashes, which are highly prized in some sections for grass lands, lime is very abundant, and the effect produced is almost entirely from the lime. Where it can be cheaply bought, oyster-shell lime is particularly prized because of its fine mechanical condition, and its use is on the increase.
Sulphate of Lime, gypsum or plaster, is used to some extent on tobacco, and at one time was highly recommended. While the plants have the power of obtaining lime from the plaster to some extent, its principal function is that of an absorbent only. It takes up water greedily, and has an affinity for ammonia, but whether sufficient to prevent in part the liability of loss of nitrogen by leaching is not demonstrated. Sulphate of lime also has some influence upon the potash compounds of the soil, setting the potash free from inert combinations. For these reasons, about five hundred pounds per acre have been used on light lands, especially where a large quantity of organic matter is present. But in the absence of tests to determine its value, the