dung, in respect to the quantity of ammonia being rated as four to one. MUCK. When successive generations of plants have grown and, with the leaves from surrounding forest trees, have decayed on the same low, swampy soil, the vegetable matter increases so rapidly that, with the exception of that supplied by the decaying mass, very little mineral matter is mixed with it. The mud from the bottom of a pond, in or around which no plants grow, consists merely of the washings from the higher ground, and deposits from the water, and must be of inferior quality. It is evident that muck must be very variable in quality, according to its origin. The best, besides imparting valuable humus to the soil, contains four per cent., or even more, of nitrogen. In some instances, on the sea coast, a rich deposit may be subject to overflow at spring tides, which, receding, leave marine animals that will further enrich it. An application to plants of such muck alone, imparts the dark green color to the leaves so indicative of ammonia. It should be dug and be permitted to dry out several months before being used, or it may be mixed with lime at the rate of three or four bushels to the ton of muck. There is no better absorbent for the earth closet, the poultry house, the stable, the cow pen, or the manure pile than salt-marsh muck. It may be drilled in with any artificial fertilizer. Woods-earth, or leaf mould, is still better as decayed vegetable matter, and as a source of humus. SUPERPHOSPHATE OR ACID PHOSPHATE OF LIME. Phosphoric acid is, next to ammonia, or the nitrates, the most important element of plant food, and it is also, next to nitrogen, the earliest to become exhausted in soil. It exists in all plants, in most soils, combined with vegetable matter, in all excrementitious matter, and in the tissues and bones of animals. Bones consist of phosphate of lime, or bone earth and gelatine. Phosphoric acid and lime unite in three different proportions. In common bone earth there are three equivalents of lime to one of phosphoric acid, and this salt of lime is called the tricalcic phosphate, or three-lime phosphate. This is not soluble in pure rain water. Large bones, as is well known, remain for ages buried in the ground, and are only very slowly dissolved by the carbonic acid in the water. The next is the reverted, or dicalcic, or two-lime phosphate, consisting of two equivalents of lime to one of phosphoric acid, which is also insoluble. The monocalcic, or one-lime phosphate, consists of one equivalent of lime and one of phosphoric acid, and is the acid-phosphate, or superphosphate of lime of the agriculturist, and is soluble in water. The manufacturer is enabled to present this valuable soluble fertilizer to agriculture by treating bones, or the South Carolina phosphates, the poor phosphatic guanos, the coprolites, or any other mineral tricalcic phosphate of lime, with sulphuric acid, or oil of vitriol. This removes two equivalents of lime (as plaster or sulphate of lime), converting it into the one-lime, or superphosphate. The surest source of phosphoric acid is finely-powdered bone meal. One ton of this contains, in its gelatine, as much nitogen as eight and one-half tons of fresh stable manure, and twenty-three per cent. of it is phosphoric acid. Bone meal is slowly soluble in the soil by the action of carbonic acid. For vegetable growing it should be decomposed in the manure pile, and supplied at the rate of five hundred pounds to the acre. The manufacturer mixes finely-powdered fish-scrap, nitrate of soda, or some other more or less nitrogenous substance with his superphosphate, and produces his "ammoniated superphosphate." This mere manipula tion the gardener may undertake more cheaply at home, and with greater satisfaction. Phosphatic fertilizers are especially beneficial to root and bulb crops. More or less of the insoluble phosphates may be mixed with and sold in the superphosphate. These have little practical value to the general agriculturist, and none to the gardener. During the fermentation of the bone meal in the manure pile, which is accelerated by the gelatine, soluble nitrogenous organic compounds and salts of ammonia are produced. These act quickly and powerfully as fertilizing agents, and render the phosphate more soluble. POTASH. No vegetable can grow without potash, for it is a constituent of every plant. Its presence has been proved to be necessary for the formation of starch in the leaves; and the experiments of Lawes and Gilbert have pointed out that it aids leguminous plants, like clover, in assimilating nitrogen, which they contain so largely. It results in soils from the disintegration of minerals, and is less apt to be absent, particularly in heavy soils, than either nitrogen or phosphoric acid. Neither the land of the truck-farmer near a city, nor any other land, which has been, even only moderately, enriched with the dung of domestic animals and accompanying vegetable matter, needs any special application of potash. If a crop, even of potatoes, fails on such soils, it will be owing either to a deficiency of the more important elements of plant food, or to other unfavorable contingencies, as of weather, tillage, drainage, etc,, rather than to a lack of potash. But on light lands frequently manured .with exclusively nitrogenous manures, like fish scrap, Peruvian guano, etc., and cropped with potatoes, or some other vegetable exhaustive of potash, an application of a salt of potash either alone, or of a fertilizer largely containing it, becomes indispensable. All potash salts, being exceedingly soluble, are liable to be leached out of sandy land. A crop of one hundred and fifty bushels of Irish potatoes will remove from the soil, in the tubers, 51.3 lbs. of potash, 1.44 lbs. of phosphoric acid, and 30.6 lbs. of nitrogen. Formerly the ashes of hard-woods was nearly the only, and limited source of potash; but recently the kainit mines in North Germany, near Stassfurt and Leopoldshall, provide this element in enormous quantities. The lower grades contain a constituent, the chloride of magnesium, which is actually injurious to plant growth. Years ago, like J. H. H. Gregory of Marblehead, Mass., I had an experience which showed the detrimental effects of this salt in the ruin of a potato crop. Mr. Gregory mixed a compost of twenty-eight bbls. of hen manure, twenty-eight bbls. of dry, rich soil, twelve bbls. of fine ground bone with three bbls. of kainit. This was allowed to heat twice before it was applied, at the rate of two quarts to the hill, and according to his custom, cabbage seed was sown in the field, on each hill. The seed sprouted; but the little seedlings were killed as soon as the first rootlets reached the fertilizer. As large quantities of this kainit are being introduced into the South, statements by Prof. Atwater (American Agriculturist, Vol. XXXVI, No. 11) are here given as a warning against the improper or indiscriminate use of the lower grades of these potash salts: The mines at Stassfurt, Leopoldshall and Westeregeln are from six hundred to one thousand two hundred feet deep, and the area of deposit is calculated at six hundred square miles. The salts, as taken from the mines, contain only a small proportion of potassium compounds, the bulk consisting of materials which have comparatively little agricultural value, and are sometimes positively injurious. They are, therefore, subjected to chemical treatment, by which the potash compounds are more or less completely purified. As prepared for market, the potash fertilizers contain potassium in the form of either chloride of potassium, or sulphate of potash, and, along with these, other compounds, as shown by the following figures from circulars of the German manufacturers: "All these brands contain other than potash compounds. Of these the sulphate of magnesia may be valuable, since it is useful as plant food, and further, aids in diffusing the potash through the soil and thus bringing it within reach of the roots of plants. The chloride of sodium, or common salt, though not needed for plant food, is useful in rendering other materials available, and hence is often quite valuable as a fertilizer. For certain crops, however, like potatoes, sugar beets, and tobacco, it is apt to be detrimental; probably on account of the chlorine which it contains. The chloride of magnesium may be injurious. Nos. 1, 2, 3, and 4, in the table, are low grade articles, furnishing only nine to eighteen per cent. of actual potash. The crude kainit, No. 1, is the ma |