COMPOST (OF. composte, It. compostn, Por tug, compost°, mixture, from Lat. componcrc, to put together). A mixture of fertilizing ma terials which has been subjected to fermentation. Composts are usually prepared by mixing animal manures or other readily putrescible substances with peat (q,v,), straw, leaves, road-scrapings, mud, loam, etc., with a view to causing fermentation and chemical changes. which will render these substances Inure active as fer tilizers than they were in their original con dition. Similar results are sometimes brought about by the use of ashes, lime, marl (qq.v.), alkali salts, etc. Frequently also preservative substances, such as gypsum, kainit, super phosphate (qq.v), etc., are added to prevent the loss of ammonia or of nitrogen in the free state, which is likely to occur during fermen tation. Composting is thus not only a means of rendering the constituents of various more or less inert materials more available as plant food, but also of preventing loss of the most valuable constituent of manures, viz. nitro gen. A compost which was formerly quite popu lar consists of alternate layers of barnyard manure, 1 part, and peat. 1-5 parts. the pro portion of the latter depending noon the fermen tative power of the manure. In this mixture the peat prevents the loss of ammonia and the valuable manure liquids, and the immure sets up a fermentation in the peat which greatly. in creases the availability of the inert ilitrogen in which this material is comparatively rich. When lime, ashes, or lime and salt mixtures are substituted for ma mire in the pent compost, the alkaline eharacter of these substances promotes the decomposition of the peat in much the sonic way as the manure. In ease of the lime and salt mixture the reaction between the lime and the salt (NaCl) results in the formation of caustic soda (Na011), which is especially active in bringing about decomposition of the peat. A recommended formula fur this compost is 50 cords of peat, 100 bushels of lime, and 17 bushels of salt. Make a brine of the salt and slake the lime in it to a fine dry powder, using about one bushel of salt to six of lin•, spread the slaked lime, while still hot, Over the peat, which should be in layers about six inches thick. Continue the alternate layers of peat and lime until the heap is four to five feet high. By substituting muriate of potash for salt. in the above mixture the same result is accomplished and at the same time a valuable fertilizing con stituent, potash, is added to the manure. The fermenting compost heap has been utilized for the reduction of bones (q.v.) and ground mine
ral phosphates; and meat, fish, slaughter-house refuse, etc., are :sometimes incorporated in it, but composts containing any considerable amount of the latter substances are likely to be very offensive. Moreover, these materials are less benefited by the process than more inert sub stances. Composting is an effective means of 'killing,' i.e. destroying the germinating lamer of cottonseed intended for use as a fertilizer. Innumerable formulas for composts have been proposed, some of which have attained consider able celebrity. Among these may he mentioned. in addition to the peat composts referred to above, Furman's formula for cotton, millet' is as follows: Barnyard manure. 750 pounds; rotton seed, 750 pounds; acid phosphate, 3(17 p Is: kainit, 133 pounds. The phut of composting these materials, which well illustrates the methods of composting in general, is briefly as follows: Put down on an impervious dirt floor first a layer of manure. then of cottonseed, and lastly of acid phosphate, in the proportions given, distributing the kainit throughout the different layers. Repeat the layers to any de sired extent and cover the heap with absorbent earth. The heap should be kept moderately moist. and if made in the autumn should stand until spring, when it is dug down, mixed, and applied. Although composting furnishes a valuable moans of converting waste materials of the farm into more active and better-balanced fertilizers. the labor involved is so great as to render the prac tice of doubtful economy for general agricultural purposes. especially since the general introdue Don of the more •om•entrated and active commer cial fertilizers. (See AlAxtatEs AND 3iAN•RINIO Composts have been recommended especially for use on grass lands and on stiff soils, or on those deficient in humus. They find their greatest use fulness, however, in hortieultural operations— for plant-beds. potting, and for use on vines, fruits, etc., which might be injured by more con eentrated fertilizers. Perennial plants, or those having long periods of growth, will utilize the fertilizing matter of composts to the best ad vantage. Composts are not so well suited to the forcing of quick-growing crops as cominereial fertilizers. For specific direetions for preparing different kinds of composts, consult: Dana, Mack Manual for Farmers (4th ed., New York, 1558) Storer, _lyriculinie in of its Re lations with Chemistry (7th ed., New York, 1897); Johnson, feat and its l'srs Os Fertilizer and Fuel (New York, 1596) ; Sempers, Manures: Bow to Make and How to Use Them (Philadel phia, 18931.