The fermentation of manure is due to different forms of bacteria. Some of these germs can exist only in the presence of oxygen, and are called "ærobic" bacteria, while others do not require free oxygen, and are designated as "anaerobic" bacteria. The aerobic organisms are responsible for the hot fermentation which is the cause of great loss of value in manure. It is well known that if manure is thrown loosely into a heap, especially if it contains large quantities of horse or sheep excrement, it soon becomes very hot and dry and oftentimes white or "fire-fanged" as it is popularly termed. During this process large losses of nitrogen are occurring. Experiments conducted to show the loss due to fermentation alone indicate that from thirty to eighty per cent of the nitrogen is removed, but that the phosphoric acid and potash are not affected. In the case of the fire-fanged material in one experiment it was found that all of the nitrogen was lost. As the value of manure depends for the most part on the nitrogen content, it follows that more than half its worth may be lost by hot fermentation.

If the manure heap is so compact that the air cannot penetrate it the aerobic bacteria are unable to live, and hence hot fermentation is not possible. The presence of a large quantity of water also checks this kind of decomposition, and for that reason the excrement of cows and pigs is not so subject to hot fermentation as is that of horses and sheep. Where the manure is in a compact mass the fermentations that take place are due to the anaerobic organisms. These bacteria cause decompositions in the manure which convert the insoluble plant food in the excrement into soluble forms,

but do so with little loss of the fertilizing constituents provided that the heap is protected from leaching rains.

Always Some Loss in Stored Manures.-Even under the best of conditions it is impossible entirely to eliminate losses in stored manure, although if properly preserved the loss may be limited to about ten per cent of the nitrogen, and none of the other two constituents. This loss, however, is insignificant in comparison

Waste of manure in a market garden. The manure from the city stables was thrown into a loose pile and allowed to undergo hot fermentation and be leached by the rains. It should have been carefully piled and protected from the weather.

with the losses which result from not saving the urine, from leaching due to rains, or from allowing the manure to undergo hot fermentations, all of which waste may be prevented to a great extent as will be explained in the next chapter.

CHAPTER XIV

PRESERVATION OF MANURE

Barn Floors Should be Perfectly Tight.-The great value of the manure produced on the farm, and the losses that may occur in it have been discussed at some length. The next point to be considered is the best method of caring for manure so as to prevent these losses as far as possible. Much that will be said under this heading has undoubtedly been already suggested to the reader by his perusal of the preceding pages, but the subject is of sufficient importance to justify devoting some space to it, even though repetition becomes

necessary.

Attention has been called to the fact that over onehalf of the value of the manure is in the liquid excrement, and it is desired to emphasize the statement, that the first consideration in caring for manure is to have that part of the barn floor upon which the excrement falls so tight that none of the liquid can drain away. The manure trough behind the cattle, especially, should be made absolutely tight by the use of pitch, cement or some other material that is impervious to water. In addition to this care should be used to supply litter in quantities large enough to absorb the urine so thoroughly that the manure may be removed without loss from dripping. If the farmer possesses a feed cutter he will be well repaid for cutting up all of the bedding materials. Straw cut in one inch lengths, for

instance, will absorb about three times as much urine as long straw. Cutting the bedding not only increases its absorptive power, but leaves the manure in a condition in which it is much more easily handled. Prominent stockmen have asserted that the greater ease with which manure containing short bedding can be removed, and spread, well repays the cost and trouble of cutting all the litter, to say nothing of the saving in bedding materials, and the latter is an important item on a farm that is stocked to its full capaciy.

Preservatives May be Used in the Barn. Most of the nitrogen present in the urine exists in the compound known as urea. This is very readily decomposed by bacteria and changed into a compound of ammonia and carbonic acid, and is known as "carbonate of ammonia." This substance is volatile, and is sometimes given off into the air in such quantities as to be readily detected by the nose (i. e., by the odor or ammonia). This kind of decomposition takes place more readily in horse and sheep manures than in that from cattle or swine, as anyone can testify who has taken care of these animals when confined in closed barns. No doubt the reader has gone into the horse barn on a winter morning when there was so much ammonia in the air that it "made the eyes water." When the odor of ammonia is perceptible it means that nitrogen is being given off from the manure, and the loss from this source may be an item of considerable importance. This loss may be prevented to some extent by the use of gypsum or land-plaster. The addition of this substance to a solution of carbonate of ammonia brings about a chemical change that converts

the ammonia into a compound that is not volatile, and hence does not pass off into the air, and at the same time the gypsum increases the value of the manure in other ways, as will be seen later. In using gypsum scatter it on the floor immediately after the barn is cleaned, and before the fresh bedding is spread. From one-half to one pound per animal each day is the amount most commonly used, although more will do no harm. It will probably pay better to apply all the land-plaster used on the farm with the manure than to sow it directly on the ground.

Kainite, muriate of potash and acid phosphate or super-phosphate are often recommended as preservatives for manure, and to prevent the loss of nitrogen. These substances are all said to be injurious to the hoofs of animals, and when used should be scattered on the floor and carefully covered with bedding. While many of the experiments seem to indicate that these materials (gypsum included) are efficient in preventing loss of nitrogen it must be admitted that there is great difference of opinion among authorities as to their merits as preservatives. Some experiments have indicated that nothing is so efficacious in preventing the loss of nitrogen from the manure as a liberal application of dry earth to the stable floor, especially if the soil used contains a large amount of humus. In some sections of the country it is considered good practice to collect and dry out muck soil for use in the stable in connection with the bedding. There is no doubt that this prevents the loss of ammonia, if properly used. Dry earth should not be used in too large quantities, however, for if sufficient is added to make the