Some years ago the question of the preservation of green crops in pits or silos attracted an extraordinary amount of attention, and a commission was appointed, in which the present writer was concerned, to consider the question. The advantages which were most obvious in this method of dealing with grass and other crops which might be too poor to be worth harvesting in the ordinary way, were the independence of weather, increased facilities for storing in wet seasons, and the greater portability of the food obtained, as, under the effects of the pressure employed, a cubic foot of grass might be made to represent nearly the weight of an ordinary truss of hay.
The method of preparation is extremely simple, although in the first instance a large amount of capital was expended in the construction of model receptacles, or silos of wood or bricks, either sunk into the ground or raised above it. Later on it was ascertained that very excellent results could be secured by merely cutting the green crop irrespective of the weather and stacking it in the ordinary way. It was found advisable to have large stacks in order to ensure sufficient pressure, and it was necessary also to cover the top of the stack with planks, close together, and to place on the planks any available heavy articles, pieces of machinery, large blocks of stone, and, in fact, any articles which might be encumbering the farm premises uselessly. The added weight, however, to the top of the ensilage stack, whatever might be its amount, did not appear to affect the density of the mass more than 4 or 5 feet down, and some very fair stacks of silage were made without any added pressure at all; but there is no doubt of the advantage of pressure in preventing mould at the upper part of the stack. It was calculated during the enquiry that the process of preserving green crops in this way, in the silo and by stacking underpressure, was extremely economical. It was found that grass preserved in this way yielded about five times the weight of the same grass made into hay. The other crops which were used for preservation by converting them into silage were rye, oats, millet, maize, barley, and sometimes wheat. And if these crops were in condition for cutting before the middle of June, before the seeds began to get hard, the land would be cleared in time for a second sowing.
Silage was intended to be used chiefly for cattle, but in reference to its use for horses also the commissioners reported as follows: -
" Strong as the evidence has been of the advantage of ensilage for keeping all stock in healthy condition, farm horses have by no means been excepted. We have received highly satisfactory accounts from several quarters of the health of working teams when given a limited proportion of silage, mixed with food. Among the plans of silos which have been submitted to us, those which consist of external walls, either above or below ground, whether of concrete or of stone, brick or clay lump cemented within, appear to be the most efficient; but in all cases, the absence of air depends upon two conditions:. first upon its expulsion from the mass of forage ensiled, and, secondly, upon its exclusion when this is covered. Whatever may be put into a silo, it should be thoroughly well trodden in, and rammed down at the edges into a compact mass; with this object the advantage of rounding off the corners has been impressed upon us by some witnesses. To ensure the exclusion of the outer air it has been found useful to cover the mass with close-fitting boarded lids or shutters in one or more divisions, with a layer of bran, saw-dust, or earth above them. Weights being required above this layer, to keep the mass compact, may be applied either in the form of any convenient dead-weight, such as bricks, boxes or baskets of stones, or of mechanical pressure exercised by means of various systems of chains, screws, or levers. Instances are known of silos being successfully weighted without the use of boards, by simply covering the ensiled material with rushes, ferns, or other waste substances, and above these with dry earth or sand to the depth of 9 inches or a foot.
"As in the case of all important innovations, it is not surprising that the introduction of the system of ensilage into this country has been met by a considerable amount of prejudice and incredulity. During the progress of our enquiry we have endeavoured amply to discount all exaggerated estimates of its merits. After summing up the mass of evidence which has reached us, we can without hesitation affirm that it has been abundantly and conclusively proved to our satisfaction that this system of preserving green fodder crops promises great advantages to the practical farmer, and if carried out with a reasonable amount of care and efficiency should not only provide him with the means of ensuring himself to a great extent against unfavourable seasons, and of materially improving the quantity and quality of his dairy produce, but should also enable him to increase appreciably the number of live stock that can be profitably kept upon any given acreage, whether of pasture or arable land, and proportionately the amount of manure available to fertilize it."
Two kinds of ensilage are recognized: sweet and sour, but the sour silage is most commonly in use. This is made by filling the silo as quickly as possible, or stacking the grass as the case may be, and putting weights on the top in order to check the rise of temperature which always occurs when the silage stack is made slowly, and results in the formation of sweet silage. In reference to the changes which grass undergoes during; the process of conversion into silage, the following tables will afford the information in a condensed form. The analysis on ensilage is the mean result of thirty.seven analyses made by Dr. Voelcker and published in the Field. The analysis of grass is that of Kuhn and Grandeau.
Meadow Grass (Grandeau) ...
Meadow Grass before flowering
Meadow Grass at the end of flowering ... ... ...
Meadow Grass (Kuhn)
Different Sweet Grasses (Kuhn)
Analysis of Ensilage.
Volatile acid (calculated as acetic acid)
Non.volatile acid (calculated as lactic acid)
Albuminous compounds ...
Indigestible woody fibre ...
Digestible cellular fibre ...
Soluble carbohydrates, extractive matter, etc. ...
Mineral matter ...
Both tables may be usefully compared with the table showing the analysis of hay at p. 111.