_Value in Fertilizers._—In estimating the value of fertilizers it is the custom to speak of the unit of valuation. A unit is one per cent. of a ton, or, in other words, 20 pounds. For example, if kainit contains 12 per cent. of potash and is sold at $12.00 per ton, then there are 12 units and they cost $12.00; therefore one unit costs $1.00, and since the unit is 20 pounds, the actual cost of the potash is 5 cents per pound. If muriate of potash, guaranteed to contain the equivalent of 50 per cent. of potash, is selling at $40.00 a ton, then we find that 50 per cent. potash is 50 units; if 50 units cost $40.00, one unit will cost 80 cents, or in this form 20 pounds cost 80 cents; therefore one pound will cost 4 cents. Now, if these are prices free on board the cars at New York, and potash is the thing we need, we must remember that in order to get equal amounts of potash delivered to our own farm, we must pay freight and haul four tons of kainit instead of one ton of muriate of potash. In other words, with these figures the higher-priced fertilizer, counting in dollars per ton, is really the cheaper article, counting in value. Any one who will secure the latest fertilizer bulletin from the nearest Experiment Station will usually find the approximate values of one pound of nitrogen, phosphoric acid and potash in the different fertilizers worked out in some part of the bulletin. These may be used in deciding whether it is better to buy and mix the fertilizers at home; then one may know what is going on the land and the form of combination it is in. Manure contains all of the elements we have discussed in more or less fixed forms. The liquid manure from animals contains a large amount of the nitrogen passed from the body and is of particular value. The most useful parts of the manure are the ones which are easiest lost; hence, if manure is piled and allowed to ferment, or if the water from the roof of the barn is allowed to wash it, serious loss occurs. A ton of fresh manure has all the value it ever will have, and if there is a piece of land upon which it can be spread, it should be done at once. The liquid manure should be soaked up by the bedding, and applied at once to the land. The holding of manure in piles or pits always causes loss of valuable elements. Sometimes we may have to hold it, but every effort should be made to arrange the crop so that it can be applied somewhere each day as made. Manure has a special value because it furnishes humus, which greatly helps the physical condition of the soil, and the bacterial and other microscopic life in the soil. FOOTNOTES: [10] NOTE.—If the yields of plats 1 and 7 do not agree closely, the effect of the fertilizer can be closely estimated by comparing the yield of each with the check plat nearest to it. Another interesting experiment is to lime one-half of each plat. CHAPTER XXIX. ROOT HOUSES AND VEGETABLE PITS.