CLOVER HAY, 2 Tons per acre. TOBACCO, 1500 lbs. per acre. CORN, 50 Bus per acre. WHEAT, 25 Bus. per acre. POTATOES, 150 Bus. per acre. OATS, 40 Bus per acre. COMPARATIVE EXHAUSTION OF NITROGEN The straw & fodder being returned to the soil. CLOVER HAY, 2 Tons per acre. CORN (with fodder), TIMOTHY HAY, WHEAT (with straw), 25 Bus per acre. OATS (with straw), 40 Bus per acre. POTATOES, 150 Bus. per acre. COMPARATIVE EXHAUSTION OF NITROGEN The whole crop being removed. for use, is about seventeen per cent. For every pound of the phosphoric acid made soluble there is formed by reversion two pounds of sulphate of lime or gypsum, and unless some economical plan can be devised to remove this increasing percentage of gypsum, no higher grade need be expected. 18. By English patented processes, which involve precipitation and "washing," this plaster is taken out, and a much higher per cent. of available phosphoric acid is obtained. The English farmer is willing to pay a fair price for an article which will show forty-five per cent. of available acid, but past experience would seem to prove that his American brother will not pay the price necessary to warrant the increase in expense, although by the process he may be offered an article which will give him available phosphoric acid at a lower rate per pound. 19. In the purchase of this class of fertilizers (acidulated South Carolina rocks) the purchaser should have reference to the price paid per pound for actual available material, and not to the price per ton. 20. Assuming that refuse bone-black, ground bone and South Carolina rock are the leading sources of fertilizer's supplies of phosphoric acid, we may give the following as their comparative prices at wholesale at a given date: Refuse bone-black, $17 50; ground bone, $29 50, and ground South Carolina rock (without acid), $8 50, all delivered at the same point. 21. The report of the Connecticut Experiment station states that "If we assume that soluble, reverted and insoluble phosphoric acid have commercial values (to be distinguished from agricultural value), which stand in the ratio of 9, 8 and 2, then the retail cost per pound of phosphoric acid in plain phosphates bought direct from New York and Philadelphia manufacturers, as shown by the analyses of the New Jersey station, has been as follows: In superphosphates from boneblack, bone-ash, &c., soluble. 7.8 cents; reverted, 6.9 cents; insoluble, 1.7 cents; in superphosphates from South Carolina and other mineral phosphates, 8.5 cents; reverted, 7.6 cents, and insoluble 1.9 cents." 22. In computing the commercial value of a fertilizer, South Carolina rock (acidulated) is usually taken as the basis. Thus, when an article of dissolved South Carolina rock can be obtained on the market for $16 50 per ton of a guaranteed analysis of sixteen and one-half per cent. of available, we may assume that its available phosphoric acid costs the purchaser five cents per pound. If without any reduction in price the guarantee is reduced to fourteen per cent., the price per pound rises to over five and one-half cents per pound. 23. To illustrate this matter still further-in the present condition of the fertilizer market an article guaranteed to fifteen per cent. will cost $19 00 per ton; one with a guarantee of forty per cent. will cost, at the same point, $34 00 per ton; in the first case the available phosphoric acid costs the purchaser 6.33 cents per pound and in the case of the high grade its cost is but 4.24 cents per pound; this is in addition to the saving in freight and handling. 24. The main difference between the (so-called) phosphatic guanos and the ordinary guano of commerce is in the fact that they have been formed in a latitude where the amount of rainfall was sufficient to wash or leach out all of their nitrogen, leaving the phosphoric acid which is thus given a higher percentage that it is entitled to in ordin ary guanos. 25. There are very few exceptions to the rule that the higher the |