Most dealers, to meet a certain demand, furnish mixtures ranging from $15 to $25 per ton. These mixtures are necessarily low grade and are more expensive than the higher priced high grade mixtures. For example: A certain potato fertilizer on the market, which we will call mixture A, has the following guaranteed analysis: Ammonia 7 to 8 per cent. Available Phosphoric Acid 6 to 7 " Actual Potash 5 to 6 " A ton of this would contain: Pounds. Nitrogen 115.4 value at 171/2c $20.19 Available Phosphoric Acid 120 " " 4c 4.80 Potash 100 " " 5c 5.00 ----- ------ Totals 335.4 $29.99 Add to this the average charge for mixing, bagging, selling, profit, etc., $8, and the cost will be $37.99. The selling price of this fertilizer would probably be not less than $40. Now suppose the farmer thinks this a high priced and expensive fertilizer and looks about for something cheaper. He finds a low grade potato fertilizer, which we will call mixture B, that has the following guarantee: Ammonia 31/2 to 4 per cent. Available Phosphoric Acid 3 to 31/2 " Actual Potash 21/2 to 3 " Just one-half the guarantee of the high grade mixture A. A ton of this contains: Pounds. Nitrogen 57.7 value at 171/2c $10.10 Available Phosphoric Acid 60 " " 4c 2.40 Potash 50 " " 5c 2.50 ----- ------ Totals 167.7 $15.00 Add average charge for mixing, etc. 8.00 ------ $23.00 The selling price of this would very likely be not less than $25. This seems at first sight to be cheaper and more reasonable. But let us see. In a ton of mixture A he gets 335.4 pounds of plant food for $40, or at an average cost of twelve cents per pound, while in a ton of mixture B he gets 167.7 pounds of plant food for $25, or at an average cost of fifteen cents per pound. To put it another way, in a ton of the high grade mixture A, he gets 335.4 pounds of plant food for $40. To get the same amount of plant food, 335.4 pounds, in the low grade mixture, B, it will be necessary to buy two tons at a cost of $50. A low grade fertilizer is always expensive even if the plant food is furnished by high grade materials. BUY ON THE PLANT FOOD BASIS