FERTILIZERS. 



Fortunately, we have a considerable Dumber 

 of experiments bearing upon this point. The 

 results of the trials of 1881 have not yet been 

 published in detail ; the general outcome, how- 

 ever, is similar to that of those of previous 

 years, which are summarized by Professor 

 Atwater as follows. The "general" experi- 

 ments are those of the former class (soil-tests), 

 and the "special" of the latter class named 

 above : 



" Estimating a bushel of corn, with its cobs 

 and stalk.s, to contain 1 pound of nitrogen, 

 and to be worth 80 cents, the effects of the ni- 

 trogenous fertilizers in the special and in the 

 general experiments may be summarized as fol- 

 lows, remembering that the superphosphate 

 and potash salt, "mixed minerals," supplied 

 the amounts of phosphoric acid and potash in 

 a crop of not far from 55 or 60 bushels, which 

 would also contain about the 72 pounds of ni- 

 trogen : 



BUSHELS OF CORN AND POUNDS OF NITROGEN IN CROP, 

 PER ACRE. 



" In the general experiments the mixture of 

 300 pounds superphosphate and 200 pounds 

 muriate of potash brought, on the average of 

 fifty-three experiments, about 43 bushels of 

 shelled corn per acre. The special experi- 

 ments, however, seem to me a fairer test of 

 what the fertilizers may do, because, while 

 made in all sorts of weather and on worn-out 

 soils, they were nearly all on soils and in lati- 

 tudes fit for corn, as many of the general ex- 

 periments were not. In these the mixture of 

 300 pounds superphosphate and 150 pounds of 

 potash salt, which can be bought for $8.25, 

 brought on the average 45 bushels of shelled 

 corn per acre. 



" The experiments of these seasons bear 

 unanimous testimony to two things: The corn 

 was helped but little by nitrogen in the fertili- 

 zers ; and it gathered a good deal from natural 

 sources. The increase of crop and of nitrogen 

 in the crop will appsar more clearly if we look 

 at it another way." 



Or, estimating the result in dollars and 

 cents 



" The experiments are numerous and deci- 

 sive enough to warrant the inference that, as 

 corn is commonly grown, nitrogenous ferti- 

 lizers in any considerable quantity would be 

 rarely profitable. They imply thnt corn has 

 somehow or other the power to gather a great 

 deal of nitrogen from soil or air, or both ; they 

 imply that in this respect it comes closer to the 

 legumes than the cereals that, in short, corn 

 may be classed with the renovating crops." 



Practical Applications. Among the general 

 conclusions derived from these experiments are 

 the following : 



1. The " Complete Chemical Fertilizer," the mixt- 

 ure of 300 pounds superphosphate, 150 to 200 pounds 

 potash salt, and 150 pounds nitrate of soda, costing 

 $15.38 per acre (including $5 per acre for freight), 

 brought the largest crops, excelling even the farm ma- 

 nures with all the crops on which the number of ex- 

 periments is large enough for a fair comparison, and 

 bringing surer returns even in cold, wet, and drought. 

 Doubtless a mixture with less potash and more phos- 

 phoric acid would have proved still more efficient. 



2. The mixture of 300 pounds of superphosphate 

 and 150 pounds of salt, costing $8.25 per acre, brought 

 a trifle less corn and decidedly more potatoes than 

 farm manures. 



3. The mixture of nitrate of soda and superphos- 

 phate, which corresponds closest of all to the ordi- 

 nary ammoniated superphosphates, fish-manures, and 

 guano, though costing more than the mixture of super- 

 phosphate and potash salt, brought less increase of 

 corn, potatoes, turnips, sweet-potatoes, and indeed of 

 every crop but oats. The number of experiments 

 with oats, however, is too small for any general con- 

 clusions. It is very probable that oats and the cereals 



generally would be more helped by nitrogen, and less 

 y potash, than the other crops. But it is a question 

 whether manufacturers of ammoniated phosphates 

 would not do better to substitute potash salts ibr the 

 nitrogenous materials in compounding their ferti- 

 lizers, at least for some crops. 



4. The mixture of nitrate of soda and potash salt 

 was the least useful in all the cases where it was tried. 



5. As to the efficiency of the materials separately, 

 the nitrate of soda was rarely profitable, the sulphate 

 of lime frequently, the muriate of potash very often, 

 and the superphosphate generally so. Doubtless, con- 

 siderable of the effect of the superphosphate was due, 

 in manv cases, to the sulphuric acid and lime. 



6. As to the effect of ashes, the results are variable, 

 though generally thev were efficacious. 



7. Not only did the " Complete Chemical Ferti- 

 lizer" bring a larger average increase than farm ma- 

 nures as actually used, and the mixture of super- 

 phosphate and potash salt nearly as large average 

 increase, but the quality of the crop was generally 

 better with the chemicals" than with the farm manures. 

 Potatoes, especially, were finer in quality and less 

 disposed to rot with the artificial fertilizers than with 

 the farm manures. 



8. The most profitable material in a given case is 

 that which is best fitted to its needs. The chief 

 factors of the problem are: 1. Soil; 2. Season; 3. 

 Feeding-capacity of the crop, its power to gather its 

 food from soil and air ; 4. Form of combination of the 

 ingredients of the fertilizers ; 5. The indirect action of 

 the fertilizer. 



Soils vary in respect to the plant-food they supply 



