58 THE POPULAR SCIENCE MONTHLY 



be lost by leaching than is added in the rain and by the azotobacter and 

 other non-symbiotic bacteria. 



While these systems are distinctly for live-stock farming or for grain 

 and hay farming, they should be considered as only suggesting the basis 

 for solving the nitrogen problem. In diversified farming a combina- 

 tion of these systems will often be preferred to either one alone. The 

 important point is that the landowner should know the essential facts 

 and base his practise upon them in order to provide for permanent fer- 

 tility with respect to nitrogen, phosphorus and limestone. 



Applicatiox of Principles Established 



Louisiana Experiments. — The longest record of a rational permanent 

 system of agriculture conducted in America is furnished by the 

 Louisiana Experiment Station. As an average of nineteen years, the 

 values per acre of three crops were $29.79 from unfertilized land, and 

 $92.04 where organic manures and phosphorus were regularly applied 1 

 in a three-year rotation of (1) cotton, (2) corn and cowpeas, (3) oats 

 and cowpeas. Here the crop values from the well-fertilized land average 

 more than three times as great as those from the unfertilized land under 

 the same rotation and with two legume cover crops grown every three 

 years. 



Ohio Experiments. — The Ohio Experiment Station has reported six- 

 teen years' results from a three-year rotation of corn, wheat and clover, 

 both from unfertilized land and from land treated with farm manure 

 and phosphorus. As a general average, the values per acre of the three 

 crops at conservative prices were $27.07 on untreated 2 land, $44.65 

 where farm manure was applied, $53.82 where manure and rock phos- 

 phate were used, and $53.61 where manure and acid phosphate were 

 applied, practically the same yields having been secured whether the 

 phosphorus was applied in raw rock phosphate or in acid phosphate, 

 costing twice as much. The well-fertilized land has produced nearly 

 twice as much as the land where no manure and phosphate were used, 

 although clover was grown every third year in the rotation and all of the 

 land was limed. 



On the basis of these figures, 8 tons of manure were worth $17.58, 

 or $2.20 per ton ; and the rock phosphate, costing about $7.50 or $8 

 per ton, was worth $57.31 ; or, if we use the Ohio methods of computing 

 the amount and value of the increase produced, each ton of raw phos- 

 phate was worth $65.63; and it may well be added that to obtain the 

 same amount of phosphorus in the common high-priced mixed manu- 

 factured commercial fertilizer, such as farmers are advised by the 



1 In addition, five pounds per acre of potassium were applied every three 

 years. 



2 Except for lime and clover. 



