858 ANNUAL, REPORT OF THE Off. Doc. 



particular farm, but they were eo plauned and conducted as to make 

 the results applicable to most parts of this State, and of general 

 interest to agriculture wherever commercial fertilizers are used. 



The general idea that pervaded the plan was to imitate nature and 

 get the land as nearly as possible in. the same condition it was when 

 a virgin soil and then continue to use nature's methods for main- 

 taining fertility. 



It is well known from chemical analysis of soils that they contain 

 sufficient phosphoric acid to furnish all that is needed for good 

 crops for many years. It has also been shown that some soils 

 which fail to produce satisfactory crops contain more phosphoric 

 acid than those that are considered fertile. Now, this difference 

 in fertility must be due to a condition of availability. 



An examination of the conditions which prevailed in virgin soils, 

 or in any soil that has just been cleared of its forest growth, soon 

 makes prominent the fact that nature has filled that soil with or- 

 ganic matter; this organic matter not only gives the soil a dark color 

 and fine physical appearance, but it also performs functions in pro- 

 ducing chemical changes that cannot take place in that same soil 

 were it destitute of organic matter. Again, we find that a virgin 

 soil will produce satisfactory crops for a number of years without 

 the intervention of commercial fertilizers, but about as soon as the 

 organic matter has been worked out, the soil fails to produce satis- 

 factory crops and the use of phosphates is resorted to. 



Now, the phosphoric acid which these soils contained was not in 

 a form soluble in water, nor was it in the form of reverted or di- 

 calcium phosphates, but it was an insoluble phosphate of lime, 

 magnesia, iron or alumina. Though termed insoluble, yet this phos- 

 phoric acid was available to crops, through the chemical changes 

 made possible by the presence of organic matter and the com- 

 pounds formed through its decomposition. It was the water charged 

 with carbonic, humic and other organic acids, formed by the de- 

 composition of vegetable matter, that was able to dissolve the in- 

 soluble phosphates of the virgin soils and place them either directly 

 at the disposal of crops, or from such combinations as could be 

 De utilized thereafter. 



As soon as the organic matter of the soil was used up, these favor- 

 able conditions no longer obtained, and crops could not avail of the 

 natural properties of the soil even though there was an abundance 

 present. Now, if nature's methods are observed again, it will be 

 noticed that wherever she is producing vegetation she has devised 

 means for depositing some vegetable matter in the soil in about 

 the same proportion as she produces. 



Taking all these facts into consideration would it not seem reason- 

 able that, in order to avail properly of the phosphates contained 



