BuEEAu OF Ageioultube. 173 



per acre of 2-8-2 fertilizer would have to be used to sup- 

 ply this amount, granting that the com could get hold of 

 all of it, which it cannot do. The seventy-five pounds of 

 nitrogen (required for fifty bushels of com) would cost 

 at least $15, and generaly more, at the usual prices of 

 mixed fertilizers. One hundred to one hundred and 

 twenty-five pounds of nitrogen would have to be applied 

 in order that the crop could obtain seventy-five pounds 

 from this source. 



There are some special crops of high value per acre, 

 such as tobacco, potatoes, cotton, vegetables, etc., on 

 which the use of the three elements, nitrogen, phosphorus 

 and potassium on some soils gives profitable results. In 

 such cases, I would unhesitatingly recommend their use, 

 at least until the soil could be built up to a point 

 where some or all of the elements could be left off by 

 rendering the supply in the soil available. 



We recommend the use of acid phosphate more fre- 

 quently than rock phosphate. We do so because we have 

 found that acid phosphate is more effective, per dollar 

 invested, than rock phosphate on soils deficient in or- 

 ganic matter, as most Kentucky soils are. We are ex- 

 perimenting with both forms. However, our experi- 

 ments are on soils quite deficient in organic matter. If 

 we find that when organic matter is restored to the soil 

 the rock phosphate is permanently more profitable, then 

 we shall as surely recommend the use of rock phosphate. 

 Besults in other States lead us to believe that such may 

 prove to be the case. There are numerous cases in this 

 State where rock phosphate is being used with great suc- 

 cess by farmers who have manure or green manure crops 

 to use with it. Bone meal is an effective form of phos- 

 phate, but the supply is exceedingly limited compared 

 with the amount of phosphates that should be used. 



It should now be evident why we lay such stress on 

 the use of phosphates. It is for the reason that nearly 

 all Kentucky soils outside the Blue Grass Region are 

 very deficient in phosphorus and some within the outer 

 circle of the Blue Grass Region. Phosphorus in these 

 soils is the first limiting element. Under this condition, 

 without the liberal use of phosphates, it is impossible to 

 produce large growths of leguminous and other crops 



