i6 



Forms of Phosphoric Acid Applied. L,imed. Unlimed. Gain from 



lyiming. 



Dissolved Boneblack 19,837 9,820 10,016 



Dissolved Bone 19,281 8,564 10,716 



Dissolved Phosphate Rock 20,205 8,951 11,253 



Fine Ground Bone 22,012 11,855 IO > r 57 



Basic Slag Meal 20,400 13,193 7,206 



Floats 20,525 10,560 9,965 



Alumina Phosphate (raw) 14,387 5,4 2 9,345 



Alumina Phosphate (ignited) 19,481 4,93 I 4,55 I 



No Phosphoric Acid 15,737 2,547 13,190 



Double Superphosphate 17, 937 4,752 13,184 



It will be seen that there was a wonderful gain in the crop, 

 in all cases, resulting from the use of lime. The acidulated phos- 

 phates appeared to be helped more by the lime than the unacidu- 

 lated forms. The authors suggested that lime might have been 

 beneficial by correcting the acidity of the first. No experiments, 

 however, were made to ascertain whether the lime would liberate 

 phosphoric acid from the insoluble phosphates of the soil. 



Some rather peculiar results were obtained by Schreiber 1 on 

 the action of calcium carbonate on mineral phosphates. Addi- 

 tion of calcium carbonate to the phosphates decreased the action 

 of the latter on the crops grown, the greater the amount, the 

 greater the injury. In some cases the effect extended to the 

 next year. The action of basic slag was not affected. 



Kellner and Bottcher 2 obtained similar results, when using 

 superphosphate, basic slag, and bone meal for oats. Addition of 

 calcium carbonate caused reduced yields in every case, but this 

 decrease was less with the superphosphate and slag than with 

 the bone meal. Comparing the amounts of increase due to phos- 

 phoric acid applied, the addition of calcium carbonate was not 

 unfavorable when used in conjunction with slag and super- 

 phosphate. With bone meal the addition of calcium carbonate 

 reduced the yields on the average by 67 per cent. No explana- 

 tion was offered for the action of the latter. 



The relation between humus and the phosphoric acid of the 

 soil, has not received very much attention. Incidentally, obser- 



1 Bied. Centr., 1900, 162. 



2 Deut. I<andw. Presse, 1900, 27, 665. 



