170 Agricultural Chemistry. 



is lacking in one or two, or all three of the constituents of plant 

 food in available form. In carrying out field tests such as these 

 it should be borne in mind that the results of one year's work 

 are not perfectly reliable, since prevailing weather conditions, 

 as well as other factors, may produce very different results. It 

 will be well to continue tne work for several years in order to 

 eliminate any differences due to differences of season. 



No Fertilizer 



15 Ibs. Nitrate of Soda 

 15 Ibs. Sulphate of Potash 

 30 Ibs. Acid Phosphate 



30 Ibs. Acid Phosphate 

 15 Ibs. Sulphate of Potash 



No Fertilizer 



15 Ibs. Nitrate of Soda 

 15 Ibs. Sulphate of Potash 



15 Ibs. Nitrate of Soda 

 30 Ibs. Acid Phosphate 



No Fertilirer 



It must also be remembered that the requirements for different 

 crops will vary. By carrying the plots through several seasons 

 and using the rotation common for that particular farm, the 

 special crop needs can also be ascertained. 



Amount of fertilizers to be applied. No definite rules can be 

 given as to the quantities of commercial fertilizers to be applied, 

 for the amount necessary to produce large crops will vary with 

 the character and state of fertility of the soil, the kind of crop 



