32 N. H. AGR. EXPERIMENT STATION. [Bulletin 170 



Summary 



1. New Hampshire soils are rich in potassium and are naturally 



adapted to the production of hay. 



2. The natural soil potassium is present as clay and in mineral 



form. 



3. The minerals have a definite solubility in water which is 



increased by the salts used in fertilizers. 



4. Calcium carbonate and lime have practically no effect on the 



solubility of soil potassium. 



5. When potassium phosphate reacts with the soil, no new 



soluble salts appear in solution. 



6. When other potassium salts react with the soil, new bases 



appear in solution. 



7. The solubility of the common acid radicals, excepting phos- 



phoric, is not affected by the action of the soil. 



8. The effect of sodium chloride, sodium nitrate, sodium car- 



bonate and acid phosphate is to greatly increase the 

 solubility of soil potassium. 



9. The reaction between these salts and the soil is chemical. 



10. Field data show that potassium fertihzers do not produce 



increased yields of hay, particularly on clay soils. 



11. The composition of the hay plotted against the yield shows 



that when no potassium fertilizers are used, the soil sup- 

 plies enough potassium for the growth of the crop. 



12. From a practical point of view, the use of potassium ferti- 



lizers on these soils is unprofitable for the production of 

 hay. 



