EFFECT OF POTASH SALTS ON CROP YIELDS 



By Sidney B. Haskell 



The response of a crop plant to the use of fertilizer potash m;iy bo 

 influenced by a number of factors: — by the kind of plant and character of 

 the soil; by the condition of the soil as influenced by cropping system 

 followed; by tillage; by the kinds and amounts of other fertilizers applied; 

 by the extent to which animal manures have been used; and possibly by the 

 particular potassium salt applied. Moisture conditions in the soil during 

 the growing season may have an influence, first on the need of fertilizer 

 potash, and secondly on the relative value of the different sources; and so 

 also may the time of the year (early or late in the growing season) in 

 which the crop is planted or makes its most luxuriant growth. 



Data which bear on some of these problems have been accumulated 

 over a period of many years at the Massachusetts Agricultural Experiment 

 Station. Crop yields from three experimental fields contribute to our 

 knowledge of the need of potash by plants growing under a soil manage- 

 ment system which does not include the use of animal manures. Data 

 from other fields add to our knowledge of the relative effect of sulfate 

 versus muriate of potash, of the possible role of sulfur as an "essential" 

 plant food, and of the influence of magnesium when applied as an ingredi- 

 ent nf the fertilizer mixture. 



History of Fields 



The fields above referred to are known in the Station publications as 

 the North and South Soil Tests, Field B (comparing muriate with sulfate 

 of potash). Field G (comparing six different carriers of potash), and Field 

 A (comparing different sources of fertilizer nitrogen, with an incidental 

 comparison of muriate of potash with sulfate of potash-magnesia). Full 

 descriptions of these fields and the experiments carried on have been given 

 repeatedly in Station publications.^ 



Soil Conditions 



All of the soil of tlie older part of the Experiment Station farm is 

 classified by the United States Bureau of Soils as the Merrimac. This is 

 a soil of glacial terrace formation, locally much modified by the action of 

 wind and water. The surface soil is fairly uniform, but the subsoil may 



' Specifically, reference is made to the following: 



For the North and South Soil Tests, Mass. Agr. Expt. Sta. Bui. No. 212. 



•For Field A, Mass. Agr. Expt. Sta. Bui. No. 204. 



For Field B, Mass. State Agr. Expt. Sta. Repts. 1884 to 1894, inclusive; INIass 



(Hatch) Agr. Expt. Sta. Repts. 1896 to 1919, inclusive. 

 For Field G, Mass. (Hatch) Agr. Expt. Sta. Repts. 1900 to 1920, inclusive. 



