EFFECT OF POTASH SALTS ON CROP YIELD 51 



On l)otli Field A and Field G an acidulated pliosphate was used as a 

 source of phosphorus; and in certain comparisons on the former field, 

 sulfate of ammonia was the source of nitrogen. It is probable that in these 

 plant food carriers sufficient sulfur has been applied to meet any deficiency 

 which there may have been in the soil. If this is the case, it follows that 

 the comparisons in question are at least a fairly adequate measure of the 

 influence of magnesia. The results of these comparative tests gi'.e no 

 great support to the contention that jxiagnesium is deficient in our soils, 

 and iience should be applied in fertilizer form. The experience on FieiJ G, 

 with potash-magnesium carbonate compared with other potash carriers, 

 slill further supports this view. It is true that some magnesium may have 

 been applied in lime; but analytical records show the amount t'> ^'^^■^ been 

 so small as *) be of no possible significance. 



Summary 



The more outstanding results of tliese long-standing field experiments 

 are summarized as follows: 



L AVhen used on a sandy loam soil in a cropping system which did 

 not include the application of animal manures, fertilizer potash was found 

 to have a significant effect on crop yields. 



2. Crops varied in response to use of this plant nutrient. Potatoes 

 were very responsive; corn less so, but in stover markedly responsive; soy 

 beans, even on soil known to be potash hungry, were almost independent 

 of applied potash. L'sed on a mixture of grass and clover, the effect of 

 fertilizer potash in increasing the proportion of clover was marked. 



3. Difference in yield of crops as produced by the comparative treat- 

 ment with diff'erent potash salts was found to be comparatively small, the 

 single marked exception being the cane fruits. 



4. When used on cane fruits, winter injury to the canes was much 

 more serious with muriate the source of potash than with sulfate. This 

 difference was reflected in yield of crop. 



5. There was a difference in the quality of potatoes grown on muriate 

 versus sulfate of potash. 



6. Few indications of crop limitation on account of lack of sulfur 

 were found, even after twenty-five years of cropping with a "no-sulfur" 

 fertilizer mixture. 



7. The iijagnesium of sulfate of potash-magnesium was found to have 

 little influence on yield of crops. 



Publication of this Document Approved by the Commission on Administration 



and Finance 



3000. 2-'27. Order. 8080. 



