16 MASS. EXPERIMENT STATION BULLETIN 324 



Summary 



The soils of Massachusetts have been completely surveyed by the U. S. Bureau 

 of Soils, aided by the State Department of Agriculture. The soils are derived 

 from glacial drift, which consists principally of material from potash-bearing 

 rocks. 



Fertilizer experiments have been limited almost wholly to soils of plain and 

 terrace formation, which were more leached than upland soils or those of alluvial 

 origin. The lighter soils required potash. Heavy clay soils did not respond to 

 potash fertilizers. 



Many analyses have been made at the experiment station of soil samples from 

 all parts of the State. Potash has been determined in an acid solution. So far 

 as can be ascertained, the percentages of potash have been influenced principally 

 by the texture of the soil. The finer the soil, the more potash has been dissolved 

 by the acid. 



The soils of two fields used for fertilizer experiments have been sampled plot 

 by plot where no potash fertilizer had been used. The samples were separated 

 into sands and silt-clay. The sands contained a lower percentage of total potash 

 by fusion than the silt-clay but held the major portion of the soil-potash. One 

 soil contained twice as much silt-clay as the other, which indicated a larger 

 amount of available potash. 



Characteristic samples of important soil series were separated into sands and 

 silt-clay. Total potash by fusion was determined in them. The average per- 

 centage of potash in sands was 2.07 and in silt-clay 2.13. The lowest percentage 

 of potash was 1.27 in the sands overlying a diorite ledge. 



A review of investigations of the water-soluble potash in soils showed that the 

 soil particles yield an important part of the potash required by crops. Efficient 

 use of potash fertilizer should include the available soil potash as part of the 

 supply for the crop. 



Clay presents more surface to the soil-solution than sand and also holds more 

 water. Therefore, clay soils supply more available potash than sandy soils of 

 similar origin. 



Publication of this Document Approved by Commission on Administration and Finance 



3M-0-'H5. No. 5617 



