10 MASS. EXPERIMENT STATION BULLETIN 324 



components contain these elements in forms which by protracted weathering 

 will become more soluble, and they will ultimately be concentrated in the finer 

 components. A comparison of soils with crystalline rocks indicates that, in the 

 process of weathering, the lime and potash seem to decrease in percentage, 

 although minerals containing them are always present. 



Potash in Sand, Silt and Clay of Two Fields 



In Bulletin 232 of this experiment station, Haskell showed that crops on Field G 

 were much less influenced b}' potash fertilizers than crops on the North Soil Test. 



The soils of the two fields were compared in pot experiments without addi- 

 tional potash but with varied supplies of water. The experiments have been 

 reported in the Journal of Agricultural Research, Vol. 35 (1927). Japanese millet 

 took up nearly twice as much potash from Field G soil as it could obtain from the 

 soil of the North Soil Test, and on both soils it took up more potash with a liberal 

 water supply than it did with a scanty supply. 



The soils of Field G and the North Soil Test were next compared by both 

 mechanical and chemical analysis. Samples were obtained from five plots on Field 

 G and from eight plots on the North Soil Test, none of which had received any 

 potash fertilizer. Each sample was a composite of several borings to the depth 

 of 8 inches. A weighed portion of the dry sample was first sifted to remove the 

 coarse sand. The fine soil was next separated into two groups of particles by 

 repeated subsidence in water. In one group were the sand grains and in the other 

 the silt and clay together with floating organic particles. For chemical analysis 

 the sands of the plots of each field were blended into a composite sample for that 

 field, and similarly with the silt clay particles. A portion of the sand sample was 

 next pulverized to a fine powder in an agate mortar. Total potash was determined 

 by fusion with calcium carbonate and ammonium chloride. 



Table 4.~Percentages of sand, silt-clay, and potash in the soil 

 of two experiment station fields 



It may be noted that the soil of every plot on Field G contained more silt 

 and clay than any plot on the North Soil Test, and the average for Field G soil 

 shows twice as much silt and clay as in the other field. The percentages of potash 

 in the two soils indicate them to be essentially alike in mineral composition. The 

 silt and clay are definitely richer in potash than the sands, but in the soil as a 

 whole the bulk of its potash is in the sands. 



