Dec, 1909.] 



POTASH IN CLAY LOAM SOILS. 



55 



EXPERIMENTS SHOWING ABSORPTION. 



Three soils were selected to show the absorbent effect on potas- 

 sium salts. One of the soils was a boulder clay, another a light 

 sandy loam and the third a sandy clay. These were chosen to 

 represent soils with three different amounts of clay. Equal 

 amounts of these soils were carefully mixed with equal amounts 

 of potassium chloride and set away in sealed jars for three 

 months. Then the contents of each jar were shaken with water 

 and the amount of dissolved potassium determined. The fol- 

 lowing table shows the amount of soil taken, the amount of 

 potassium added, the amount of potassium absorbed and the 

 amount recovered in the solution. 



Table XI. — Shoiring the Absorptive Poioers of Clay, Sandy Clay, 

 and Sandy Loam Soils in Relation to Potash. 



These results show how much more readily the clay soil 

 changes the potassium to an insoluble condition. Had the mois- 

 ture content of the soils been higher, more potassium would have 

 been changed. After potassium salts are applied to soils, it is 

 difficult to recover any appreciable part of it afterwards. These 

 experiments show why this is true. The clay soil, as seen in 

 these experiments, removed about two thirds of the amount 

 added, while the soil containing the least amount of clay acted 

 on only a little more than half as much. 



The conditions in these experiments are much less favorable 

 for changing the potassium into an insoluble form than is found 

 under normal field conditions, where there are large fluctuations 



