714 EXPERIMENT STATION RECORD. 



" The presence of lime and carbonate of lime prevents tlie formation of 

 soluble iron and aluminum, or, what doubtless is more exact, precipitates these 

 bases from solution. 



" The reaction between fuller's earth and the salt solutions takes place 

 rapidly. Veitch has shown that in soils the reaction extends through a greater 

 period of time. The amount of reacting bases depends upon the concentration 

 of the salt solution. 



" The reaction between clays and soluble carbonates results in the removal 

 of the bases from solution and the formation of bicarbonates or free CO2. The 

 amount of bases removed from solution depends upon the concentration of the 

 carbonate .solution. 



" The acid character of the solutions formed in these ways does not demand 

 the presence of an acid to complete an explanation for their formation. 



" Where a free base is present it is simply removed from solution without 

 forming any soluble reaction product. 



" AYhen such salts as potassium phosphate come in contact with clays, soils, 

 or mucks, both base and acid are rapidly removed from solution. There are 

 no soluble by-products formed during the reactions involved. 



" In the presence of clay the solubility of lime is greatly depressed. 



" The absorptive capacity of volatile substances is shown by the absorption 

 of ammonia and iodin. 



" The absorptive properties of the soils is illustrated by analogy, when filter 

 paper is allowed to react with litmus solution, or when carbon black reacts 

 with salt solutions. 



" The general behavior of muck toward the salt solutions is not unlike that 

 of the clay. The acid character of the salt extract of the muck is due to the 

 absorption of the base or the liberation of free organic acid, or both. Iron 

 and aluminum do not enter into these reactions to any marked extent. 



"The acidified alkali extract of muck will precipitate lime and small (luan- 

 tities of potassium from solution, but will not remove i)hosphoric acid from 

 solution. 



" In a general way the tendency for clay soils, etc., is to reduce the solu- 

 bility of bases with which they come in contact. 



" Where iron and aluminum are found in clay or soil extracts, the presence 

 of soil acids is not necessary to explain the character of the solution. In 

 muck and peaty soils the acid chai-acter of the salt extracts is largely due to 

 increased solubility of the organic decomposition products. 



" The reactions shown . . . explain the rapid disappearance from solution 

 when potassium, ammonia and phosphoric acid are added to soils for fertilizers." 



The potash requirements of a clay soil, F. AY. Morse and B. E. Curry (New 

 Hampshire 8ta. Rpts. 1907-8, pp. 263-271).— The investigations reported in this 

 article were made with typical upland and lowland clay soils of granitic origin 

 collected from different fields on the college farm. 



Chemical analyses of the soils showed a higher percentage of both total 

 potash and water-soluble potash in the lowland soils, although the ratio 

 between soluble and total potash was the same for the two classes of soils. 

 The composition of the hay crop grown on the soils indicated that the decrease 

 of potash in the soil was directly proportional to the increase in yield of crop. 



The results of experiments with different fertilizing materials indicate 

 "that potassium is not the limiting element in hay production on these strong 

 clay soils. The drain on the soil potash is proportional to the yield of the crop 

 as a general rule; but any treatment which will bring about increased pi'oduc- 

 tion of the crop may be independent of potash, since the soil shows a capacity 

 to meet any increased demand for that constituent." 



