852 



STATE BOARD OP AGRICULTURE. 



requirements of four different soils to wliicli were added 10 c. c. of dilute 

 (about N/lOO) HCl and dilute A1.,(N0;,,), in 2 om. portion of soil, and 

 also the requirement before treatment. These data will serve to typify 

 the j>eneral results that were obtained by treating different soils with 

 II.SO^, HNO3, HoCoO^, AlCl,,, Fe(NIO.).,, etc. Table 10 contains the lime 

 requirement of three different soils which were treated with an excess 

 of dilute (N/100) HCl and then washed and dried. 



TABLE 9. LIME REQUIREMENT OF SOILS TO WHICH WERE ADDED HCl AND AhCNOj)! 



TABLE 10. 



LIME REQUIREMENT OF SOILS WHICH WERE TREATED WITH DILUTE 

 HCl, WASHED, AND DRIED. 



Soil. 



Pounds 



CaO 

 per acre. 



Soil No. 1 before treatment 

 Soil No. 1 after treatment . 

 Soil No. 2 before treatment 

 Soil No. 2 after treatment . 

 Soil No. 3 before treatment 

 Soil No. 3 after treatment. 



6,730. 



8,974.4 

 10,096.2 

 13,461.6 



9,525.3 

 12,339.8 



Considering first the data in Table 9 it will be immediately seen that 

 the presence of 10 c. c. of either HCl or Al2(N03)e in 2 gram portion 

 of soil increased the lime requirement markedly. In the case of 

 the HCl the increase over the untreated soils is about the same for all 

 soils and amounts to about 3 c. c. N/25 Ca(0H)2 or about 3,365 pounds 

 CaO per acre. In the case of the ^.^(NOg)^ the magnitude of the in- 

 crease is also approximately the same for all soils, and is about 5 c. c. 

 of N/25 Ca(0H)2 or 5,609 pounds CaO per acre. 



In many experiments not here repeated the amounts of HCl or 

 Al2(N03)6 added to 2 grams of soil were gradually increased from to 

 10 c. c. by 2 c. c. portions. In every case the lime requirement of the 

 soil increased directly with the amount of the acid or acid salt added. 



The magnitude of the increase of the lime requirement of the soils 

 appears to be approximately equal to the amount of lime required to 

 neutralize the quantity of the acid or acid salt added. Thus, 10 c. c. of 

 HCl of the strength employed required 2.8 c. c. of N/25 Ca(0H)2 to be 

 neutralized, while 10 c. c. of Al2(N0'3)c solution took up nearly 6 c. c. of 



