JOIBALOFAGRICDLTDRALISEARCH 



Vol. XV Washington, D. C, November ii, 1918 No. 6 



SOIL ACIDITY AS AFFECTED BY MOISTURE CONDI- 

 TIONS OF THE SOIL 



By S. D. Conner * 



Associate Chemist in Soils and Crops, Purdue University Agricultural Experiment Station a> "^V ''^< 



<^> h 



INTRODUCTION O^ <Vy ^^' 



In an investigation of soils from tiled and untiled land it has been '"^ 



found that the drained was not as acid as the undrained soil (2)} To 

 throw more light on the effect of moisture on soil acidity, five typical 

 acid Indiana soils were selected for investigation under controlled mois- 

 ture conditions: Soil A, a yellow silty clay from Jennings County; soil B, 

 a whitish silt loam from Jennings County; soil C, a brown silt loam from 

 Tippecanoe County; soil D, a black peaty sand from La Porte County; 

 and soil E, a dark-brown peat from De Kalb County. 



Equal quantities of each of these soils, the analyses of which are given 

 in Table I, were kept in pots in the greenhouse at full water-holding 

 capacity, at one-half water-holding capacity, and at one-fourth water- 

 holding capacity. Other portions of each soil were taken when pots 

 were filled and kept in an air-dry condition in the laboratory. The 

 pots were of galvanized iron of 770 cubic inches capacity, heavily coated 

 on the inside with paraffin. The soil in each pot was kept rnder the 

 desired moisture conditions by weighing them two or three times each 

 week and replenishing the evaporated moisture with pure distilled water. 

 The water-holding capacity of each soil was determined by placing a 

 perforated bottom cylinder containing about 100 gms. of loose dry soil 

 in a vessel of water and allowing the sample to become thoroughly satu- 

 rated, then weighing. The soils fully saturated with water soon became 

 more or less puddled, and the moisture determinations of these samples 

 taken at the end of the test showed less than the calculated percentage 

 of water. The moisture determinations of the samples with one-fourth 

 and one-half water-holding capacity were approximately the same as the 

 calculated percentages. The soils were placed in the pots February 27, 

 1917, and the experiment was continued for one year, after which they 

 were sampled by means of a soil tube, taking a vertical core of soil to the 

 full depth of the pot. Each sample was thoroughly mixed and divided 



' Reference is made by number (italic) to ' 'Literature cited," p. 329. 



Journal of Agricultural Research, Vol. XV, No. 6 



Washington, D. C. Nov. 11, 1918 



qd (321) Key No. Iud.-4 



