594 Journal of Agricultural Research . vol. vi, NO. 16 



DESCRIPTION OF PROCEDURE AND METHODS 



Earthen pots 6.5 inches in diameter by 7.5 inches in depth were used. 

 Each pot contained 13.2 pounds of sand, while in the soil series each 

 contained 8.8 pounds of brown silt loam. Sand and soil were used as 

 mediums of control, and to these two materials were added the various 

 forms and amounts of calcium and magnesium. 



Various < methods were pursued in extracting the sand. At first 

 dilute hydrochloric acid (HC1) was kept in contact with the sand for 48 

 hours, but this failed to remove all the calcium and magnesium. Later 

 the sand was extracted with stronger acid (1,350 c. c. of concentrated 

 hydrochloric acid plus i ,000 c. c. of distilled water) for periods of from 9 

 to 14 days. Sand was also digested on a steam bath for 4 days with this 

 same strength acid. None of the above processes were able to remove 

 all the calcium and magnesium from the sand, as will be seen from the 

 analysis reported. 



At intervals varying from 10 days to 2 weeks plant food was added 

 from the following solutions : 



(i) Potassium sulphate, 50 gm. to 2% liters of water; (2) ammonium 

 nitrate, 80 gm. to 2> liters of water; (3) disodium phosphate, 26.1 gm. 

 to 2^2 liters of water; (4) ferric chlorid, 0.4 gm. to i liter of water. 



The calcium and magnesium were applied in forms previously men- 

 tioned. The moisture content of the sand was at first 12 per cent, but 

 it was later raised to 14 per cent, while for the brown silt loam it was 24 

 per cent. Every 10 days the pots were brought to standard weight by 

 adding distilled water. 



All crops were grown in the agronomy greenhouses at the University 

 of Illinois. The principal crops used in these studies were wheat (Triti- 

 cum spp.), alfalfa (Medicago saliva), soybeans (Sofa max), and cowpeas 

 (Vigna sinensis). Oats (Avena saliva}, clover (Trifolium pratense), timo- 

 thy (Phleum pralense), and sweet clover (Melilolus alba) were also used 

 to test the effect of artificial carbonates upon germination. 



In the wheat and soybean series, 10 seeds per pot were planted and 

 7 plants permitted to grow, while for alfalfa 15 plants were permitted 

 to grow whenever possible. 



In making determinations for calcium and magnesium, the soils 

 were first fused with sodium peroxid and from this point the usual 

 method was employed. The calcium oxalate was dissolved in dilute 

 sulphuric acid (H 2 SO 4 ) and the calcium calculated from the amount of 

 N/io potassium permanganate required to oxidize the oxalic acid thus 

 formed. The magnesium was precipitated as magnesium-ammonium 

 phosphate and burned to the pyrophosphate. In analyzing the plants 2 

 gm. of finely ground material were ashed, taken up in hydrochloric acid, 

 and the calcium and magnesium determined as above stated. Acid 

 extractions of the dolomites and limestones proved as good as fusions. 



