598 



Journal of Agricultural Research 



Vol. VI, No. 16 



EFFECTS OF CALCIUM AND MAGNESIUM IN PREPARED CARBONATES AND 

 IN DOLOMITE UPON WHEAT AND ALFALFA IN BROWN SILT LOAM (SERIES 

 C AND D) 



Magnesium and calcium in prepared carbonates were less harmful in 

 brown silt loam than in sand (series C and D). In fact, applications of 

 o.i per cent of magnesium or 0.35 per cent of magnesium carbonate 

 gave an increase over the check, and 0.7 per cent of the carbonate was 

 practically as good. It must be remembered that the soil before treat- 

 ment contained 0.305 per cent of calcium and 0.352 per cent of magnesium. 

 The calcium and magnesium were added in the relation of 5 to 4, but the 

 amounts in the soil changed this ratio to 5 to 7.1. Applications of 3.5 

 tons of prepared magnesium carbonate per acre were beneficial, 7 tons 

 were about equal to the check, while upward of 10 tons caused practically 

 no growth of the plants. 



Table IV. — Yields of wheat and alfalfa (in grams per pot on a water-free basis) in brown 



silt loam — series C and D 



Treatment. 



Brown silt loam only 



Do 



Percentage of magnesium in mag- 

 nesium carbonate plus calcium car- 

 bonate : 



0.1 



.2 



•3 



•4 



•5 



.6 



Percentage of magnesium in dolomite 

 Ci: 



0.2 



•4 



.6 



2 



4 



Molecular 

 ratio cf 

 calcium 

 to mag- 

 nesium. 



5 : 9 

 5 : 9 



5 : 7- 

 5:7- 

 5 = 7- 



5:7- 



5:7- 

 5 : 7- 

 5 : 7- 



5:7- 

 5:7- 

 5 : 7- 

 5 : 7- 

 5 = 7- 



5:4 

 5:4 

 5=4 

 5=4 

 5:4 

 5 : 4 

 5:4 

 S:4 

 5 : 4 

 5 : 4- 



Wheat, series C 



Pot 

 No. 



Tops. 



«. 9 

 9-3 



11. o 

 8.1 

 8.1 



1. 45 

 4.08 



•9 



.18 



1.85 

 .09 

 .09 

 .09 



9-5 2 

 10.5 

 9. 61 

 9.07 

 10. o 



9-5 2 

 8. 9 



S-7i 

 6. 07 



7-5 2 



6.8 



7-9 



16 

 o 



55 



°7 

 81 



17 

 72 

 18 



35 

 09 

 09 



Alfalfa, series D. 



Pot 



No. 



4.64 

 4.28 



5-96 



5-i7 

 5-o 



5-35 

 5.08 



4-37 

 5-43 

 5-43 

 5.60 



5-i7 

 5-52 



6.86 

 6-53 



6-95 



6-5 



2.49 



2.85 



1. 69 



6. 05 

 5.08 

 6.85 

 5.88 

 3-74 

 6.15 

 4. 72 

 4.64 

 5.08 

 3-65 



Maclntire (18), while working with three different kinds of soils, found 

 that 8 tons per acre of precipitated magnesium carbonate were decidedly 

 toxic to wheat. He also found that both the oxids and the carbonates of 

 precipitated magnesium were many times more soluble than the cor- 

 responding forms of calcium, while in the case of the native mineral 



