59 6 



Journal of Agricultural Research 



Vol. VI, No. 16 



EFFECT OF MAGNESIUM AND CALCIUM IN PREPARED CARBONATES AND 

 IN DOLOMITE UPON WHEAT AND ALFALFA GROWN IN SAND (SERIES A 

 AND B) 



The sand used in series A and B was extracted as previously described, 

 washed free from acid, and the application made on the moisture-free 

 basis. Pots i and 2 of series A and pots 21 and 22 of series B received 

 no calcium or magnesium. Pots 3 and 4 of series A and pots 23 and 24 

 of series B received 2 per cent of dolomite Ci or 0.2 per cent of the element 

 magnesium. Pots 9 to 20, inclusive, of series A and pots 29 to 40, inclusive, 

 of series B received magnesium and calcium in prepared carbonate in 

 amounts varying from 0.1 per cent to 0.6 per cent of magnesium. The 

 magnesium carbonate was alkaline and of the following formula: 

 Mg(OH) 2 . 4 MgC0 3 . 



Table II contains the yields for the above treatments. When added 

 to sand, the lowest applications of magnesium in the prepared carbonate 

 very materially retarded germination and inhibited growth; whereas 

 amounts of 0.6 per cent of magnesium in dolomite caused no injury and 

 even benefited growth. 



The ratio of calcium to magnesium throughout this and all succeeding 

 tables is reported as molecular calcium to molecular magnesium, with 

 calcium always expressed as 5. The yields and percentages in all the 

 tables are reported on the water-free basis. The wheat, series A, was 

 harvested 83 days after being planted, while the alfalfa, series B, was 

 harvested 84 days after being planted. 



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



series A and B 



The pots receiving magnesium and calcium in the prepared carbonates 

 in a ratio of calcium to magnesium, as 5 to 4, inhibited germination and 

 permitted no growth. 



