Nov. 1, 1919 Carbonates of Calcium and Magnesium on A cid Soils 121 



Table II. — Yields of air-dry wheat and clover and undried blood turnip beets on acid 

 soils treated -with natural carbonates of calcium and magnesium 



o A basic application of 72 pounds diammonium phosphate and 100 pounds dipotassiuin phosphate per 

 million pounds of soil was made to each pot. In addition the yellow clay soil received a total of 90 pounds 

 per milljon of ammonium nitrate, applied in three equal successive applications. 



The 12,000-pound applications of calcite and magnesite gave different 

 results on the two soils. The most apparent of these differences were 

 noted in the detrimental effects of the 12,000-pound magnesite applica- 

 tion on the black sand and the increased crop yields on the yellow clay 

 due to additional magnesite. While the increases due to heavier appli- 

 cations were not proportionally larger, they checked the results of the 

 4,000-pound applications. The greatest increases in crop yields for the 

 12,000- over the 4,000-pound applications of natural carbonates were 

 with the calcite on the black sand. It should be noted that the yield of 

 beets on the black sand, although much increased over that obtained 

 with the 4,000-pound calcite application, is not so large as that obtained 

 with the 4,000-pound treatment of magnesite. 



These varying yields with different crops are in accord with the results 

 obtained by Coupin (i) who found that the action of magnesium car- 

 bonate was different on different species of plants. 



Plate I shows the appearance of the various crops grown on the acid 

 yellow clay soil. Pot 4, not discussed in the tables, had an application 

 of one-half as much calcite as pot 5. 



Plate 2 shows the appearance of the various crops grown on the acid 

 black sand. Pot 4 had one-half as much calcite as was applied to pot 5. 

 The appearance of the beets in this series would indicate that magnesium 

 was not so harmful to beets as it was to wheat and clover. 



At certain stages of growth the wheat growing in the pots treated 

 with magnesite showed a dark green color, as noted by others (5) , while 

 the wheat in the calcite-treated pots was a light yellowish green. Al- 

 though the magnesite caused almost as much wheat increase in all 

 except the 12,000-pound magnesite application on the black sand, 



