116 ALFALFA FAEMING IN AMERICA. 



will attack vegetable matter or humus in tlie soil. 

 Applied in excess it will destroy bacterial life, so 

 caustic lime is not so safe to use as the raw rock 

 ground, the true carbonate of lime. On the other 

 hand one can use less of it and get effect sooner, be- 

 cause of its energy. The difficulty in its use to pro- 

 mote alfalfa growing is that one ought to use more 

 than lime enough to correct acidity when he is lay- 

 ing land down to alfalfa; he ought to correct the 

 acidity and leave a goodly store of lime carbonate 

 lying in the soil, so that alfalfa roots will be in actual 

 contact as the plants grow. This one can hardly 

 do with safety with caustic lime. 



Use of Caustic Lime.— How much caustic lime 

 can be safely used and how can it best be applied 1 



Soils differ in their power to absorb lime safely. 

 Strong clays and soils full of sour humus can take 

 most; sandy, poor soils must be limed with care if 

 caustic lime is used. There is some danger of ' ' lime 

 burn," that is, of making soil temporarily barren 

 by giving it an excess of caustic lime. The poorer 

 the soils in humus the more danger of this. Yet I 

 have seen alfalfa fields in Maryland where the only 

 good alfalfa present was where the piles of lime had 

 been slaked, and where probably the lime had been 

 applied at the raite of ten tons to the acre or more. 



How much caustic lime can we use? No one 

 knows just at present. I saw this experiment tried 

 in Tennessee: On Idlehour Farm, near Knoxville, 

 Tenn., James P. McDonald had tried to grow alfalfa 

 on Tennessee River lands. It had miserably failed. 



