1 64 SYSTEMS OF PERMANENT AGRICULTURE 



soils and other swamp soils, it would seem altogether rational to 

 make temporary use of caustic lime to hasten the decomposition 

 of the soil and consequent liberation of nitrogen, if such treatment 

 is necessary, which is not usually the case. 



There may possibly be conditions under which soils contain 

 large amounts of phosphorus and potassium which are too slowly 

 available for profitable crop production, and in such cases it might 

 be good farm practice for a time to make use of lime to hasten 

 the liberation of these mineral elements of plant food. We should 

 bear in mind, however, that this use of lime on a soil which is already 

 deficient in nitrogen, or other plant food, only serves to still further 

 exhaust the soil of its meager supply of these elements. Without 

 a doubt, this is the most common condition and the most common 

 effect of the continued use of caustic lime. It is true that the 

 immediate effect is usually somewhat increased crops, but it should 

 be borne in mind that when a farmer pays out money for lime to be 

 used for this purpose, he is purchasing a stimulant which will ulti- 

 mately leave his land in worse condition than before, especially 

 in the loss of nitrogen and organic matter. 



Of course, the landowner must be governed somewhat by the 

 cost of the material. As a rule, fine-ground limestone will be both 

 the best and the most economical form of lime to use, wherever it 

 can easily be obtained. If caustic lime be used, we should make 

 special provision to maintain the humus in the soil by making 

 even larger use of farm manure, legume crops, and green manures. 



It might be expected that burned lime would produce a greater 

 increase in the crops for the first year or two than would be pro- 

 duced by the ground limestone, more especially where the mineral 

 elements, phosphorus and potassium, are not applied; for the 

 reason stated, that ground limestone produces only the milder ac- 

 tion, chiefly of correcting the acidity of the soil and thus encourag- 

 ing the multiplication and activity of the nitrogen-gathering and 

 nitrifying bacteria; whereas, .the burned lime not only produces 

 this same effect, but it also acts as a powerful soil stimulant, or 

 soil destroyer, attacking and destroying the organic matter and 

 thus liberating plant food from the soil, usually resulting in more 

 or less waste of valuable nitrogen and humus. 



The most extended investigation ever conducted relating to the 



