New York Agbicultueal Experiment Station. 69 



contained in most soils, and there is no reason for supposing that in 

 the marl they are much more available than in the soil. It has also 

 been suggested that the oyster shells may have contained .5 per ct. 

 nitrogen. But, even if so, its effect would have been slight and 

 mainly confined to the first crop; whereas the plat receiving ground 

 oyster shells gave in later years larger increases than the one receiv- 

 ing burned oyster shells. These objections are only begging the 

 question and the experiment still bears testimony to the comparative 

 value of caustic lime and carbonate of lime. 



Pennsylvania experiments. — As an example of the fact that caustic 

 lime, when applied under certain conditions or in rather large 

 amounts, will produce injury which may more than counteract all 

 of its good effects, we have the results of 25 years' experiments at 

 the Pennsylvania station. 



Caustic Lime vs. Ground Limestone: Pennsylvania Experiments; 25 Years' 



Results. 



Value of increase or 



decrease ( — ) per 



acre each 4 years. 



Rotation of corn, 



oats, wheat, hay. 



Caustic lime, 2 tons per acre each 4 years 



Ground limestone, 4 tons per acre each 4 years . 



-1.60 

 8.40 



In this experiment both forms of lime are applied in larger quan- 

 tities than are profitable under almost any condition. Also no 

 special provision has been made to supply organic matter other 

 than by the use of the clover and timothy sod. The caustic lime 

 has not only been applied at a loss, but the crop yields from the 

 land receiving caustic lime have been less than with no special treat- 

 ment at all. On other plats in this experiment the same amount 

 of caustic lime has been applied and in addition 12 tons of manure 

 per acre each 4 years. The lime in this way has during the 25 years 

 given better returns than the lime alone, although not so good as 

 the limestone alone. But during the first eight years of the experi- 

 ment the lime and manure gave lower yields than 12 tons of manure 

 alone. 



In some recent pot-culture work at the Pennsylvania station to 

 study the growth of clover as influenced by lime in different forms 

 and amounts, lime in different forms was compared in quantities 

 ranging all the way from a few hundred pounds to more than 3 

 tons of ground limestone per acre. The following conclusions, 

 among others, were reached from the work: 



" An important fact in this extensive test is that finely-ground 

 limestone has been fully as prompt and effective in reducing soil 



