Il4 STORRS AGRICULTURAL EXPERIMENT STATION. 
phosphoric acid and potash cost from 3 to 7 cents per pound.* 
Furthermore, nitrogen is the most unstable of all the fertiliz- 
ing ingredients ; for if it is available in larger quantities than 
are immediately used by the crop it is readily wasted in various 
ways. It is very important, therefore, that the farmer should 
know the kinds of fertilizing materials and the amounts per 
acre in which he can use nitrogen for the different crops to the 
best advantage. In the experiments reported herewith, nitro- 
gen has been supplied in nitrate of soda, in sulphate of am- 
monia, and in dried blood. Of these materials, nitrate of soda 
is the one in which the nitrogen is considered most available 
to the plants; sulphate of ammonia yields its nitrogen a little 
more slowly, while the nitrogen of organic materials, like dried 
blood, is commonly the least available. The amounts of each 
of these materials used in the experiments varied according 
to the amount of nitrogen required by the experiment, as ex- 
plained later on pages 117 to. 1 19, under the descriptions of “soil 
test” and “special nitrogen ” experiments. 
While nitrogen is the most expensive ingredient in fer- 
tilizers, it is at the same time the basis of the costly but very 
valuable and important ingredient of feeding stuffs, protein. 
Protein compounds generally contain about 16 per cent. of 
nitrogen. On most farms in New England the amount of 
protein produced is much less than is needed for feeding pur- 
poses. To supply this deficiency the farmer often has to buy 
large quantities of such feeds as bran, middlings, cotton-seed 
and gluten meals, etc. The problem for him, therefore, is to 
find out how he can increase the amount of protein produced on 
his farm, and ‘do it more cheaply than he can buy it in feed- 
ing stuffs. 
There are two ways in which the farmer may increase the 
amount of protein produced upon his farm. One way is to 
grow more of the leguminous crops, such as clover, soy beans, 
and the like, which not only contain large proportions of pro- 
tein, but gather much of their nitrogen from the air and do 
not require it in fertilizers. The other way is to increase the 
relative proportions of protein in the grasses and cereals by the 
proper use of nitrogenous fertilizers. Both methods are prac- 
tical, as shown by the experiments summarized in this article. 
The fact that the yield of the common grasses and the cereals 
is largely increased by the use of nitrogenous fertilizers, while 

*See page rer. 
