252 Bureau of Farmers' Institutes. 



cause the object of the crop is leaf and stem for pasture or hay 

 or forage, and nitrogen promotes this form of growth. 



(c) Leguminous Crops such as clover, peas, beans, vetches, etc., 

 have the power of securing nitrogen from the air, but need very 

 liberal supplies of potash and phosphoric acid. 



(d) Cereals possess certain marked characteristics in their 

 methods of growth and feeding. Their roots branch just beneath 

 the surface and each separate shoot sends out feeding roots in 

 every direction, thus reaching the lower layers of the soil in the 

 later stages of growth. Their peculiar root system enables cereals 

 to feed quite readily upon the less soluble potash and phosphoric 

 acid compounds of the soil. A considerable part of the growth 

 of many of these crops occurs early in the season before the un- 

 available nitrogen is changed into nitrates, and, therefore, they 

 are, with the exception of Indian corn, greatly helped by early 

 applications of nitrate-nitrogen. Hence, early application of 

 nitrate-nitrogen helps wheat, rye, oats and barley. With corn, 

 the growth comes largely after other cereals have ripened, in July 

 and August, and by this time the insoluble soil nitrogen has 

 changed largely into nitrates. 



(e) Fruit Crops. — Fruit trees are slow in growth and slow 

 feeding; hence they can utilize less available forms of plant food. 

 Their supplies of food should be of such a character as to favor 

 slow and continuous rather than rapid growth. For example, 

 ground bone is a good source of nitrogen and 'phosphoric acid. 



(/) Market-Garden Crops include many crops greatly varying 

 in their feeding habits, but they are all raised with one object in 

 view — to secure tenderness and succulence by means of very 

 rapid growth. This is secured by large applications of nitrate- 

 nitrogen along with very liberal quantities of potash and phos- 

 phoric acid. 



In order to ascertain with greater certainty what food elements 

 are lacking in the soil, the surest way is for each farmer to do 

 some experimenting on his own soil and crops. The exact man- 

 ner of doing this will be considered under the following head in 

 connection with the amount of plant food to be used. 



3. What Amount of each Fertilizing Constituent is 



Needed. 



Inseparably connected with the question of what elements of 

 plant food are needed is the question, " How much of each element 

 is needed? " Perhaps, the question more often asked than any 



