N--. 6. DEPARTMENT OF AGRICULTURE. 687 



the character of the growth. This element gives a rauk growth of 

 Ijotato vines of a dark green color. Vvhere the vines grow rank 

 without application of nitrogenous fertilizers, we cannot hope to in- 

 crease yields to any profitable extent by their use. Indeed, there is 

 always danger of diminished yields as a result of excessive use of 

 Ibis element. This is frequently observable in old barn lots and in 

 other spots that have had the leachings of manure. The vines grow 

 to extraordinary size, while the tubers are very small at digging time. 

 It may not be possible to state with certainty the cause of this 

 phenomenon, but it has been supposed that the potato will not di- 

 vert its energy to the development of tubers until the vines have 

 reached a stage that permits the storage of some energy for this pur- 

 pose, and where there is a quality in the soil inciting to extreme 

 growth of vine, that stage of development favorable to forming 

 tubers is reached too late in the season for good results. Be that 

 as it may, the known fact that injury may result from the presence 

 of an excessive quantity of nitrogen in the soil is all that the prac- 

 tical grower needs to place him on his guard. It is safe to say, how- 

 €:ver, that most cultivated soils incline to be deficient in this element 

 unless stable manure or the legumes is used, and the question with 

 the grower often is not whether nitrogen could increase yields, but 

 whether it would do so with profit, or in what quantities could it be 

 used in view of its costliness. 



For Early Potatoes. — The nitrogen of the soil does not enter avail- 

 nble forms rapidl}' in cool or dry weather. The grower of potatoes 

 for early market usually finds it profitable to supply an available 

 form of it to his early-jjlanted crop to force growth before there is 

 sufficient heat in the soil to convert its own nitrogen into forms re- 

 quired by plants. For this purpose the nitrate of soda is a common 

 source. It is quickly available in the soil, and I prefer not to use it 

 until the plants appear above ground, as the fertilizer will leach 

 away if there are no plant roots ready to appropriate it. Slower or- 

 ganic forms of this element, such as tankage, dried blood, fish, etc., 

 are desirable carriers of nitrogen for use of plants in mid-summer 

 when decay is rapid on account of heat. It is suggested that one- 

 tbird of the nitrogen be supplied in nitrate of soda, and two-thirds 

 in dried blood, fish or other organic forms. 



Nitrogen exists in unstable forms, and cannot be stored in the 

 soil indefinitely. It wastes rapidly in the summer if no plant roots 

 are ready to use it. If a potato-grower finds that he can use pur- 

 chased nitrogen vvith profit, as is eminently true in the seaboard 

 sands devoted to the early crop, it is advisable to provide part of the 

 supply in organic forms that yield up plant food through decay as 

 the season progresses, and to supply some immediately available 

 nitrogen, in nitrate form, as a top-dressing during the late spring 

 months. 



