PROCEEDINGS OF THE ANNUAL MEETING. 



279 



'^Buckwheat, rye, and clover are the principal crops used for green 

 manuring. Buckwheat has been found very useful, as a growth may be 

 obtained on comparativel^y poor soils, soils that in the first instance 

 would not support a growth of clover, and undoubtedly both it and 

 winter rye, when turned while green, vastly improve many soils. The 

 legumes (clover, peas, beans, etc.), how^ever, are still more valuable, 

 inasmuch as they not only furnish a supply of readily digestible food 

 obtained from the soil, but add a store of nitrogen derived from the 

 atmosphere. It is owing to this power of atmospheric nitrogen-assimila- 

 tion (which takes place by the agency of certain micro-organisms in the 

 tubercles on the rootlets) that the legumes have been termed 'nitrogen col- 

 lectors' in contradistinction to all other plants, w^hich are classed as 

 'nitrogen consumers.' The legumes appear to be richest in this element 

 at the period of flowering, a fact which suggests this time as the l)est 

 rime for ])lowing under the crop." 



The following table shows the calculated amount of Crimson, Mam 

 moth, Common Red, and Alfalfa clovers per acre, upon the surface of the 

 ground just before the period of killing frosts in the autumn. [The 



It will be seen that Crimson clover gave the remarkably heavv vield 

 of ten tons of green material per acre. It will, however, also be noticed 

 that the percentage of water is considerably higher in the green material 

 of this variety than in that of any other; also that the weight of roots 

 is compai-atively low. Among other striking points which may be 

 noticed, is the large weight of root material furnished by the Alfalfa, 

 owing to which this plant ranks first in total yield of nitrogen per acre. 



There is little to be said in favor of soja beans or cow peas as cover- 

 crops for northern localities. The}' grow rapidly, produce a considerable 

 amount of foliage and vine, but are cut down by the first light frosts, 

 in autumn. Apart from their office as collectors of nitrogen, they do 

 not seem to furnish as much surface protection as buckwheat or rye, 

 and certainly not so much as field peas. 



Examining the values of the four clovers from the standj)oint of the 

 approximate amount of nitrogen returned to the soil, per acre, we find, 

 by assuming that 70 pounds or two thirds of the nitrogen in the tops and 

 roots of the Crimson clover came from the air, at fifteen cents per pound 

 it would have a fertilizing value from this source alone of .flO.SO. The 

 (tops, leaves, and roots of Alfalfa would give about 124 pounds, which, 



