12 
Bulletin 99. 
Crimson clover is, so far as I have seen, a failure with us; red 
clover is by no means a pronounced success, though it will grow; 
pea vines do not make a sufficiently early growth. Some of the 
vetches might be better, but they, too, are not early enough. Rye 
might be used if we aimed at adding succulent organic matter, 
which would easily decay, but would add no nitrogen or other fer¬ 
tilizing substance. 
In green manuring we take nothing away from the soil, nor 
do we use the crop grown for any other purpose, but simply return 
it to the soil in its succulent and easily fermentable condition, to¬ 
gether with the total content of plant food which it has gathered 
from the soil. The effects produced may be marked, but they are 
not due to actual addition of plant food, as in the case of the addi¬ 
tion of mineral manures, but are due to the availability of the plant 
food contained in the crop, the effect of the fermenting material 
upon the soil and probably to the humus substances produced. 
I have stated that alfalfa is our best plant for this purpose. It 
is out of the question to use this plant for this purpose, except in 
some systems of rotation, which is, under all circumstances, ad¬ 
visable, whether the last crop is to be potatoes or sugar beets. I am 
not prepared to even suggest what rotation will prove to be most 
advisable; some of our practical men can work that out in detail. 
I fully appreciate the fact that a good plantation of alfalfa 
which will yield 3 1-2 to 5 tons of alfalfa hay per acre, is a valuable 
asset on a farm, but some of our people are coming to realize that 
it is a good thing to plow under, too, though it is not the easiest task 
to perform, especially when it is in full growth in the spring time. 
alealea our best plant to use as a green manure. 
There are several considerations which lead me to think this 
the best plant which we possess for this purpose. 
Our soils are only fairly rich in nitrogen, and an addition of 
this element from time to time is very advisable. Alfalfa is an 
energetic gatherer of this substance, largely from the atmosphere, 
the young alfalfa shoots being relatively very rich in this element. 
There are but few plants, even among the legumes, by means of 
which we can add nitrogen to the soil so cheaply as by means of 
alfalfa. 
Alfalfa is not only an energetic gatherer of nitrogen from the 
atmosphere, but it is also an energetic gatherer of other plant food 
from the soil, so much so that a ton of alfalfa hay made from plants 
cut in May before any blossom buds had appeared, contained about 
60 pounds of potash, equivalent to 111 pounds of the pure sulfate of 
potash, and whose value would be $3.00 at the price prevailing last 
year, while the nitrogen in the same would be worth $8.50, nearly. 
