96 
In America we commonly harvest from 5 to 8 tons of alfalfa per acre during the 
season, and a total yield of iO tons of well-cured hay is not infrequent, and no nitro- 
genous fertilizer is used. Dyer does not give his yield of cured hay, but he reports 
the average annual yield of green or freshly cut alfalfa forage as. shown in the fol- 
lowing table: 
4.1/cUfa yields in fertilizer experiments (Bernard Dyer). 
Plant food applied. 
Green 
alfalfa 
per acre. 
Plant food applied. 
Green 
alfalfa 
per acre. 
Tons. 
11.4 
L4.2 
Phosphates, potash, 2 cwt. nitrate 
Phosphates, potash. 4 cwt. nitrate 
Tons. 
15.9 
Phosphates, potash, l cwt. nitrate 
14.8 
Dyer estimates the value of the green forage at $2.50 a ton, and as the cured hay 
would certainly be worth at least $10 a ton in England, it seems safe to conclude 
that the highest yield which he obtained, even with the use of sodium nitrate, did 
not exceed 4 tons per acre. This is less than the increase only which has been 
obtained by proper inoculation. It should also be stated that the annual application 
of potassium in Dyer's experiments was less than would be contained in 2 tons of 
ordinary alfalfa hay, and the question arises whether the effect of the sodium nitrate 
in increasing the yield of alfalfa may not have been due in part at least to the liber- 
ation of potassium from the soil by the addition of sodium, or even to the partial 
substitution of sodium for potassium by the alfalfa plant. Results obtained at 
Woburn by the agricultural experiment station of the Royal Agricultural Society of 
England tend to confirm the suspicion that the benefit of the sodium nitrate was 
indirect, to some extent at least, as will be seen by referring to the following table: 
Alfalfa yields in fertilizer experiments at Woburn. 
Plat 
No. 
Annual fertilizer per acre. 
None 
8 hundredweight phosphates « 
1 bund re< 1 weight potassium sulphate 
2 hundredweight ammonium sulphate 
•1 hundredweight sodium nitrate 
Phosphates, a potash, and ammonium sulphate 
Phosphates, « potash, and sodium nitrate 
Green alfalfa 
per acre. 
1897. 
Tons. 
15.0 
16.0 
17.3 
12.1 
17.2 
22. 1 
23.9 
iv. is. 
Tons. 
8.5 
12.1 
8.0 
11.1 
16.6 
16.4 
"4 hundredweight superphosphate and 4 hundredweight hone dust. 
It will be observed that potassium sulphate produced a higher yield than sodium 
nitrate, the difference being greater the second year than the first. Dyer makes no 
comment on this fact, but, in referring to the effect of nitrogen, he says: "The bad 
effect of sulphate of ammonia used alone on plat 4 is probably due to the scarcity of 
lime in the soil, which is unsuitable for the continuous use of this fertilizer unless 
lime be occasionally applied, either as lime or in some such form as basic slag or bone 
meal. In conjunction, however, with bone dust, superphosphate, and sulphate of 
potash, sulphate of ammonia has produced a substantial increase. Nitrate of sot la, 
even without the use of mineral fertilizers, has produced a very remunerative return 
in these two years, but it has done far better in conjunction with mineral fertilizers." 
These conclusions are not justified by the data given, because of the fact that there 
was no plat fertilized with phosphorus and potassium without nitrogen. Each of 
the elements phosphorus and potassium, when used singly, proved beneficial (except 
in 1898 the acid phosphate appears to have produced an injurious effect upon the 
alfalfa, probably due to its increasing the acidity of the soil), and if both mineral 
elements had been applied to one plat no doubt the yield would have been larger 
than where either one was used alone. Furthermore, if the soil were acid, as Dyer 
evidently believes, it was unsuited for the alfalfa bacteria. 
The fact that reprints of Dyer's reports, advocating the use of sodium nitrate for 
leguminous crops, are being very widely circulated in America, presumably by 
"Jour. Royal Agr. Soc, December, 1899 (through reprint of Dyer's report). 
