THE MONTHLY BULLETIN 



CALIFORNIA STATE COMMISSION OF HORTICULTURE. 



Vol. IV. September, 1915. No. 9. 



SULPHUR AS A FERTILIZER FOR ALFALFA.* 



By F. C. Reimer, Superintendent of the Southern Oregon Experiment Station 



Talent, Oregon. 



During the past four years the Southern Oregon Experiment Station 

 has been conducting extensive fertilizer experiments on alfalfa in the 

 Rogue River Valley. During the first two years of our work it was 

 found that the yield of alfalfa could be increased from 25 to 500 per 

 cent— depending on the type of soil— by the application of 300 pounds 

 per acre of either superphosphate or gypsum. Applications of either 

 potash, nitrogen, or lime had no effect on the crop. 



The marked increases in yield the first year were attributed, at that 

 time, to the phosphorous in the superphosphate. The second year of 

 our work we also used ground phosphate rock as a source of phos- 

 phorous ; this was used by itself on some plots, and in conjunction with 

 stable manure on others. These plots produced absolutely no increases 

 over the check plots. The plots which received applications of super- 

 phosphate at the same time produced marked increases in yield. 



The fact that the ground phosphate rock had no effect on the crop, 

 but that the superphosphate and gypsum both gave marked increases 

 in yield, indicated that the increases in yield from the use of super- 

 phosphate were possibly not due to the phosphorous which it contains. 



Superphosphate contains phosphorous, calcium, and sulphur. 

 Gypsum contains calcium and sulphur. Since applications of lime did 

 not have any effect on the crop we concluded that it was not the calcium 

 in the superphosphate and in the gypsum which produced the increases 

 when these substances were applied. It is well known that all plants 

 use sulphur, although usually in small quantities. Since superphos- 

 phate and gypsum both contain sulphur, we thought that possibly it 

 was the sulphur that was producing the increases in yield. Experi- 

 ments were started, therefore, to determine this point. 



A portion of a field was selected where the alfalfa had been produc- 

 ing unsatisfactory yields for several years, and which had never 

 received fertilizer of any kind. Two plots were fertilized with flowers 

 of sulphur, one plot with iron sulphate, one plot with superphosphate, 

 and two plots with ground phosphate rock. Check plots receiving no 

 fertilizer were left alongside the fertilized plots for comparison. The 

 plots receiving the ground phosphate rock gave no increases in yield 

 over the check plots; the plots receiving the flowers of sulphur, iron 

 sulphate, and superphosphate at the rate of 300 pounds per acre, each 

 produced an increase of slightly more than 100 per cent over the un- 

 fertilized check plots. The stand on these plots was much thicker, 



♦Address before the State Fruit Growers' Convention, ,Palo Alto, CaL, July, 1915.. 



