io8 



Journal of Agricultural Research 



Vol. XXII, No. 2 



To say that percentage of sulphur will not increase regardless of sul- 

 phate concentration in the nutrient media without increasing the avail- 

 able nitrogen would not be in accordance with data already obtained. 

 It does appear, though, that when the lack of nitrogen is sufficient to 

 lower the nitrogen content compared to the normal nitrogen content of 

 the clover there is a tendency toward decreased sulphur assimilation. 

 It is interesting to compare the rape plant with the clover in this respect. 



The figures given in Table IV show that the clover cut before the blos- 

 soming stage not only contains a higher percentage of total nitrogen but 

 also a higher percentage of nitrogen insoluble in acetic acid. As the per- 

 centage of nitrogen removed by this fraction varies, so also does the per- 

 centage of sulphur. There appears to be a definite relationship between 

 the sulphur and nitrogen content in this insoluble portion, thus adding 

 more significance to this fraction in regard to quality and perhaps rep- 

 resenting the true protein of the clover hay. No difference in ash con- 

 tent caused by variation in fertilizer treatment was observed in the 

 diflerent pots. The ash content of the different crops did vary however, 

 as is sho\vn in Table IV. 



EXPERIMENTAL WORK WITH THE RAPE PLANT 



The Medford loam soil used in the first part of this work was used in 

 this experiment. After the clover roots were removed the soil was re- 

 turned to the pots and seeded to rape. Three gm., of sodium nitrate 

 were added to those cultures which had received nitrate nitrogen in 

 the clover experiment. The plants were harvested after a growing period 

 of 50 days. At the end of this time there had been a cessation of growth, 

 and the basal leaves dried up and fell off. The results appear in Table V. 



Table V. — Analytical results obtained with rape 



Treatment. 



Control , 



NaNOg 



NaNOg and Na, SO4. . 



Na2 SO4 



NaNOj and CaSO^ 

 CaS04 



Ash. 



Per 



cent. 

 13.6 

 19. 



IS- 



3 

 9 

 o 



18.3 

 17-7 

 22. o 



19.4 

 14.7 



16. 2 

 31. 9 

 21. 9 



« Pots from the inoculated series. 



The presence of added sulphates appeared to have retarded growth of 

 the rape, as there is a greater dry-weight yield on the controls. With 



