896 EXPERIMENT STATION RECORD. 



parison could not be made for clover, because the crop failed so fre- 

 quently. 



In the wheat crop the dry matter obtained by continuous culture 

 was, on the unfertilized section and on that receiving superphosphate 

 alone, less than half as much, and on the section treated with a com- 

 plete fertilizer, considerably less than that secured in rotation. 



Amounts of nitrogen contained in the crops. — Only an inconsiderable 

 amount of nitrogen was contained in turnips not fertilized. The amount 

 was increased twofold to fourfold under the influence of phosphatic 

 fertilizers alone, which induced the growth of numerous fibrous feeding 

 roots. With a complete fertilizer the amount of nitrogen in the crop 

 was greatly increased in both systems of culture. The large turnip 

 crops obtained by the aid of nitrogenous manures on land which for 

 about fifty years had received no carbonaceous application indicates 

 that the atmosphere is ''the chief, if not the exclusive, source of the 

 carbon of the crops." 



The nitrogen taken up by barley on the superphosphate section and 

 on the unfertilized plat was considerably greater in rotation than in con- 

 tinuous culture. With a complete fertilizer barley in rotation took up 

 less nitrogen on the plats from which the turnip crop had been removed 

 than in continuous culture. Under all conditions of manuring, about 

 75 per cent of the nitrogen of the barley crop was contained in the 

 grain. 



Beans in rotation took up more than twice as much nitrogen as in 

 continuous culture. In rotation the amounts were 36 lbs. per acre per 

 annum on the unfertilized section, 40 to 50 lbs. with superphosphate, 

 and 63.0 to 70.2 lbs. with a complete fertilizer. Under all conditions 

 clover took up much more nitrogen than beans — without manure, 47 to 

 55 lbs.; with superphosphate alone, 124.5 to 144.6 lbs.; with a complete 

 fertilizer 167 to 168.4 lbs. per acre. Of the nitrogen in the bean crop 

 (beans and straw) at least 75 per cent was in the beans. 



Wheat under all conditions of fertilization utilized more nitrogen in 

 rotation than in continuous culture. Continuous culture gave more 

 nearly equal results when a complete fertilizer was employed. Under 

 all conditions the grain stored up more than twice as much nitrogen as 

 the straw. 



Amounts of phosphoric acid in the crops. — Only about half as much 

 phosphoric acid was taken up by the turnip crop in continuous culture 

 as in rotation, due to the unfavorable mechanical effects of the former 

 system by which the total crop was reduced. In rotation and when well 

 fertilized, 5 to 6 times as much phosphoric acid was accumulated in the 

 roots as in the leaves. 



Without fertilizers and also with superphosphate, barley took up 

 much more phosjDhoric acid in rotation than in continuous culture; with 

 a complete fertilizer the two systems of culture gave equal results when 

 turnips were fed on the land, but when removed the rotation crops 

 stored up less phosphoric acid than those under continuous culture. 



