FIELD CROl'S, 127 



The iv.snlts indicato that an increane in the wator cdiiti'iit ul' tia- snil within tiic 

 liniit.M of the experiment int-reased the yield of clover and the (jnantity of its most 

 important food elements. The yield of rye grass was also increased, hut owing to 

 the dearth of nitrogen in the soil no appreciable increase in its i)rotein content was 

 obtained. The (piality of the crops, however, suffered frcjm an increase in the 

 water content. The first cutting of clover showed a decrease in the percentage of 

 protein and fat. In the rye grass the decrease in protein was greater than in the 

 clover, which the authors again attriV)ute to the insufficient supply of nitrogen in 

 the soil. The percentage of dry matter in the green clover decreased with the 

 increase of water in the soil. In general the percentage of ash in the plants increa.sed 

 as the water content of the soil increased. The infiuence of the fertilizers on the 

 jiercentage of jirotein in the clover was very small but (juite marked in the rye grass 

 grown on the soil lowest in water content. 



Agricultural, botanical, and chemical results of experiments on the mixed 

 herbage of permanent grass lands, conducted for many years in succession 

 on the same land; the chemical results, J. B. L.\wes and J. H. Gilbert {I'ltil. 

 Trans. Roy. Soc. London, ser. B, 192 {1900), pp. 139-210).— The topics treated in this 

 paper are the botanical composition of the mixed herbage, chemical composition of 

 the separated graminous, leguminous, and other herbage of the mixed produce of 

 grass land; the state of existing knowledge as to the function of the mineral or ash 

 constituents of vegetation; the conditions under which carbon dioxid is determined 

 in i)lant ashes and the results obtained; and the dependence of the chemical compo- 

 sition of various crops on the character and the stage of their growth and on the fer- 

 tilizers applied. 



"The results show that the chemical composition of the mixed herbage is very 

 directly dependent, not only on the supplies within the soil, and on the seasons, but 

 also very prominently on the description of plants encouraged, and on the character 

 of their development. . . . 



"There were very characteristic differences in the composition of the ashes of dif- 

 ferent crops, according to the amounts of nitrogen they assimilated. Red clover, for 

 example, yields large amounts of nitrogen over a given area, part of which is due to 

 fixation, but much is certainly taken up as nitrates from the soil; and the results 

 show that the greater the amount cf nitrogen assimilated the more is the ash char- 

 acterized by containing fixed base in combination with carbonic acid, presumably 

 representing organic acid in the vegetable substance before incineration. 



" The conclusion was that, independently of any specially physiological function 

 of the bases, such as that of potash in connection with the formation of carbo- 

 hydrates, for example, their office was prominently also that of carriers of nitric 

 acid, and that when the nitrogen had been assimilated the base was left as a residue 

 in combination with organic acid, which, according to the character of the plant, 

 was represented more or less completely by carljonic acid in the ash. 



"Further, existing knowledge — as to the condition in which nitrogen is found in 

 soil waters, as to the action of nitrates used as manures, as to the presence of nitrates 

 in still-growing plants, and as to the connection between the nitrogen assimilated 

 and the composition of the ash as has been illustrated — points to the conclusion tliat, 

 at any rate, a large amount of the nitrogen of the chlorophyllons vegetation on the 

 earth's surface is derived from nitrates; while, so far as this is the case, the rai>oi 

 (I'rtre of much of the fixed base found in the ashes of plants would seem to be clearly 

 indicated. . . . 



"When the more functionally important constituents are availal)le in relative 

 al)undance, those which are of less importance in this respect are taken up and 

 retained in less amount than they otherwise would be, the result being determined 

 in great measure by the character of growth induced. 



