72 CULTURE OF FARM CROPS. 



organic but nitrogenous manure, being in deficiency, must be 

 supplied. In brief, Liebig, believing in the deficiency of 

 mineral constituents, indecrees their ultimate withdrawal 

 from the soil, and counsels their supply as the primary work 

 of the farmer. Lawes and Gilbert, holding the converse, say, 

 trust to the supply of mineral constituents which all soils 

 have, and which will be brought into active agency by 

 deep cultivation, but supply the nitrogenous constitu- 

 ents which they have not. These two schools have for 

 years maintained a controversy which has resulted in much 

 that has been practically valuable and suggestive, although 

 of much also that has scarcely been within the claims of 

 the dignity of science. It is right to state that the general 

 belief of the farmers of Great Britain is coincident with 

 that of Lawes and Gilbert, and which may be, as it has 

 been often, expressed thus " phosphates for the turnips, 

 nitrogen for the wheat." This much being premised, what 

 is now given from an able report by Messrs. Lawes and 

 Gilbert 021 the subject of manures for the wheat will be 

 easily understood. After alluding to the controversy to 

 which we have above drawn the attention of the reader, 

 Messrs. Lawes and Gilbert thus proceed : 



" But independently of the evidence of direct experiment, 

 such as is afforded in the results above referred to, we 

 would here reiterate the opinion given in substance in for- 

 mer papers, and founded on a very extensive acquaintance 

 with the practical experience of farmers in the use of ar- 

 tificial manures in every district of Great Britain for many 

 years past, that in 99 cases out of 100 in which wheat 

 grown in the ordinary course of agriculture requires further 

 manuring, it would be much more increased by the appli- 

 cation of nitrogenous than of purely mineral manures ; in 

 other words, that in the ordinary course of agriculture with 

 rotation, as practised in this country, the supply of mineral 

 constituents immediately available for the wheat crop is 

 almost invariably in excess, relatively, to. the immediately 

 available supply of nitrogen from the atmosphere, or the 

 accumulated stores within the soil itself. Furthermore, 



