The Lois Weedon Plan of Growing Wlieat. 595 



pliere, a sufficiency of nitrogen for full crops, in an available and 

 assimilable form ? 



Certainly, if we were to rely upon the mean results of the 

 42 analyses referred to by Baron Liebig (in the last Number 

 of this Journal) in illustration of the amount of nitrogen con- 

 tained in soils, we should be led to conclude that many soils, 

 at least, had enough of the mineral constituents of our crops for 

 thousands of years, under the ordinary practices of rotation, 

 and for hundreds of years of the growtli of wheat on the Lois 

 ^Veedon system. Almost all other published analyses of 

 soils would lead to a similar conclusion ; in fac t, we know of 

 scarcely any that would not. It must be freely confessed, how- 

 ever, tl)at the methods by which soils have hitherto generally 

 been analysed, have proved themselves, in their results, to be little 

 fitted to afford the information for which the analyses were 

 undertaken. Nevertheless, judging from the whole of the evi- 

 dence of tills kind at command, it may perhaps safely be con- 

 cluded that, excepting the one constituent phosphoric acid, 

 the greater proportion of soils which are termed " heavy^^ 

 *' clayey" or " loamy" do contain, within a workable depth, a 

 sufficiency of mineral constituents for thousands, or hundreds, of 

 years, as above supposed. It is, however, by no means so clear, 

 that many of them would not fall short rather in annual liberation 

 in available fur m, than in actual yercentaye amount of the neces- 

 sary mineral constituents. Indeed, there is evidence enough 

 in agricultural experience to show that, although the ordinary 

 practice of rotation leaves, in most soils, a balance of available 

 mineral constituents, and therefore demands a supply of nitrogen 

 from without, yet, with this supply alone, the point of the re- 

 quirement of more immediately available mineral constituents 

 for full and healthy crops is in its turn frequently soon arrived 

 at. In fact, it is the " condition," both as regards mineral and 

 nitrogenous supplies, rather than the actually existing amount of 

 them in the soil, that becomes defective. And in the lighter soils 

 more especially it is, that the condition ».s regards the mineral con- 

 stituents of our crops, or i\\p floating capital so to speak, both bears 

 a nuicli larger j)roj>ortion to the availahle stores of the soil itself, 

 and is more dependent on restoration or supply from without. 



In Mr. Smith's ^^ heavy land,'^ with its clayey subsoil inter- 

 mixed, disintegrated, and well weathered (and perhaps even in 

 his " light land," with its dressing of marl), it is quite dear, 

 from the continued good results, that the annuallv available 

 mineral siii)ply, or the mineral condition, is not at present im- 

 paired ; nor, so far as existing; knowh'dge of such matters can lie 

 relied upon at all, need Mr. Smith be alarmed lest the dormant 

 stores, at least of his heavy soil, should not last the centurv 



