The Lois Weedoii Plan of Growing Wheat. 599 



the soils. We are therefore (though without calling them in 

 question) unable to form any such judgment from the results 

 themselves of the probable limit of error arising from mani- 

 pulation and other causes, as duplicate analyses would have 

 enabled us to do. And when it is borne in mind, that most 

 of the published analyses show an amount of nitrogen in soils 

 only amounting to from one-tenth to one-quarter of 1 per cent,, 

 it will easily be seen that slight errors of analysis, such as 

 in most subjects of investigation would be quite immaterial, 

 are here of the utmost consequence — if, at least, we should 

 wish to discuss, by the aid of such analyses, such differences 

 between soil and soil, or between the same soil in the conditions 

 in which it would yield respectively a given amount of crop 

 below a usual average, or a full one, equal to twice as much as 

 the former. In illustration of this, we need only say that 100 lbs. 

 of amm<mia, added to an acre of soil weighing 4,000,000 lbs. 

 (and whi(;li every intelligent farmer knows would, on most soils, 

 increase his crop enormously), would, if well mixed with the 

 bulk of soil, only raise its ammonia by 00025 per cent. — or 1 

 part in 40,000. Tliis fact should not be lost sight of in the 

 consideration of the figures which will shortly follow. 



Next to the determinations of nitrogen in soils by Dr. Krocker, 

 as referred to above, the most extensive series quoted by Baron 

 Liebig is that made at the instance of the Royal College of Rural 

 Economy in Berlin. Baron Liebig introduces these results as 

 follows (and the italics in the second paragraph are his own) : — 



*' The fact of the presence of this enormous amount of nitrogen in the soil 

 has been confirmed by the researches made at the instance of tlie Royal Collei;e 

 of Rural Econon:iy in Berlin (' Annalen der Landvvirthschaft,' vol. xiv., p. 2). 

 The College of Rural Economy caused land of apparently uniform quality to 

 l>e selected in fourteen different localities in Prussia for these experiments. 

 At ten or twelve different points of each of tliese fields an equal quantity of 

 earth was taken by the spade from the entire depth of the arable soil ; these 

 jKjrtions, in each case, were thoroughly mixed, and from the mass samples 

 were taken. 



" In each sample the amount of nitrogen was determined Tyy three different 

 cliemists separately, and from their results have been calculated for one acre of 

 land, to the depth of 1 foot (the specific gravity of the soil being taken at 1"5), 

 the following ipiantities of nitrogen, expressed however in pounds oi ammonia 

 (17 lbs. of ammonia contain 14 lbs, of nitrogen)." — Jour. Hoy. Ag. Soc. Evg., 

 vol, xvii., {lart 1, p. 285, 



As these determinations are introduced to the r(>ader by so 

 high an authority in the matter of chemical analysis, as being 

 made " h}/ three different chemists separately " i\n(\ as Baron Liebig 

 arranges the soils in the order of their richness in nitrogen, 

 according to the mean of the three experiments for each soil, it 

 may be interesting to examine what was the sort of agreement 



