4 
SIR J. B. LA WES AND PROFESSOR J. H. GILBERT ON THE 
subsoil. In the case of leguminous crops again, the evidence was in favour of the 
supposition that, in some cases, the whole of the nitrogen had been taken up as nitric 
acid, but that in others that source was inadequate. 
The results further showed that, under otherwise parallel conditions, there was very 
much more nitrogen as nitric acid, in soils and subsoils, down to a depth of 108 inches, 
where leguminous than where gramineous crops had for some time been grown. 
Table II., p. 6, gives, in a condensed form, the most important of the previously 
published results relating to this branch of the subject. It shows the amounts of 
nitrogen as nitric acid, calculated acre, in lbs., according to determinations made 
in samples of soil collected in 1883, at each of 12 depths of 9 inches each, that is 
down to 108 inches in all, under the following conditions :— 
1. Where wheat had been grown in alternation with fallow, without any manure, 
since 1850 that is for more than 30 years. 
2. On a plot where mineral manures had occasionally been applied, but no nitrogen 
for more than 30 years; where Trifotiwm pratense had been sown 12 times during the 
30 years, 1848-77, but in 8 out of the last 10 trials the plant had died off in the 
winter or spring succeeding the sowing, in 4 without giving any crop, and in the 
other 4 yielding very small cuttings; and where, consequent on the failure of the 
clover, during the 30 years 1 crop of wheat and 5 of barley had been taken, and the 
land had been 12 years left fallow. Trifolium repens was then sown, namely, in 1878, 
1880, 1881, and 1883; and it yielded crops in 1879, 1881, and 1882, but none in 
1883, when the soil samples were taken. 
3. On 2 plots with the same previous history as that of the Trifolium repens plots 
prior to 1878, but where Vida saliva has since been sown; and where, notwith¬ 
standing the previous failure of the red clover, the Vida yielded fair crops in 1878, 
1879, 1880, and 1881, and large crops in 1882, and in 1883, before the soil samples 
were taken. 
We are now able to give amended, and more complete estimates, of the amounts of 
nitrogen removed per acre in the produce from the different plots, both during the 
preliminary period up to 1877 inclusive, and during the period of the direct experi¬ 
ments with the various leguminous plants. As each leguminous plot is only -it of 
acre in area, it is obvious that calculations of the produce, per acre, can only be 
approximately correct. We have, therefore, in each case taken the average yield of 
three plots, 4, 5, and 6, with one and the same plant, but with somewhat different 
mineral manures. Thus, plot 4 has received a mixture of superphosphate of lime and 
potash sulphate ; plot 5 a mixture of potash, soda, and magnesia salts ; and plot 6 the 
same as plot 5, with superphospate of lime in addition. Direct determinations of 
nitrogen have, in almost all cases, been made ; and we believe that the estimates of it 
per acre may be considered as close approximations to the truth, and at any rate quite 
sufficiently so for the purposes of illustration and of argument for which the}^ are used. 
The results are given in the following Table (I.). 
