14 
SIR J. B. LAWES AND PROFESSOR J. H. GILBERT ON THE 
the leguniinoiis crop ln,nd different mineral manures had occasionally been applied. 
They were as follows :— 
Plot 2. Superphosphate of lime. 
Plot 3. Sulphate of potash. 
Plot 4. Sulphate of potash and superphosphate. 
Plot 5. Salts of potash, soda, lime, and magnesia. 
Plot 6. As 5, with superphosphate in addition. 
Soil samples were taken from each of the 5 plots, and also from 5 places directly 
opposite to them on the immediately adjoining fallow-wheat, land. Tire following 
table (V.) shows the percentage of nitrogen in the fine sifted surface soil, 9 inches in 
depth, as dried at 100° C., in the sample from each plot. It also shows the mean for 
the five plots, the mean of determinations made on mixtures from the five plots, and 
the general means of these two sets of determinations. It should be added that each 
figure given is the mean of three or more determinations made by the soda-lime 
method. 
Table V.—Nitrogen per cent, in soil samples collected March, 1881. 
Aitrogen per cent, in fine surface soil, 9 inches deep. Calculated on the soil as 
dried at 100° C. 
Leguminous crop soils. 
Pallow--\vlieat soil. 
Per cent. 
Per cent. 
Plot 2. 
OT064 
0-0938 
o 
0T036 
0-0930 
„ 4. 
0-0950 
0-0931 
„ 5. 
0-1100 
0-0957 
), 6. 
0-1156 
0-1007 
Means. 
0-1061 
0-0953 
On mixture. 
0-1055 
0-0984 
General means .... 
0-1058 
0-0969 
There can be no doubt that both the leguminous crop and the fallow-wheat surface 
soils had lost nitrogen during the preceding 30 years or more ; but whilst in 1881 the 
surface soil of the plots which had grown many leguminous crops showed an average 
of 0T058 per cent, of nitrogen, that of -the plot which had grown wheat in alter¬ 
nation with fallow, and yielded over so many years only about half as much in crops, 
contained only 0-0969 per cent. It may be thought that the difference is not great; 
but a glance at the details which give these means can leave no doubt that it is real; 
nor can there be any doubt that it is characteristic also. The further results will 
afford confirmation of this. 
