128 
INVESTIGATIONS ON KOTHAMSTE1) SOILS. 
than plats 3 and 4, but the loss has been progressive, though the 
diminution seems to have been slower latterly than in earlier years. 
Plats 10a and 10b, notwithstanding their 400 pounds per aere per 
annum of ammonium salts, show, in the absence of mineral manures, a 
gradual but steady loss of soil nitrogen, and the carbon also decreases. 
Plats 6, 7, and 8, all supplied with full minerals, but progressively 
increasing dressings of ammonium salts (200, 400, and 600 pounds per 
acre per annum respectively), all show a decrease of nitrogen since 
1881, and the carbon also declines. 
Plats 11, 12, 13, and 14, the series which all receive the same dress- 
ing of ammonium salts (400 pounds per acre per annum) and super- 
phosphate, but differ in other saline applications, show on the whole 
a decline in both carbon and nitrogen. 
Plat 9a, manured with sodium nitrate and full minerals, shows a 
decrease in both carbon and nitrogen. It is to be noted that its neigh- 
bor, plat 01), which receives only sodium nitrate, without minerals, 
was in 1881, as well as in 1893, much poorer both in nitrogen and car- 
bon than plat 9a, which receives phosphates and potash, as well as 
sodium nitrate, and which, in consequence, persi stently grows larger 
crops, necessarily leaving larger root and stubble residues. 
Plat 16 shows well the evidences of its checkered history. Liber- 
ally manured from 1852 to 1864, with full minerals and as many as 
800 pounds of ammonium salts per annum, it was in 1865 the richest of 
all the chemically manured plats as regards nitrogen contents, show- 
ing as much as 0.1210 per cent of nitrogen. Then it was unmanured 
for nineteen years, and toward the close of these starvation years, in 
1881, we find it to have fallen in nitrogen contents to 0.1066 per cent, 
a decline of 373 pounds per acre in sixteen years, or 23 pounds per 
annum. Since 1884, however, it has had full minerals and 550 pounds 
per annum of sodium nitrate, and after these nine years of prosperity 
it shows, in 1893, a regain of 114 pounds per acre of its lost nitrogen. 
Plats 17 and 18, nitrogenously and minerally manured in alternate 
years, and giving alternately high and low crops, are still gaining 
nitrogen, not having apparently reached the turning point in accumu- 
lation shown much earlier on most of the chemically manured plats. 
Th<> following table (Table 69) shows conveniently, together with 
the surface-soil nitrogen contents of the various plats already given, 
the gain and loss indicated by the samples during each period, and 
also the difference at- each date between each plat and plat 5, the plat 
fully supplied with minerals, but without any nitrogenous dressing, 
and therefore the plal in the best posit ion to utilize soil nitrogen, and 
on this, and also on other grounds, the best- standard of comparison 
for many of the plats. 
