In connection with the loss by drainage of nitrogen in the form of nitrates, it may be mentioned that the water of many of the famous rivers contains large quantities of nitrates. Thus the water of the Seine has been found to contain fifteen parts of nitrates per million of water, and the Rhine eight parts per million. Some idea of what this amounts to per annum may be obtained by the statement that "the Rhine discharges daily 220 tons of saltpetre into the ocean, the river Seine 270, and the Nile 1100 tons."—(Storer's Agric. Chem., vol. i. p. 318.)
NOTE VII. (p. 142).
Examples of Decrease of Nitrogen in Rothamsted Soils.
| Nitrogen in | |
| 1st 9 inches. | |
| Per cent. | |
| Old pasture | 0.250 |
| Arable land in ordinary culture | 0.140 |
| Wheat unmanured, 38 years | 0.105 |
| Wheat and fallow unmanured, 31 years | 0.096 |
| Barley unmanured, 30 years | 0.093 |
| Turnips unmanured, 25 years | 0.085 |
Manuring, Produce of Wheat, and Alteration in the Composition of the Soil in Broadbalk Field, Rothamsted, from 1865 to 1881.
| Average | Nitrogen per acre | |||||
| produce | in 1st 9 inches | |||||
| per acre. | of soil. | |||||
| Gain or | ||||||
| Manures per acre, annually | Dressed | Total | loss in | |||
| Plot. | applied, 16 years, 1865-81. | grain. | produce. | 1865. | 1881. | 16 years. |
| bush. | lb. | lb. | lb. | lb. | ||
| 3 | Unmanured | 11-7/8 | 1715 | 2507 | 2404 | - 103 |
| 5a | Mixed mineral manure | 12-3/4 | 1963 | 2574 | 2328 | - 246 |
| 10a | Ammonium salts, 400 lb. | 17-7/8 | 2881 | 2548 | 2471 | - 77 |
| 11a | Ammonium salts, with superphosphate | 23-1/4 | 3856 | 2693 | 2676 | - 17 |
| 7a | Ammonium salts, with mixed mineral manure | 28 | 4993 | 2829 | 2908 | + 79 |
| 9a | Nitrate of soda, 550 lb., and mixed mineral manure | 36 | 6949 | 2834 | 2883 | + 49 |
| 16a | Unmanured* | 13-1/2 | 2194 | 2907 | 2557 | - 350 |
| 2 | Farmyard manure, 14 tons | 31-1/2 | 5356 | 4329 | 4502 | + 173 |
| * During 1852-64 received annually ammonium salts, 800 lb., with mixed mineral manure, and yielded an average product of 39-1/2 bushels of grain and 46-5/8 cwt. of straw. | ||||||
Amount of Drainage and Nitrogen as Nitrates in Drainage-water from unmanured Bare Soil, 20 and 60 inches deep—average of Thirteen Years.
| Nitrogen per acre | |||||||
| Amount of | Per million | ||||||
| drainage | of water | Per acre. | |||||
| 20-inch | 60-inch | 20-inch | 60-inch | 20-inch | 60-inch | ||
| Rainfall. | gauge. | gauge. | gauge. | gauge. | gauge. | gauge. | |
| Inches. | Inches. | Inches. | lb. | lb. | |||
| March | 1.70 | 0.85 | 0.94 | 7.3 | 8.9 | 1.41 | 1.89 |
| April | 2.25 | 0.72 | 0.79 | 8.3 | 9.0 | 1.35 | 1.61 |
| May | 2.48 | 0.80 | 0.79 | 8.4 | 9.1 | 1.53 | 1.63 |
| June | 2.59 | 0.78 | 0.78 | 9.2 | 9.1 | 1.62 | 1.60 |
| July | 2.85 | 0.68 | 0.62 | 13.5 | 11.8 | 2.08 | 1.66 |
| August | 2.69 | 0.84 | 0.76 | 15.1 | 13.3 | 2.87 | 2.28 |
| September | 2.70 | 0.97 | 0.82 | 17.7 | 13.4 | 3.86 | 2.50 |
| October | 3.12 | 1.86 | 1.68 | 13.8 | 11.9 | 5.83 | 4.53 |
| November | 3.20 | 2.44 | 2.32 | 11.8 | 11.4 | 6.50 | 5.98 |
| December | 2.34 | 1.88 | 1.88 | 9.5 | 10.6 | 4.06 | 4.51 |
| January | 2.13 | 1.79 | 1.93 | 7.4 | 8.9 | 2.99 | 3.88 |
| February | 2.16 | 1.84 | 1.74 | 7.7 | 9.1 | 3.19 | 3.57 |
| March-June | 9.02 | 3.15 | 3.30 | 8.3 | 9.0 | 5.91 | 6.73 |
| July-September | 8.24 | 2.49 | 2.20 | 15.6 | 13.0 | 8.81 | 6.44 |
| October-Feb. | 12.95 | 9.81 | 9.55 | 10.2 | 10.4 | 22.57 | 22.47 |
| Whole year | 30.21 | 15.45 | 15.05 | 10.7 | 10.5 | 37.29 | 35.64 |