+------------------------+---------------------+---------------------+ | | Rich Soil: Plot 2. | Poor Soil: Plot 3. | | | Lb. per Acre. | Lb. per Acre. | +------------------------+---------------------+---------------------+ |Nitrogen in soil in 1865|·175 per cent. = 4340|·105 per cent. = 2720| |Nitrogen added in | | | |manure, rain (5 lb. per | | | |annum), and seed (2 lb. | | | |per annum) | 10,140 | 340 | +------------------------+---------------------+---------------------+ |Nitrogen expected in | | | |1914 | 14,480 | 3060 | |Nitrogen found in 1914 |·259 per cent. = 5950|·095 per cent. = 2590| +------------------------+---------------------+---------------------+ |Loss from soil | 8530 | 470 | |Nitrogen accounted for | | | |in crops | 2500 | 750 | +------------------------+---------------------+---------------------+ |Balance, being dead loss| 6030 | -280[J] | |Annual dead loss | 123 | - 6[J] | +------------------------+---------------------+---------------------+ [J] Gains. Possibly the result of bacterial action. A further remarkable fact connected with the decomposition of the nitrogen compounds is that it seems invariably to be accompanied by an evolution of gaseous nitrogen. Apparently there are two cases. Under anaerobic conditions many of the soil organisms have the power of obtaining their necessary oxygen from nitrates, thereby causing a change in the molecule which leads in some cases to liberation of gaseous nitrogen; but the same result seems to be attained in aerobic conditions, especially when carbon is being rapidly oxidised. It is possible that the reaction is the same, and that in spite of the general aerobic conditions there is locally an anaerobic atmosphere. But it is also possible that some direct oxidation of protein or amino-acids may yield gaseous nitrogen. However it is brought about it affects a considerable proportion of the entire stock of nitrogen, and it becomes more serious as cultivation is intensified. Thus, on the Broadbalk plot receiving farmyard manure the loss is particularly heavy; on the unmanured plot it cannot be detected. The nitrogen balance-sheet is shown in Table XVII.