SOURCES OF NITROGEN

Otago Daily Times, Issue 22911, 19 June 1936, Page 9

SOURCES OF NITROGEN

One of the finest things done by the American cxperimen, stations has been the exhaustive tests they have made to determine which, types of fertilisers give the best results under practical conditions. , Unfortunately all their work has been done with crops, for grass is not of such moment with them as it is with us. One of their most interesting series of experiments in this connection has been to test out the comparative values of nitrate of soda, sulphate of ammonia and dried blood (the natural organic nitrogenous manure). The stations which have provided the most complete data are those of New Jersey and Pennsylvania. The former has carried out the experiments from 1008 apd the latter from 1882 to the present lime. The results of both these stations are in thorough agreement, and all the other States which have carried out similar trials have also arrived at the same conclusion. And the common conclusion is that sulphate of ammonia is easily the best nitrogenous manure when the soil is also limed. Under acid conditions, when liming has been neglected, the result from the use of sulphate of ammonia progressively declines, as docs also the result from the use of dried blood, but to a lesser extent. On the other hand, the nitrate of soda apparently enjoys an acid condition in the soil.

In an official survey of the extended American national work on the nitrogen problem a late report says: “Natural organics (dried blood, etc.) are not readilv leached and do not materially increase soil acidity. They have, however, a low total availability. This property cannot be corrected. Nitrate nitrogen (nitrate of soda) has a high total availability and in the form of calcium (lime) and sodium nitrate doca not increase soil acidity. On the other hand, nitrate nitrogen is not ns readily absorbed as is ammonium nitrogen (sulphate of ammonia) and is very readily lost by leaching. This property of nitrate nitrogen cannot be changed. Ammonium nitrogen (sulphate of ammonia) is readily absorbed, has a high total availability and is not easily leached from the soil. Its one weakness is that, particularly in the form of ammonium salts, it materially increases soil acidity. This action, however, is easily corrected by the use of limestone. When limestone is used with sulphate of ammonia it is, in most cases, the best source of nitrogen that con be used in fertilisers.”