Acidifying and Neutralizing Effects of Nitrogen Fertilizers on Forest Soil

摘要

The supply of ammonium nitrate probably results at a number of locations in some acidification of the forest soil which, however, is difficult to detect. A realistic assessment is that the acidification effect of a single-shot fertilizing operation (150 kg N/hectare) corresponds on average to 40 to 60 kg of Ca 0/hectare in increased liming requirements, which in its order of magnitude is comparable with 3 to 4 years of atmospheric acid rainfall in central Sweden. If limestone or dolomite are added to the fertilizer (ammonium calcium nitrate) in the long term an acid-neutralizing effect is achieved. If it is regarded as desirable, in conjunction with a supply of nitrogen, also to neutralize the excess from the acid rainfall, then the amount of added limestone should be increased in the ammonium calcium nitrate currently employed. If the nitrate leaching problem is disregarded, calcium nitrate provides a good alternative to ammonium calcium nitrate as regards the liming effect. This property of being effective at deeper levels of the root zone, is likely to be of particular value. Urea can be regarded as a neutral nitrogen fertilizing agent, suitable from the soil conservation viewpoint, on non-nitrifying soils. In the past its use as nitrogen fertilizer has, however, been restricted because of its low efficiency as compared with ammonium nitrate. 9 refs., 1 fig., 3 tabs. (ERA citation 10:040127)