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本文估计了1985和1994年波罗的海和北海集水区的氮淋溶总传输,是瑞典公布的将氮向海传输量减少50%的议案所展开的研究一部分。采用一模拟模型对不同区域、作物、土壤和施肥方式下的标准淋溶速率进行了计算。标准淋溶速率是正常气候和收获条件下每年从根区淋溶的氮量。结果表明:氮淋溶量减少了25%,从1985年的30kg N/hm~2到1994年的22kg N/hm~2。氮的总传输量减少了29%,从1985年的77000t到1994年的55000t。减少的主要原因是:①1994年草地面积的增加和谷物面积的减少;②氮利用效率的增加导致单一作物标准淋溶速率的减少;③耕地总面积的减少。传输量减少的原因50%归因于谷物地向草地的转换,40%归因于氮利用效率的提高,10%归因于耕地的减少。
This paper estimates the total N-leached transport in the Baltic Sea and North Sea catchments in 1985 and 1994 as part of a study published by Sweden in a motion to reduce nitrogen transmission to the sea by 50%. A simulation model was used to calculate the standard leaching rate in different regions, crops, soils and fertilizers. The standard leaching rate is the annual nitrogen leaching from the root zone under normal climate and harvest conditions. The results showed that the leaching amount of nitrogen decreased by 25%, from 30kg N / hm ~ 2 in 1985 to 22kg N / hm ~ 2 in 1994. Total nitrogen transmission decreased by 29%, from 77,000 t in 1985 to 55,000 t in 1994. The main reasons for the decrease are as follows: (1) The increase of grassland area and grain area in 1994; (2) The increase of nitrogen use efficiency leads to the decrease of standard leaching rate of single crop; (3) The decrease of total area of cultivated land. 50% of the decrease in transmission is due to the conversion of cereals to grassland, 40% to an increase in nitrogen use efficiency, and 10% to a decrease in arable land.