Influence of the agricultural land agglomeration to the nutrients of the river water in the Tokachi River basin
Influence of the agricultural land agglomeration to the nutrients of the river water in the Tokachi River basin
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DOI：
10.1007/s10333-016-0546-y
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发表时间：
2017-04
影响因子：
2.2
通讯作者：
Y. Yamazaki;T. Muneoka;H. Okazawa;M. Kimura;O. Tsuji
中科院分区：
文献类型：
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作者：
Y. Yamazaki;T. Muneoka;H. Okazawa;M. Kimura;O. Tsuji
十胜河流域的农业活动导致河流水质恶化，令人关切。然而，减少施肥或减少农业用地面积，同时保持作物产量作为水质保护的努力并不容易。2007-2011年，在基流条件下，对十胜河流域的总氮（T-N）、总磷（T-P）浓度及氮磷比（原子和质量）进行了调查。分析了农用地比例和农用地空间连续性（SC），以检验水质保护的有效土地利用管理。土壤中T-P含量较低（0.03- 0.26mg/L），主要是由于农田土壤中的灰成土具有较高的磷吸收系数。T-N浓度（0.4-6.6 mg/L）和N：P质量比（6.3 ~ 39）趋于较高值。T-N浓度和N：P比值与农用地比例和SC呈正相关。特别是与农用地供应链的相关系数高于与农用地比例的相关系数。在农业用地占流域总面积40%以上的流域中，存在着农业用地占流域总面积比例高、农业用地可持续利用率低的支流。此外，在不显著减少十胜川流域农业用地比例的情况下，通过设置一定规模的农业用地连通度，可以有效抑制氮素径流。
The deterioration of river water quality as a result of agricultural activities in the Tokachi River basin is concerning. However, it is not easy to reduce fertilization or to decrease agricultural land area while maintaining crop yields as an effort of water quality conservation. We investigated the total nitrogen (T-N) and the total phosphorus (T-P) concentrations and the N:P ratio (atomic and mass) in the Tokachi River basin during 2007–2011 under base flow conditions. The proportion of agricultural land and the Spatial Continuity (SC) of agricultural land were analyzed to examine effective land use management for water quality conservation. T-P showed comparatively low concentrations (0.03–0.26 mg/L) because Andosols in the agricultural land, which have high phosphate absorption coefficients. While the T-N concentrations (0.4–6.6 mg/L) and the N:P mass ratio (6.3–39) tended to high values. T-N concentration and the N:P ratio had positive correlations with the proportion and the SC of agricultural land. In particular, the correlation coefficients of the relationships with the SC of agricultural land were higher than those of the proportion of agricultural land. In watersheds having more than 40 % of agricultural land, it was confirmed that there were some tributaries which had a high proportion of agricultural land but had low SC of agricultural land. Besides, the results suggested that the nitrogen runoff could be suppressed by setting the connectivity of agricultural land with certain scale without reducing the proportion of agricultural land in the Tokachi River basin significantly.