The influence of watershed land use on lake N:P in a predominantly agricultural landscape
The influence of watershed land use on lake N:P in a predominantly agricultural landscape
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DOI：
10.4319/lo.2001.46.4.0970
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发表时间：
2001-06-01
影响因子：
4.5
通讯作者：
Downing, JA
中科院分区：
文献类型：
--
作者：
Arbuckle, KE;Downing, JA
本研究检验了以下假设：以中耕作物农业（例如玉米或大豆）为主的流域中的湖泊的 N:P 系统性地高于拥有大片牧场的流域中的湖泊。目前的富营养化生物地球化学模型表明，农业氮和磷通量导致受纳水域的 N:P 系统性下降。相比之下，不同的农业活动（即行耕与畜牧业）使用截然不同的 N 和 P 修正，并且农业流域的通量在观察到的 N:P 范围广泛（即低于雷德菲尔德至 > 100）时出现分歧。畜牧业导致低氮磷通量，中耕种植则导致高氮磷通量。在美国（爱荷华州）农业高度发达的地区，对流域内 113 个湖泊进行了农业流域土地利用与湖泊养分化学计量之间的联系测试，这些湖泊中种植有不同数量的中耕作物（0%-95%）和牧场（0%-36%）。多元回归分析表明，牧地面积较大的流域湖泊N:P较低，而中耕为主的流域湖泊N.P普遍较高，牧草面积>30%的流域湖泊N:P最低。接近雷德菲尔德水平。在 90% 以上的流域从事中耕作物农业的湖泊中，N:P 最常见（> 50 个原子）。农业实践的动态需要在养分化学计量模型中纳入农业系统之间的现实差异。集约化中耕作物农业产生的 N:P 化学计量水平通常在原始水源和公海中观察到，而畜牧业的增加将导致 N:P 降至通常与蓝藻水华相关的低水平。
This study tests the hypothesis that lakes in watersheds dominated by row-crop agriculture (e.g., maize or soybeans) have systematically higher N:P than lakes in watersheds with large tracts of pasturelands. Current biogeochemical models of eutrophication suggest that agricultural nitrogen and phosphorus fluxes lead to a systematic decline in the N:P of receiving waters. In contrast, different agricultural activities (i.e., row-cropping vs. animal agriculture) use greatly divergent N and P amendments, and fluxes from agricultural watersheds diverge through a broad range of observed N:P (i.e., sub-Redfield to > 100). Animal agriculture leads to low N:P fluxes and row-cropping to high N:P. The connection between agricultural watershed land use and lake nutrient stoichiometry was tested in a highly agricultural region of the United States (Iowa) on 113 lakes in watersheds with different amounts of row-crop (0%-95%) and pastureland (0%-36%). Multiple regression analysis shows that lakes in watersheds with large areas in pasturelands have low N:P, whereas lakes in watersheds dominated by row-cropping have systematically high N.P Lakes in watersheds with > 30% pasture had the lowest N:P. approaching Redfield levels. N:P was most frequently high (> 50 as atoms) in lakes with > 90% of their watersheds in row-crop agriculture. The dynamics of agricultural practice necessitates the inclusion of real-world differences among agricultural systems in nutrient stoichiometric models. Intensive row-crop agriculture yields N:P stoichiometry at high levels usually observed in pristine headwaters and open oceans, whereas increased animal agriculture will drive N:P to low levels usually associated with cyanobacterial blooms.