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首页> 外文期刊>Ecological Modelling >Integrating soil carbon cycling with that of nitrogen and phosphorus in the watershed model SWAT: Theory and model testing
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Integrating soil carbon cycling with that of nitrogen and phosphorus in the watershed model SWAT: Theory and model testing

机译：在分水岭模型SWAT中将土壤碳循环与氮和磷的循环整合在一起：理论和模型测试

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摘要

In this paper we describe and test a sub-model that integrates the cycling of carbon (C), nitrogen (N) and phosphorus (P) in the Soil Water Assessment Tool (SWAT) watershed model. The core of the sub-model is a multi-layer, one-pool soil organic carbon (SC) algorithm, in which the decomposition rate of SC and input rate to SC (through decomposition and humification of residues) depend on the current size of SC. The organic N and P fluxes are coupled to that of C and depend on the available mineral N and P, and the C:N and N:P ratios of the decomposing pools. Tillage explicitly affects the soil organic matter turnover rate through tool-specific coefficients. Unlike most models, the turnover of soil organic matter does not follow first order kinetics. Each soil layer has a specific maximum capacity to accumulate C or C saturation (Sx) that depends on texture and controls the turnover rate. It is shown in an analytical solution that Sx is a parameter with major influence in the model C dynamics. Testing with a 65-yr data set from the dryland wheat growing region in Oregon shows that the model adequately simulates the SC dynamics in the topsoil (top 0.3m) for three different treatments. Three key model parameters, the optimal decomposition and humification rates and a factor controlling the effect of soil moisture and temperature on the decomposition rate, showed low uncertainty as determined by generalized likelihood uncertainty estimation. Nonetheless, the parameter set that provided accurate simulations in the topsoil tended to overestimate SC in the subsoil, suggesting that a mechanism that expresses at depth might not be represented in the current sub-model structure. The explicit integration of C, N, and P fluxes allows for a more cohesive simulation of nutrient cycling in the SWAT model. The sub-model has to be tested in forestland and rangeland in addition to agricultural land, and in diverse soils with extreme properties such high or low pH, an organic horizon, or volcanic soils.
机译：在本文中，我们描述并测试了一个子模型，该子模型在土壤水评估工具（SWAT）分水岭模型中整合了碳（C），氮（N）和磷（P）的循环。该子模型的核心是多层单池土壤有机碳（SC）算法，其中，SC的分解率和对SC的输入率（通过残留物的分解和腐殖化）取决于当前的大小。 SC。 N和P的有机通量与C的通量耦合，并取决于可利用的矿物质N和P，以及分解池的C：N和N：P比率。耕作通过特定于工具的系数显着影响土壤有机质的转化率。与大多数模型不同，土壤有机质的周转不遵循一级动力学。每个土壤层都有特定的最大容量来累积C或C饱和度（Sx），这取决于质地并控制周转率。在解析解决方案中显示，Sx是对模型C动力学具有重大影响的参数。使用来自俄勒冈州旱地小麦种植区的65年数据集进行的测试表明，该模型可以充分模拟三种不同处理方法在表土（最高0.3m）中的SC动态。最佳的分解和增湿速率以及控制土壤水分和温度对分解速率的影响的三个关键模型参数显示出较低的不确定性，这由广义似然不确定性估计确定。但是，在表层土壤中提供精确模拟的参数集往往高估了地下土壤中的SC，这表明在当前子模型结构中可能无法表示深度表达的机制。 C，N和P通量的显式集成可以在SWAT模型中更紧密地模拟养分循环。除了农业用地以外，还必须在林地和牧场中测试该子模型，并在具有高或低pH值，有机层或火山土壤等极端特性的各种土壤中进行测试。

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