Simulation of C and N mineralisation during crop residue decomposition:: A simple dynamic model based on the C:N ratio of the residues
Simulation of C and N mineralisation during crop residue decomposition:: A simple dynamic model based on the C:N ratio of the residues
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DOI：
10.1023/a:1004813801728
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发表时间：
2001-01-01
期刊：
影响因子：
4.9
通讯作者：
Mary, B
中科院分区：
文献类型：
--
作者：
Nicolardot, B;Recous, S;Mary, B
利用一个简单的动力学模型，模拟了在非限制性氮条件下作物残体分解过程中，在实验室培养中获得的C和N矿化动力学。该模型包括残体、微生物生物量和腐殖化有机质三个部分。用7个参数来描述碳、氮通量。分解的碳要么矿化为CO2，要么被土壤微生物吸收，微生物腐烂产生碳腐殖化和次生碳矿化。氮动力学是由C率和C：N比的车厢保持恒定的氮限制的情况下。该模型的参数化使用表观C和N矿化动力学获得27个不同的残留物（器官的油菜植物），表现出非常广泛的变化，化学成分和氮含量。模型中除残留物和土壤有机质的C：N比外，其余5个参数均通过非线性拟合和CO2和矿质氮的观测值与模拟值之间的差异最小化得到。三个参数，即分解速率常数的残留物，生物量C：N比和腐殖化速率，与残留物C：N比有很强的相关性。这些参数与残留物C：N比之间建立了双曲线关系。与此相反，其他两个参数，即微生物生物量的衰减率和微生物生物量同化残留碳的产量，不相关的残留物C：N比，因此，在模型中是固定的。因此，针对作为唯一标准的残基C：N比参数化的模型，然后在一组48个残基上进行评价。通过考虑未用于参数化的21个残留物，获得了独立验证。表观C和N矿化的动力学模型进行了合理的模拟。该模型倾向于高估碳矿化，这可能会限制其用于C预测，但由于土壤中残留物的分解，N固定或矿化的动力学预测良好。模型表明，随着残留物C：N比的增加，分解物C：N比增加。较高的腐殖化，预测与较低的C：N比的基板。这一简单的动力学模型有效地预测了作物残体在土壤中分解过程中氮素的演变。
C and N mineralisation kinetics obtained in laboratory incubations during decomposition of crop residues under non-limiting nitrogen conditions were simulated using a simple dynamic model. This model includes three compartments: the residues, microbial biomass and humified organic matter. Seven parameters are used to describe the C and N fluxes. The decomposed C is either mineralised as CO2 or assimilated by the soil microflora, microbial decay producing both C humification and secondary C mineralisation. The N dynamics are governed by the C rates and the C:N ratio of the compartments which remain constant in the absence of nitrogen limitation. The model was parameterised using apparent C and N mineralisation kinetics obtained for 27 different residues (organs of oilseed rape plants) that exhibited very wide variations in chemical composition and nitrogen content. Except for the C:N ratio of the residues and the soil organic matter, the other five parameters of the model were obtained by non-linear fitting and by minimising the differences between observed and simulated values of CO2 and mineral N. Three parameters, namely the decomposition rate constant of the residues, the biomass C:N ratio and humification rate, were strongly correlated with the residues C:N ratio. Hyperbolic relationships were established between these parameters and the residues C:N ratio. In contrast, the other two parameters, i.e. the decay rate of the microbial biomass and the assimilation yield of residue-C by the microbial biomass, were not correlated to the residues C:N ratio and were, therefore, fixed in the model. The model thus parameterised against the residue C:N ratio as a unique criterion, was then evaluated on a set of 48 residues. An independent validation was obtained by taking into account 21 residues which had not been used for the parameterisation. The kinetics of apparent C and N mineralisation were reasonably well simulated by the model. The model tended to over-estimate carbon mineralisation which could limit its use for C predictions, but the kinetics of N immobilisation or mineralisation due to decomposition of residues in soil were well predicted. The model indicated that the C:N ratio of decomposers increased with the residue C:N ratio. Higher humification was predicted for substrates with lower C:N ratios. This simple dynamic model effectively predicts N evolution during crop residue decomposition in soil.