Aspects of nitrogen use efficiency of cauliflower I. A simulation modelling based analysis of nitrogen availability under field conditions
Aspects of nitrogen use efficiency of cauliflower I. A simulation modelling based analysis of nitrogen availability under field conditions
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花椰菜氮素利用效率方面 I. 基于模拟模型的田间氮素有效性分析
DOI：
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发表时间：
2003
影响因子：
0.6
通讯作者：
H. Stützel
中科院分区：
文献类型：
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作者：
H. Kage;C. Alt;H. Stützel
从几个田间试验的数据（8种作物下广泛变化的氮供应黄土壤土）被用于模拟模型为基础的分析花椰菜的氮的可用性。该模型由描述根系生长、硝态氮向根系运移和硝态氮在土壤中垂直运移的组成部分组成。根观察2年多来表明分配给细根的干物质的比例增加氮缺乏。花椰菜根系生长模型的R2= 0.75。在对土壤水分收支进行合理描述的基础上，准确描述了花椰菜生长期硝态氮的垂直运移规律。然而，这种移动的幅度仅限于约60厘米的土壤深度，即使在高降雨期后，因为土壤的持水能力很高。确定硝酸盐有效性的因素的分析表明，表观质量流量是非常重要的条件下，极高的氮供应量高的硝酸盐氮留在土壤中的生长季节结束。否则，硝酸盐的主要部分必须通过扩散运输到根部。单根模型为基础的计算，最大的硝酸盐运输到根高估了氮的有效性，所示的临界土壤硝态氮的估计太低。引入限制吸收活动期的根被用来弥合理论计算和经验结果之间的差距。情景计算进行了不同的土壤条件和管理措施，以获得N供应和残留土壤硝态氮水平之间的函数关系。
Data from several field experiments (eight crops grown under a widely varying nitrogen supply on a loess loam soil) were used for a simulation modelling based analysis of nitrogen availability of cauliflower. The model was built out of components describing root growth, nitrate transport to the roots and the vertical nitrate transport within the soil. Root observations obtained over 2 years indicated an increased fraction of dry matter allocated to the fine roots under N deficiency. An adopted version of a root growth model for cauliflower described the rooting data with an R2=0·75. Based upon an acceptable description of the soil water budget, vertical nitrate movement during the growth period of cauliflower was accurately described. The magnitude of this movement, however, was limited to soil depths of about 60 cm even after periods of high rainfall, because of a high soil water holding capacity. An analysis of the factors determining nitrate availability indicated that apparent mass flow was only of high importance for conditions of extremely high N supply where high amounts of nitrate nitrogen remain in the soil up to the end of the growing season. Otherwise, the dominating fraction of nitrate has to be transported to the roots by diffusion. Single root model based calculations of maximum nitrate transport to roots overestimated N availability as indicated by estimates of critical soil nitrate N that were too low. The introduction of a restricted uptake activity period of the roots was used to bridge the gap between theoretical calculations and empirical results. Scenario calculations were carried out to obtain functional relationships between N supply and residual soil nitrate levels for different soil conditions and management practices.