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在各种不同的气候和土壤条件下,定量估计主要农作物的生产和生长,是以模拟模型的提出和发展为前提的。为此目的,本文对几类层次有序的生产状况——即某一层次生产状况的模拟结果,可以看作是其它层次的计算输入——进行了分类讨论。所谓最高层次的主产状况,是指水分和养分都处于最佳有效状况而言的;次一层的生产状况一般把水分看作是限制因子;而在更次一层的状况中,还应考虑主要植物养分供应的限制。同时,不同的生产状况要达到模拟产量水平,还应进行归还和增加产量输入的评价。按技术规范,要确定用于前两层生产状况计算所需的有关气象及自然土壤资料。这表明环境不均匀性在很大程度上决定了问题的复杂性。气象数据在时间上以及土壤数据在空间上的平均,将会导致资料的变形和破坏。为了避免此类情况的发生,来自原始观测点的数据应始终维持它们的可利用性。而且,计算机的可行性及数据库管理系统也暗示没有任何理由,来原谅先平均后计算的方法,用以代替其它方法的使用。
Quantitative estimation of the production and growth of major crops under various climatic and soil conditions is based on the presentation and development of simulation models. To this end, the paper discusses the classification of several types of hierarchical production conditions - that is, the simulation results of a certain level of production status, which can be regarded as input to other levels of computation. The so-called highest level of main producing condition refers to the fact that both water and nutrients are in the best and effective condition. The next level of production generally regards moisture as a limiting factor, and in further situations, Consider the restrictions on nutrient supply to major plants. In the meantime, different production conditions should reach the simulated production level, and the evaluation of return and output increase should also be carried out. According to the technical specifications, the relevant meteorological and natural soil information required for the calculation of the first two production levels should be determined. This shows that the environmental heterogeneity determines the complexity of the problem to a large extent. Meteorological data over time and soil data in the spatial averaging, will lead to the deformation and destruction of the data. To avoid this from happening, the data from the original observation points should always maintain their availability. Moreover, the viability of the computer and the database management system imply that there is no reason to forgive the means of averaging afterwards in lieu of the use of other methods.