土壤侵蚀建模中作物参数测定方法研究

目前所采用的取样方法具有很好的可操作性和组织性,但其结果对过高地估测田间每一作物带的相关值非常敏感.同时,其结果不能随作物不同组合和时间的变化而改变,限制了其方法在不同的土地利用类型和种植制度上的应用.为了克服这些弱点,本研究采用随机选点的方法,将固定测点变为田间随机测点,测定随机点控制范围的参数.记录测点作物带的名称非常重要,因为在统计分析时将根据该作物在田间的权重来计算参数值.20个测点能代表一个作物带进行标准差分析,因此建议每一地块40测点.分析证明可将测定间隔时间从现在的一个星期延长到两个星期,但应增加一次作物收获前的测定.

Study on the methodology of crop parameter measurement for soil erosion modeling

The present sampling approach has worked very well from practical and organizational point of view, but its results have been proven to be sensitive to overrepresentation of one of the cropping strips within the field. Also the results give no flexibility in changing field crop compositions and give no flexibility in time, which limits the application for evaluation of alternative land use and cropping systems. To overcome these problems the present sampling method should be adapted. The same random selection of points can be used, but instead of fixing the exact area of measurements, which could be on the border of two strips, it should be used to select the crop strip to be sampled. Measurements of the parameters should then be taken around the selected point only in the selected strip. Recording the name of the kind of cropping strip is important as statistical analysis will have to focus on parameterization of the different cropping strips with the field means coming from the weighted averages. A sample size of 40 measurements is recommended, then around 20 measurements for per cropping strip will be available to get a proper estimate of the standard deviations. The present measuring interval of the plant parameters can be changed to two weeks, with inclusion of extra measurements just before the harvest of plant parameters.