延安市宝塔区土壤养分地球化学评价中的变权效果

Variational weight effect in the geochemical evaluation of soil nutrients in Baota District of Yan’an City

基于变权理论,采用离散度衡量状态向量的权重调节需求力,调节度鉴别状态变权向量的权重调节供给力,调权水平权衡两者之间的平衡点,以选择合适的状态变权向量,构建土壤养分地球化学变权综合评价模型,以解决常权评价难以突出缺量养分元素的限制性作用,而引起评价失真的问题。结果显示:该方法操作性强,简单易行,能较好地反映土壤养分元素状态变权规律;积型与和型状态变权向量因其调节度难以控制,适用范围受限;而指数型状态变权向量的调节度随参数而变,调权效果易于控制,适用范围广,具有较好的变权效果。宝塔区土壤养分数据离散度低,均衡性高,综合确定调权水平为0.8,幂参数α=2.5248时,权重向N、Corg转移合理,惩罚有度,科学地调整了土壤养分综合评价等级,等级由二等变三等2处,三等变四等42处,四等变五等131处,且识别出N、Corg为宝塔地区土壤养分的短板元素,整体限制了土壤养分质量提升,为因地制宜,科学改良土壤提供了必要依据。

Based on the theory of variable weight,the authors used the weight of the state vector measured by the divergence degree to regulate the demand force,the weight of the variable state vector identified by the adjustment degree regulated the supply force,and the weight level of the adjustment weight weighed the balance point between the two so as to select the appropriate state.Change vector,a comprehensive evaluation model of soil nutrient geochemical transformation power,was constructed to solve the problem of evaluation distortion due to the difficulty of highlighting the restrictive effect of nutrient element.The results show that the method is easy to operate and can reflect the changing law of soil nutrient element.The weight vector of product and sum state is difficult to control because of its adjustment degree,and its application range is limited.However,the adjustment degree of exponential state variable vector varies with parameters,the adjustment effect is easy to control,and the application is wide,and it has a good change effect.The soil nutrient data in the pagoda area has low dispersion and high equilibrium.The comprehensive determination of the weight adjustment level is 0.8,the power parameterα=2.5248,and the weight is transferred to N and Corg.The penalty is reasonable,and the comprehensive evaluation level of soil nutrients is scientifically adjusted.The grade changes from second class to third class,42 third class to fourth class,and 131 fourth class to fifth grade,and N and Corg are identifiedas the short plate elements of soil nutrients in the pagoda area which overall limit the improvement of soil nutrient quality.The results obtained by the authors providea necessary basis for scientific improvement of the soil under local conditions.