陕西关中土壤富硒标准研究与探讨——以小麦为例

Exploring selenium enrichment criteria for soils in the Guanzhong area,Shaanxi Province:A case study of wheat

建立陕西省富硒小麦产地土壤硒阈值不仅关系到天然富硒小麦精益化、精细化、精确化生产,更能够提高富硒土地利用效率,促进陕西富硒产业发展。本文以1∶25万土地质量地球化学调查数据为基础,依托陕西省近年来采集的544组土壤及其对应的小麦籽实样品硒含量数据,基于关中地区表层土壤硒地球化学异常下限和小麦—土壤隶属函数结果,提出以0.27×10^(-6)作为陕西省富硒小麦产地土壤硒阈值。实证研究发现,采用随机抽样得到的验证集的小麦富硒率达到83.78%,第三方检验的富硒率高达87.14%,以该阈值圈定的土地生产出的小麦能够满足中国营养学会规定的硒推荐摄入量(60μg/d),土地面积约为1500 km^(2)(225万亩),比按0.3×10^(-6)圈出的富硒土地增加了640 km^(2)(96万亩)。由此可见,按照农作物种类有针对性地界定富硒土壤界限值,能够较大程度地提高富硒土地利用效率,促进富硒产业发展,为制定陕西省富硒土壤标准提供科学依据。

Establishing the selenium threshold for soils in selenium-rich wheat producing areas in Shaanxi Province is closely related to the lean,fine-scale,and accurate production of natural selenium-rich wheat.Moreover,it can improve the utilization efficiency of sele-nium-rich land,thus promoting the development of selenium-rich industry in this province.This study determined the selenium thresh-old of soils in selenium-rich wheat producing areas in Shaanxi at 0.27×10^(-6) based on the 1∶250000 land quality geochemical survey data,the selenium concentration data of 544 sets of soil samples and corresponding wheat seed samples collected in Shaanxi in recent years,the lower limit of geochemical anomalies of selenium in topsoil in the Guanzhong area,and the wheat-soil function.The empiri-cal study showed that the validation set formed via random sampling yielded a selenium accumulation rate of 83.78%,while the third-party inspection yielded a selenium accumulation rate of 87.14%.The wheat produced from selenium-rich land delineated based on the selenium threshold 0.27×10^(-6) satisfies the recommended nutrient intake of selenium(60μg/d)stipulated by the Chinese Nutrition So-ciety.Furthermore,the area of the selenium-rich land is about 1500 km^(2)(2250000 mu),increasing by 640 km^(2)(960000 mu)com-pared with that of land delineated based on a selenium threshold of 0.3×10^(-6).Therefore,determining selenium-rich soil threshold by crop species can greatly improve the utilization efficiency of selenium-rich land,thus promoting the development of the selenium-rich industry.This study provides a scientific basis for setting selenium enrichment criteria for soils in Shaanxi Province.