黄土高原旱地长期种植作物对土壤微量元素形态和有效性的影响  

Effects of long-term cropping on the forms and the availability of micronutrients in dryland soils on the Loess Plateau

作　　者：魏孝荣[1] 郝明德[1] 邵明安[1] 

机构地区：[1]中国科学院水利部水土保持研究所黄土高原土壤侵蚀与旱地农业国家重点实验室

出　　处：《生态学报》2005年第12期3196-3203,共8页Acta Ecologica Sinica

基　　金：中国科学院野外台站基金资助项目;中国科学院知识创新资助项目(KZCX2-413-3);国家科技攻关资助项目(2001BA508B15)~~

摘　　要：在长期定位试验的基础上,用连续浸提方法对土壤微量元素进行形态分级,研究了长期种植作物条件下黄土高原旱地土壤中微量元素的形态组成及其在不同土壤组分间的分配特征,探讨了种植系统对土壤微量元素有效性的影响.土壤中有效态微量元素含量的剖面分布除与土壤中微量元素的全量有关外,还与不同的种植系统有关.各种植系统有效锌和有效铜含量均低于休闲土壤,有效锌以小麦连作和苜蓿连作降低最多,有效铜以小麦连作和粮豆轮作降低最多.小麦连作系统40 cm以上土层土壤有效锰含量和休闲土壤接近,40～100cm土层低于休闲土壤,苜蓿连作和粮豆轮作整个剖面土壤有效锰含量均有所增加.各种植系统40cm以上土层土壤有效铁含量均高于休闲土壤,40～100cm土层土壤有效铁分布趋势相同,其含量均随土层深度的增加而增加,并且小麦连作低于休闲土壤,粮豆轮作高于休闲土壤,苜蓿连作与休闲相近,这些结果表明长期种植作物可以显著改善土壤锰素营养和铁素营养状况.苜蓿连作和小麦连作使锌和铁从矿物态向有机结合态转化,增加了土壤有效锌和有效铁的储备,粮豆轮作系统各形态锌低于休闲土壤,并且土壤中锌的总贮量有所减少;各种植系统土壤氧化物结合态铁在耕层增加,在古耕层降低,这也表明种植作物可以活化深层土壤难溶态铁.长期种植作物使耕层土壤各形态铜含量降低,粮豆轮作和小麦连作系统古耕层土壤各形态铜含量较休闲土壤有所增加.3种种植系统碳酸盐结合态、氧化物结合态和有机结合态锰含量均有不同程度的下降,且耕层土壤交换态、碳酸盐结合态和有机结合态锰高于古耕层,氧化物结合态和矿物态锰含量低于古耕层.The low availability of soil micronutrients in dryland of the Loess Plateau cannot meet the need of crop growth and then it has become one of the limiting factors for the agriculture production in this area for many years. The current cropping systems applied in the area may have effects on the availability of soil micronutrients. The long-term field cropping experiment, which composed of fallow （FA）, continuous clover cropping （CC）, continuous wheat cropping （WC）, and clover-legumes rotation （CLR）, was initiated in 1984 in the Loess Plateau. After 18 years observations, soil samples were collected from plough layer （PL） and plow sole （PS） and then the samples were used for classifying the soil micronutrients into five forms, i.e. , exchangeable （Ex）, carbonate bond （Cr-）, oxides bond （Ox-）, organic matter bond （Ore-）, and mineral bond （Min-）, by using an amended sequential extraction technique. In addition, soil samples from 0- 100cm soil depth were also taken for the determination of available micronutrient contents so that the effects of long-term cropping on the forms and availability of soil micronutrients in the area can be assessed. The results showed that the distribution of micronutrients in soils related not only with total contents of the elements in soil, but also with cropping systems. The available Zn and Cu in the three cropping systems were all lower than those in FW. WC and CC have the lowest soil available Zn contents, and the available contents of Cu in CC and CLR are the lowest. The content of available Mn in WC is similar to that in 0-40cm soil depth but lower than that in 40-100cm of FA, respectively. Meanwhile, the contents of available Mn were increased in CC and CLR systems compared with those in FW. The contents of available Fe in the three cropping systems were also increased in 0-40cm soil depth and presented the same distribution trend in 40- 100cm that the contents increased with the increase of soil depth. Moreover, the available Fe was lo

关 键 词：种植作物 微量元素 形态 有效性 

分 类 号：S154.4[农业科学—土壤学]