【摘要】 对连续施肥18年和31年后的苜蓿连作、小麦连作及粮豆轮作系统土壤不同铜源及其有效性进行了研究,结果表明:（1）土壤有效铜含量随施肥年限增加而增加,其中小麦连作耕层土壤单施有机肥有效铜含量增加最显著,比2002年增加了0.69 mg·kg^-1.（2）土壤中铜的形态以矿物态为主,其次是有机结合态、氧化物结合态和碳酸盐结合态,交换态铜含量极低.2015年粮豆轮作系统土壤交换态铜含量较2002年相比有所增加;其他各种植系统耕层土壤碳酸盐结合态、氧化物结合态、有机结合态铜含量增加,矿物态铜含量却有所降低.（3）有效铜与交换态铜相关系数达0.588,二者的直接通径系数为0.829,均为最高,表明交换态铜为土壤有效铜的主要来源和直接来源.碳酸盐结合态铜与交换态铜间接通径系数最大,表明碳酸盐结合态铜可以通过形态转化而成为土壤中有效铜的一部分.矿物态铜与有效铜间直接通径系数较高,为0.571,表明矿物态铜可作为土壤有效铜的潜力来源.有效铜与氧化物结合态、有机结合态铜之间相关系数、直接通径系数均为负值,表明有机结合态、氧化物结合态铜对有效铜没有贡献.更多还原

【Abstract】 Cu fractions and availability were studied in alfalfa,wheat continuous and crop-legume rotation cropping system soils under continuous fertilization after 18 and 31 years.Results showed that;（1） Fertilization increased the available Cu content in every cropping system soils compared to 2015 and 2002.The largest increase of the available Cu at 0 15 cm depth in soils was found in the wheat continuous cropping system under the application of manure,the increase was 0.69 mg · kg^-1.（2） The main fraction of Cu in soils was mineralbound,followed by organic matter-,oxide-,and carbonate-bound Cu;exchangeable Cu content was very low.The contents of exchangeable Cu in crop-legume rotation cropping system soils were increased after long-term fertilization in 2015 compared with those in 2002.Fertilization reduced mineral-bound Cu contents at 0 15 cm depth in soils,while increased carbonate-,oxide-,organic matter-bound Cu contents.（3） Exchangeable Cu had the highest coefficient（0.588） with the available Cu,and the direct path coefficient was the highest（0.829）,therefore exchangeable Cu was the major and direct source of the available Cu.Carbonate-bound Cu had the greatest positive indirect path coefficient with exchangeable Cu,which showed that it could increase the available Cu content by the transformation of fraction.The direct path coefficient between mineral-bound Cu and exchangeable Cu was 0.571 and it was higher,it indicated that mineral-bound Cu might be the repository of the available Cu.The direct path coefficient and correlation coefficient between the available Cu and the organic matter-,oxide-bound Cu were negative,which indicated that these two fractions did not contribute to the available Cu.更多还原