不同黄河泥沙充填复垦土壤剖面对土壤与作物中元素分布的影响
Effects of different Yellow River sediment filling reclaimed soil profiles on the distribution of elements in soil and crops
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摘要: 利用黄河泥沙充填是滨黄河地区采煤沉陷地复垦的有效手段,但是复垦的土地存在覆土不 足、保水保肥性差、农作物产量低等问题,故需要开展黄河泥沙复垦采煤沉陷地土壤剖面重构技术 以及元素在不同剖面中的迁移转化研究,以指导复垦工艺及后续的农田利用及管理。 本研究以黄 河泥沙为填充材料,借鉴传统农业土壤剖面特点和现有充填复垦技术形成的土壤剖面特点,综合考 虑表层覆土厚度等因素,设计 4 种不同的土壤剖面构型:30 cm 土+70 cm 黄河泥沙、50 cm 土+ 50 cm 黄河泥沙、30 cm 土+40 cm 黄河泥沙+15 cm 土+15 cm 黄河泥沙、50 cm 土+40 cm 黄河泥沙+ 10 cm 土。 通过室内土柱玉米栽培试验,在玉米生长过程中,表层施肥添加主量营养元素氮(N)、 磷(P)、钾(K)和表层灌水添加有害重金属元素铅(Pb)、镉(Cd)、砷(As)、汞(Hg)、铬(Cr),玉米生 长结束后,从土柱表层开始以 10 cm 为单位采集土柱样品,并采集玉米植株样品,测试其中的 N,P, K,Pb,Cd,As,Hg,Cr 含量。 研究发现,具有相同覆土厚度的剖面构型 1 和剖面构型 3、剖面构型 2 和剖面构型 4,各元素的分布规律整体比较相似,但由于剖面构型 3 增加了中间夹心土层、剖面构 型 4 增加了底层土层,增强了对元素的吸附作用,对 N,P 的保持作用增强;K 在所有剖面中未见明 显规律;重金属被吸附在表层,在所有剖面构型中规律一致。 在作物实验中,增加中间夹心土层的 剖面构型 3 有利于 N,P 的保留;K 主要由玉米吸收,在土壤中几乎无保留;玉米中的重金属属于较 弱吸收,污染风险较低。 分析实验用的土壤及黄河泥沙的粒度分布、pH、有机质及矿物组成,由于 黄河泥沙粒度较大、pH 较低、有机质含量较低且黏土矿物成分包括绿泥石和伊利石等含量较低,不 利于元素的保留,故增加了中间夹心土层的剖面构型有利于肥力、水分的保持,但是考虑到复垦工 艺的操作难度,建议采用剖面构型 3(30 cm 土+40 cm 黄河泥沙+15 cm 土+15 cm 黄河泥沙)。Abstract: The use of Yellow River sediment as filling material in the mining subsided area along Yellow River can not only provide sufficient and safe filling materials, but also play a certain role in the dredging of Yellow River. However,there are some problems such as insufficient cover soil,poor water and fertilizer conservation and low crop yield in the reclaimed land filled with Yellow River sediment. Therefore,it is necessary to carry out the research on the soil profile reconstruction technology and the migration and transformation of elements in different soil profiles of the reclaimed land filled with Yellow River sediment,so as to guide the reclamation process and subsequent farmland utili⁃ zation and management. Based on the characteristics of the traditional agricultural soil profile and the soil profile formed by the existing filling reclamation techniques,and the factors such as the thickness of surface cover soil, four different soil profile configurations were designed,including the 30 cm soil + 70 cm Yellow River sediment,the 50 cm soil + 50 cm Yellow River sediment,the 30 cm soil + 40 cm Yellow River sediment + 15 cm soil + 15 cm Yellow River sediment and the 50 cm soil + 40 cm Yellow River sediment + 10 cm soil. Through the indoor soil col⁃ umn corn cultivation experiment,during the growth of corn,the main nutrient elements such as nitrogen(N),phosphor⁃ us(P),potassium(K)were added by fertilizing on the column surface and some harmful heavy metal elements such as lead( Pb), cadmium ( Cd), arsenic ( As), mercury ( Hg) and chromium ( Cr) were added by surface watering. After the growth of corn,the soil samples were collected from the surface of the soil column in 10 cm units,and the samples of corn plants were collected to test the contents of N,P,K,Pb,Cd,As,Hg and Cr. It is found that the profile of the same surface soil thickness such as profile configuration 1 and 3, the distribution law of each element is similar. However,due to the addition of central interlayer in the profile configuration 3,which enhances the adsorption of elements,the retention of N and P is enhanced. In the profile configuration 2 and 4,although the overall law of each element is similar,the configuration 4 increases the bottom layer of 10 cm soil layer,and the retention of N and P is enhanced. The distribution of K in all configurations is no regular. While heavy metals are adsorbed on the surface lay⁃ er,the law of heavy metals distribution of all configurations are same and the Cd migration is slightly stronger. Com⁃ pared with the profile configuration 1 and the profile configuration 2, the content of N and P nutrient elements in the maize plants of profile configuration 3 is relatively high. In terms of maintaining soil fertility and promoting plant growth,the profile configuration 3 has a great advantage. In the crop experiments,the increase of soil thickness is beneficial to the retention of N and P. The K is mainly absorbed by corn and is almost unretained in the soil. Heav⁃ y metals in maize are weakly absorbed and the pollution risk is low. The particle size distribution,pH,organic matter and mineral composition of the soil and Yellow River sediment are analyzed. Due to the larger particle size,lower pH, and lower organic matter content of Yellow River sediment,the lower content of clay minerals including chlorite and il⁃ lite,it is not conducive to the retention of elements. Thus,increasing the profile configuration of the middle sandwich soil layer is beneficial to the retention of fertility and moisture. However,due to the difficulty of the reclamation process,it is recommended to adopt the profile configuration 3(30 cm soil + 40 cm Yellow River sediment +15 cm soil +15 cm Yellow River sediment).