农田土壤氯离子累积与迁移机理
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摘要
研究人为活动和环境因素对农田土壤质量的作用强度与演替规律,对于掌握土壤中物质的迁移规律、阐明该区的农业历史、以及加强土壤管理等极为重要。本文以研究陕西关中地区农田土壤中Cl-的含量基本状况及它的空间分布规律作为理论依据,探讨农田土壤中Cl-与该区的人为活动历史及环境条件变化的关系,旨在揭示旱地气候特征对土壤氯离子累积、迁移规律影响,更为重要的是反映长期的社会及人文活动对土壤的形成、土壤质量演变的作用与影响。试验通过对旱地农田土壤中氯离子水平分布规律、垂直动态分布规律,作物吸收特性以及迁移机理等进行了系统研究,结果表明:
1.关中农田土壤中Cl-主要来源于农家有机肥的施用,说明农田土壤中Cl-含量与人为培肥耕作活动历史有着密切的关系。农田土壤耕层Cl-含量主要集中在20~60mg?kg-1,有明显的累积趋势,但累积速度偏低。
2.关中农田土壤中Cl-含量水平分布规律与塿土覆盖层的厚度的分布规律相一致,距村庄最近者,土壤熟化度最高,覆盖层最厚,Cl-含量也最高,充分证明了农田耕层土壤中Cl-含量变化规律成为人为土壤培肥与耕作活动历史的有力证据,同时也证明Cl-含量与土壤肥力水平有一定相关性,Cl-含量在某些方面可以具有“土壤肥沃度指示性元素”的功能。
3.受自然降雨与蒸发因素的影响,田间土壤Cl-含量在剖面上的分布规律表现出极强的季节性动态变化趋势,自然环境条件在农田土壤氯离子平衡中起到重要的作用。因此,监测Cl-在土壤剖面上的累积迁移规律,能够完整地说明在长期地土壤培肥过程中氯离子累积状况与累积速率。另外,对于掌握土壤水分的运动,进行土壤墒情管理也具有重要的意义。
4.作物在生育过程对氯离子吸收与利用的规律,成为农田土壤氯离子平衡的重要因素。通过田间试验与盆栽试验证明,作物对Cl-具有奢侈吸收功能,通过作物收获物可以带走农田耕层土壤中大量的Cl-。作物具有很强的生理吸收容纳能力,土壤水分状况有助于氯离子迁移,供给作物吸收。在目前情况下,农田土壤还具有很大的氯容量。
5.土壤结构性和孔隙分布特征是影响Cl-迁移的主要因素。通过研究Cl-在不同质地和不同粒径团聚体土壤中的阻滞因子R和扩散弥散系数Dsh表明:Cl-尽管被认为属于非反应性离子,它的迁移仍然受到土壤中结构体间孔隙和结构体内部孔隙的明显影响,说明土壤的结构性是影响氯离子迁移的物质基础。
Studying the affecting intensity and succession rule of farming soil quality influencing by human activities and environmental factors, it is important in mastering the transfer regulation, illuminating agricultural history and enhancing soil management. According to Cl- content and Cl- spatial distribution of farming soil in Shaanxi Guanzhong, we discussed the relationship between Cl- in farmland soil and the history of human activities and the change of environment, disclosing the influence of climate in dry area on the accumulation and transfer of Cl-, reflecting the function and influence of soil formation and soil quality evolvement under long-time activities of society and human.
The distribution rule of Cl- level and vertical dynamic distribution in dry farmland soil was systematically studied, as well as the trait of crop absorption and transfer mechanism, the results are as follows:
1. The Cl- of farmland soil in Guanzhong mostly comes from farmyard manure, Which showed Cl- content in farmland soil has close relation with the history of human fertilization and farming. Cl- content in topsoil of fields mostly accumulates in 20~60mg?kg-1, and has obvious accumulation trend, but its accumulative velocity is a little low.
2. There is the same trend between Level distribution of Cl- content of farmland soil and the thickness of cumulic epipedon in Lou soil, The soil which is most close to villages, highest mellow degree of soil, the cumulic epipedon is the thickest and Cl- content is the highest in it, manifested that the change rule of Cl- content in farmland topsoil can be a effective evidence of history of human fertilization and farming, and Cl- content has certain correlation with soil fertility, Cl- content can function as “indicating element of soil fertility ” in some aspect.
3. Influenced by natural rainfall and evaporation, The Cl- content’s distribution in time space in fields presents very strong seasonal dynamic trend. Natural environment factors play an important role in Cl- balance of farmland soil. So to monitor of Cl- accumulation and transport in soil profile is significant in explaining the accumulative state and velocity of Cl- in long-term fertilization, and controlling the movement of water and managing soil water condition.
4. The absorption and utilization of Cl- in crop growth process has become an important factor in Cl- balance in farmiland soil. Field and pot experiments showed that crops have
luxurious absorption of Cl-, crops can carry away a mount of Cl- from farmland soil. Crops have strong capacity of physiological absorption and acceptance. The condition of soil water could help Cl- transfer, absorb Cl- by crops. At present, there is large potential capacity of Cl- in the farmland soil.
5. The soil structure and porosity distribution are main factors that influence Cl- transfer. The retardance factor and DSH of Cl- in different texture and diameter aggregate showed: Although Cl- is thought as non-reflecting ion, its transfer is still significantly influenced by the porosity in soil structure or between the soil structures obviously. Soil structure is the substantial basis of Cl- tranfer.
1.关中农田土壤中Cl-主要来源于农家有机肥的施用,说明农田土壤中Cl-含量与人为培肥耕作活动历史有着密切的关系。农田土壤耕层Cl-含量主要集中在20~60mg?kg-1,有明显的累积趋势,但累积速度偏低。
2.关中农田土壤中Cl-含量水平分布规律与塿土覆盖层的厚度的分布规律相一致,距村庄最近者,土壤熟化度最高,覆盖层最厚,Cl-含量也最高,充分证明了农田耕层土壤中Cl-含量变化规律成为人为土壤培肥与耕作活动历史的有力证据,同时也证明Cl-含量与土壤肥力水平有一定相关性,Cl-含量在某些方面可以具有“土壤肥沃度指示性元素”的功能。
3.受自然降雨与蒸发因素的影响,田间土壤Cl-含量在剖面上的分布规律表现出极强的季节性动态变化趋势,自然环境条件在农田土壤氯离子平衡中起到重要的作用。因此,监测Cl-在土壤剖面上的累积迁移规律,能够完整地说明在长期地土壤培肥过程中氯离子累积状况与累积速率。另外,对于掌握土壤水分的运动,进行土壤墒情管理也具有重要的意义。
4.作物在生育过程对氯离子吸收与利用的规律,成为农田土壤氯离子平衡的重要因素。通过田间试验与盆栽试验证明,作物对Cl-具有奢侈吸收功能,通过作物收获物可以带走农田耕层土壤中大量的Cl-。作物具有很强的生理吸收容纳能力,土壤水分状况有助于氯离子迁移,供给作物吸收。在目前情况下,农田土壤还具有很大的氯容量。
5.土壤结构性和孔隙分布特征是影响Cl-迁移的主要因素。通过研究Cl-在不同质地和不同粒径团聚体土壤中的阻滞因子R和扩散弥散系数Dsh表明:Cl-尽管被认为属于非反应性离子,它的迁移仍然受到土壤中结构体间孔隙和结构体内部孔隙的明显影响,说明土壤的结构性是影响氯离子迁移的物质基础。
Studying the affecting intensity and succession rule of farming soil quality influencing by human activities and environmental factors, it is important in mastering the transfer regulation, illuminating agricultural history and enhancing soil management. According to Cl- content and Cl- spatial distribution of farming soil in Shaanxi Guanzhong, we discussed the relationship between Cl- in farmland soil and the history of human activities and the change of environment, disclosing the influence of climate in dry area on the accumulation and transfer of Cl-, reflecting the function and influence of soil formation and soil quality evolvement under long-time activities of society and human.
The distribution rule of Cl- level and vertical dynamic distribution in dry farmland soil was systematically studied, as well as the trait of crop absorption and transfer mechanism, the results are as follows:
1. The Cl- of farmland soil in Guanzhong mostly comes from farmyard manure, Which showed Cl- content in farmland soil has close relation with the history of human fertilization and farming. Cl- content in topsoil of fields mostly accumulates in 20~60mg?kg-1, and has obvious accumulation trend, but its accumulative velocity is a little low.
2. There is the same trend between Level distribution of Cl- content of farmland soil and the thickness of cumulic epipedon in Lou soil, The soil which is most close to villages, highest mellow degree of soil, the cumulic epipedon is the thickest and Cl- content is the highest in it, manifested that the change rule of Cl- content in farmland topsoil can be a effective evidence of history of human fertilization and farming, and Cl- content has certain correlation with soil fertility, Cl- content can function as “indicating element of soil fertility ” in some aspect.
3. Influenced by natural rainfall and evaporation, The Cl- content’s distribution in time space in fields presents very strong seasonal dynamic trend. Natural environment factors play an important role in Cl- balance of farmland soil. So to monitor of Cl- accumulation and transport in soil profile is significant in explaining the accumulative state and velocity of Cl- in long-term fertilization, and controlling the movement of water and managing soil water condition.
4. The absorption and utilization of Cl- in crop growth process has become an important factor in Cl- balance in farmiland soil. Field and pot experiments showed that crops have
luxurious absorption of Cl-, crops can carry away a mount of Cl- from farmland soil. Crops have strong capacity of physiological absorption and acceptance. The condition of soil water could help Cl- transfer, absorb Cl- by crops. At present, there is large potential capacity of Cl- in the farmland soil.
5. The soil structure and porosity distribution are main factors that influence Cl- transfer. The retardance factor and DSH of Cl- in different texture and diameter aggregate showed: Although Cl- is thought as non-reflecting ion, its transfer is still significantly influenced by the porosity in soil structure or between the soil structures obviously. Soil structure is the substantial basis of Cl- tranfer.
引文