Motavalli P P, Kremer R J, Fang M, Means N E
Department of Soil, Environmental and Atmospheric Sciences, University of Missouri, Columbia, MO 65211, USA.
J Environ Qual. 2004 May-Jun;33(3):816-24. doi: 10.2134/jeq2004.0816.
One of the potential environmental effects of the recent rapid increase in the global agricultural area cultivated with transgenic crops is a change in soil microbially mediated processes and functions. Among the many essential functions of soil biota are soil organic matter decomposition, nutrient mineralization and immobilization, oxidation-reduction reactions, biological N fixation, and solubilization. However, relatively little research has examined the direct and indirect effects of transgenic crops and their management on microbially mediated nutrient transformations in soils. The objectives of this paper are to review the available literature related to the environmental effects of transgenic crops and their management on soil microbially mediated nutrient transformations, and to consider soil properties and climatic factors that may affect the impact of transgenic crops on these processes. Targeted genetic traits for improved plant nutrition include greater plant tolerance to low Fe availability in alkaline soils, enhanced acquisition of soil inorganic and organic P, and increased assimilation of soil N. Among the potential direct effects of transgenic crops and their management are changes in soil microbial activity due to differences in the amount and composition of root exudates, changes in microbial functions resulting from gene transfer from the transgenic crop, and alteration in microbial populations because of the effects of management practices for transgenic crops, such as pesticide applications, tillage, and application of inorganic and organic fertilizer sources. Possible indirect effects of transgenic crops, including changes in the fate of transgenic crop residues and alterations in land use and rates of soil erosion, deserve further study. Despite widespread public concern, no conclusive evidence has yet been presented that currently released transgenic crops, including both herbicide and pest resistant crops, are causing significant direct effects on stimulating or suppressing soil nutrient transformations in field environments. Further consideration of the effects of a wide range of soil properties, including the amount of clay and its mineralogy, pH, soil structure, and soil organic matter, and variations in climatic conditions, under which transgenic crops may be grown, is needed in evaluating the impact of transgenic crops on soil nutrient transformations. Future environmental evaluation of the impact of the diverse transgenic crops under development could lead to an improved understanding of soil biological functions and processes.
全球转基因作物种植面积最近迅速增加，其潜在的环境影响之一是土壤微生物介导的过程和功能发生变化。土壤生物群的许多重要功能包括土壤有机质分解、养分矿化与固定、氧化还原反应、生物固氮以及溶解作用。然而，相对较少的研究考察了转基因作物及其管理对土壤中微生物介导的养分转化的直接和间接影响。本文的目的是综述与转基因作物及其管理对土壤微生物介导的养分转化的环境影响相关的现有文献，并考虑可能影响转基因作物对这些过程影响的土壤性质和气候因素。旨在改善植物营养的目标遗传性状包括植物对碱性土壤中低铁有效性的更高耐受性、增强对土壤无机和有机磷的获取以及增加对土壤氮的同化。转基因作物及其管理的潜在直接影响包括由于根系分泌物数量和组成的差异导致土壤微生物活性的变化、转基因作物基因转移引起的微生物功能变化以及转基因作物管理措施（如施用农药、耕作以及施用无机和有机肥料）的影响导致的微生物种群改变。转基因作物可能产生的间接影响，包括转基因作物残体的归宿变化以及土地利用和土壤侵蚀速率的改变，值得进一步研究。尽管公众广泛关注，但尚无确凿证据表明目前已发布的转基因作物，包括抗除草剂和抗虫害作物，正在对田间环境中土壤养分转化的刺激或抑制产生重大直接影响。在评估转基因作物对土壤养分转化的影响时，需要进一步考虑多种土壤性质的影响，包括黏土含量及其矿物学、pH值、土壤结构和土壤有机质，以及转基因作物可能种植的不同气候条件。对正在研发的各种转基因作物的未来环境影响评估可能会增进对土壤生物学功能和过程的理解。
