蚯蚓资源在海冰水改良渤海湾滨海盐渍土壤中的应用前景

Potential Application of Earthworm for Saline Soil Remediation with Sea Ice in the Bohai Bay

海冰在其成冰过程中盐分大量析出而盐度较低,可能成为干旱季节的一种灌溉水资源。海冰水改良滨海盐渍土是在渤海湾地区利用海冰融解的低盐水灌溉和淋洗高盐土壤的一种措施,该措施应用的同时也产生土壤熟化时间慢、土壤结构恶化、土壤养分的流失和土壤生物种群数量减少等问题。本文在收集和分析大量资料基础上,论述了蚯蚓与盐渍土壤的相互关系:盐碱地土壤中蚯蚓种类和盐渍土壤对蚯蚓的影响因素。根据在盐渍土壤中,蚯蚓活动能够增加有机物的分解和养分释放,同时使盐碱地土壤的团聚体结构、渗透率、生物数量和活性得以恢复和改善,进一步阐述了在海冰水改良滨海盐渍土壤中引入蚯蚓的可行性,并探讨引入蚯蚓改良滨海盐渍土壤的研究方法和存在的问题以及今后的研究方向。

Soil salinization is one of the biggest threats to agricultural lands. The problem of low productivity of saline soil may be ascribed not only to their salt toxicity or shortage of water resources but also to the lack of organic matter and available nutrients. Salt separation from sea ice in freezing processes can result in a lower salinity in sea ice, which may become a resource of irrigation in dry seasons. In the area of the Bohai bay, sea ice melt-water could be a promising approach to reclaiming saline soil through irrigation and leaching of salt soil in the context of fresh water resources scarcity in winter and spring. The application of sea ice melting water could be conductive to increasing yields of different crops and leaching soil salinity of the root zone into depth soil if adopting reasonable irrigation scheduling. However, the processes of reclamation have resulted in a series of problems such as a longer time of saline soil reclamation, deterioration of soil structure, losses of soil nutrients, environmental effects of salinity on soil organism population （e.g., microorganisms, earthworms, nematodes, protozoa and other soil fauna） as well as soil enzyme activities. In this present paper, the authors discussed the relationship between earthworm resources and saline soil, including different earthworm species in the Bohai bay areas and the influencing factors on soil salinity on earthworm numbers and activities. Earthworms are important components of the soil fauna in a wide variety of soils. There have been numerous studies indicating that earthworm activities may have the capability to increase decomposition rate of organic materials, release available nutrients for crops and increase the number of soil microorganism and fauna. Meanwhile, the activities of earthworm （burrowing, comminution, feeding, casting activities） in soil may also be useful for the formation of soil aggregations and improvement of soil physical structure and permeability. Then, existing methods for collecting and reproducing earthworm species which are suitable for restoring saline soil were discussed. This study demonstrated that it is most likely that earthworm inoculation can be useful in saline soil remediation under the condition of sea ice water agricultural irrigation. Meanwhile further investigation is necessary to study the inoculated methods for earthworms getting into saline soil. A variety of experiments will be carried out in laboratories with the objective to investigate what kind of conditions （soil temperature, salinity, water content and pH） of saline soils are suitable for earthworms and the effects of earthworm activities on the decomposition of organic residues added into saline soil.