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Reclamation and Utilization of Saline Soils in Arid Northwestern China: A Promising Halophyte Drip-Irrigation System Lei Wang, Zhen-Yong Zhao, Ke Zhang, and Chang-Yan Tian* State Key Laboratory of Desert and Oasis Ecology, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China arable land resources, occupy a significant strategic position in agriculture. Recently, rational reclamation and suitable utilization of saline soils in arid areas has become a major issue in China and has attracted increasing awareness from both government administrators and scientists. In China, about 25 million hectare saline soils in arid area remain uncultivable because of high salinity and water scarcity. Various approaches to reclaim saline soils including engineering, mechanical, chemical and biological are widely applied in northwestern China.1 However, such approaches have not yielded desirable results due to high costs or water limitations. Revegetation of saline soils with salt hyperaccumulating halophytes is a proactive phytoremediation method. Many halophytes such as Suaeda maritima and Sesuvium portulacastrum are reported to accumulate high contents of salt in their above ground tissues,2 and saline soils can be remediated by harvesting the plants regularly. To plant halophytes with limited water resources, this is a question of primary importance for arid saline soil recovery. Drip-irrigation is an effective irrigation technique to improve water use efficiency and is widely applied in traditional crops all over the world, especially in arid regions. This technology has the potential to plant halophytic crops and to obtain high-yield ithin the context of arable land and fresh water limits biomass with less irrigation water. Many halophytes have and a large population, the ability of China’s agriculture succulent leaves or small leaves, so we expect that water to meet demands for food, fodder, and fuel presents a falling consumption for halophyte cultivation may be less than or tendency. Therefore, it is crucial for China to find appropriate similar to local crops grown under drip-irrigation. We hope that methods and effective technologies to solve the food security by using this system, a crucial step will be taken to break the problem, to achieve agricultural stability and sustainable bottleneck of biological reclamation of saline soils in arid areas. development. Saline agriculture is proposed as one of the Not only can saline agriculture reclaim saline soils efficiently, best solutions to deal with this threat. Success stories in saline it can also directly provide food, fodder, renewable energy and agriculture have been documented in India and Pakistan. raw materials for industry. Scientists have found thousands of Nearly 70% of the total area of China’s saline soils occur in arid halophytes with great potential for development. Halophytes or semiarid regions,1 so developing water-saving saline grown under saline conditions show levels of biomass and seed agriculture is perhaps an efficient method for the optimized production comparable to conventional crops. For instance, matching of agricultural water and soil resources. As an Salicornia bigelovii, an oil-seed halophyte, could produce ca. 18 advanced irrigation technique with water-saving advantages, tons ha−1 of biomass and 2 tons ha−1 of seeds.3 Some drip-irrigation is widely used in traditional agriculture halophytes have high nutritional value as forage or fodder throughout China. Here, we propose that planting halophyte crops.4 The restricting factor is their high salt content, but this crops under drip-irrigation conditions may be a promising limitation can be moderated by leaf protein extraction. approach for reclamation and utilization of saline soils in arid Although the direct consumption of halophytic crops by northwestern China. humans and animals is limited, their seeds are being considered China’s National Medium- and Long-Term Program for as new sources of grains or vegetable oils. Recent research Food Security (2008−2020) shows that China’s food security carried out in Pakistan showed that some halophytes have faces serious challenges, including rigid growth of commissary potential as bioethanol crops.5 consumer demand, reduction of the arable land, and shortage of agricultural water resources. According to the Ministry of Land Resources of China, China is approaching the arable land “red Received: March 22, 2013 line” (120 million hectare) because of urbanization, salinizaition Accepted: May 1, 2013 and desertification. Saline soils, which are precious candidate
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© XXXX American Chemical Society
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dx.doi.org/10.1021/es4017415 | Environ. Sci. Technol. XXXX, XXX, XXX−XXX
Environmental Science & Technology
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Although planting halophytes with drip-irrigation can potentially benefit the reclamation of arid saline soils, problems may exist, partly due to the complexity of agro-ecosystems and the absence of related experiments. For example, though we propose that halophyte drip-irrigation systems may play a crucial role in removing salt and improving soil quality, it remains unclear how much water is really needed for halophytic crops, particularly when other artificial or natural factors are considered. It remains controversial whether the halophytic crops will suffer from severe pests and diseases. At present, there are no mature techniques for selecting and cultivating halophytic crops in China. Some suggestions are highlighted here to address these potential problems. First, potential halophytic crops should be tested under saline field conditions. China has about 500 native halophytes, a precious resource for saline soil reclamation and utilization purposes. Meanwhile, good halophytic crops from foreign countries should be introduced into China. Second, fundamental research and long-term field experiments need to be conducted. Optimizing the growth of different halophytes will require different water or fertilizer demands. Third, it is essential to study the occurrence of and find appropriate countermeasures to pests and diseases in halophytic crops under drip-irrigation conditions. Only when such aspects are addressed, can reclamation and utilization of saline soils using halophyte drip-irrigation systems have a prosperous future in arid and semiarid regions of northwestern China.
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AUTHOR INFORMATION
Corresponding Author
*Phone: +86-991-7885301; fax: +86-991-7885320; e-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS This work was supported by Project of Science and Technology Plan of the Xinjiang Uygur Autonomous Region (2011301062) and the West Light Foundation of the Chinese Academy of Sciences (XBBS201101).
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REFERENCES
(1) Fan, Z. L.; Ma, Y. J.; Ma, Y. J. Salinized soils and their improment and utilization in west China. Arid Zone Res. 2001, 18 (3), 1−6 (in Chinese). (2) Ravindran, K. C.; Venkatesan, K.; Balakrishnan, V.; Chellappan, K. P.; Balasubramanian, T. Restoration of saline land by halophytes for Indian soils. Soil Biol. Biochem. 2007, 39 (10), 2661−2664. (3) Glenn, E. P.; Oleary, J. W.; Watson, M. C.; Thompson, T. L.; Kuehl, R. O. Salicornia bigelovii Torr.: An oilseed halophyte for seawater irrigation. Science 1991, 251 (4997), 1065−1067. (4) Khan, M. A.; Ansari, R.; Ali, H.; Gul, B.; Nielsen, B. L. Panicum turgidum, a potentially sustainable cattle feed alternative to maize for saline areas. Agric. Ecosyst. Environ. 2009, 129 (4), 542−546. (5) Abideen, Z.; Ansari, R.; Khan, M. A. Halophytes: Potential source of ligno-cellulosic biomass for ethanol production. Biomass Bioenerg. 2011, 35 (5), 1818−1822.
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