资源环境约束下的天津市盐渍土农业利用研究

盐渍土作为一种重要的宜耕后备资源,其农业开发利用已成为解决人口、粮食、资源和环境等问题的重要措施。论文通过天津市盐渍土农业利用中面临的水土资源短缺、环境污染与经济效益差等问题进行系统分析后得出：目前天津市盐渍土面积为32.42×10⁴ hm²,其中,重度盐渍土与盐土大多分布在滨海平原地区,这些区域恰恰是补充耕地的主要来源,然而由于其盐渍化程度原本就高,即使改良后很快又会返盐;天津市目前年均缺水量为6×10⁸~9×10⁸ m³,水资源短缺已成为限制农业发展的重要瓶颈问题,若改良这些盐渍土宜耕后备资源并继续采用传统的农业耕作方式,将会进一步加大农业用水缺口,农药、化肥、地膜的过量施用,也加重了环境污染危害;并且,耗费巨大成本改良后的耕地,由于比较效益差、后续利用与管理资金难以维系,面临着无人耕种的困境。随着城市化与社会经济发展结构的变化,农业早已不再是天津市国民经济发展的主导产业。但是为了保障国家粮食安全,天津市也必须承担一定的耕地保有量和基本农田保护任务。鉴于大都市区对蔬菜的巨大需求,综合考虑区域资源、环境与效益因素,在滨海平原的盐渍土上发展设施水培蔬菜,不仅可有效缓解耕地保护压力,保护生态环境、提高经济效益,将北京市的蔬菜基地外迁至滨海平原,也有助于促进京津一体化发展。

Agricultural Utilization of Saline-alkaline Soil under the Constraint of Resources and Environment in Tianjin

With the sprawl of cities and towns and the spring-up of secondary and tertiary industries, more and more attentions have been paid to the development and utilization of saline-alkali soil in order to alleviate and partially solve the pressure on food safety and security, as well as natural resource and environment carrying capacity. The contradiction between urbanization and food supply in Tianjin has become much more severe with the culturable land and irrigating water shortage caused by the absorption of some urban functions and migrant labors from Beijing. The problems of environmental pollution and poor economic performance also came into existence. Properly using land for agricultural purpose without breaking out the carrying capacities of natural resources and environment has brought the requirement of utilizing local saline-alkali soil. In order to find out an effective method to solve the problem, this paper carried out systematic studies on the agricultural utilization of saline-alkali soil in Tianjin. From field survey and lab experiment data, it can be found that the total amount of saline-alkali soil in the study area is 32.42×10⁴ hm², and the main source that can be developed into farmland locates in the coastal plain areas. However, since traditional farming mechanism can’t maintain the arability of newly added farmland for a long period, these lands could turn back to the former conditions before development. The annual water deficit in Tianjin is about 6×10⁸-9×10⁸ m³. Water shortage has become the bottle neck for agricultural development. Irrigation desalting and traditional farming mechanism (e.g. the usage of chemical fertilizer and mulch etc.) will increase the water deficit and cause severe water supply disequilibrium, environment contamination and accumulation of poisonous waste. Furthermore, without scientific and sustainable fiscal inputs into agriculture, these newly added farmland may eventually be abandoned and turned into vacant and underutilized land. The changing socio-economic structure and urbanization have taken away the place of agriculture as the dominant industries in Tianjin. So, systematic consideration of regional resources, environment and benefits is the key during the process of saline-alkali soil development. From this point of view, water-cultured vegetable industry is the way of land development and soil improvements which can reduce the potential risks mentioned above and alleviate the pressure of food supply and environment protection.