环渤海盐碱地台田季节性脱盐效率与生产效益分析

Seasonal Changes in Desalination Mechanisms and Economic Benefit Analysis on the 'Raised Field-Shallow Pond' in Saline-Alkali Regions around the Bohai Sea

环渤海滨海地区淡水资源缺乏,季节性旱、涝与盐碱、地下潜水矿质化共生,是该地区农业生产极不稳定的主要原因。本文选择东营地区台田-浅池与黄骅重盐碱地实验台田-浅池为研究对象,采用野外实验与调查问卷相结合的方式,对比分析了两地台田-浅池模式脱盐效率和生产效益。结果表明气候季节性变化导致盐荒地表层盐量变化大,严重影响作物生长发育。台田减轻或遏制了季节性雨热条件变化下的剧烈反盐,耕层全年脱盐效率达58.8%,其中东营沙性土质台田耕层年平均脱盐效率为79.7%,种植棉花产量4500kg/hm2,与传统利用模式相比增加50%;黄骅台田耕层年平均脱盐效率为37.9%,种植棉花产量3000kg/hm2。台田浅池模式能起到降盐、稳盐及抗洪调蓄水源的作用,利于环渤海盐碱地粮食产量稳定和土地高效生产。本文研究结果可为环渤海重盐碱地土壤改造、粮食增产、土地综合利用提供重要参考。

There are 30 million hectares of saline-alkali soil land in China, accounting for 7% of the total state-owned arable land. Fresh water resources are extremely scarce around the Bohai Sea coastal areas. In addition, droughts, waterlogging, salinity and groundwater mineralization frequently happen over the areas. As a result, agricultural productions for this region are extremely instable in general. In the present work, the land use pattern of the ＇raised field-shallow pond＇ model for agricultural lands in Dongying City, Shandong Province, and heavily saline-alkali land in Huanghua County, Hebei Province were investigated by incorporating field experiments with questionnaire survey. The desalination efficiency and production improvement benefits in the two study sites were compared and analyzed in detail. Results showed that climatic factors often leaded to a significant variation in surface salt in salty wastelands during periods of seasonal changes, which greatly affected the crop growth and development. More salinity in topsoil was accumulated during a short period of hot weather in summer. If precipitation amount was relatively large, surface runoff would result in serious losses of heavily sticky soil due to its poor permeability, which was however contrary to the full desalinization efficiency of salt. It was found that the ＇raised field-shallow pond＇ model can reduce or restrain water and soil loses to some degree, thereby indicating an important role in dramatic salt reductions and in alleviating or eliminating acuity salt accumulation during periods of seasonal rain and heat changes. The desalinization efficiency of the furrow layer in the ＇raised field -shallow pond＇ model was estimated to be roughly 58.8% and the average desalination efficiency of the sandy soil furrow layer of the ＇raised field-shallow pond＇ in Dongying City was about 79.7%. The cotton yield was 4500 kg per hectare; it was increased by 50% compared with the traditional farming mode. The input-output ratio was about 1：3.75. It was also found that the average desalination efficiency of the clay soil furrow layer of the ＇raised field-shallow pond in Huanghua County was 37.9%, with showing a cotton yield of 3000 kg per hectare and an input-output ratio of 1：2.5. The ＇raised field-shallow pond＇ plays a prominent role in desalination, salt-stability and water resources regulation and storage during periods of seasonal rain and heat changes. It can also be a field for farming and fishing, providing farmers with productive lands and fishing ponds as well as regulating salt content in infertility lands. This study would offer meaningful reference for soil transformation for heavily saline-alkali lands, grain production improvement, land utilization and eco-economic development around the Bohai Sea coastal areas.