Purpose

The assessment of soil quality related to different reclamation years and land use/cover types is the key parameter to evaluate the success of reclamation activities in coastal saline soil.

Materials and methods

Soil samples were collected from natural bare flat and coastal wetlands that have been reclaimed for different times (7, 32, 40, and 63 years) to investigate the change in soil quality during the process of reclamation in this study. Soil quality was evaluated using a soil quality index (SQI), which was calculated by the selected minimum dataset (MDS) and the technique for order preference by similarity to ideal solution (TOPSIS) methods.

Results and discussion

Soil water content (SWC), bulk density (BD), electrical conductivity (EC), and pH were observed significantly decreased whereas soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), urease (URE), and acid and alkaline phosphatase (ACP and ALP) activities notably increased after 60 years of reclamation. However, amylase (AMY) activity increased first and then decreased, and dehydrogenase (DEH) activity showed weak differences within 60 years reclamation. Further, TN, EC, AMY, and ACP activity were in the MDS with 12 soil properties as soil quality indicators. The SQI values varied from 0.05 in the bare flat soils to 0.86 in the soils after 63 years of reclamation and improved with increasing reclamation years. In addition, the SQI values of different land use/cover types were in the order of bare flat (0.07 ± 0.03) < uncultivated land (0.22 ± 0.16) < Spartina alterniflora (0.25 ± 0.16) < fishpond (0.57 ± 0.10) ≈ wheat land (0.58 ± 0.08) ≈ broad bean land (0.58 ± 0.07) < rape land (0.73 ± 0.15).

Conclusions

Soil quality improved with the increase of reclamation years. Additionally, low levels of TN and high concentrations of EC were the primary constraints restricting soil quality in bare flat and soil in the early stage of reclamation, whereas AMY activity was the main obstacle after 30 years of reclamation.

中文翻译：

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东部农垦海盐土壤长期开垦对土壤质量的影响

目的

与不同开垦年限和土地利用/覆被类型相关的土壤质量评估是评估沿海盐渍土壤开垦活动成功与否的关键参数。

材料和方法

从已经开垦了不同时间（7、32、40和63年）的天然裸露的平坦和沿海湿地收集土壤样品，以研究本研究在开垦过程中土壤质量的变化。使用土壤质量指数（SQI）评估土壤质量，该指数由选定的最小数据集（MDS）和与理想溶液法（TOPSIS）相似的顺序偏好技术计算得出。

结果和讨论

观察到土壤含水量（SWC），堆密度（BD），电导率（EC）和pH显着降低，而土壤有机碳（SOC），总氮（TN），总磷（TP），脲酶（URE），开垦60年后，酸性和碱性磷酸酶（ACP和ALP）的活性显着增加。但是，淀粉酶（AMY）活性先升高，然后下降，而脱氢酶（DEH）活性在开垦60年内显示出较弱的差异。此外，TN，EC，AMY和ACP活性在MDS中以12种土壤特性作为土壤质量指标。在开垦63年后，SQI值从裸露的平地土壤中的0.05到土壤中的0.86，随着开垦年限的增加而提高。此外，不同土地利用/覆盖类型的SQI值按裸地（0.07±0.03）<互花米草（0.25±0.16）<鱼池（0.57±0.10）≈小麦地（0.58±0.08）≈蚕豆地（0.58±0.07）<油菜地（0.73±0.15）。

结论

随着开垦年限的增加，土壤质量得到改善。此外，在开垦初期，低水平的总氮和高浓度的EC是限制裸露土地和土壤质量的主要限制因素，而开垦30年后，AMY活性是主要障碍。