Soil health evaluation approaches along a reclamation consequence in Hangzhou Bay, China

Reclamation has been widely used to alleviate the degradation of cultivated upland and support the increasing grain demand. However, the response of soil ecosystem functioning and soil health to the reclamation of coastal wetlands remains unclear. A reclaimed soil chronosequence over 1000 years in Hangzhou Bay, China, was analyzed to assess two key approaches to evaluate soil health. We used the minimum data set along with the soil quality index (SQI) area and the sensitivity-resistance approaches. The physicochemical properties of the reclaimed soils changed drastically at the initial stage (during the first 60 years) but only marginally thereafter. Owing to continuous freshwater irrigation, plant cultivation, fertilization, and desalination, from natural tidal flats converted to vegetable fields, the SQI and soil multifunctional index increased along the reclamation chronosequence. The soil properties sensitive to the reclamation of coastal wetlands (electrical conductivity, exchangeable potassium, and enzyme activities) explained most of the variation in the SQI area, followed by the resistance indicators. This suggests that small changes in the sensitivity indicators might have considerable impacts on the improvement of soil quality. The most resistant properties with the slowest changes included pH and physical characteristics-water content, bulk density, and aggregate size classes. The quality indicators identified for reclaimed soils in Hangzhou Bay based on the SQI area and sensitivity-resistance approaches can be useful for soil health evaluation for soils affected by natural and anthropogenic factors. These approaches and indicators can be effectively used to evaluate soil quality and develop sustainable agriculture.

Automated summary

Reclamation has been widely used to alleviate land degradation and support increased grain demand. However, the impact of reclamation on soil ecosystem functioning and soil health in coastal wetlands is still uncertain. Through analyzing a chronosequence of reclaimed soils in Hangzhou Bay, China, over a 1000-year period, two key approaches for evaluating soil health were assessed. The findings suggest that even small changes in sensitivity indicators can have significant impacts on improving soil quality.