Abstract
Analysis of soil properties, the compositional traits in bulk soil and different fractions and their responses to afforestation practices may possibly facilitate clarification of the mechanisms underlying soil changes. Soil properties, the compositional functional groups and minerals were determined in the bulk soil and fractions from forests and adjacent farmlands. The afforestation of farmland could induce accumulation of soil organic carbon [SOC] (+18%) and nitrogen [N] (+4%) with pH increase (+4%), and declines in electric conductivity (−15%) and bulk density (−3%). Sand and aggregates [SA] and easily oxidized fraction [EO] mainly contributed to the SOC and N accumulation. Moreover, afforestation-induced changes were observed in O-H & N-H stretching (−26%), feldspar (+52%) and huntite crystallinity (−40%). The changes of soil properties were strongly associated with the changes in functional groups, followed by minerals. Of them, asymmetric COO- & C = O stretching & O-H bending, symmetric COO- stretching, huntite and smectite-vermiculite crystallinity were the key factors responsible for the changes of soil properties. Our findings highlight that degraded farmland afforestation could strongly affect soil properties in the bulk soil, and the changes in fractions (mainly SA and EO) as well as their changes in the compositional traits strongly supported these bulk soil changes.
Highlights
Afforestation of degraded farmland appears to be a sustainable alternative to forest conservation because it has the potential to provide woody perennials, and is considered as an important option for carbon sequestration and degraded soil improvement[1]
The objectives of this study were to explore (1) how large afforestation-induced changes in soil properties, and which soil fractions mainly contribute to the changes? (2) what kind of changes were in X-ray diffraction (XRD)-mineral features and Fourier transform infrared spectroscopy (FTIR)-functional groups, and which soil fractions contribute to these changes? (3) What’s the associations between soil compositional traits and variations of soil properties? This study is expected to provide the underlying mechanisms of changes in soil properties after afforestation of farmland, and the related data will provide supports for the evaluation of afforestation on soil rehabilitation
The maximum percentage was that of acid-insoluble fraction (AI)+easily oxidized fraction (EO), followed by AI, and sand and aggregate (SA), while the minimum percentage were in EO, particulate fraction (PT) and soluble fraction (SB)
Summary
Afforestation of degraded farmland appears to be a sustainable alternative to forest conservation because it has the potential to provide woody perennials, and is considered as an important option for carbon sequestration and degraded soil improvement[1]. Together with the FTIR and XRD techniques, ectomycorrhizal influences on particle size, surface structure, mineral crystallinity, functional groups of soil colloids from different soil origins could be elucidated[18]; and the compositional traits of glomalin related soil protein (GRSP) and their differences in different land uses could be determined[24,25,26]. By using a combination of the FTIR and XRD techniques and soil physicochemical fractionation, we want to provide an insight into the changes in soil compositional traits following afforestation from the perspective of functional groups and mineral crystallinity in the bulk soil and different soil fractions. We hypothesized that afforestation can strongly alter SOC, fertility and physiochemical properties in the bulk soil and different soil fractions, while underlying reasons for these changes are related with the compositional traits of FTIR-functional groups and XRD-mineral features. The objectives of this study were to explore (1) how large afforestation-induced changes in soil properties, and which soil fractions mainly contribute to the changes? (2) what kind of changes were in XRD-mineral features (relative crystallinity) and FTIR-functional groups (relative content), and which soil fractions contribute to these changes? (3) What’s the associations between soil compositional traits and variations of soil properties? This study is expected to provide the underlying mechanisms of changes in soil properties after afforestation of farmland, and the related data will provide supports for the evaluation of afforestation on soil rehabilitation
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
