Estimating the influence of related soil properties on macro- and micro-aggregate stability in ultisols of south-central China
2016
Wang, Jun-guang | Yang, Wei | Yu, Bing | Li, Zhao-xia | Cai, Chong-fa | Ma, Ren-ming
Stable macro- or micro-aggregates are important for preventing soil degradation. The interactions among soil aggregates and stabilizing agents—like clay, soil organic matter (SOM), Fe, and Al oxides—are complex and have not been fully understood.Eight ultisol samples were collected from the surface (0–10cm) and subsurface layers (10–20cm). The macro-aggregate stability was determined by wet sieving, and the micro-aggregate distribution was determined via particle size distribution analysis; however, no chemical dispersant (sodium hydroxide) was applied. Using the PLSR models, the main soil properties that affect macro-aggregate and micro-aggregate stability were estimated.All soils were strongly acidic (pH4.28–5.56) with low SOM content (<20gkg−1). The dithionite-citrate-bicarbonate extractable Fed and Ald were the dominant forms in Fe and Al oxides, much greater than acid ammonium oxalate extractable Feo and Alo. For most soils, the percentage of >5mm aggregates was the highest, and the percentage of 2–1mm aggregates was the lowest after wet sieving. Soil parent materials had a significant effect on the particle size distribution of the micro-aggregates. The stability of macro-aggregates and micro-aggregates from Quaternary red clay was stronger than that from Shale (p<0.05). Regardless of the soil parent materials, the water stability of surface cropland soil macro-aggregates was significantly lower than that of the other land-use types, but the micro-aggregate stability exhibited no trend across different land use types.Ald was the most important binding agent of the macro-aggregates, and clay was the main binding agent of the micro-aggregates, followed by the Fed, Alo, CEC and SOM, while Feo was the weakest agent.
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