Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, 48824, USA.
Department of Horticulture, Michigan State University, East Lansing, MI, 48824, USA.
Sci Rep. 2021 Nov 9;11(1):21998. doi: 10.1038/s41598-021-01533-7.
Bioenergy cropping systems can substantially contribute to climate change mitigation. However, limited information is available on how they affect soil characteristics, including pores and particulate organic matter (POM), both essential components of the soil C cycle. The objective of this study was to determine effects of bioenergy systems and field topography on soil pore characteristics, POM, and POM decomposition under new plant growth. We collected intact soil cores from two systems: monoculture switchgrass (Panicum virgatum L.) and native prairie, at two contrasting topographical positions (depressions and slopes), planting half of the cores with switchgrass. Pore and POM characteristics were obtained using X-ray computed micro-tomography (μCT) (18.2 µm resolution) before and after new switchgrass growth. Diverse prairie vegetation led to higher soil C than switchgrass, with concomitantly higher volumes of 30-90 μm radius pores and greater solid-pore interface. Yet, that effect was present only in the coarse-textured soils on slopes and coincided with higher root biomass of prairie vegetation. Surprisingly, new switchgrass growth did not intensify decomposition of POM, but even somewhat decreased it in monoculture switchgrass as compared to non-planted controls. Our results suggest that topography can play a substantial role in regulating factors driving C sequestration in bioenergy systems.
生物能源种植系统可以为减缓气候变化做出重大贡献。然而，关于它们如何影响土壤特性（包括孔隙度和颗粒有机物质（POM））的信息有限，而这些特性是土壤碳循环的重要组成部分。本研究的目的是确定生物能源系统和田间地形对新植物生长下土壤孔隙特征、POM 和 POM 分解的影响。我们从两种系统（单一种植柳枝稷（Panicum virgatum L.）和原生草原）中收集了完整的土壤芯，在两个截然不同的地形位置（洼地和斜坡），将一半的土壤芯种植柳枝稷。在新柳枝稷生长前后，使用 X 射线计算机断层扫描（μCT）（18.2 µm 分辨率）获取孔隙度和 POM 特性。与柳枝稷相比，多样化的草原植被导致土壤 C 含量更高，相应地，半径为 30-90 µm 的孔隙体积更大，固-孔界面更大。然而，这种影响仅存在于斜坡上的粗质地土壤中，并且与草原植被的更高根生物量有关。令人惊讶的是，新柳枝稷的生长并没有加剧 POM 的分解，与未种植对照相比，甚至在单一种植柳枝稷中有所减少。我们的研究结果表明，地形可以在调节生物能源系统中碳固存的因素方面发挥重要作用。
