Lei Du , Sara L. Bauke , Ramona Mörchen , Oliver Schmittmann , Wulf Amelung
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引用次数: 0
Abstract
Organic matter (OM) injection into subsoil is expected to improve subsoil properties and thus increase crop nutrient and water uptake from the subsoil. Nevertheless, detailed knowledge of the fate and persistence of injected OM in subsoil does not yet exist. For this study, we sampled a field experiment, where two types of compost of different composition (Bio-waste compost and Green-waste compost, differing in carbon:nitrogen ratio) had been injected into the subsoil at three application amounts each (3, 5, and 7 kg dry mass m−1), and assessed the distribution of soil organic carbon (SOC) into different density fractions, the temperature sensitivity of soil respiration (Q10), and microbial necromass in subsoil. The results demonstrate that both Bio-waste and Green-waste compost injections enhanced the SOC stock, respiration rates, and temperature sensitivity in both top- and subsoil. In the subsoil, respiration rates were increased by 78 %, simultaneously compost addition enhanced microbial growth (increase in fungal residues by 123 %) but also increased the amount of carbon (C) in the mineral fraction. Significant differences in the δ13C values of density fractions and Q10 values were only detected between compost types rather than the amount of injected compost. Especially the Bio-waste compost with a narrower C:N ratio contributed to slightly greater soil labile C content, and ultimately elevated respiration rates in the subsoil. Hence, the fate of subsoil incorporated C is controlled by its composition rather than by the injected amount. Moreover, a higher contribution of fungal necromass C to the increase in Q10 values after compost injection was observed in the present study than for bacterial necromass C, suggesting that fungi are largely responsible for the final, enhanced storage of the C injected.
期刊介绍:
Soil & Tillage Research examines the physical, chemical and biological changes in the soil caused by tillage and field traffic. Manuscripts will be considered on aspects of soil science, physics, technology, mechanization and applied engineering for a sustainable balance among productivity, environmental quality and profitability. The following are examples of suitable topics within the scope of the journal of Soil and Tillage Research:
The agricultural and biosystems engineering associated with tillage (including no-tillage, reduced-tillage and direct drilling), irrigation and drainage, crops and crop rotations, fertilization, rehabilitation of mine spoils and processes used to modify soils. Soil change effects on establishment and yield of crops, growth of plants and roots, structure and erosion of soil, cycling of carbon and nutrients, greenhouse gas emissions, leaching, runoff and other processes that affect environmental quality. Characterization or modeling of tillage and field traffic responses, soil, climate, or topographic effects, soil deformation processes, tillage tools, traction devices, energy requirements, economics, surface and subsurface water quality effects, tillage effects on weed, pest and disease control, and their interactions.