Soil Respiration Components and their Temperature Sensitivity Under Chemical Fertilizer and Compost Application: The Role of Nitrogen Supply and Compost Substrate Quality

Abstract

Understanding autotrophic (Ra) and heterotrophic (Rh) components of soil respiration (Rs) and their temperature sensitivity (Q10) is critical for predictingsoil carbon (C) cycle and its feedback to climate change. In agricultural systems, these processes can be considerably altered by chemical fertilizer and compost application due to changes in nitrogen (N) supply and substrate quality (decomposability). We conducted a field experiment including control, urea, and four compost treatments. Ra and Rh were separated using the root exclusion method. Composts were characterized by chemical analyses, 13C solid‐state nuclear magnetic resonance, and lignin monomers. Annual cumulative Ra, along with root biomass, increased with soil mineral N, while Rh was suppressed by excessive N supply. Thus, Ra was stimulated but Rh was decreased by urea alone application. Annual Rh was increased by application of compost, especially that containing most lignin vanillyl and syringyl units, O‐alkyl C, di‐O‐alkyl C, and manganese. However, during the initial period, Rh was most effectively stimulated by the compost containing most carbohydrates, lignin cinnamyl units, phenolic C, and calcium. Ra was mediated by N release from compost decomposition and thus exhibited similar responses to compost quality as Rh. The Rh Q10 was reduced, while Ra Q10was increased by chemical fertilizer and compost application. Moreover, the Rh Q10 negatively related to soil mineral N supply and compost indicators referring to high substrate quality. Overall, our results suggest that N supply and substrate quality played an important role in regulating soil C flux and its response to climate warming.

Soil CO2 Efflux Response to Combined Application of Adaptation Technologies, Nitrogen Fertilization, and External Carbon Amendment in Wheat and Barley Field

“…The effect of compost on Rs also depends on the composition and quality of the compost, which means, e.g. amount of dissolved organic C, lignin, minerals, or C:N ratio (Chen et al, 2019;Ma et al, 2019). The temporality of the compost amendment on Rs was also confirmed in previous studies.…”

“…Newly available organic C can be rapidly decomposed by microorganisms resulting in an increase in Rs as observed, e.g. by Wilson et al (2018) or Chen et al (2019). The effect of compost on Rs also depends on the composition and quality of the compost, which means, e.g.…”

Seasonal Dynamics of Soil Respiration and Its Autotrophic and Heterotrophic Components in Subtropical Camphor Forests

“…The study suggested that the fractional contribution of R a to R s may be greater in boreal forests than in temperate forests, reflecting regional differences in ecosystem dynamics [39]. These study findings contribute to our understanding of the variation in R a and R h contributions to R s , highlighting a multitude of factors influencing these dynamics with the potential to exhibit regional distinctions [40].…”

Response of Different Coffee-Based Agroforestry Management on Microbial Respiration and Density

“…Applying inorganic fertilizers mixed with organic fertilizers and the temperature changes due to pruning heavily influencing soil respiration, specifically autotrophic respiration. Applying N fertilizer (inorganic fertilizers) increases root biomass, even in a small dose, and triggers autotrophic respiration (Chen et al 2017), due to root exudates secretion and microbial activity in the soil to decompose OM (Chen et al 2017(Chen et al , 2019. Heterotrophic respiration is suspected as a main driver, which determines soil respiration due to the given management at 20-40 cm depth.…”