The relative importance of influence factors to field soil respiration is shifted by straw incorporations: comprehensive analysis of the seasonal variability

Abstract

Purpose

Understanding the effects of agricultural managements (e.g., straw incorporation) on soil respiration (R_s) and its temperature sensitivity (Q₁₀) is crucial for accurate estimation of the soil carbon sequestration potential under an increasing-temperature scenario in the future. However, how the influence drivers regulate R_s and whether their relative roles are changed under different agricultural practices remain unexplored.

Materials and methods

Static chambers were used to monitor field CO₂ flux in one growing season for a straw return experiment, which had been amended with different amounts of straw (CK, no straw return; S₄, straw amendment at 4000 kg ha⁻¹; and S₈, straw amendment at 8000 kg ha⁻¹) for five consecutive years.

Results and discussion

Our monitoring showed that R_s was elevated with intensified use of straw and confirmed soil temperature, soil moisture, and rainfall were important seasonal drivers of R_s. Moreover, the lower coefficient of variations (CV) for each series of treatments of R_s was detected at the vigorous growth stage of the crop, implying the biotic factor of crop roots might also exert a role simultaneously. Straw addition tended to reduce Q₁₀, probably due to the fact that the microbial degradation of SOC in S₄ and S₈ was less sensitive to temperature change. Interestingly, the Q₁₀ of S₄ but not S₈ was significantly smaller (P < 0.05) than that of CK as the reduced magnitude of Q₁₀ for S₄ was more profound. This result corresponded with more proportional growth of crop root of S₈ than S₄. By comprehensively analyzing the seasonal variability of our data set, we inferred that for S₈, the negative impact of straw incorporation on Q₁₀ would be more offset by upregulated root metabolism.

Conclusions

Although additional works were needed to corroborate and specify this explanation, present research highlighted the abiotic and biotic factors should both be incorporated to analyze the underlying mechanisms responsible for the seasonal dynamics of soil C emissions under agricultural managements.

from Energy Ecology Environment Ambio via Terpsi Hori on Inoreader https://ift.tt/2Ljbmw9