Temporal Variation of Earthworm Impacts on Soil Organic Carbon under Different Tillage Systems

Abstract

Previous research has shown the varied effect of earthworms on soil carbon dynamics. We carried out a 180-day incubation experiment with earthworms and maize residue additions under conventional tillage (CT) and no tillage (NT) system conditions to quantify the earthworm effect in the black soil of northeastern China. Earthworms did not affect soil CO2 emissions, while residue addition significantly increased such emissions. The effects of earthworms on dissolved organic carbon (DOC) and microbial biomass carbon (MBC) gradually weakened with time in CT with and without residue addition, but gradually increased with time in NT with residue addition. In the CT system, earthworms accelerated the soil organic carbon (SOC) mineralization; and the newly added residue decomposed into SOC. In the NT system, earthworms accelerated the decomposition of native residues increasing the SOC content; this increase in decomposition rates by earthworms was greater than the inhibitory effect imposed by the addition of the new residue. Earthworms and residues combine to play a single role in CT and NT. This result will help in the understanding of the role of earthworms and residue in SOC dynamics, and in the development of management strategies to improve SOC.

Legacy Effects of Agricultural Practices Override Earthworm Control on C Dynamics in Kiwifruit Orchards

“…The lack of a significant "earthworm effect" could be due to the fact that our mesocosm experiment did not include the return of aboveground plant residues, which was the usual practice in the INT and ORG systems. Both epigeic and anecic earthworms prefer to consume the surface plant remains instead of the C stored in the soil, and by incorporating this new C down the profile and casting, they significantly enhance soil C stabilization (Zhang et al, 2013;Guo et al, 2019). Despite these limitations, our study showed that intensive managements not only had detrimental effects on the composition and structure of soil detrital food webs by favoring smaller sized organisms against macrofauna in agreement with previous studies (Tsiafouli et al, 2015;Lago et al, 2019), but also led to significantly greater amounts of C being lost from these soils.…”

“…Accordingly, in this study, more CO 2 and DOC were lost from the CONV managed soils with the highest values of microbial biomass. Because microorganisms use DOC to produce their microbial biomass (Guo et al, 2019), a gradual decrease of the DOC/DON ratio was observed over time. This implies that CONV agricultural practices would not only contribute to increased soil respiration rates, but they could also lead to soil organic C depletion in the long term.…”

“…The higher values of this ratio measured at the end of the incubation period indicated that these opposite effects between microbial biomass and the leaching of soluble C and N fractions weakened over time in the ORG treatments, more so in the presence of earthworms. In the absence of new residue additions, earthworms would have had to consume the organic C stored in the soil, leading microbial biomass to decrease and DOC to increase later in time (Lubbers et al, 2017;Guo et al, 2019).…”

Subsoiling during summer fallow in rainfed winter-wheat fields enhances soil organic carbon sequestration on the Loess Plateau in China

“…Although tillage depth under STF increased to 30–40 cm, fewer crop residues were incorporated at this depth because the soil was loosened rather than turned over. Therefore, the higher SOC concentration under NTF and STF than that under PTF at 0–10 cm may have been due to sufficient carbon inputs from crop residues [ 40 ].…”

The Toxic Effects of Sulfoxaflor Induced in Earthworms (Eisenia fetida) under Effective Concentrations

“…Earthworms are widely distributed in soil [11,12]. There is much evidence to prove the importance of earthworms in ecosystem functioning [13][14][15]. In previous research, Wang et al [11] used a filter paper method to determine the toxicity of neonicotinoids to earthworms and found that compared with other pesticides, nicotinic insecticides showed higher toxicity to earthworms.…”