Conventional tillage decreases the abundance and biomass of earthworms and alters their community structure in a global meta‐analysis. (31st May 2017)

• Record Type: Journal Article
• Authors: Briones, María Jesús I.; Schmidt, Olaf
• Is Part Of: Global change biology. Volume 23:Number 10(2017)
• Page Start: 4396
• Page End: 4419
• Publication Date: 2017-05-31
• Subjects: agricultural management -- community composition -- ecological groupings -- Oligochaeta -- tillage systems; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.13744
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: The adoption of less intensive soil cultivation practices is expected to increase earthworm populations and their contributions to ecosystem functioning. However, conflicting results have been reported on the effects of tillage intensity on earthworm populations, attributed in narrative reviews to site‐dependent differences in soil properties, climatic conditions and agronomic operations (e.g. fertilization, residue management and chemical crop protection). We present a quantitative review based on a global meta‐analysis, using paired observations from 165 publications performed over 65 years (1950–2016) across 40 countries on five continents, to elucidate this long‐standing unresolved issue. Results showed that disturbing the soil less (e.g. no‐tillage and conservation agriculture [CA]) significantly increased earthworm abundance (mean increase of 137% and 127%, respectively) and biomass (196% and 101%, respectively) compared to when the soil is inverted by conventional ploughing. Earthworm population responses were more pronounced when the soil had been under reduced tillage (RT) for a long time (>10 years), in warm temperate zones with fine‐textured soils, and in soils with higher clay contents (>35%) and low pH (<5.5). Furthermore, retaining organic harvest residues amplified this positive response to RT, whereas the use of the herbicide glyphosate did not significantly affect earthworm population responses to RT. Additional meta‐analyses confirmed that epigeic and, more importantly, the bigger‐sized anecic earthworms were the most sensitive ecological groups to conventional tillage. In particular, the deep burrower Lumbricus terrestris exhibited the strongest positive response to RT, increasing in abundance by 124% more than the overall mean of all 13 species analysed individually. The restoration of these two important ecological groups of earthworms and their burrowing, feeding and casting activities under various forms of RT will ensure the provision of ecosystem functions such as soil structure maintenance and nutrient cycling by "nature's plough." Abstract : For the first time, we provide quantitative evidence showing that no‐tillage and conservation agriculture significantly increase earthworm abundance and biomass. We also identified several explanatory variables (climatic and edaphic properties, agronomic practices including organic matter and herbicide applications) that modulated these responses. Additional meta‐analyses confirmed that reduced tillage resulted in population increases in epigeic and anecic earthworms which will be critical to ensure soil ecosystem functions.