Plant presence reduces root and shoot litter decomposition rates of crops and wild relatives

Janna M Barel,Wietse De Boer,Gerlinde B De Deyn,Thomas W Kuyper

doi:10.1007/s11104-019-03981-7

Janna M Barel, Wietse De Boer + Show 2 more

Open Access

https://doi.org/10.1007/s11104-019-03981-7

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Abstract

AimsRoots contribute greatly to carbon cycling in agriculture. Measuring aboveground litter decomposition could approximate belowground turn-over if drivers of decomposition, f.e. litter traits and plant presence, influence shoot and root decomposition in a comparable manner. We tested coordination of above- and belowground litter traits and decomposition rates for six pairs of crops and closely related wild plants and studied the influence of plant presence on decomposition.MethodsAbove- and belowground traits were measured, compared and related to decomposition rates. Shoot and root litters were incubated in presence of the same plant species as the litter species (own) or in presence of two other plant species (a grass or forb).ResultsShoots decomposed 1.43–1.98 times faster than (resp.) wild plant and crop roots. Decomposition correlated negatively with litter carbon and lignin concentrations, except crop root decomposition which correlated negatively with nitrogen concentration. Unexpectedly, plant presence reduced litter decomposition, with strongest effects for root litters in presence of forbs.ConclusionsCarbon cycling might be slower than predicted solely based on shoots decomposition rates, especially in presence of growing plants. While root decomposition of wild plants can be approximated by shoot decomposition, crop shoots are a poor proxy for crop root decomposition.

Highlights

In both natural and agro-ecosystems, plant roots are a major source of biomass for carbon-cycling (Freschet et al 2013; Jackson et al 2017)
Carbon cycling might be slower than predicted solely based on shoots decomposition rates, especially in presence of growing plants
While root decomposition of wild plants can be approximated by shoot decomposition, crop shoots are a poor proxy for crop root decomposition

Summary

Introduction

In both natural and agro-ecosystems, plant roots are a major source of biomass for carbon-cycling (Freschet et al 2013; Jackson et al 2017). Roots account up to 60% of primary productivity (Jackson et al 2017), and represent 33% of the average annual litter input (Freschet et al 2013). Roots on average represent 10% of plant biomass production of which 46% carbon (C) is retained in soil organic matter versus only 8% of aboveground C inputs into soil (Jackson et al 2017). Litter nitrogen (N) concentration is generally found to stimulate decomposition, while concentrations of structure-related compounds, measured by C or lignin concentrations, relate negatively with decomposition rates (Cornwell et al 2008; Freschet et al 2012; Vivanco and Austin 2006; Zhang et al 2008)

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Conclusion