Species identity, rather than species mixtures, drives cover crop effects on nutrient partitioning in unfertilized agricultural soil

Lucas Freund,Alexandre Buttler,Pierre Mariotte,Mathieu Santonja,Bernard Jeangros

doi:10.1007/s11104-020-04782-z

Abstract

AimsPrevious cover crop studies mainly focused on the links between plant uptake and soil fertility, and there is a clear knowledge gap regarding the role of microbes in these processes. Our aim was then to better understand the effects of plant mixtures (versus monoculture) and the specific effects of each plant species on nitrogen (N) and phosphorus (P) partitioning between plant, soil, and more particularly microbial pools.MethodsMonocultures and mixtures composed of black oat, field pea and Indian mustard were grown during two months in a greenhouse. The concentrations of carbon (C), N and P were measured in both plant and microbial biomass at final harvest, together with soil available N and P.ResultsOverall, our findings highlight stronger selection effect (i.e., presence of key species) rather than complementarity effects (i.e., species mixture) to affect the measured parameters. The presence of pea increased the biomass production of oat and mustard, as well as the nutrient concentration of oat, whereas pea P concentration decreased in presence of oat and mustard N and P concentrations were negatively impacted respectively by the presence of oat and pea. We also observed a strong competition between plants and microbes for both soil N and P.ConclusionsThe oat-pea and the oat-pea-mustard mixtures represented the best compromise between biomass production, nutrient storage and biomass C:N ratio, thus insuring a good organic matter decomposition and nutrient provision for the following main crop.

Highlights

Conventional field cropping systems often require high fertilizer inputs to meet yield and economic goals
The oat-pea and the oat-pea-mustard mixtures represented the best compromise between biomass production, nutrient storage and biomass C:N ratio, insuring a good organic matter decomposition and nutrient provision for the following main crop
The shoot and root N concentrations of the cover crop were highest in presence of pea, especially in monoculture and in the mixture with mustard, while they were relatively low in the treatments without pea (Table 2)

Summary

Introduction

Conventional field cropping systems often require high fertilizer inputs to meet yield and economic goals. In agro-ecosystems, one way to improve nutrient cycling, sustainably maintain soil fertility and protect soil structure is to grow cover crops in rotation with the main crops. Legumes (Fabaceae) are useful because they are efficient N fixers and may in some cases improve N uptake for neighboring plants (Dubach and Russelle 1994; Temperton et al 2007). They are able to increase phosphorus (P) availability for other plants, due to the release of organic anions or acids in the rhizosphere (Nuruzzaman et al 2005; Hinsinger et al 2011).

Methods

Results

Discussion

Conclusion