Balancing legume-cereal proportions in cover crop mixtures to minimize N2O emissions

Guillermo Guardia; Diego Abalos; Emanuele Ribatti; Federico Ardenti; Federico Capra; Giacomo Mortella; Vincenzo Tabaglio; Miguel Ángel Ibáñez; Ji Chen; Andrea Fiorini

doi:10.1016/j.geoderma.2025.117195

Balancing legume-cereal proportions in cover crop mixtures to minimize N₂O emissions

Guillermo Guardia^*, Diego Abalos, Emanuele Ribatti, Federico Ardenti, Federico Capra, Giacomo Mortella, Vincenzo Tabaglio, Miguel Ángel Ibáñez, Ji Chen, Andrea Fiorini

^*Corresponding author for this work

Department of Agroecology - Climate and Water

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

Abstract

Legume-cereal cover crop mixtures offer a promising approach to reduce nitrate leaching and enhancing soil fertility. However, the impacts of these mixtures on N₂O emissions during both the cover cropping and post-incorporation phases, as well as the relative contribution of roots and shoots to N₂O emission, remain uncertain. To address these knowledge gaps, we conducted a two-phase greenhouse experiment. In the first phase, cover crops were grown encompassing six treatments: control (no cover crop), pure vetch (Vicia villosa Roth), pure rye (Secale cereale L.), and mixtures with 33 %, 50 % and 66 % of the pure rye sowing rate paired with 66 %, 50 % and 33 % of the pure vetch sowing rate, respectively. In the second phase, focusing on the post-incorporation effects, the same treatments were arranged in mesocosms with both roots and shoots, and in mesocosms with roots only. During the first phase, the proportion of fine/very fine roots and root length density were negatively correlated with mineral N content and N₂O emissions. Mixing rye with vetch increased total dry biomass and N yield for all mixtures compared to rye alone. In mixtures, the proportion of fine roots, root length density, and the root C:N ratio decreased compared to rye. Most of the N₂O emissions occurred after cover crop incorporation, with roots contributing more (average 57 %) than shoots (average 31 %). Total N₂O emissions increased with increasing proportion of vetch, but the mixture with 33 % vetch and 66 % rye maintained N₂O emissions as low as rye monoculture. Our study indicates that adjusting the seed proportion in legume-cereal mixtures serves as an effective tool to balance the benefits of pure legume (increased total biomass, and C and N yields) and pure cereal (decreased N₂O emissions and soil mineral N pool) cover cropping.

Original language	English
Article number	117195
Journal	Geoderma
Volume	454
ISSN	0016-7061
DOIs	https://doi.org/10.1016/j.geoderma.2025.117195
Publication status	Published - Feb 2025

Keywords

Denitrification
Green manure
Greenhouse gas emissions
Intercropping
Nitrogen cycling
Pulses

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10.1016/j.geoderma.2025.117195Licence: CC BY

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title = "Balancing legume-cereal proportions in cover crop mixtures to minimize N2O emissions",

abstract = "Legume-cereal cover crop mixtures offer a promising approach to reduce nitrate leaching and enhancing soil fertility. However, the impacts of these mixtures on N2O emissions during both the cover cropping and post-incorporation phases, as well as the relative contribution of roots and shoots to N2O emission, remain uncertain. To address these knowledge gaps, we conducted a two-phase greenhouse experiment. In the first phase, cover crops were grown encompassing six treatments: control (no cover crop), pure vetch (Vicia villosa Roth), pure rye (Secale cereale L.), and mixtures with 33 %, 50 % and 66 % of the pure rye sowing rate paired with 66 %, 50 % and 33 % of the pure vetch sowing rate, respectively. In the second phase, focusing on the post-incorporation effects, the same treatments were arranged in mesocosms with both roots and shoots, and in mesocosms with roots only. During the first phase, the proportion of fine/very fine roots and root length density were negatively correlated with mineral N content and N2O emissions. Mixing rye with vetch increased total dry biomass and N yield for all mixtures compared to rye alone. In mixtures, the proportion of fine roots, root length density, and the root C:N ratio decreased compared to rye. Most of the N2O emissions occurred after cover crop incorporation, with roots contributing more (average 57 %) than shoots (average 31 %). Total N2O emissions increased with increasing proportion of vetch, but the mixture with 33 % vetch and 66 % rye maintained N2O emissions as low as rye monoculture. Our study indicates that adjusting the seed proportion in legume-cereal mixtures serves as an effective tool to balance the benefits of pure legume (increased total biomass, and C and N yields) and pure cereal (decreased N2O emissions and soil mineral N pool) cover cropping.",

keywords = "Denitrification, Green manure, Greenhouse gas emissions, Intercropping, Nitrogen cycling, Pulses",

author = "Guillermo Guardia and Diego Abalos and Emanuele Ribatti and Federico Ardenti and Federico Capra and Giacomo Mortella and Vincenzo Tabaglio and Ib{\'a}{\~n}ez, {Miguel {\'A}ngel} and Ji Chen and Andrea Fiorini",

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T1 - Balancing legume-cereal proportions in cover crop mixtures to minimize N2O emissions

AU - Guardia, Guillermo

AU - Abalos, Diego

AU - Ribatti, Emanuele

AU - Ardenti, Federico

AU - Capra, Federico

AU - Mortella, Giacomo

AU - Tabaglio, Vincenzo

AU - Ibáñez, Miguel Ángel

AU - Chen, Ji

AU - Fiorini, Andrea

PY - 2025/2

Y1 - 2025/2

N2 - Legume-cereal cover crop mixtures offer a promising approach to reduce nitrate leaching and enhancing soil fertility. However, the impacts of these mixtures on N2O emissions during both the cover cropping and post-incorporation phases, as well as the relative contribution of roots and shoots to N2O emission, remain uncertain. To address these knowledge gaps, we conducted a two-phase greenhouse experiment. In the first phase, cover crops were grown encompassing six treatments: control (no cover crop), pure vetch (Vicia villosa Roth), pure rye (Secale cereale L.), and mixtures with 33 %, 50 % and 66 % of the pure rye sowing rate paired with 66 %, 50 % and 33 % of the pure vetch sowing rate, respectively. In the second phase, focusing on the post-incorporation effects, the same treatments were arranged in mesocosms with both roots and shoots, and in mesocosms with roots only. During the first phase, the proportion of fine/very fine roots and root length density were negatively correlated with mineral N content and N2O emissions. Mixing rye with vetch increased total dry biomass and N yield for all mixtures compared to rye alone. In mixtures, the proportion of fine roots, root length density, and the root C:N ratio decreased compared to rye. Most of the N2O emissions occurred after cover crop incorporation, with roots contributing more (average 57 %) than shoots (average 31 %). Total N2O emissions increased with increasing proportion of vetch, but the mixture with 33 % vetch and 66 % rye maintained N2O emissions as low as rye monoculture. Our study indicates that adjusting the seed proportion in legume-cereal mixtures serves as an effective tool to balance the benefits of pure legume (increased total biomass, and C and N yields) and pure cereal (decreased N2O emissions and soil mineral N pool) cover cropping.

AB - Legume-cereal cover crop mixtures offer a promising approach to reduce nitrate leaching and enhancing soil fertility. However, the impacts of these mixtures on N2O emissions during both the cover cropping and post-incorporation phases, as well as the relative contribution of roots and shoots to N2O emission, remain uncertain. To address these knowledge gaps, we conducted a two-phase greenhouse experiment. In the first phase, cover crops were grown encompassing six treatments: control (no cover crop), pure vetch (Vicia villosa Roth), pure rye (Secale cereale L.), and mixtures with 33 %, 50 % and 66 % of the pure rye sowing rate paired with 66 %, 50 % and 33 % of the pure vetch sowing rate, respectively. In the second phase, focusing on the post-incorporation effects, the same treatments were arranged in mesocosms with both roots and shoots, and in mesocosms with roots only. During the first phase, the proportion of fine/very fine roots and root length density were negatively correlated with mineral N content and N2O emissions. Mixing rye with vetch increased total dry biomass and N yield for all mixtures compared to rye alone. In mixtures, the proportion of fine roots, root length density, and the root C:N ratio decreased compared to rye. Most of the N2O emissions occurred after cover crop incorporation, with roots contributing more (average 57 %) than shoots (average 31 %). Total N2O emissions increased with increasing proportion of vetch, but the mixture with 33 % vetch and 66 % rye maintained N2O emissions as low as rye monoculture. Our study indicates that adjusting the seed proportion in legume-cereal mixtures serves as an effective tool to balance the benefits of pure legume (increased total biomass, and C and N yields) and pure cereal (decreased N2O emissions and soil mineral N pool) cover cropping.

KW - Denitrification

KW - Green manure

KW - Greenhouse gas emissions

KW - Intercropping

KW - Nitrogen cycling

KW - Pulses

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DO - 10.1016/j.geoderma.2025.117195

M3 - Journal article

AN - SCOPUS:85217056771

SN - 0016-7061

VL - 454

JO - Geoderma

JF - Geoderma

M1 - 117195

ER -

Balancing legume-cereal proportions in cover crop mixtures to minimize N₂O emissions

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Keywords

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