TY - JOUR

T1 - A critical review of the impacts of cover crops on nitrogen leaching, net greenhouse gas balance and crop productivity

AU - Abdallah, Mohamed

AU - Hastings, Astley

AU - Cheng, Kun

AU - Yue, Qian

AU - Chadwick, Dave

AU - Espenberg, Mikk

AU - Truu, Jaak

AU - Rees, Robert M.

AU - Smith, Pete

N1 - © 2019 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

PY - 2019/8

Y1 - 2019/8

N2 - Cover crops play an increasingly important role in improving soil quality, reducing agricultural inputs and improving environmental sustainability. The main objectives of this critical global review and systematic analysis were to assess cover crop practices in the context of their impacts on nitrogen leaching, net greenhouse gas balances (NGHGB) and crop productivity. Only studies that investigated the impacts of cover crops and measured one or a combination of: nitrogen leaching, soil organic carbon (SOC), nitrous oxide (N2O), grain yield and nitrogen in grain of primary crop, and had a control treatment were included in the analysis. Long‐term studies were uncommon, with most data coming from studies lasting 2‐3 years. The literature search resulted in 106 studies carried out at 372 sites and covering different countries, climatic zones and management. Our analysis demonstrates that cover crops significantly (p<0.001) decreased N leaching and significantly (p<0.001) increased SOC sequestration without having significant (p>0.05) effects on direct N2O emissions. Cover crops could mitigate the NGHGB by 2.06 ±2.10 Mg CO2‐eq ha−1 y−1. One of the potential disadvantages of cover crops identified was the reduction in grain yield of the primary crop by ≈4%, compared to the control treatment. This drawback could be avoided by selecting mixed cover crops with a range of legumes and non‐legumes, which increased the yield by ≈13%. These advantages of cover crops justify their widespread adoption. However, management practices in relation to cover crops will need to be adapted to specific soil, management and regional climatic conditions.

AB - Cover crops play an increasingly important role in improving soil quality, reducing agricultural inputs and improving environmental sustainability. The main objectives of this critical global review and systematic analysis were to assess cover crop practices in the context of their impacts on nitrogen leaching, net greenhouse gas balances (NGHGB) and crop productivity. Only studies that investigated the impacts of cover crops and measured one or a combination of: nitrogen leaching, soil organic carbon (SOC), nitrous oxide (N2O), grain yield and nitrogen in grain of primary crop, and had a control treatment were included in the analysis. Long‐term studies were uncommon, with most data coming from studies lasting 2‐3 years. The literature search resulted in 106 studies carried out at 372 sites and covering different countries, climatic zones and management. Our analysis demonstrates that cover crops significantly (p<0.001) decreased N leaching and significantly (p<0.001) increased SOC sequestration without having significant (p>0.05) effects on direct N2O emissions. Cover crops could mitigate the NGHGB by 2.06 ±2.10 Mg CO2‐eq ha−1 y−1. One of the potential disadvantages of cover crops identified was the reduction in grain yield of the primary crop by ≈4%, compared to the control treatment. This drawback could be avoided by selecting mixed cover crops with a range of legumes and non‐legumes, which increased the yield by ≈13%. These advantages of cover crops justify their widespread adoption. However, management practices in relation to cover crops will need to be adapted to specific soil, management and regional climatic conditions.

KW - C sequestration

KW - N content

KW - N in grain

KW - N leaching

KW - catch crop

KW - cover crop

KW - green manure

KW - net greenhouse gas balance

KW - nitrate

KW - nitrous oxide emissions

KW - soil organic carbon

KW - yield

U2 - 10.1111/gcb.14644

DO - 10.1111/gcb.14644

M3 - Article

C2 - 30955227

VL - 25

SP - 2530

EP - 2543

JO - Global Change Biology

JF - Global Change Biology

SN - 1365-2486

IS - 8

ER -