Anaerobic soil disinfestation with incorporation of straw and manure significantly increases greenhouse gases emission and reduces nitrate leaching while increasing leaching of dissolved organic N

Greenhouse vegetable production in China mostly involves excessive N fertilization and flood irrigation. This causes serious soil degradation and spreading of soil borne diseases. As a countermeasure against soil borne diseases anaerobic soil disinfestation (ASD) is applied during the summer fallow period. Current practices involve the incorporation of organic C sources, covering of the soil with plastic film and flood irrigation. However, farmers not only apply straw but also organic manure in ASD which may result in significant greenhouse gas emissions and N leaching. A field experiment was conducted in a greenhouse during the summer fallow period to test the impact of three ASD practices on soil GHG (N2O, CO2 and CH4) emissions and N leaching: 1) control (CK), bare soil, no ASD; 2) ASD without straw incorporation (ASD-S); 3) ASD plus straw incorporation (ASD+S) and 4) ASD plus straw and chicken manure incorporation (ASD+SM). Applying any form of ASD resulted in an increase in N2O emissions from approximately 1 kg N ha(-1) month(-1) to 10.7 (ASD)-47.0 (ASD+SM) kg N ha(-1) month(-1). Furthermore, N leaching from treatments of ASD ranged from 24.1-54.2 kg N ha(-1) month(-1), with highest values in ASD-S. However, while N leaching in ASD-S was solely in the form of NO3-, DON leaching was with approximately 12-20% a significant component of total N leaching in ASD+S and ASD+SM. Overall, ASD +SM showed the highest environmental N losses, which were dominated by N2O emissions. This highlights the need to advise farmers and policy makers to ban the incorporation of chicken manure instead of straw only during the ASD period and to optimize irrigation schemes instead of flood irrigation to reduce environmental N losses. Putting in more environmental sound ASD practices will certainly help to improve the sustainability of greenhouse vegetable production. (C) 2021 Elsevier B.V. All rights reserved.