Impact of anaerobic soil disinfestation on seasonal N2O emissions and N leaching in greenhouse vegetable production system depends on amount and quality of organic matter additions

Assessing the environmental sustainability of different soil disinfestation methods used in solar greenhouse vegetable production systems

Overuse of fertilizers and irrigation and continuous monocropping is increasingly jeopardizing vegetable production in solar greenhouses as it causes serious soil degradation and the spread of soil-borne diseases. As a countermeasure, the practice of anaerobic soil disinfestation (ASD) has been recently introduced, which is carried out during the summer fallow period. However, ASD may increase N leaching and greenhouse gas emissions when large amounts of chicken manure are applied. This study assesses how the use of different amounts of chicken manure (CM) combined with rice shells (RS) or maize straw (MS) affects soil O₂ availability, N leaching, and greenhouse gases (GHG) emissions during and following the ASD period. Application of RS or MS alone effectively stimulated long-lasting soil anaerobiosis without major stimulating effects on N₂O emission and N leaching. Seasonal N leaching and N₂O emissions were in the ranges of 144-306 and 3-44 kg N ha^-1, respectively, and were strongly increasing with increasing rates of manure application. Combining high rates of manure application with additional incorporation of crop residues further increased N₂O emissions by 56 %-90 % as compared to the standard practice of farmers (1200 kg N ha^-1 CM). About 56 %-91 % of seasonal N₂O emissions occurred during the ASD period, whereas N leaching mainly occurred in the cropping period (75 %-100 %). Our study shows, that for priming ASD incorporation of crop residue is sufficient and that the addition of chicken manure for ASD is not needed and should be reduced or even prohibited as it does not improve yields but stimulates the emission of the strong GHG N₂O.