The impact of long-term organic farming on soil-derived greenhouse gas emissions

| Type artikkel: Publisert studie
Agricultural practices contribute considerably to emissions of greenhouse gases. So far, knowledge on the impact of organic compared to non-organic farming on soil-derived nitrous oxide (N2O) and methane (CH4) emissions is limited. We investigated N2O and CH4 fluxes with manual chambers during 571 days in a grass-clover– silage maize – green manure cropping sequence in the long-term field trial “DOK” in Switzerland.

Forfattere:

Colin Skinner , Andreas Gattinger, Maike Krauss, Hans-Martin Krause , Jochen Mayer , Marcel G. A. van der Heijden og Paul Mäder

År:

2018

Finansiert av:

We gratefully acknowledge the financial support for this project provided by the Swiss Federal Offices for the Environment (FOEN) and Agriculture (FOAG). A. G. received additional funding from the Mercator Foundation Switzerland (Grant No. 2011-0294) and Swiss National Science Foundation within the frame of the National Research Program “Soil as a Resource” (Grant No. 406840_143137).

We compared two organic farming systems – biodynamic (BIODYN) and bioorganic (BIOORG) – with two non-organic systems – solely mineral fertilisation (CONMIN) and mixed farming including farmyard manure (CONFYM) – all reflecting Swiss farming practices–together with an unfertilised control (NOFERT). We observed a 40.2% reduction of N2O emissions per hectare for organic compared to non-organic systems. In contrast to current knowledge, yield-scaled cumulated N2O emissions under silage maize were similar between organic and non-organic systems. Cumulated on area scale we recorded under silage maize a modest CH4 uptake for BIODYN and CONMIN and high CH4 emissions for CONFYM. We found that, in addition to N input, quality properties such as pH, soil organic carbon and microbial biomass significantly affected N2O emissions. This study showed that organic farming systems can be a viable measure contributing to greenhouse gas mitigation in the agricultural sector.

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