XH9QS9D6

2784

15 janvier 2021 10:05

15 janvier 2021 10:05

In a context of global warming, recent studies are attempting to identify agricultural management practices that combine low greenhouse gas (GHG) emissions and optimal yields. In that purpose, an experimentation was established in 2017 in order to compare the yields, carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions from 4 distinguished agricultural treatments adapted to blueberry productions. In the UBC farm in West Vancouver, British Columbia, GHG emissions were measured for almost 2 years using closed static chambers. The UBC farm is a certified organic farm and has coarse sandy soils and high organic carbon content well suited for the blueberry bushes. Organic blueberry farming is regularly using sawdust covers as a promising management tool for weed control and water retention despite its known increase in CO2 emissions. Decomposing sawdust creates different environments as it ages that have various and unclear impacts on the GHG fluxes. Under both renewed and old sawdust conditions, different blood meal application forms were compared, the solid application in granular form was spread above the mulch and the fertigated application dissolved in the irrigation water targeting the roots. Blood meal is a rapidly available nitrogen fertiliser used by organic blueberry growers for an easier synchronisation between nitrogen availability and plant needs. There is little research on how ageing surface mulches interact with organic fertiliser to impact GHG emissions. Our results showed increases in every GHG emissions by the renewed sawdust, supposedly caused by the priming effects due to the fresh input of organic carbon. Under old sawdust conditions, we did not find significant effects of the fertilisation form. However, in new sawdust conditions, it has been demonstrated that momentarily the fertigation would significantly increase CO2 emissions. On the contrary, during the first production season, fertigation has mitigated N2O emissions drastically under renewed sawdust environments. Yet, the application form of the blood meal never significantly affected CH4 fluxes. The yield analyses showed no significant difference induced by the treatments but surprisingly, smaller yield were suggested for fertigation under renewed sawdust conditions by a visual interpretation of the results. We conclude that blood meal fertigation does not lead neither to an overall reduction of the global warming potential nor to increased productions. In that regards, we do not recommend farmers investing in an extra fertigation equipment. However, the interaction between granular blood meal and renewed sawdust is alarming. If the sawdust was meant to be spread more frequently, blueberry growers would be recommended to consider fertigation practices in order to reduce N2O emissions.

None

• AB - Spécifique
• FREDO durabilité
• FREDO environnement
• FREDO fertilisation
• GEO Canada
• greenhouse gas emission
• petits fruits

2020-10-13T22:00:00Z

13 octobre 2020