Grant: Alliance Grants

Intensification of agriculture requires heavy machinery, fertilizers and herbicides which create pollution, soil erosion and green house gases and decrease soil fertility and biodiversity. The planting of cover crops and no-till agriculture are regenerative soil management strategies recently adopted between vine rows in some vineyards. Because healthy soils contain abundant carbon, which increases soil aggregate structure and acts as a repository for nutrients, regenerative strategies often focus on increasing carbon in the soils. Soil carbon storage also counters greenhouse gas emissions and increases soil microbe biodiversity. However, because these techniques can result in short-term decreased yield and improvements to soil health take years to observe, there is resistance among some agriculturalists to adopt these strategies. The manager of the vineyard for Pelee Island Winery was an early proponent of cover cropping in vineyards. Over 20 years ago he planted "resident vegetation" consisting of native perennials in some of their fields. It is assumed that soil carbon increased after introducing the resident vegetation, but the size of the carbon stocks or whether the rate of carbon accumulation has peaked is unknown. Fresh organic matter is initially incorporated into the most labile pool of carbon in the soil and the formation of more resilient soil organic matter can be limited by the addition of fertilizers which enhance microbial mineralization. To evaluate the use of resident vegetation as a mechanism of increasing soil carbon stocks we will use stable isotope techniques to demonstrate that some carbon added to the soil from the resident vegetation becomes associated with minerals where it is protected from microbial decay. The varying duration of the use of resident vegetation (2 to 21 years) in different fields makes the Pelee Island vineyard an ideal natural laboratory to assess 1) the ongoing effects of resident vegetation on carbon capture in the calcareous soils of south-western Ontario and 2) the impact this practice has had on soil health and soil microbial activity - these results are critical to Pelee Island Winery to direct future soil management strategies that affect grape production and for participation in Canada's proposed carbon tax offset system.