Cumulative impact of cover crops on soil carbon sequestration and profitability in a temperate humid climate

Abstract

planting and termination, CC species, and cropping system, duration of the experiment), quantity and quality of CC residues, and the climatic conditions 15. Therefore, assessment of SOC storage in response to CC treatments is needed for various production systems. Cover crop research has evaluated CC effects on soil quality 13-14,16-17 and crop production 16,18-22. Long-term studies are needed to assess the potential of CCs to sequester C 4,23-25 and have primarily focused on evaluating the amount of soil C sequestered with CCs than control 26-28 rather than the change in SOC stock 29. Consistent with aforementioned long-term studies, we evaluated the differences in surface SOC storage with and without CCs in our experiment. Soil organic C represents a stable pool of soil C, which is rarely impacted by the seasonal variation due to climatic conditions 30. It takes several years (≥ 6-years) to detect changes in SOC stocks due to CCs 23,29 and therefore, long-term studies are needed to provide a quantitative evidence about CC effects on SOC storage. The results from the long-term trials assist growers in making improved decisions about selecting appropriate CCs for enhancing agroecosystem services, primary productivity and profit margins. Evidence in the literature regarding the impacts of CCs on crop yields is inconclusive, as there is considerable variability in results across studies. For example, while some studies have found that CCs positively affect subsequent crop yields 31,32 , other studies have found no significant effect 33,34 or even decreased yields 35,36. There is even less evidence regarding impacts of CCs on profit margins. For example, Schomberg et al. 37 reported that returns for cotton in the southern USA were higher with winter CCs, while Flower et al. 38 observed lower profit margins with CCs in a cereal rotation in Australia. Due to the lack of studies discussing CC impacts on profit margins, two recent studies have highlighted the need for additional research on the long-term economic returns from CCs 23,39. The objectives of this study were to (i) evaluate the cumulative effects of CC on soil C sequestration, primary productivity, and profit margins, and (ii) determine if current and projected C prices may be an effective strategy for incentivising the quantity of soil C sequestered by CCs. To meet these objectives, a long-term CC experiment located at Ridgetown, Ontario Canada, established in 2007 and repeated at an adjacent site in 2008 was utilized 13-14,18-20,40. Previously in this experiment, CC treatment effects on N fertility, crop productivity, and soil quality have indicated enhancements with CCs compared to the no cover crop control (no-CC) 13-14,18-20,40. The Ridgetown experiment is one of the very few longest running CC trials making direct comparisons among CCs in North America. This provides a unique opportunity to advance our understanding of the CC-induced effects on soil C storage across different CC treatments. In addition, by evaluating the economics of CCing combined wit...

Changes in Soil Labile Organic Matter as Affected by 50 Years of Fertilization with Increasing Amounts of Nitrogen

“…The proportion of LF in the total OC was high, ranging from 14.88-26.23% in the autumn, to 13.62-23.33% in the spring, in the fertilization treatments. Our results showed that higher crop yields build up a greater supply of labile organic substrate, which in general creates a greater possibility for carbon sequestration in the soil [44].…”

Chemical composition of cover crops and soil organic matter pools in no‐tillage systems in the Cerrado

“…In this context, the results reveal the importance of diversification of soil cover rotation with cover crops in intense crop cultivation systems to maintain soil C stocks (Chahal et al, 2020; Rosolem et al, 2016). The chemical composition of different cover crops with an appropriate N:lignin ratio is fundamental for C sequestration in the soil under systems using cover crop rotations in the Cerrado region.…”

“…Inclusion of legumes in crop rotations provides N to microorganisms that synthesize stable fractions of soil organic matter (SOM), in addition to promoting protection and stability of C, consequently reducing greenhouse gas (GHG) emissions (Nishigaki et al, 2021; Yao et al, 2019). The adoption of cover crops in cropping systems is recommended as a management strategy to increase soil C stocks (Chahal et al, 2020; Rosolem et al, 2016).…”

A Pathway to Carbon Neutral Agriculture in Denmark

“…This study, however, also found wide variability and was based on those farmers who used cover crops, which may not be representative of other farmers. Another U.S. study found that cover crops were profitable for growing vegetables but not for use with grains and oilseeds (Chahal et al 2020). Because of differing conditions, these studies only suggest that the potential for cover crops to be more costeffective if continued for several years should be studied in Denmark.…”