New research published into the effectiveness of tillage and cover crops on the net ecosystem carbon balance.
Scientists at the University of California have found that vineyard site characteristics, namely, soil texture and climate, were key determinants of the carbon storage potential of vineyards in Mediterranean climates – such as those found in coastal and inland California wine grape production regions. The research by Zumkeller et al. published in Frontiers in Plant Science (Front. Plant Sci., 21 November 2022, Sec. Crop and Product Physiology, https://doi.org/10.3389/fpls.2022.1024606), provides more evidence that the vineyard agroecosystem can serve as a carbon sink for short-term implementation of cover crops with no-till practice.
As noted by the researchers, the potential for carbon storage in vineyards is of great interest to offset greenhouse gas emissions and mitigate the effects of climate change; sustainable soil management practices such as cover crop adoption and reduced tillage may contribute to soil organic carbon (SOC) sequestration. They hypothesized that the vineyard agroecosystem can serve as a carbon storage pool, and the effectiveness of the ecological functioning of no-till and cover crops will be determined by site characteristics, including climate and soil texture.
The researchers investigated the synergic effects of implementation of cover crops and no-till practices by quantifying carbon inputs and losses at the vineyard scale through the net ecosystem carbon balance (NECB) determination in two different wine production regions and investigated the contributions of specific site characteristics toward these vineyard floor management practices in two hyperarid seasons in California. They calculated the NECB of three cover crops [perennial grass (Poa bulbosa hybrid cv. Oakville Blue); annual grass (barley, Hordeum vulgare); resident vegetation (natural weed population)] under conventional tillage and no-till management.
Results provided evidence that vineyards can serve as carbon sinks. Corroborating previous research, under sandy soils, tillage and type of cover crop had little to no effect on the NECB. However, under the finer-textured soils, conventional tillage reduced the NECB through a reduction in soil organic carbon (SOC) and increase in soil respiration (Rs), or soil CO2 efflux. The type of cover crop also impacted the NECB, as cover crops that produced greater biomass increased the NECB. Ultimately, vineyard site characteristics, including soil texture and climate, were key determinants of the effectiveness of carbon storage potential, as they can determine SOC and Rs of vineyards in Mediterranean vineyard agroecosystems in both Napa and Fresno. Overall, the research concluded that the implementation of no-till and cover crop practices should be carefully considered with a thorough understanding of the specific site characteristics to fully maximize their effectiveness.
A summary of key learnings from the paper:
- Almost 36 billion tons of soils are lost annually due to water and wind erosion (Alsina et al., 2014; Borrelli et al., 2017; Wolff et al., 2018).
- The Intergovernmental Panel on Climate Change (IPCC) has estimated that by 2030, global soil organic carbon (SOC) sequestration has the potential to mitigate up to about 5.3 Gt CO2 per year (Porter et al., 2017).
- Vineyard agroecosystems represent a large potential for agricultural soil carbon sequestration (SCS): grape vineyards, including wine, table, and raisin grapes, make up 341,555 hectares (844,000 acres) of agricultural land in California alone [California Department of Food and Agriculture (CDFA), 2022].
- Traditionally, the interrows of many vineyards were kept free of vegetation with the use of herbicides and tillage. However, it has been shown that both practices may have detrimental effects on soil quality and the surrounding ecosystem (Patiño-Zúñiga et al., 2009; Ferreira et al., 2020; Gatti et al., 2022). Thus, the adoption of cover crops and reduction of interrow tillage have been proposed as sustainable alternatives to conventional vineyard floor management practices (Alsina et al., 2013).
- Research suggested that cover crops may not only reduce soil erosion and water runoff but also improve water infiltration in most soils of temperate regions by increasing soil organic matter, so soils and water can be better conserved (Álvaro-Fuentes et al., 2008; Steenwerth and Belina, 2008a; Belmonte et al., 2018; Cataldo et al., 2020).
- The large SCS potential can attribute to the grapevine’s long-life cycle and permanent woody organs allow them to potentially store higher amounts of carbon compared to annual crops (Alonso et al., 2014; Nistor et al., 2018).
- There are limitations to SCS, including a lack of standardized methods of SOC determination and uncertainty regarding the stability of different soil carbon pools (Powlson et al., 2011).
- The effectiveness and rate of long-term SOC sequestration in agricultural soils can be largely influenced by site-specific conditions including climate, soil texture, other soil physiochemical properties, and management practices (Carlisle et al., 2010; Powlson et al., 2011).
*for references in text please see: Zumkeller et al. Front. Plant Sci., 21 November 2022, Sec. Crop and Product Physiology, https://doi.org/10.3389/fpls.2022.1024606.