In France, the term service crop is used rather than cover crop. It refers to different services the crop delivers to the soil and vines. Just like in South Africa, a lot of research is done to better understand the benefits of these crops in a holistic farming system. This article compares the risks and benefits of different termination methods.
Project layout
- A three-year experiment was conducted to evaluate six winter cover crop termination strategies. Three methods, mower (M), tillage (T) and roller-crimper (R), were compared at two stages: early termination during winter (E) and termination during budburst (B).
- Cover crop measurements included biomass, C:N ratio, weeds, and mulch.
- Soil measurements included organic matter, microbial biomass, water, and nitrogen stocks.
- Grapevine measurements included leaf water potential, yield, pruning ratio and YAN.
- The experiment was conducted in a conventional Shiraz block on SO4 rootstock.
- The cover crop mix utilised was fava beans, oats, peas, and white mustard.
Design of the experiment: blocks and treatments. E: early termination; B: budburst termination; M: mower; R: roller; T: mower+tillage. (Figure is reproduced as permitted by the open access policy of the European Journal of Agronomy.)
Results
- Waiting until budburst to terminate crops yielded two to three times more biomass than winter termination.
- Soil tillage was the most effective termination method, resulting in the least regrowth. Tillage also led to the least weed biomass at the flowering stage in two of the three seasons.
- The roller-crimper was less effective in terminating cover crops, but the best way to maintain plant residue on the soil surface.
- Higher microbial biomass was recorded in the budburst, no-tillage termination treatments.
- Termination using tillage resulted in higher soil water stocks and improved grapevine water status.
- During two seasons, soil inorganic nitrogen stocks were almost four times higher than M and R treatments. The YAN content mirrored this trend.
- T treatments also yielded higher pruning weights than M and R treatments. The same trend applies to bunch numbers per vine.
Significance of the study
This study emphasises the complexity of cover crop management and the fact that regional and seasonal circumstances dictate management actions. Early versus late termination decisions must be made based on seasonal rainfall patterns. If weed management is an important factor, the tillage treatment must be considered. In dryland conditions where optimal soil water at flowering is required, tillage will more successfully suppress cover crop regrowth and weed competition. When soil health and optimal microbial biomass are pursued, a season or two of no-till methods should be considered.
Reference
Garcia, L., Krafft, G., Enard, C., Bouisson, Y., Metay, A. (2024). Adapting service crop termination strategy in viticulture to increase soil ecosystem functions and limit competition with grapevine, European Journal of Agronomy 156, 127161, https://doi.org/10.1016/j.eja.2024.127161
Image: Flickr (Creative Commons license)