Integrating cover crops as a source of carbon for anaerobic soil disinfestation

Authors: VECCHIA, LUCA - University Of Milan; DIGIOIA, FRANCESCO - Pennsylvania State University; FERRANTE, ANTONIO - University Of Milan; Hong, Jason; WHITE, CHARLES - Pennsylvania State University; Rosskopf, Erin

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2020
Publication Date: 10/20/2020
Citation: Vecchia, L., Digioia, F., Ferrante, A., Hong, J.C., White, C., Rosskopf, E.N. 2020. Integrating cover crops as a source of carbon for anaerobic soil disinfestation. Agronomy Journal. p.1614. https://doi.org/10.3390/agronomy10101614.
DOI: https://doi.org/10.3390/agronomy10101614

Interpretive Summary: The adoption of anaerobic soil disinfestation (ASD) as a biologically-based method for the management of soilborne pests and pathogens at the commercial scale strictly depends on the availability of effective and low-cost sources of carbon (C). A three-phase pot study was conducted to evaluate the performance of twelve cover crop species as alternative sources of C in comparison to molasses. Buckwheat produced the greatest above-ground and total plant dry biomass and accumulated the largest amount of total C. In the second phase, simulating the application of ASD in a pot-in-pot system, molasses-amended soil achieved substantially higher levels of anaerobicity, and lowered soil pH at 3 and 7 days after treatment application compared to soil amended with the cover crops tested. However, the level of anaerobicity achieved by each source of C appeared to be associated to the total amount of C applied with each treatment. In the third phase of the study, after the ASD simulation, lettuce was planted to assess the impact of cover crop- and molasses-based ASD on lettuce yield and quality and it was observed that treatments had limited effects on lettuce plant growth and quality and none of the treatments caused plant stunting or phytotoxicity. Tested cover crop species and molasses had a significant impact on the availability of macro and micro-elements in the soil, which in turn influenced the uptake of minerals in lettuce. Fast growing cover crops like buckwheat or oat, capable of accumulating high levels of C in a relatively short time, may represent a viable alternative to substitute or be combined with standard C sources like molasses, which would provide an on-farm C source and reduce cost of application. Further research is needed to assess the performance of cover crops at the field scale and verify their decomposability and efficacy in managing soil-borne pests and pathogens.

Technical Abstract: The loss of efficacious soil fumigants and increased interest in biologically-based soilborne pest management techniques has led to the development of anaerobic soil disinfestation (ASD). ASD provides broad-spectrum pest control and yields similar to those achieved using chemical fumigants, but it is dependent upon identifying carbon sources that are easily decomposed and result in high levels of soil anaerobicity. Molasses is an excellent carbon source for ASD but has limited availability in some locations and can be expensive, particularly if it must be shipped, therefore, locally-available carbon sources are being sought in many regions. Farmer focus groups on ASD have suggested that on-farm carbon sources, such as cover crops that produce high levels of biomass, would be an attractive alternative. Cover crops suitable for use in the Mid-Atlantic region were compared to molasses for their utility for ASD and their impacts on crop nutrients and phytoxicity. No issues arose with regard to negative impacts on a lettuce crop, but levels of available carbon from cover crops alone were not adequate for generating high levels of anerobicity, therefore additional research will need to be conducted on higher cover crop seeding rates, as well as combinations of cover crops with high carbon inputs like molasses. This approach could reduce the quantity of molasses needed, thus reducing the overall cost of ASD.