Cover crop inclusion and residue retention improves soybean production and physiology in drought conditions

Authors: Whippo, Craig; Saliendra, Nicanor; Liebig, Mark

Submitted to: Heliyon
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/16/2024
Publication Date: 4/20/2024
Citation: Whippo, C.W., Saliendra, N.Z., Liebig, M.A. 2024. Cover crop inclusion and residue retention improves soybean production and physiology in drought conditions. Heliyon. 10.Article.e29838. https://doi.org/10.1016/j.heliyon.2024.e29838.
DOI: https://doi.org/10.1016/j.heliyon.2024.e29838

Interpretive Summary: Soybean production in central and western North Dakota has increased despite high drought risks. Drought condition limit soybean productivity because they require high photosynthesis rates to support energy-requiring nitrogen fixation. Management strategies such as retaining crop residues and including cover crops in crop rotations can improve agricultural resilience. This study found that a management strategy that included cover crops and residue retention resulted in 29% greater yields under drought conditions compared to a prevailing management system that did not include cover crops and residue retention. The performance improvement associated with including cover crops and residue retention can be explained by lengthening the reproductive growth phase, improved water uptake and water use efficiency, and greater photosynthetic capacity. These results suggest that farmers can improve soybean productivity and yield stability by incorporating cover crops and residue retention into their management practices.

Technical Abstract: CONTEXT: Soybean (Glycine max (L.) Merr.) planting has increased in central and western North Dakota despite frequent drought occurrences that limit productivity. Soybean plants need high photosynthetic and transpiration rates to be productive, but they also need high water use efficiency when water is limited. Retaining crop residues and including cover crops in crop rotations are management strategies that could improve soybean drought resiliency in the northern Great Plains. OBJECTIVE: We aimed to examine how a management practice that included cover crops and residue retention impacts agronomic, ecosystem water and carbon dioxide flux, and canopy-scale physiological attributes of soybeans in the northern Great Plains under drought conditions. METHODS: We compared two soybean fields over two years with business-as-usual and aspirational management that included residue retention and cover crops during a drought year. This comparison was based on yield, aboveground biomass, Phenocam images, and fluxes from eddy covariance and ancillary measurements. These measurements were used to derive meteorological, physical, and physiological attributes with the ‘big leaf’ framework. RESULTS: Soybean yields were 29% higher under drought conditions in the field managed in a system that included cover crops and residue retention. This yield increase was caused by extending the maturity phenophase by 5 days, increasing agronomic and intrinsic water use efficiency by 27% and 33%, respectively, increasing water uptake, and increasing the rubisco-limited photosynthetic capacity (Vcmax25) by 42%. CONCLUSIONS: The inclusion of cover crops and residue retention into a cropping system improved soybean productivity because of differences in water use, phenology timing, and photosynthetic capacity. IMPLICATIONS: These results suggest that farmers can improve soybean productivity and yield stability by incorporating cover crops and residue retention into their management practices because these practices allow soybean plants to shift to a more aggressive water uptake strategy.