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Article

Impact of Cover Crop Monocultures and Mixtures on Organic Carbon Contents of Soil Aggregates

1
Department of Biological Sciences, Alabama State University, Montgomery, AL 36101, USA
2
Department of Agronomy and Horticulture, University of Nebraska-Lincoln, Lincoln, NE 68583, USA
3
Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
*
Author to whom correspondence should be addressed.
Academic Editor: Heike Knicker
Soil Syst. 2021, 5(3), 43; https://doi.org/10.3390/soilsystems5030043
Received: 16 July 2021 / Revised: 2 August 2021 / Accepted: 3 August 2021 / Published: 6 August 2021
Cover crops are considered an integral component of agroecosystems because of their positive impacts on biotic and abiotic indicators of soil health. At present, we know little about the impact of cover crop types and diversity on the organic carbon (OC) contents of different soil aggregate-size classes. In this study, we investigated the effect of cover plant diversity on OC contents of different soil aggregates, such as macro- (<2000–500 μm), meso- (<500–250 μm), and micro-aggregates (<250 μm). Our experiment included a total of 12 experimental treatments in triplicate; six different monoculture treatments such as chickling vetch (Vicia villosa), crimson clover (Trifolium incarnatum), hairy vetch (Vicia villosa), field peas (Pisum sativum), oilseed radish (Raphanus sativus), and mighty mustard (Brassica juncea), and their three- and six-species mixture treatments, including one unplanted control treatment. We performed this experiment usingdeep pots that contained soil collected from a corn-soybean rotation field. At vegetative maturity of cover plants (about 70 days), we took soil samples, and the soil aggregate-size classes were separated by the dry sieving. We hypothesized that cover crop type and diversity will improve OC contents of different soil aggregate-size classes. We found that cover plant species richness weakly positively increased OC contents of soil macro-aggregates (p = 0.056), whereas other aggregate-size classes did not respond to cover crop diversity gradient. Similarly, the OC contents of macroaggregates varied significantly (p = 0.013) under cover crop treatments, though neither monoculture nor mixture treatments showed significantly higher OC contents than the control treatment in this short-term experiment. Interestingly, the inclusion of hairy vetch and oilseed radish increased and decreased the OC contents of macro- and micro-aggregates, respectively. Moreover, we found a positive correlation between shoot biomass and OC contents of macroaggregates. Overall, our results suggest that species-rich rather than -poor communities may improve OC contents of soil macroaggregates, which constitute a major portion of soil systems, and are also considered as important indicators of soil functions. View Full-Text
Keywords: cover crops; soil organic carbon; soil aggregate-size classes; soil health; cover crop monocultures; cover crop mixtures cover crops; soil organic carbon; soil aggregate-size classes; soil health; cover crop monocultures; cover crop mixtures
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MDPI and ACS Style

Topps, D.; Khabir, M.I.u.; Abdelmagid, H.; Jackson, T.; Iqbal, J.; Robertson, B.K.; Pervaiz, Z.H.; Saleem, M. Impact of Cover Crop Monocultures and Mixtures on Organic Carbon Contents of Soil Aggregates. Soil Syst. 2021, 5, 43. https://doi.org/10.3390/soilsystems5030043

AMA Style

Topps D, Khabir MIu, Abdelmagid H, Jackson T, Iqbal J, Robertson BK, Pervaiz ZH, Saleem M. Impact of Cover Crop Monocultures and Mixtures on Organic Carbon Contents of Soil Aggregates. Soil Systems. 2021; 5(3):43. https://doi.org/10.3390/soilsystems5030043

Chicago/Turabian Style

Topps, Daphne, Md I.u. Khabir, Hagir Abdelmagid, Todd Jackson, Javed Iqbal, Boakai K. Robertson, Zahida H. Pervaiz, and Muhammad Saleem. 2021. "Impact of Cover Crop Monocultures and Mixtures on Organic Carbon Contents of Soil Aggregates" Soil Systems 5, no. 3: 43. https://doi.org/10.3390/soilsystems5030043

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