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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Sustainable Agricultural Systems Laboratory » Research » Publications at this Location » Publication #329538
Title: Living cover crops have immediate impacts on soil microbial community structure and function

Author
item FINNEY, DENISE - Pennsylvania State University
item KAYE, JASON - Pennsylvania State University
item Buyer, Jeffrey

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/29/2016
Publication Date: N/A
Citation: N/A

Interpretive Summary: Cover crops are used in sustainable agricultural systems to suppress weeds, scavenge nutrients, and add organic matter to the soil. Nitrogen fixing cover crops can also supply nitrogen to the following cash crop. Cover crops have been shown in past studies to affect the soil microbiome, but results varied depending on which cover crops were used and whether they were incorporated into the soil or left on the surface. In this study we examined the effects of 8 different cover crop species, grown singly or in combination, while they were still growing. Cover cropping increased soil microbial biomass relative to a no cover crop control, and specific cover crops were found to differentially affect the soil microbiome. Oat and rye cover crops increased arbuscular mycorrhizal fungi (AMF), which are beneficial symbionts of many crop plants, while hairy vetch increased fungi other than AMF. These results may lead to intentional management of the soil microbiome, in order to enhance soil health, through selection of appropriate cover crops. This information will be useful to scientists studying the soil microbiome.

Technical Abstract: Cover cropping is a widely promoted strategy to enhance soil health in agricultural systems. Despite a substantial body of literature demonstrating links between cover crops and soil biology, an important component of soil health, research evaluating how specific cover crop species influence soil microbial communities remains limited. This study examined the effects of eight fall-sown cover crop species grown singly and in multi-species mixtures on microbial community structure and soil biological activity using phospholipid fatty acid (PLFA) profiles and laboratory incubation, respectively. Fourteen cover crop treatments and a no cover crop control were established in August 2011 and 2012 on adjacent fields in central Pennsylvania. Soil communities were sampled from bulk soil in fall and spring, approximately two and nine months after cover crop planting and prior to cover crop termination. In both fall and spring, cover crops led to an increase in total PLFA concentration relative to the control (5.34 nmol g-1, P=0.045 and 10.22 nmol g-1, P=0.001, respectively), and in spring the highest PLFA concentrations were observed in canola (Brassica napus L., 89.74 + 5.58 nmol g-1) and the mixture containing all eight species (94.48 + 7.61 nmol g-1). Further, individual cover crop species favored particular microbial functional groups. Arbuscular mycorrhizal (AM) fungi were more abundant beneath oat (Avena sativa L.) and cereal rye (Secale cereale L.) cover crops. Non-AM fungi were positively associated with hairy vetch (Vicia villosa L.). These cover crop-microbial group associations were present not only in monocultures, but also multi-species cover crop mixtures. Soil biological activity was positively correlated with both the size (total PLFA: r=0.50, P<0.001) and composition (fungal:bacterial ratio: r=0.81, P<0.001) of the microbial community. This research establishes a clear link between cover crops, microbial communities, and soil health. We have shown that while cover crops generally promote microbial biomass and activity, there are species-specific cover crop effects on soil microbial community composition that ultimately influence soil biological activity. This discovery paves the way for intentional management of the soil microbiome to enhance soil health through cover crop selection.