Although the importance of the soil microbiome in mediating plant community structures and functions has been increasingly emphasized in ecological studies, the biological processes driving crop diversity overyielding remain unexplained in agriculture. Based on the plant–soil feedback (PSF) theory and method, we quantified to what extent and how soil microbes contributed to intercropping overyielding. Soils were collected as inocula and sequenced from a unique 10‐year field experiment, consisting of monoculture, intercropping and rotation planted with wheat ( In wheat & faba bean (W&F) and maize & faba bean (M&F) systems, soil microbes drove intercropping overyielding compared to monoculture, with 28%–51% of the overyielding contributed by microbial legacies. The overyielding effects resulted from negative PSFs in both systems, as crops, in particular faba bean grew better in soils conditioned by other crops than itself. Moreover, faba bean grew better in soils from intercropping or rotation than from the average of monocultures, indicating a strong positive legacy effect of multispecies cropping systems. However, with positive PSF and negative legacy benefit effect of intercropping/rotation, we did not observe significant overyielding in the W&M system. With more bacterial and fungal dissimilarities by metabarcoding in heterospecific than its own soil, the better it improved faba bean growth. More detailed analysis showed faba bean monoculture soil accumulated more putative pathogens with higher
Litter decomposition facilitates the recycling of often limiting resources, which may promote plant productivity responses to diversity, that is, overyielding. However, the direct relationship between decomposition, We test whether local adaptation of microbes, that is, home‐field advantage (HFA), N‐priming from plant inputs or precipitation drive decomposition and whether decomposition generates overyielding. Within a grassland diversity‐manipulation, altering plant richness (1, 2, 3 and 6 species), composition (communities composed of plants from a single‐family or multiple‐families) and precipitation (50% and 150% ambient growing season precipitation), we conducted a litter decomposition experiment. In spring 2020, we deployed four replicate switchgrass, Precipitation was a strong, independent driver of decomposition. Switchgrass decomposition accelerated with grass richness and decelerated as phylogenetic dissimilarity from switchgrass increased, suggesting decomposition is fastest at ‘home’. However, decomposition slowed with switchgrass density. In plots that contained switchgrass, we observed no relationship between decomposition and fungal saprotroph dissimilarity from switchgrass. However, in plots without switchgrass, decomposition slowed with increasing saprotroph dissimilarity from switchgrass. Combined these findings suggest that HFA is strongest when closely related neighbours, that is, heterospecific neighbours, are present in the community, rather than other individuals of the same species, that is, conspecifics. Legumes accelerated decomposition with more litter N remaining in those plots, suggesting that N‐inputs from planted legumes are priming decomposition of litter C. However, decomposition and overyielding were unrelated in legume communities. While in grass communities, overyielding and decomposition were positively related and the relationship was strongest in plots with low densities of switchgrass, that is, with heterospecific neighbours. Combined these findings suggest that plant species richness and community composition stimulate litter decomposition through multiple mechanisms, including N‐priming, but only HFA from local adaptation of microbes on closely related species correlates with overyielding, likely through resource recycling. Our results link diversity with ecosystem processes facilitating above‐ground productivity. Whether diversity loss will affect litter decomposition, productivity or both is contingent on resident plant traits and whether a locally adapted soil microbiome is maintained.
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- Award ID(s):
- 1738041
- NSF-PAR ID:
- 10489931
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Functional Ecology
- ISSN:
- 0269-8463
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Improved understanding of bacterial community responses to multiple environmental filters over long time periods is a fundamental step to develop mechanistic explanations of plant–bacterial interactions as environmental change progresses.
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