Interaction of Inherited Microbiota from Cover Crops with Cash Crops

Abstract

Cover crops (CC) provide important ecosystem services that are demanded to achieve more sustainable agrosystems. However, the legacy effects of CC on the microbial community structure and its interactions with the subsequent cash crops (CaC) are still poorly understood, especially when CC mixtures are involved. In this work, five CC (3 monocultures and 2 mixtures) were selected in an experiment under semi-controlled conditions to investigate if CC monocultures and mixtures differed in their effects on soil and crop variables and if the identity of the subsequent crop modulates these effects. The two most consumed crops worldwide, wheat and maize, were sown separately after CC. The legacy effects of CC on the studied microbial variables largely depended on the interaction with the CaC. The vetch and the barley-vetch mixture stood out by providing the microbial conditions that enhanced the absorption of macro- and micronutrients, to finally seek the highest wheat biomass (>80% more than the control). In maize, the effects of CC on soil microbiota were more limited. The soil microbial responses for CC mixtures were complex and contrasting. In wheat, the barley-vetch mixture behaved like barley monoculture, whereas in maize, this mixture behaved like vetch monoculture. In both CaC, the barley-melilotus mixture differed completely from its monocultures, mainly through changes in archaea, Glomeromycota, and F:B ratio. Therefore, it is necessary to deepen the knowledge on the CC-CaC-microbial interactions to select the CC that most enhance the sustainability and yield of each agrosystem.

Cover crop identity determines root fungal community and arbuscular mycorrhiza colonization in following main crops

“…Within the ryegrass + clover mixture, the ryegrass legacy dominated over the clover legacy with respect to both colonization and community structure of the fungi in the roots of the main crops. These results are in line with recent work on soil microbial communities of Ulcuango et al (2021) who found that the legacy of a barley-vetch mixture resulted in soil microbial communities which resembled the microbial communities of the grass and differed from that of the legume. Interestingly, we found few indicator-OTUs classified as pathotrophic, yet several of these appeared to be indicator-OTUs for the clover CC treatment.…”

“…Root colonization by fungi was assessed by staining fresh root subsamples of oat and endive using the ink and vinegar method (Vierheilig et al, 1998). Percentage of total AMF, arbuscles, vesicles and non-AMF (different from AMF) root colonization were determined using a light microscope according to the magnified intersections method (McGonigle et al, 1990).…”

Estimating the Reduction in Cover Crop Vitality Followed by Pelargonic Acid Application Using Drone Imagery

“…Cultivation of cover crops is a valuable and sustainable agricultural practice that offers agroecosystems numerous benefits. However, several factors need to be considered in the management of cover crops, including the method used to desiccate them [1,2]. While being desirable in agroecosystems, many cover crops have the potential to become troublesome weeds and, thus, may reduce the yields of subsequent crops if consideration is not given to their proper desiccation [1,2].…”

“…However, several factors need to be considered in the management of cover crops, including the method used to desiccate them [1,2]. While being desirable in agroecosystems, many cover crops have the potential to become troublesome weeds and, thus, may reduce the yields of subsequent crops if consideration is not given to their proper desiccation [1,2]. Moreover, in climate-smart conservation tillage systems, cover crop desiccation is a tool used to prepare a weed-free seedbed [3,4].…”

Nurturing belowground life: the role of cover crops in shaping soil microbial communities in agroecosystems

“…The neutralisation of cover crop-induced shifts in the indigenous soil microbiome will depend on the identity of the main crop. This notion was nicely illustrated by Ulcuango et al (2021)who showed that the differential effects of vetch, sweet clover and barley cover crops on the bacteria, fungal, AMF and archaeal communities depended on the identity of the main crop. In this case, vetch and sweet clover induced similar soil microbial responses in wheat and maize main crops, by promoting the total abundance of fungi, bacteria and archaea, while the effect of the barley cover crop was less pronounced and significantly distinct among the two main crops.…”