Explore the vast range of titles available.

Biogeochemical cycles are fundamental to the functioning of plant–soil systems, driving the availability and transfer of essential nutrients (like carbon (C), nitrogen (N), phosphorus (P), and sulfur (S)) as well as beneficial elements (like silicon (Si)). These interconnected cycles regulate ecosystem productivity, biodiversity, and resilience, forming the basis of critical ecosystem services. This review explores the mechanisms and dynamics of biogeochemical C, N, P, S, and Si cycles, emphasizing their roles in nutrient/element cycling, plant growth, and soil health, especially in agricultural plant–soil systems. The coupling between these cycles, facilitated mainly by microbial communities, highlights the complexity of nutrient/element interactions and corresponding implications for ecosystem functioning and stability. Human activities including industrial agriculture, deforestation, and pollution disrupt the underlying natural processes leading to nutrient/element imbalances, soil degradation, and susceptibility to climate impacts. Technological advancements such as artificial intelligence, remote sensing, and real-time soil monitoring offer innovative solutions for studying and managing biogeochemical cycles. These tools enable precise nutrient/element management, identification of ecosystem vulnerabilities, and the development of sustainable practices. Despite significant progress, research gaps remain, particularly in understanding the interlinkages between biogeochemical cycles and their responses to global change. This review underscores the need for integrated approaches that combine interdisciplinary research, technological innovation, and sustainable land-use strategies to mitigate human-induced disruptions and enhance ecosystem resilience. By addressing these challenges, biogeochemical processes and corresponding critical ecosystem services can be safeguarded, ensuring the sustainability of plant–soil systems in the face of environmental change.

Biogeochemical element cycling in plant-soil systems is fundamental for ecosystem dynamics and services [...].Biogeochemical element cycling in plant-soil systems is fundamental for ecosystem dynamics and services [...].

Silicon (Si) speciation and availability in soils is highly important for ecosystem functioning, because Si is a beneficial element for plant growth. Si chemistry is highly complex compared to other elements in soils, because Si reaction rates are relatively slow and dependent on Si species. Consequently, we review the occurrence of different Si species in soil solution and their changes by polymerization, depolymerization, and condensation in relation to important soil processes. We show that an argumentation based on thermodynamic endmembers of Si dependent processes, as currently done, is often difficult, because some reactions such as mineral crystallization require months to years (sometimes even centuries or millennia). Furthermore, we give an overview of Si reactions in soil solution and the predominance of certain solid compounds, which is a neglected but important parameter controlling the availability, reactivity, and function of Si in soils. We further discuss the drivers of soil Si cycling and how humans interfere with these processes. The soil Si cycle is of major importance for ecosystem functioning; therefore, a deeper understanding of drivers of Si cycling (e.g., predominant speciation), human disturbances and the implication for important soil properties (water storage, nutrient availability, and micro aggregate stability) is of fundamental relevance.

Plants’ ability to take up silicon from the soil, accumulate it within their tissues and then reincorporate it into the soil through litter creates an intricate network of feedback mechanisms in ecosystems. Here, we provide a concise review of silicon’s roles in soil chemistry and physics and in plant physiology and ecology, focusing on the processes that form these feedback mechanisms. Through this review and analysis, we demonstrate how this feedback network drives ecosystem processes and affects ecosystem functioning. Consequently, we show that Si uptake and accumulation by plants is involved in several ecosystem services like soil appropriation, biomass supply, and carbon sequestration. Considering the demand for food of an increasing global population and the challenges of climate change, a detailed understanding of the underlying processes of these ecosystem services is of prime importance. Silicon and its role in ecosystem functioning and services thus should be the main focus of future research.

Healthy peatlands are the largest terrestrial carbon (C) store despite covering only approximately 3% of total global land surface. However, peatland health is threatened by anthropogenic exploitation and degradation by drainage. Consequently, large-scale ambitious projects to re-wet and restore peatlands have been initiated. It is hoped that they will sequester C and provide a nature-based solution to climate change. The organic-rich peat soils contained in peatlands play an important role in the global C cycle and other biogeochemical cycles, including global silicon (Si) cycling. Testate amoebae (TA) are a dominant group of microbial consumers in peatlands, and their siliceous shells form protozoic Si pools, which represent an important biological sink for Si in these ecosystems. Seasonal variations and the influence of peatland microtopography on protozoic Si pools are unexplored areas of research. In this study, we present data on protozoic Si pools in a former raised bog under restoration management. Our findings show variability in protozoic Si pools between seasons, microtopography, and vegetation cover. There was a clear trend of higher protozoic Si pools in hummocks than in hollows in all seasons, and higher protozoic Si pools were associated with higher water table depth and lower temperatures in colder/wetter months (November/autumn, February/winter) than that in warmer/drier months (May/spring, August/summer). These results suggest that future quantification of protozoic Si pools in peatlands should consider fine-scale spatiotemporal variables as an important feature in the experimental design.

The significance of biogenic silicon (BSi) pools as a key factor for the control of Si fluxes from terrestrial to aquatic ecosystems has been recognized for decades. However, while most research has been focused on phytogenic Si pools, knowledge of other BSi pools is still limited. We hypothesized that different BSi pools influence short-term changes in the water-soluble Si fraction in soils to different extents. To test our hypothesis we took plant (Calamagrostis epigejos, Phragmites australis) and soil samples in an artificial catchment in a post-mining landscape in the state of Brandenburg, Germany. We quantified phytogenic (phytoliths), protistic (diatom frustules and testate amoeba shells) and zoogenic (sponge spicules) Si pools as well as Tiron-extractable and water-soluble Si fractions in soils at the beginning (t0) and after 10 years (t10) of ecosystem development. As expected the results of Tiron extraction showed that there are no consistent changes in the amorphous Si pool at Chicken Creek (Hühnerwasser) as early as after 10 years. In contrast to t0 we found increased water-soluble Si and BSi pools at t10; thus we concluded that BSi pools are the main driver of short-term changes in water-soluble Si. However, because total BSi represents only small proportions of water-soluble Si at t0 (< 2 %) and t10 (2.8–4.3 %) we further concluded that smaller (< 5 µm) and/or fragile phytogenic Si structures have the biggest impact on short-term changes in water-soluble Si. In this context, extracted phytoliths (> 5 µm) only amounted to about 16 % of total Si contents of plant materials of C. epigejos and P. australis at t10; thus about 84 % of small-scale and/or fragile phytogenic Si is not quantified by the used phytolith extraction method. Analyses of small-scale and fragile phytogenic Si structures are urgently needed in future work as they seem to represent the biggest and most reactive Si pool in soils. Thus they are the most important drivers of Si cycling in terrestrial biogeosystems.

For the majority of higher plants, silicon (Si) is considered a beneficial element because of the various favorable effects of Si accumulation in plants that have been revealed, including the alleviation of metal(loid) toxicity. The accumulation of non-degradable metal(loid)s in the environment strongly increased in the last decades by intensified industrial and agricultural production with negative consequences for the environment and human health. Phytoremediation, i.e., the use of plants to extract and remove elemental pollutants from contaminated soils, has been commonly used for the restoration of metal(loid)-contaminated sites. In our viewpoint article, we briefly summarize the current knowledge of Si-mediated alleviation of metal(loid) toxicity in plants and the potential role of Si in the phytoremediation of soils contaminated with metal(loid)s. In this context, a special focus is on metal(loid) accumulation in (soil) phytoliths, i.e., relatively stable silica structures formed in plants. The accumulation of metal(loid)s in phytoliths might offer a promising pathway for the long-term sequestration of metal(loid)s in soils. As specific phytoliths might also represent an important carbon sink in soils, phytoliths might be a silver bullet in the mitigation of global change. Thus, the time is now to combine Si/phytolith and phytoremediation research. This will help us to merge the positive effects of Si accumulation in plants with the advantages of phytoremediation, which represents an economically feasible and environmentally friendly way to restore metal(loid)-contaminated sites.

Sustainable and resilient crop production is facing many challenges. The restoration of natural reactive silicon cycles offers an opportunity to improve sustainability through reducing phosphorus fertilizer use and to increase crops’ resilience to drought stress and pests. We therefore call upon farmers, agri-food-researchers, and policymakers to pave the road for transforming agriculture to a silicon-improved sustainable crop production, which represents a promising approach to achieve food security under global change.