Ferrous wheel hypothesis II: Abiotic incorporation of mineral nitrogen into organic pools in volcanic soils of temperate forest ecosystems.

Understanding the pathways of nitrogen (N) retention in pristine forest soils is essential for effective ecosystem management and nutrient conservation. The incorporation of nitrate (NO) and nitrite (NO) into organic N in soils without microbiological contribution remains a very intriguing question. This study explores the abiotic incorporation of nitrate (NO) and nitrite (NO) into organic N of volcanic soil under sterilized and anoxic conditions, providing insights into mineral N losses occurring as dissolved organic N (DON) rather than the commonly accepted nitrate leaching.

Weathering by mycorrhizal fungi defines a threshold for nutrients in ecosystems along an aridity gradient.

The Earth's surface is in constant change due to biotic and abiotic processes. During the last decades awareness arose that these biotic and abiotic processes might intensely interfere. Biogenic weathering, the acceleration of mineral weathering by autotroph-symbiont couples fuelled by photoassimilates for the sake of an equilibrated nutrient supply of involved biota, potentially drives denudation rates at ecosystem level.

Contribution of arbuscular mycorrhiza and exoenzymes to nitrogen acquisition of sorghum under drought.

Introduction: For low-fertile and degraded soils of sub-Saharan Africa, nitrogen (N) is often the most growth-limiting factor restricting crop yields. The often-suggested exploitation of advantageous rhizosphere traits such as enzyme secretion and/or the symbiosis with arbuscular mycorrhizal fungi (AMF) remains to be validated as a potential strategy to overcome N limitation, especially when N deficiency co-occurs with further abiotic stresses such as water scarcity.

Methods: Three sorghum genotypes were cultivated in soil mesocosms with a root-exclusion compartment, where only AMF could scavenge for nutrients under drought and optimal conditions.

Effects of phosphorus availabilities on growth and yield of foxtail millet: insights from high-throughput phenotyping platforms.

Foxtail millet performance under low phosphorus (P) is determined by growth potential, with tiller number as a key indicator. Yield is influenced by P dilution rather than total P concentration. Foxtail millet, renowned for its high nutrient content and drought resilience, faces limited breeding investment despite being cultivated in vulnerable agri-systems.

Distinct water and phosphorus extraction patterns are key to maintaining the productivity of sorghum under drought and limited soil resources.

Nutrient and water limitations contribute to yield losses in semi-arid regions. Therefore, crop rotations incorporating nitrogen-fixing legumes and drought-tolerant sorghum varieties offer a strategy to improve the utilization of scarce soil resources. Under semi-arid, field-like conditions, sorghum crop rotations with either cowpea pre-crop or fallow, including two early and three late maturing genotypes, were tested to identify stress adaptation traits of sorghum to water and phosphorus limitations.

Cover crop monocultures and mixtures enhance bacterial abundance and functionality in the maize root zone.

Cover cropping is an effective method to protect agricultural soils from erosion, promote nutrient and moisture retention, encourage beneficial microbial activity, and maintain soil structure. Re-utilization of winter cover crop root channels by maize roots during summer allows the cash crop to extract resources from distal regions in the soil horizon. In this study, we investigated how cover cropping during winter followed by maize ( L.

Microbial strategies for phosphorus acquisition in rice paddies under contrasting water regimes: Multiple source tracing by P and P.

Microbial acquisition and utilization of organic and mineral phosphorus (P) sources in paddy soils are strongly dependent on redox environment and remain the key to understand P turnover and allocation for cell compound synthesis. Using double P labeling, we traced the P from three sources in a P-limited paddy soil: ferric iron-bound phosphate (Fe-P), wheat straw P (Straw-P), and soil P (Soil-P) in microbial biomass P (MBP) and phospholipids (Phospholipid-P) of individual microbial groups depending on water regimes: (i) continuous flooding or (ii) alternate wetting and drying. P labeling combined with phospholipid fatty acid analysis allowed to trace P utilization by functional microbial groups.

The mobilization and transport of newly fixed carbon are driven by plant water use in an experimental rainforest under drought.

Non-structural carbohydrates (NSCs) are building blocks for biomass and fuel metabolic processes. However, it remains unclear how tropical forests mobilize, export, and transport NSCs to cope with extreme droughts. We combined drought manipulation and ecosystem 13CO2 pulse-labeling in an enclosed rainforest at Biosphere 2, assessed changes in NSCs, and traced newly assimilated carbohydrates in plant species with diverse hydraulic traits and canopy positions.

Drought re-routes soil microbial carbon metabolism towards emission of volatile metabolites in an artificial tropical rainforest.

Drought impacts on microbial activity can alter soil carbon fate and lead to the loss of stored carbon to the atmosphere as CO and volatile organic compounds (VOCs). Here we examined drought impacts on carbon allocation by soil microbes in the Biosphere 2 artificial tropical rainforest by tracking C from position-specific C-pyruvate into CO and VOCs in parallel with multi-omics. During drought, efflux of C-enriched acetate, acetone and CHO (diacetyl) increased.

Is plant biomass input driving soil organic matter formation processes in grassland soil under contrasting management?

Grassland management practices vary in stocking rates and plant removal strategies (grazing versus mowing). They influence organic matter (OM) inputs, which were postulated as main controls of soil organic carbon (SOC) sequestration and might therefore control SOC stabilization. The aim of this study was to test this hypothesis by investigating the impacts of grassland harvesting regimes on parameters related to soil microbial functioning and soil organic matter (SOM) formation processes.

Intracellular carbon storage by microorganisms is an overlooked pathway of biomass growth.

The concept of biomass growth is central to microbial carbon (C) cycling and ecosystem nutrient turnover. Microbial biomass is usually assumed to grow by cellular replication, despite microorganisms' capacity to increase biomass by synthesizing storage compounds. Resource investment in storage allows microbes to decouple their metabolic activity from immediate resource supply, supporting more diverse microbial responses to environmental changes.

In situ diversity of metabolism and carbon use efficiency among soil bacteria.

The central carbon (C) metabolic network harvests energy to power the cell and feed biosynthesis for growth. In pure cultures, bacteria use some but not all of the network's major pathways, such as glycolysis and pentose phosphate and Entner-Doudoroff pathways. However, how these pathways are used in microorganisms in intact soil communities is unknown.

Long-term nitrogen and phosphorus fertilization reveals that phosphorus limitation shapes the microbial community composition and functions in tropical montane forest soil.

Microorganisms govern soil nutrient cycling. It is therefore critical to understand their responses to human-induced increases in N and P inputs. We investigated microbial community composition, biomass, functional gene abundance, and enzyme activities in response to 10-year N and P addition in a primary tropical montane forest, and we explored the drivers behind these effects.

Keep oxygen in check: An improved in-situ zymography approach for mapping anoxic hydrolytic enzyme activities in a paddy soil.

Paddy soils regularly experience redox oscillations during the wetting and draining stages, yet the effects of short-term presence of oxygen (O) on in-situ microbial hotspots and enzyme activities in anoxic ecosystems remain unclear. To fill this knowledge gap, we applied soil zymography to localize hotspots and activities of phosphomonoesterase (PME), β-glucosidase (BG), and leucine aminopeptidase (LAP) in three compartments of rice-planted rhizoboxes (top bulk, rooted, and bottom bulk paddy soil) under oxic (+O) and anoxic (O) conditions. Short-term (35 min) aeration decreased PME activity by 13-49 %, BG by 4-52 %, and LAP by 12-61 % as compared with O in three soil compartments.

The spatial distribution of rhizosphere microbial activities under drought: water availability is more important than root-hair-controlled exudation.

Root hairs and soil water content are crucial in controlling the release and diffusion of root exudates and shaping profiles of biochemical properties in the rhizosphere. But whether root hairs can offset the negative impacts of drought on microbial activity remains unknown. Soil zymography, C imaging and neutron radiography were combined to identify how root hairs and soil moisture affect rhizosphere biochemical properties.

Two-Phase Conceptual Framework of Phosphatase Activity and Phosphorus Bioavailability.

The activity of extracellular phosphatases is a dynamic process controlled by both plant roots and microorganisms, which is responsible for the mineralization of soil phosphorus (P). Plants regulate the availability of soil P through the release of root mucilage and the exudation of low-molecular weight organic acids (LMWOAs). Mucilage increases soil hydraulic conductivity as well as pore connectivity, both of which are associated with increased phosphatase activity.

Ectomycorrhizal and non-mycorrhizal rhizosphere fungi increase root-derived C input to soil and modify enzyme activities: A C pulse labelling of Picea abies seedlings.

Consequences of interactions between ectomycorrhizal fungi (EcMF) and non-mycorrhizal rhizosphere fungi (NMRF) for plant carbon (C) allocation belowground and nutrient cycling in soil remain unknown. To address this topic, we performed a mesocosm study with Norway spruce seedlings [Picea abies (L.) H.

Microbial functional changes mark irreversible course of Tibetan grassland degradation.

The Tibetan Plateau's Kobresia pastures store 2.5% of the world's soil organic carbon (SOC). Climate change and overgrazing render their topsoils vulnerable to degradation, with SOC stocks declining by 42% and nitrogen (N) by 33% at severely degraded sites.

Microbial iron reduction compensates for phosphorus limitation in paddy soils.

Limitation of rice growth by low phosphorus (P) availability is a widespread problem in tropical and subtropical soils because of the high content of iron (Fe) (oxyhydr)oxides. Ferric iron-bound P (Fe(III)-P) can serve as a P source in paddies after Fe(III) reduction to Fe(II) and corresponding HPO release. However, the relevance of reductive dissolution of Fe(III)-P for plant and microbial P uptake is still an open question.

Deep-rooted perennial crops differ in capacity to stabilize C inputs in deep soil layers.

Comprehensive climate change mitigation necessitates soil carbon (C) storage in cultivated terrestrial ecosystems. Deep-rooted perennial crops may help to turn agricultural soils into efficient C sinks, especially in deeper soil layers. Here, we compared C allocation and potential stabilization to 150 cm depth from two functionally distinct deep-rooted perennials, i.

Soil phosphorus status and P nutrition strategies of European beech forests on carbonate compared to silicate parent material.

Unlabelled: Sustainable forest management requires understanding of ecosystem phosphorus (P) cycling. Lang et al. (2017) [ https://doi.

Biogels in Soils: Plant Mucilage as a Biofilm Matrix That Shapes the Rhizosphere Microbial Habitat.

Mucilage is a gelatinous high-molecular-weight substance produced by almost all plants, serving numerous functions for plant and soil. To date, research has mainly focused on hydraulic and physical functions of mucilage in the rhizosphere. Studies on the relevance of mucilage as a microbial habitat are scarce.

Elucidating Drought-Tolerance Mechanisms in Plant Roots through H NMR Metabolomics in Parallel with MALDI-MS, and NanoSIMS Imaging Techniques.

As direct mediators between plants and soil, roots play an important role in metabolic responses to environmental stresses such as drought, yet these responses are vastly uncharacterized on a plant-specific level, especially for co-occurring species. Here, we aim to examine the effects of drought on root metabolic profiles and carbon allocation pathways of three tropical rainforest species by combining cutting-edge metabolomic and imaging technologies in an in situ position-specific C-pyruvate root-labeling experiment. Further, washed (rhizosphere-depleted) and unwashed roots were examined to test the impact of microbial presence on root metabolic pathways.