Nitrogen Resources Research Articles

Biological characterization and in vitro fungicide screening of a new causal agent of walnut leaf spot in Guizhou Province, China.

Walnut (Juglans regia L.) is a widely grown nut plant worldwide, including in Guizhou Province, located in southwest China. The high quality and special taste make Guizhou walnuts, particularly those produced in Hezhang County, a "Chinese National Geographical Indication Product" that substantially contributes to the local economy and grower's income. In July 2022, a serious occurrence of leaf spot disease was observed in a walnut plantation area, Shuitang Town, Hezhang County, Guizhou Province, China (27°07'67″N, 104°64'61″E). The causal agent was identified as Didymella segeticola through morphological characterization and amplification and sequencing of the internal transcribed spacer (ITS) region, beta-tubulin (TUB) gene, and glyceraldehyde-3-phosphate dehydrogenase (G3PD) gene. Koch's postulates, including re-isolation and identification, were performed to confirm its pathogenicity on healthy leaves. To our knowledge, this is the first report of D. segeticola causing leaf spot on walnuts worldwide. Further, to determine its biological characteristics, which could be utilized for future disease management, the effects of temperature, light, and carbon and nitrogen resources on mycelial growth, conidia production, and conidia germination and the effects of humidity on conidia germination were studied. The optimum temperature for mycelial growth of representative strain D. segeticola C27 was 20°C. Increasing the light period significantly decreased conidia production and conidia germination. Maltose and beef extract were the best carbon and nitrogen sources, respectively, for the pathogen. Conidia germination was enhanced at 90% humidity. In vitro screening of effective fungicides was conducted. Among the 20 screened fungicides, difenoconazole showed the best inhibition rate, with an EC50 (concentration for 50% of the maximal effect) of 0.0007 μg/mL. Tetramycin also showed sufficient inhibitory effects against D. segeticola, with an EC50 value of 0.0009 μg/mL. Our study provides new insights into the causal agent of walnut leaf spot in Guizhou, China, as well as the first pathogen characteristics and promising candidate fungicides for its management.

Successive monoculture of Eucalyptus spp. alters the structure and network connectivity, rather than the assembly pattern of rhizosphere and bulk soil bacteria

Eucalyptus as a fast-growing timber tree plays a crucial role in maintaining wood supplication and ecosystem balance worldwide. Nonetheless, the management practices of Eucalyptus plantation in southern China have resulted in productivity decline and soil degradation due to high-intensity successive cultivation. Soil bacteria is a sensitive indicator of soil quality, how does the successive planting of Eucalyptus regulate the soil bacterial community structure for instance the abundance of oligotrophic bacteria, network complexity, and soil bacteria assembly remain ambiguity. To explicate the underlying influencing mechanisms of successive cultivation of Eucalyptus plantations on soil bacterial community structure. Four harvests of Eucalyptus plantations that underwent 0, 1, 2, and 3 times of harvesting were conducted to examine variations in the bacterial community between rhizosphere and bulk soils after successive planting of Eucalyptus. An adjacent evergreen broadleaf forest was employed as control. The present study revealed that successive planting of Eucalyptus increased and reduced the relative abundance of Chloroflexi (oligotrophic bacteria) and Proteobacteria (copiotrophic bacteria), respectively. Continuous planting of Eucalyptus did not modify the assembly pattern of soil bacterial communities, which was governed by stochastic processes. Successive planting of Eucalyptus decreased co-occurrence network complexity, and elevated the proportion of rare microorganisms in the keystone bacterial taxa. Soil particle size composition (clay, silt, sand) indirectly influenced the structure of soil bacterial communities by directly affecting pH, carbon, nutrients, and their stoichiometric ratios. Improving soil physical structure, increasing the input of soil carbon, nitrogen, and other nutrient resources, and maintaining a balanced resource allocation may be effective strategies for ensuring enhanced productivity and sustainable utilization of soil in successive Eucalyptus plantations.

Integrating electrochemical pretreatment with microalgae treatment for nitrogen and phosphorus removal and resource recovery from swine wastewater

This study integrates electrochemical pretreatment with microalgae (Scenedesmus obliquus) treatment to enhance nitrogen and phosphorus removal and resource recovery from swine wastewater. By optimizing electrochemical and microalgae treatment conditions, the dilution factor and the hydraulic retention time for microalgae treatment were reduced to 5 times and 7 days, respectively. Under the optimized operational conditions, removal efficiencies of total nitrogen and ammonia could reach over 89 %and 96 %,respectively, and the removal efficiency of total phosphorus was over 99 %. The study also found that aluminum was more suitable than iron for anode as it produced fewer residues. Additionally, the electrochemical pretreatment reduced Cu2+ and Zn2+ concentrations, mitigating negative impacts on microalgal growth. The microalgae biomass harvested from developed processes was rich in saturated fatty acids, which was desirable for biodiesel production. This approach addresses the challenges of nutrient removal for swine wastewater treatment with high quality biomass recovery.

Multiple element approach to P recovery and recycling: A green and sustainable strategy by using fused magnesia waste ash

Recovery of phosphorus through controlling the crystallization of struvite (MgNH4PO4·6H2O), a slow-release fertilizer, is highly attractive, but costly if large amounts of magnesium and alkali have to be added. In this study, a strategy for synchronously recovering phosphorus and nitrogen resources from wastewater and magnesium resources from solid waste was proposed. We demonstrated the fused magnesia waste ash (FMWA), an industrial by-product of magnesia which might serve as a cost-effective source of magnesium and alkali. The results showed that a recovery efficiency of 93.0 % PO43− and 88.8 % NH4+ from synthetic wastewater and 46.6 % Mg2+ from the FMWA was achieved when the ratio of [Mg2+]:[NH4+]:[PO43−] was 1.8:1:1. The magnesium release potential of FMWA was 10 times more than that of other known magnesium-containing solid wastes, due to the process in electric melting furnace damaged the lattice structure of magnesite and converted magnesite to magnesia. XRD analysis showed that crystalline struvite was the major product. The undissolved components of FMWA (MgCO3, MgO and SiO2) acted as crystal seeds, increasing the particle size and accelerating struvite precipitation. The application of FMWA for phosphorus fixation can reduce costs by 98.3 % compared with MgCl2. This research paves the way for employing FMWA in efficient recovery of phosphorus from wastewater, simultaneously achieving the resource utilization of industrial waste.

Electrodialysis with sacrificial magnesium anode for nutrient recovery from primary municipal wastewater: Effect on membrane fouling behaviours

The fertilizer industry is experiencing tremendous stress due to its dependence on limited natural resources and high energy consumption, thus great attention has been paid for alternative nitrogen and phosphorus resources. This study employed electrodialysis (ED) with sacrificial magnesium anode to recover nitrogen and phosphorus (towards struvite formation) from primary municipal wastewater and examined the effects of various operating conditions on ED membranes' fouling behaviour. The results revealed that (1) lowering the concentrate to feed volume (C/F) ratio would reduce overall ED stack resistance, while at a C/F < 0.5, the magnesium corrosion rate decreased with an increase of pH in the concentrate stream; (2) the cation exchange membranes (CEM) adjacent to the feed chamber were more susceptible to foulant depositions (especially organics) than the anion exchange membrane (AEM); the total foulant density was linearly correlated with the increased electrical resistance; (3) increasing current density led to higher ion transport rate, however also promoted membrane fouling for the wastewater containing more solids; (4) the ammonium and phosphate mass transport rates were enhanced by increasing their concentrations in the feed instead of elevating current density. Higher concentrations of nutrient levels in the feed facilitated reduced scaling on membranes, possibly due to more formation of struvite. This study highlights the feasibility of simultaneously treating primary wastewater and recovering nutrients by combining gravity-driven membrane (GDM) filtration with ED.

Glacier extinction homogenizes functional diversity via ecological succession

AbstractQuestionsThe disappearance of glaciers threatens biodiversity and the functioning of ecosystems. Yet, questions remain about the response of functional diversity to glacier retreat. How does glacier retreat influence functional diversity? How does glacier retreat influence the relationship between taxonomic diversity and functional diversity? How does glacier retreat impact community mean and intraspecific trait variability (ITV) of key functional traits?LocationFour retreating glacier ecosystems in the Italian Alps. Plant communities spanning 0 to ca 5000 years on average after glacier retreat, including a scenario of glacier extinction.MethodsWe quantified functional diversity analyzing twelve plant traits associated to carbon and nitrogen cycling, resource allocation, and reproduction of 117 plant species. We addressed how functional diversity changes with glacier retreat and taxonomic diversity (i.e., plant species richness).ResultsPlant functional diversity decreases with glacier extinction while increasing with species richness. The positive relationship between taxonomic and functional diversity becomes flatter, that is, less important, with glacier retreat. We document sharp changes in functional niche position and breadth with glacier retreat. Key functional traits associated with carbon cycling and resource allocation change substantially with ecological succession triggered by glacier retreat. Traits associated to nitrogen cycling show little change. We also found that flowering start shifted earlier in the season while flowering period increased with glacier retreat.ConclusionOur results demonstrate the pervasive impact of glacier extinction on the functioning of plant communities. Changes in functional mean and functional variation indicate shifts in niche position and niche breadth which could have implications for species adaptation to changing environments.

Metabolic Response of the Lycium barbarum Variety 'Ningqi No. 7' to Drought Stress.

Lycium barbarum has been widely planted in arid and semi-arid areas due to its drought-resistant ability, which is of great economic value as a medicinal and edible homology plant. In this study, the metabolome of the L. barbarum variety "Ningqi 7" under different drought stress conditions was compared and analyzed by the non-targeted UPLC-MS (ultra-high performance liquid chromatography with mass spectrometry) technique. The results showed that drought stress significantly decreased the water content of leaves, increased the activity of antioxidant enzymes in plants, and up-regulated the metabolites and pathways involved in osmoregulation, antioxidant stress, energy metabolism, and signal transduction. Under moderate drought (40-45% FC), L. barbarum accumulated osmoregulatory substances mainly through the up-regulation of the arginine metabolism pathway. At the same time, phenylalanine metabolism and cutin, suberine, and wax biosynthesis were enhanced to improve the antioxidant capacity and reduce water loss. However, in severe drought (10-15% FC), L. barbarum shifted to up-regulate purine metabolism and lysine degradation and redistributed energy and nitrogen resources. In addition, vitamin B6 metabolism was significantly upregulated in both groups of stress levels, playing a key role in antioxidant and growth regulation. These observations delineate the metabolic adaptations of L. barbarum "Ningqi 7" in response to drought stress.

Effects of Planting Density and Nitrogen Management on Light and Nitrogen Resource Utilization Efficiency and Yield of Summer Maize in the Sichuan Hilly Region

The low efficiency of light and nitrogen resources, poor yield and profit, and environmental pollution of maize production are main problems in many areas of China. We hypothesized that optimizing nitrogen fertilizer density management strategies could alleviate the above issues. To address this, a 3-year on-site experiment with three planting densities and four nitrogen rates was conducted in the Sichuan Hilly Region. The results indicated that increasing the planting density could increase the extinction coefficient and solar radiation interception of maize populations as well as enhance the utilization efficiency of light and nitrogen resources and yield. For every 100 kg ha−1 increase in nitrogen fertilizer, RUE increased by 0.16%, NUE decreased by 25.0%, and soil apparent nitrogen loss quantity increased by 67.8 kg ha−1. There was a certain interaction between planting density and nitrogen rate. The appropriate planting density and nitrogen rate combination was 67,500 plants ha−1 with 180 kg N ha−1 under the experimental condition. Excessive close planting in weak-light areas and excessive nitrogen reduction after densification are not advisable. This study indicated that nitrogen–density strategies should be matched with the local natural resources such as sunlight. The results provide a theoretical for high-yield and high-quality maize production in these areas.

Ecosystem-scale carbon dynamics in desert Shrublands: Unraveling the complex interplay among leaf functional and physiological traits and environment

Understanding the relationships and dynamics of environmental variables, leaf traits, and photosynthetic parameters in determining gross ecosystem productivity (GEP) is fundamental to assessing the carbon (C) cycle. However, existing knowledge in this area, especially concerning desert ecosystems, remains entirely inadequate. In this study, we used near-continuous eddy covariance, foliar, and photosynthetic data acquired from an Artemisia ordosica-dominated shrubland over a seven-year period (2013–2019). The study proceeded to assess: (i) the influence of environmental variables on GEP as a function of leaf phenology, (ii) the role of foliar traits and photosynthetic parameters in regulating GEP, and (iii) resource use strategies adopted by A. ordosica in response to adverse environmental conditions. Analysis of controlling factors indicated that various environmental and photo-physiological factors influenced GEP to different extents, depending on leaf phenology. During the leaf-expanding phase, GEP was largely controlled by maximum carboxylation rate (Vcmax). With leaf expansion, the leaf dark respiration rate (Rd), stomatal conductance (Gs), and light compensation point (LCP) played pivotal roles in an upregulation of GEP. However, during the leaf-coloring phase, GEP was limited by the maximum electron transport rate (Jmax). Our findings accentuate A. ordosica's conservative strategy in nitrogen resource investment, which influences the shrubland's role as a C sink. These insights emphasize the importance of considering both climatic and plant physiological controls, especially as it pertains to photosynthesis, when seeking to understand broader C dynamics in desert ecosystems.

Nitrogen cycling and resource recovery from aquaculture wastewater treatment systems: a review

Nitrogen cycling and resource recovery from aquaculture wastewater treatment systems: a review

Asymmetric Zn-N4 atomic sites embedded hollow fibers as stable Zn anode for high-performance Zn-ion hybrid capacitor

Zn based electrochemical energy storage systems (EES) have attracted tremendous interests owing to their low cost and high intrinsic safety. Nevertheless, the uncontrolled growth of Zn dendrites and the side reactions of Zn metal anodes (ZMAs) severely restrict their applications. To address these issues, we design the asymmetric Zn-N4 atomic sites embedded hollow fibers (AS-IHF) as the flexible host for stable ZMAs. Through introducing different nitrogen resources in the synthesis, two kinds of coordination, i. e. Zn-N (pyridinic) and Zn-N (pyrrolic), are introduced in the Zn-N4 atomic module synchronously. The asymmetric Zn-N4 module with regulated micro-environment facilitates the superior zincophilic features and promotes the Zn adsorption. Meanwhile, the highly porous structure of the hollow fiber effectively reduces local current density, homogenize Zn ion flux, and alleviate structure stress. All the advantages endow the high efficiency and good stability for Zn plating/stripping. Both theoretical and experimental results demonstrate the high reversibility, low nucleation overpotential, and dendrite-free behavior of the AS-IHF@Zn anode, which afford the high stability in high-rate and long-term cycling. Moreover, the solid-state Zn-ion hybrid capacitor (ZIHC) based on AS-IHF@Zn anode shows the high flexibility, reliability, and superior long-term cycling capability in a wide-range of temperatures (−20–25 °C). Therefore, the present work not only gives a new strategy for modulating local environments of single atomic sites, but also propels the development of flexible power sources for diverse electronics.

Precision Nitrogen Management in Spring Rice (Oryza sativa L.) using Decision Support Tools in Chitwan, Nepal

The blanket prescription of nitrogen (N) fertilizer often results in irrational fertilization. To address this issue and align the application of nitrogen fertilizers with the crop-specific demand, it is imperative to save nitrogen resources, maximize the uptake and net income, and subside environmental pollution. In this context, a field experiment was carried out in Kumroj, Chitwan, Nepal during 2022 to assess the growth, yield, and profitability of rice production by comparing different precision nitrogen management practices. The study was carried out in a randomized complete block design with seven treatments and three replications. The treatments included decision support tools for nitrogen management such as the Green Seeker (GS), the Soil plant analysis development Development (SPAD) meter, and the Leaf Color Chart (LCC) combined with basal application of nitrogen at 30 kg ha–1 and the Urea briquette Deep Placement (UDP), the Polymer Coated Urea (PCU), and the Recommended Dose of Fertilizers (RDF, 120 kg N ha–1). The growth, yield, yield attributes, and financial data were taken. Precision nitrogen management techniques significantly enhanced rice growth and yield parameters. GS–guided application required the highest nitrogen demand (155 kg ha–1), while SPAD (80 kg ha–1) and UDP (78 kg ha–1) resulted in lower usage. PCU and UDP enhanced plant height, leaf area index, and above–ground dry matter. Higher grain yield (6.64 t ha–1) was attained with LCC, SPAD (6.44 t ha–1), and UDP (6.41 t ha–1) treatments. GS application exhibited the highest straw yield (11.17 t ha–1), while LCC demonstrated the highest benefit–cost ratio (1.96). This study concluded that SPAD and UDP demonstrated the potential to save nitrogen resources, while LCC and UDP were found profitable.

Unraveling the diversity of hyphal explorative traits among Rhizophagus irregularis genotypes

Differences in functioning among various genotypes of arbuscular mycorrhizal (AM) fungi can determine their fitness under specific environmental conditions, although knowledge of the underlying mechanisms still is very fragmented. Here we compared seven homokaryotic isolates (genotypes) of Rhizophagus irregularis, aiming to characterize the range of intraspecific variability with respect to hyphal exploration of organic nitrogen (N) resources, and N supply to plants. To this end we established two experiments (one in vitro and one in open pots) and used 15N-chitin as the isotopically labeled organic N source. In Experiment 1 (in vitro), mycelium of all AM fungal genotypes transferred a higher amount of 15N to the plants than the passive transfer of 15N measured in the non-mycorrhizal (NM) controls. Noticeably, certain genotypes (e.g., LPA9) showed higher extraradical mycelium biomass production but not necessarily greater 15N acquisition than the others. Experiment 2 (in pots) highlighted that some of the AM fungal genotypes (e.g., MA2, STSI) exhibited higher rates of targeted hyphal exploration of chitin-enriched zones, indicative of distinct N exploration patterns from the other genotypes. Importantly, there was a high congruence of hyphal exploration patterns between the two experiments (isolate STSI always showing highest efficiency of hyphal exploration and isolate L23/1 being consistently the lowest), despite very different (micro) environmental conditions in the two experiments. This study suggests possible strategies that AM fungal genotypes employ for efficient N acquisition, and how to measure them. Implications of such traits for local mycorrhizal community assembly still need to be understood.

Exploiting the roles of nitrogen sources for HEA increment in Cordyceps cicadae.

Cordyceps cicadae, as a new food ingredient, is a valuable edible and medicinal fungi. However, its resources are severely depleted due to environmental limitations and excessive harvesting practices. N6-(2-hydroxyethyl) adenosine (HEA), as an important product of Cordyceps cicadae, has the potential to be used in medical industry due to its diverse disease curing potential. However, the disclosure of HEA synthesis still severely limited its application until now. In this study, the kinetic curves for adenosine and HEA under shaker fermentation were explored. The kinetics of HEA and adenosine production exhibited a competitive pattern, implicating a possibility of sharing a same step during their synthesis. Due to HEA as a derivative of nitrogen metabolism, the effect of different nitrogen sources (peptone, yeast extract, ammonium sulfate, diammonium oxalate monohydrate, ammonium citrate dibasic, and ammonium citrate tribasic) on HEA production in Cordyceps cicadae strain AH 10-4 had been explored under different incubation conditions (shaker fermentation, stationary fermentation, and submerged fermentation). Our results indicated that the complex organic nitrogen sources were found to improve the accumulation of HEA content under shaker fermentation. In contrast, the optimal nitrogen source for the accumulation of HEA under stationary fermentation and submerged fermentation was ammonium citrate tribasic. But submerged fermentation obviously shortened the incubation time and had a comparable capacity of HEA accumulation by 2.578 mg/g compared with stationary fermentation of 2.535 mg/g, implicating a possibility of scaled-up production of HEA in industry by submerged fermentation. Based on the dramatic HEA production by ammonium sulfate as nitrogen resources between stationary and shaker fermentations, alanine, aspartate and glutamate as well as arginine metabolic pathway were related to the production of HEA by comparative transcriptome. Further investigation indicated that glutamic acid, which is an analog of Asp, showed an optimum production of HEA in comparison with other amino acids.

Electrochemical nitrogen reduction reaction catalyzed by a cucurbit[6]uril-phosphomolybdic-copper cation hybrid

The electrocatalytic nitrogen reduction reaction (NRR) provides an energy-saving and environmentally friendly method to synthesize ammonia. Herein, a molybdenum-containing hybrid material (Q[6]-PMA-Cu) was prepared form the assembly of Keggin-type phosphomolybdic acid (PMA) with cucurbit[6]uril (Q[6]) and Cu2+ cations. Q[6]-PMA-Cu with multiple active sites and stable properties not only enables a high selectivity for NRR, but also shows a distinct advantage to suppress HER process, affording a high ammonia yield of 135.04±4.25 µg h−1 mgcat−1 with a Faradaic efficiency (FE) of 85.48±3.33%. 15N2 isotope labeling and control experiments were conducted to verified the nitrogen resource of ammonia formation. The results of experiments and DFT calculations demonstrates the reaction mechanism along the alternate association pathway, of which the metal active sites (Mo & Cu) play crucial role in electron transfer and the presence of hydrophobic Q[6] is responsible to inhibit side reaction of HER.

The Simultaneous Efficient Recovery of Ammonia Nitrogen and Phosphate Resources in the Form of Struvite: Optimization and Potential Applications for the Electrochemical Reduction of NO3.

In response to the need for improvement in the utilization of ammonium-rich solutions after the electrochemical reduction of nitrate (NO3--RR), this study combined phosphorus-containing wastewater and adopted the electrochemical precipitation method for the preparation of struvite (MAP) to simultaneously recover nitrogen and phosphorus resources. At a current density of 5 mA·cm-2 and an initial solution pH of 7.0, the recovery efficiencies for nitrogen and phosphorus can reach 47.15% and 88.66%, respectively. Under various experimental conditions, the generated struvite (MgNH4PO4·6H2O) exhibits a typical long prismatic structure. In solutions containing nitrate and nitrite, the coexisting ions have no significant effect on the final product, struvite. Finally, the characterization of the precipitate product by X-ray diffraction (XRD) revealed that its main component is struvite, with a high purity reaching 93.24%. Overall, this system can effectively recover ammonium nitrogen from the NO3--RR solution system after nitrate reduction, with certain application prospects for the recovery of ammonium nitrogen and phosphate.

The Physiological Adjustments of Two Xerophytic Shrubs to Long-Term Summer Drought

Adaptive characteristics of plants, such as those associated with photosynthesis and resource use efficiency, are usually affected by synthesis costs and resource availability. The impact of extreme climate events such as long-term drought on plant physiological functions needs to be examined, particularly as it concerns the internal management of water and nitrogen (N) resources. In this study, we evaluated the resource management strategies for water and N by xerophytic shrubs, Artemisia ordosica and Salix psammophila, under extreme summer drought. This was carried out by comparing the plants’ physiological status during periods of wet and dry summer conditions in 2019 and 2021. Compared with the wet period, A. ordosica and S. psammophila both decreased their light-saturated net carbon (C) assimilation rate (Asat), stomatal conductance (gs), transpiration rate (E), leaf N content per leaf area (Narea), and photosynthetic N use efficiency (PNUE) during the summer drought. Whether in wet or dry summers, the gas-exchange parameters and PNUE of A. ordosica were generally greater than those associated with S. psammophila. The instantaneous water use efficiency (IWUE) response to drought varied with species. As a drought-tolerant species, the A. ordosica shrubs increased their IWUE during drought, whereas the S. psammophila shrubs (less drought-tolerant) decreased theirs. The divergent responses to drought by the two species were largely related to differences in the sensitivity of gs, and as a result, E. Compared with A. ordosica, S. psammophila’s inferior plasticity regarding gs response affected its ability to conserve water during drought. Our research illustrates the need for assessing plasticity in gs when addressing plant adaptation to long-term drought. A high dry-season IWUE in xerophytic shrubs can benefit the plants by augmenting their C gain.

Shifting focus from external to in situ organic resources – The redesign of four tropical long-term experiments

Long-term experiments (LTEs) are critical for evaluating strategies that can maintain or increase crop yields, soil fertility and soil organic carbon (SOC), and help adapt to climate change. Yet, scientific knowledge is advancing and research questions are evolving. Therefore, it is important to review the objectives of LTEs over time. A change in their design may be necessary to keep the experimental treatments scientifically interesting, innovative, and relevant in the context of evolving agricultural challenges. Here, we describe the process of redesigning four LTEs in Kenya. These LTEs are unique in that they represent four different pedoclimatic conditions but with identical experimental treatments across sites. Initially, they focused on investigating how to maintain or increase SOC and maize yields over time by applying a combination of mineral nitrogen (N) and external organic resources. Specifically, the experimental treatments consisted of maize monoculture with different rates (1.2 and 4 t C ha−1 yr−1) and qualities of organic resources, either with or without mineral N fertilizer input. After about 20 years, it became clear that SOC was lost in most treatments. Therefore, continuing with the current experimental design was not an option. Taking advantage of the fact that the different former treatments led to different levels of soil degradation, we redesigned the LTEs to study the effectiveness of regenerative cropping strategies in rebuilding SOC and increasing crop yields starting from the different levels of soil degradation. The focus shifted from external to in situ organic inputs by increasing the root biomass of the cultivated crops. The newly established cropping system treatments are maize-legume rotation, maize-legume intercropping (double row configuration) and relay intercropping of maize with forage grass. A key finding from the previous phase of the experiments, namely, that external organic inputs with low C:N ratios are most efficient in building SOC, has been incorporated into the redesign. The relative contribution of external versus in situ organic resources is tested by splitting the cropping system treatments into those receiving either farmyard manure or green manure in the form of Tithonia diversifolia prunings and those receiving no external inputs. Split-plot treatments with and without mineral N were retained. The overall objective of studying mechanisms of tropical soil fertility maintenance and, more specifically, SOC formation, remained unchanged. However, the redesign aligned the LTEs with the current state of knowledge and pressing research questions, specifically focusing on the relative effectiveness of in-situ versus external organic inputs in SOC formation.

Electrically charged forward osmosis for enhancing urea recovery from synthetic urine

Human urine, known as liquid gold, provides 80 % of the nitrogen sources in wastewater treatment plants through urea, making urea recovery an effective method for recycling nitrogen resources. In this work, a novel urea electrically charged forward osmosis (UEFO) system was used to treat human urine to enhance the accumulation of water penetration and urea recovery by overcoming concentration polarization and reverse solute flux. The system contained four chambers with an effective volume of 28 mL and was equipped with external glass vials. The feed solution was 40 mL of urine and the draw solution was 50 mL of potassium chloride solution. With the addition of an electric field, Cl−, SO42− and PO43− were transported from the feed solution (FS) to the anode chamber through the AEM, while OH– and SO42− were transported from the cathode chamber to the draw solution (DS) through the AEM, resulting in high osmotic pressure difference between the DS and FS, which enhanced the urea recovery. With the enhancement of current intensity from 0 to 0.04 A, water flux and urea increased from 8.02 LMH and 39.78 mg to 12.74 LMH and 56.16 mg (accounting for 76.82 % of total urea), respectively. These results demonstrated that the UEFO system could overcome the limitations of traditional FO systems (50 % recovery barrier) and showcased a promising performance for urea recovery from human urine by integrating electrochemical and osmotic-driven processes.

Proteome reorganization and amino acid metabolism during germination and seedling establishment in Lupinus albus.

During germination plants rely entirely on their seed storage compounds to provide energy and precursors for the synthesis of macromolecular structures until the seedling has emerged from the soil and photosynthesis can be established. Lupin seeds use proteins as their major storage compounds, accounting for up to 40% of the seed dry weight. Lupins are therefore a valuable complement to soy as a source of plant protein for human and animal nutrition. The aim of this study was to elucidate how storage protein metabolism is coordinated with other metabolic processes to meet the requirements of the growing seedling. In a quantitative approach, we analysed seedling growth, as well as alterations in biomass composition, the proteome, and metabolite profiles during germination and seedling establishment in Lupinus albus. The reallocation of nitrogen resources from seed storage proteins to functional seed proteins was mapped based on a manually curated functional protein annotation database. Although classified as a protein crop, Lupinus albus does not use amino acids as a primary substrate for energy metabolism during germination. However, fatty acid and amino acid metabolism may be integrated at the level of malate synthase to combine stored carbon from lipids and proteins into gluconeogenesis.