Low Nutrient Research Articles

Multi-class plant hormone HILIC-MS/MS analysis coupled with high-throughput phenotyping to investigate plant-environment interactions.

Plant hormones are chemical signals governing almost every aspect of a plant's life cycle and responses to environmental cues. They are enmeshed within complex signaling networks that can only be deciphered by using broad-scale analytical methods to capture information about several plant hormone classes simultaneously. Methods used for this purpose are all based on reversed-phase (RP) liquid chromatography and mass spectrometric detection. Hydrophilic interaction chromatography (HILIC) is an alternative chromatographic method that performs well in analyses of biological samples. We therefore developed and validated a HILIC method for broad-scale plant hormone analysis including a rapid sample preparation procedure; moreover, derivatization or fractionation is not required. The method enables plant hormone screening focused on polar and moderately polar analytes including cytokinins, auxins, jasmonates, abscisic acid and its metabolites, salicylates, indoleamines (melatonin), and 1-aminocyclopropane-1-carboxylic acid (ACC), for a total of 45 analytes. Importantly, the major pitfalls of ACC analysis have been addressed. Furthermore, HILIC provides orthogonal selectivity to conventional RP methods and displays greater sensitivity, resulting in lower limits of quantification. However, it is less robust, so procedures to increase its reproducibility were established. The method's potential is demonstrated in a case study by employing an approach combining hormonal analysis with phenomics to examine responses of three Arabidopsis ecotypes toward three abiotic stress treatments: salinity, low nutrient availability, and their combination. The case study showcases the value of the simultaneous determination of several plant hormone classes coupled with phenomics data when unraveling processes involving complex cross-talk under diverse plant-environment interactions.

The Effect of Mycorrhiza and Plant Growth-Promoting Rhizobacteria Supplementation on Zea mays saccharata Sturt. Growth and Productivity Grown on Low Nutrients Soil

Marginal land has low nutrient content (nitrogen, phosphorus, potassium). Addressing nutrient deficiencies on marginal land requires a strategic approach. Biological fertilizers like Arbuscular Mycorrhizal Fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) enhance nutrient availability through symbiotic interactions. In addition, organic fertilizers such as compost could provide organic matter and improve soil structure to increase plant growth and productivity. Combining these three fertilizers with the addition of low doses of NPK fertilizer can increase the growth and productivity of maize crops on sub-marginal land. This study aims to determine the effect of AMF, consortium of PGPR, and a low dose of NPK on the growth and productivity of maize and soil nutrients on sub-marginal land by measuring plant growth up to 8 WAP (week after planting) (parameters: plant height, stem diameter, number of leaves, leaf area, chlorophyll content, stomatal density) and productivity (parameters: cob length, cob weight with husk, fresh weight, dry weight) and levels of N, P, and K elements at 8 WAP in the soil after planting. All treatments showed an increase in the level of N and K elements, while the P element showed a decrease compared to the control (soil without treatment). Moreover, each parameter did not show a significant difference, but the P2 (Compost + PGPR consortium + AMF + 50% of NPK) treatment showed the best growth and productivity. Overall, the data showed the utilization of PGPR and AMF combination was able to reduce the usage of chemical fertilizer by 50%.

Herbicidal and Nitrogen Efficacy on Weed Management in Wheat Fields of Eastern Uttar Pradesh, India

Weeds can significantly affect crop yield and nutrient uptake, making effective management crucial in wheat fields. This study, conducted during the winter (Rabi) season of 2018-19 at the Agricultural Research Farm of Banaras Hindu University in Varanasi, aimed to assess the combined impact of different nitrogen levels and herbicide treatments on weed control and wheat production. The objective was to determine the best practices for reducing weed competition and improving crop performance. The experiment was set up using a split plot design with three replications. The treatments comprised of 3 nitrogen levels and 5 weed control methods. The study identified nine prevalent weed species in wheat fields, including Phalaris minor, Anagallis arvensis, Cynodon dactylon, Chenopodium album, Melilotus indicus, Vicia sativa, Medicago denticulata, Solanum nigrum, and Cyperus rotundus, with Anagallis arvensis, Chenopodium album and Vicia sativa being the most dominant. The application of Sulfosulfuron (25 g ha-1) combined with 2, 4-D (750 ml ha-1) resulted in the lowest weed density and biomass and the highest weed control efficiency. Additionally, performing hand weeding twice (30 and 60 days after sowing) in conjunction with 180 kg N ha-1, followed by the application of Sulfosulfuron (25 g ha-1) + 2, 4-D (750 ml ha-1), significantly reduced Anagallis arvensis, Chenopodium album and Vicia sativa population and biomass and improved weed control effectiveness. Higher weed dry weight and population results in lower plant nutrient uptake and lower dry matter of crop plant and yield.

Impact of low nutrient environment on placental formation and metabolism: Novel insights from the MEM mouse model

Impact of low nutrient environment on placental formation and metabolism: Novel insights from the MEM mouse model

A fungal endophyte increases plant resilience to low nutrient availabilities: a case of Fe acquisition in legumes.

Microbial inocula are considered a promising and effective alternative solution to the use of chemical fertilizers to support plant growth and productivity since they play a key role in the availability and uptake of nutrients. Here, the effect of a beneficial of a fungal root endophyte, Fusarium solani strain K (FsK), on nutrient acquisition efficiency of the legume Lotus japonicus was studied, and putative mode-of-action of the endophyte at a molecular level was determined. Plant colonization with the endophyte resulted in increased shoot and root fresh weight under Fe deficiency compared to control nutrient conditions. Plant inoculation with FsK was associated with a significant increase in macro- and micronutrient concentration in leaves at an early stage of endophyte inoculation and a replenishment of Fe content under prolonged iron starvation. The mechanistic basis of the plant growth promotion capabilities of the endophyte is exerted at the transcriptional level since we recorded changes in the expression levels of genes related to iron uptake in FsK-colonized plants under stress conditions compared to uninoculated plants. In addition, the observed changes in the ethylene biosynthesis-related genes suggest a possible implication of ethylene in the mode of action used by FsK to enhance plant response to nutrient stress conditions. Finally, we demonstrated that the endophyte possesses a reductive high-affinity Fe uptake system and identified a ferric reductase that was induced in planta under Fe deficiency conditions, indicating that this fungal Fe homeostasis mechanism may result in a benefit in nutrient acquisition for the plant as well.

The effectiveness of combination of arbuscular mycorrhizal fungi and compost ameliorant on sengon growth in former coal mine soil

Abstract Mining activities give a negative impact to the soil which become the ex-coal mine soil. The soil has a solid soil structure and low nutrient content so is not suitable for planting. The problems need to be improved by being treated with biological agents from soil microorganisms such as Arbuscular Mycorrhizal Fungi (AMF). The provision of AMF on ex-coal mine soil with the addition of ameliorant compost can be one strategy that can be used. AMF can help increase plant growth and help the process of absorption of phosphate (P) by plants. Compost from goat manure can help the association between AMF and plant roots, also being a source of nutrients that are free from chemicals. The plants which suitable for this association are sengon. Sengon commonly used to help revegetation of ex-mining soil because it is able to withstand various conditions of overgrown soil. This study aims to determine the effect of the addition of a combination of AMF and compost on the growth of sengon plants in the soil of ex-coal mines. Observations were made weekly until the age of three months, the best results were the results at the end of the observation. The results showed that the AMF dose and the addition of compost had an effect on percent AMF colonization, increasing plant height, dry weight of plant roots increasing plant stem diameter, and number of leaves.

Chain forming diatoms use different strategies to avoid diffusion limited N assimilation

AbstractFormation of large colonies by phytoplankton is considered a disadvantage during low nutrient and non‐turbulent conditions because of diffusion limitation and competition by neighboring cells. This is assumed by diffusion models and not empirical measurements. Here, we measured cell‐specific dissolved inorganic carbon (DIC) and nitrate () assimilation in two chain‐forming Skeletonema marinoi strains by combining secondary ion mass spectrometry with stable isotopic tracer incubations. The pelagic strains were recently germinated from resting stages and thus not adapted to high nutrient regimes of laboratory cultures. During the exponential phase, the cells assimilated excess relative to DIC. The DIC and assimilation varied with chain length or the position of the cell within chains but did not follow any consistent trend. Solitary cells were rare and did not exceed 6% of all cells. During the nitrogen‐limited stationary phase, assimilation was lower than modeled by mass transfer theory at diffusion limitation. assimilation rates were apparently limited by the biological uptake rate at nitrate concentrations < 0.46 μmol L−1. We conclude that S. marinoi is adapted to high nutrient concentrations and may seldom be diffusion limited in coastal waters with ambient concentrations > 0.46 μmol L−1. These findings contrast those previously reported in larger chain forming diatoms, for example, Chaetoceros, which appear to circumvent diffusion limitation at low ambient concentrations and succeed S. marinoi during spring blooms.

Nutrient availability influences the thermal response of marine diatoms

AbstractUnderstanding how phytoplankton growth responds to temperature is critical for forecasting marine productivity in a warming ocean. While previous laboratory studies have shown that phytoplankton thermal traits such as optimal temperature (Topt) can be affected by nutrient availability, it is unclear whether this can be extrapolated to natural communities. To address this, we tested the impacts of nutrient availability on the thermal responses of two cosmopolitan diatom genera, Pseudo‐nitzschia and Leptocylindrus, through a series of in situ manipulation experiments on natural phytoplankton communities. Analysis of the thermal performance curves revealed that nutrient limitation during summer not only limited the growth of these two genera but also reduced their Topt and the maximum growth rates (μmax). Topt was close to or lower than in situ temperature under ambient nutrient conditions, suggesting that further warming may have a detrimental effect on their growth. However, increasing nutrient supply could counteract this by enhancing Topt and μmax. To further confirm the interactive effects of nutrients and temperature on diatoms, we analyzed a 20‐yr monitoring dataset on Pseudo‐nitzschia, Leptocylindrus, and the whole diatom assembly in Hong Kong coastal waters. We found that the abundances of marine diatoms were significantly higher at high temperatures under nutrient‐rich environments while relatively low under low nutrient concentrations. Findings on natural diatom cell density align with the growth performance derived from in situ manipulation experiments, suggesting that abundant nutrients bolster marine diatoms in coping with warming. Our results highlight the importance of considering the influence of nutrient availability on thermal response of phytoplankton growth, which sheds light on how marine primary production may change under climate warming.

Political Economic Role in Natural Quality Management and its Impact on Plant Ecology: Why Arar-Juniper Plants Disappeared

Wadi-Arar is a unique region that has lost some of its most important natural features within 200 years, including plants, geographical lakes, and valleys. The study aimed to investigate the disappearance of the juniper plant, a vital species in Saudi Arabia, in recent decades. The research highlighted various factors influencing the quality of life for the juniper plant and its habitats. It sought to identify the primary factors causing changes in the natural conditions of the plant and those influencing its growth. The findings indicated a significant impact of the Suez Canal on the Arar region, the sole connection between Africa and Asia, and Europe. This influence extends beyond geopolitical factors in the surrounding area, as the existence of the Suez Canal disrupted the natural life cycle of many animal species over thousands of years of migrations and coexistence across Earth's continents. These animals previously provided natural organic fertilizer to the soil, supporting plant growth. However, due to low rainfall resulting in low natural nutrients and high salinity, the plants' viability has diminished, reflecting a history of administrative and geopolitical decisions.

Exploring the variations in molecular characteristics of dissolved organic matter driven by aquaculture types

In recent decades, global aquaculture has expanded rapidly, raising concerns about coastal environmental degradation due to unregulated or poorly regulated discharge of aquaculture tailwater. Despite the crucial role of dissolved organic matter (DOM) in biogeochemical processes and aquatic biodiversity, the influence of aquaculture type on the molecular characteristics of DOM remains largely unexplored. Herein, this study investigated the variations in chemical and spectroscopic properties as well as molecular characteristics and composition of DOM across different aquaculture types including crustacean, fish and shellfish. Our findings revealed notable differences in DOM quantities among different aquaculture types, with crustacean and fish aquaculture water containing higher DOM amount compared to shellfish aquaculture water. This disparity can be attributed to the more frequent formulated feeds of crustacean and fish in contrast to shellfish aquaculture. Furthermore, distinct differences were also observed in the characteristics and composition of DOM among the different aquaculture waters. Specifically, DOM in shellfish aquaculture water exhibited a higher abundance of unsaturated and reduced molecules as well as increased aromaticity compared to the other two aquaculture waters. Conversely, DOM from fish aquaculture water showed a greater contribution from terrestrial origin characterized by elevated levels of plant-based components such as lignin-like and tannin-like compounds. Interestingly, DOM from shellfish aquaculture water contained lower levels of microbial-derived components such as lipid-like and protein-like compounds, likely due to reduced microorganism populations resulting from lower nutrients availability and higher salinity. Overall, these significant variations in characteristics and composition of DOM underscore the potential impacts of aquaculture type on the DOM biogeochemical cycle and the environmental quality in aquatic ecosystems.

RESPON PRODUKSI TANAMAN BAWANG MERAH (Allium ascalonicum L.) TERHADAP BOKASHI KOTORAN SAPI DAN PUPUK ROCK FOSFAT PADA MEDIA GAMBUT

The development of shallot cultivation in Riau needs to be done by optimizing peatlands. However, problems such as low pH and low nutrient availability need to be addressed. The use of cow manure bokashi can increase the availability of soil nutrients and the addition of P fertilizer from rock phosphate is expected to increase the availability of P in peat soil. The purpose of this study was to determine the role of cow manure bokashi and rock phosphate fertilizer in increasing the production of shallot plants in peat media. This research was carried out at the UIR Experimental Garden, Pekanbaru, from September to December 2022. The materials used in this study were Brebes shallot seedlings, cow manure bokashi, rock phosphate, urea, KCl. The tools used in the research included hoes, tape measure, cutter knife, analytical scales, camera and stationery. The research method used a Factorial Completely Randomized Design (CRD). The first factor was the dose of cow manure bokashi with 4 treatment levels: without cow manure bokashi, 40, 80 and 120 g/polybag Bokashi cow manure. The second factor was the dose of rock phosphate fertilizer with 4 treatment levels: 0, 0.8 g/polybag, 1.6, 2.4 g/polybag. Each experimental unit was repeated 3 times. Observational data were analyzed statistically and further tested for HSD the 5% level. Application of cow manure bokashi with rock phosphate can increase shallot production. Application of cow manure bokashi 80 g/polybag with rock phosphate dose of 2.4 g/polybag increased the wet and dry shallot bulb weight.

Potential of Arbuscular Mycorrhizal Fungi to Overcome Drought Stress and Low Nutrient Availability in Dryland Farming

There is an increasing rate of land conversion in Indonesia that can threaten food self-sufficiency. Therefore farmers and the government must expand agriculture by developing agriculture on potential available lands such as drylands. However, drylands in Indonesia have low productivity due to low water and nutrient availability. This article aims to determine the potential use of arbuscular mycorrhizal fungi to overcome drought stress and low nutrient availability in drylands. The method used in writing this article is a desk literature study conducted by collecting data from various sources, such as scientific journals, seminar proceedings, and online reports available in related government office in West Nusatenggara Province. The data obtained were then analyzed qualitatively by identifying, reviewing, and synthesizing information to produce a complete and comprehensive explanation. The results of the literature study showed that arbuscular mycorrhizal fungi have the potential to overcome drought stress and low nutrient availability in drylands. The use of arbuscular mycorrhizal fungi can be a sustainable solution to increase agricultural productivity in drylands.

Potential of Arbuscular Mycorrhizal Fungi to Overcome Drought Stress and Low Nutrient Availability in Dryland Farming

There is an increasing rate of land conversion in Indonesia that can threaten food self-sufficiency. Therefore farmers and the government must expand agriculture by developing agriculture on potential available lands such as drylands. However, drylands in Indonesia have low productivity due to low water and nutrient availability. This article aims to determine the potential use of arbuscular mycorrhizal fungi to overcome drought stress and low nutrient availability in drylands. The method used in writing this article is a desk literature study conducted by collecting data from various sources, such as scientific journals, seminar proceedings, and online reports available in related government office in West Nusatenggara Province. The data obtained were then analyzed qualitatively by identifying, reviewing, and synthesizing information to produce a complete and comprehensive explanation. The results of the literature study showed that arbuscular mycorrhizal fungi have the potential to overcome drought stress and low nutrient availability in drylands. The use of arbuscular mycorrhizal fungi can be a sustainable solution to increase agricultural productivity in drylands.

Nutrient cycling on dairy farms in the Netherlands: The role of farm structure, management and trade-offs

Food production is a major driver for crossing planetary boundaries. Improving nutrient cycling may enable maintaining production while reducing environmental losses. This study assesses the current state of Dutch dairy on-farm nutrient (nitrogen- N, phosphorus - P) cycling through re-use of manure, scope for improvement and potential trade-offs. Data of 27 farms between 2006–2022 were used.Nutrient use efficiency (Output/Input) varied widely, with an average of 0.39 (0.29–0.47) for N and 0.88 (0.69–1.01) for P. Combining circularity and efficiency indicators showed that most gain in efficiency could be made by increasing cycled flow. Management related with improved cycling had lower external nutrient inputs, both from fertiliser and feed. Farm structure mattered for farm performance, as extensive farms with lower external N inputs from fertiliser or feed had higher N cycling and lower greenhouse gas emissions, but at the costs of agricultural land use and productivity.

Mapping taste and flavour traits to genetic markers in lettuce Lactuca sativa

Lettuce is the most highly consumed raw leafy vegetable crop eaten worldwide, making it nutritionally important in spite of its comparatively low nutrient density in relation to other vegetables. However, the perception of bitterness caused by high levels of sesquiterpenoid lactones and comparatively low levels of sweet tasting sugars limits palatability. To assess variation in nutritional and taste-related metabolites we assessed 104 members of a Lactuca sativa cv. Salinas x L. serriola (accession UC96US23) mapping population. Plants were grown in three distinct environments, and untargeted NMR and HPLC were used as a rapid chemotyping method, from which 63 unique Quantitative Trait Loci (QTL) were identified. We were able to identify putative regulatory candidate genes underlying the QTL for fructose on linkage group 9, which accounted for up to 36 % of our population variation, and which was stable across all three growing environments; and for 15-p-hydroxyyphenylacetyllactucin-8-sulfate on linkage group 5 which has previously been identified for its low bitterness, while retaining anti-herbivory field effects. We also identified a candidate gene for flavonoid 3′,5′- hydroxylase underlying a polyphenol QTL on linkage group 5, and two further candidate genes in sugar biosynthesis on linkage groups 2 and 5. Collectively these candidate genes and their associated markers can inform a route for plant breeders to improve the palatability and nutritional value of lettuce in their breeding programmes.

Causal feedback loops modify lake chlorophyll a–nutrient relationships over two decades of nutrient reductions and climate warming

AbstractUnderstanding how the causal feedback between phytoplankton and environmental drivers controlling the chlorophyll a (Chl a, as a proxy of phytoplankton biomass)–nutrient relationships are modulated under different ecosystem conditions is a major challenge in aquatic ecology. Using an empirical dynamic model (convergent cross mapping) on a 20‐yr dataset on 20 Danish lakes, we quantified hypothesized causal feedback networks for each lake and related them to lake system properties (e.g., mean water depth, nutrient concentrations and extent of reduction, climate warming) vs. the Chl a–nutrient relationship (estimated from generalized least square models). The results showed prevalent causal feedback across the studied lakes, which demonstrated clear patterns for the tested ecosystem variations. Weaker causal feedbacks were found in deeper lakes and lakes with larger warming trends, while stronger causal feedbacks appeared in lakes experiencing greater reductions of TP (total phosphorus) and TN (total nitrogen). Moreover, these causal feedbacks showed a strong and positive coupled pattern. Most of the causal feedbacks worked as enhancement loops, which promote the sensitivity of phytoplankton to TP, not least in shallow lakes with a high TP reduction, and as regulatory loops, which force a shift in the Chl a–TN relationship from a more negative slope in lakes experiencing a high nutrient reduction and weak warming to a positive slope in lakes with low nutrient reduction and stronger warming. Our findings suggest a mechanistic explanation of how internal feedbacks regulate the Chl a–nutrient relationships across a broad gradient of nutrient reductions, climate warming, and lake morphologies.

Soil properties predict below-ground community structure, but not nematode microbiome patterns in semi-arid habitats.

Microbial and microeukaryotic communities are extremely abundant and diverse in soil habitats where they play critical roles in ecosystem functioning and services that are essential to soil health. Soil biodiversity is influenced by above-ground (vegetation) and below-ground factors (soil properties), which together create habitat-specific conditions. However, the compound effects of vegetation and soil properties on soil communities are less studied or often focused on one component of the soil biota. Here, we integrate metabarcoding (16S and 18S rRNA genes) and nematode morphology to assess the effects of habitat and soil properties shaping microbial and microeukaryotic communities as well as nematode-associated microbiomes. We show that both vegetation and soil properties (soil bulk density) were major factors structuring microbial and microeukaryotic communities in semi-arid soil habitats. Despite having lower nutrients and lower pH, denser soils displayed significantly higher alpha diversity than less dense soils across datasets. Nematode-associated microbiomes have lower microbial diversity, strongly differ from soil microbes and are more likely to respond to microscale variations among samples than to vegetation or soil bulk density. Consequently, different nematode lineages and trophic groups are likely to display similar associated microbiomes when sharing the same microhabitat. Different microbiome taxa were enriched within specific nematode lineages (e.g. Mycobacterium, Candidatus Cardinium) highlighting potentially new species-specific associations that may confer benefits to their soil nematode hosts. Our findings highlight the importance of exploring above- and below-ground effects to assess community structure in terrestrial habitats, and how fine-scale analyses are critical for understanding patterns of host-associated microbiomes.

Effects of long-term nighttime warming on extractable soil element composition in a Mediterranean shrubland

Understanding the soil biogeochemical responses to increasing global warming in the near future is essential for improving our capacity to mitigate the impacts of climate change on highly vulnerable Mediterranean ecosystems. Previous studies have primarily focused on the effects of warming on various biogeochemical processes. However, there is limited knowledge about how the changes in water availability associated to high temperatures can alter the bioavailability and dynamics of soil elements, thereby impacting ecosystem productivity, species composition, and pollution through soil biogeochemical and hydrological processes. In this study, we investigated the effects of long-term nighttime warming on the extractable concentrations of organic carbon (EOC), total nitrogen (ETN), total phosphorus (ETP), and 17 mineral elements (arsenic (As), calcium (Ca), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), potassium (K), magnesium (Mg), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), sulfur (S), strontium (Sr), vanadium (V), and zinc (Zn)) through environmental experiments in a semi-arid Mediterranean shrubland. We explored the potential biotic and abiotic mechanisms underlying the seasonal and long-term changes in extractable-mobilizable elemental composition and concentrations. Our findings revealed that prolonged warming led to higher mean annual soil temperature (with an average increase of 0.67 °C from 1999 to 2014), accumulation of soil organic matter (EOC) and extractable concentrations of soil elements (particularly increased ETP and extractable Ca, Mg, Cu, Sr, Mn, and As). These changes were attributed to uniformly higher activities of extracellular soil enzymes and/or lower plant photosynthetic and nutrient uptake capacity linked to more water deficit under warmer conditions. Seasonality unevenly altered element extractable concentrations, with soil microclimate (temperature and water content) and biological (soil microbial and plant) activity being the main drivers of this variability, thus influencing soil element composition. These results suggest significant fluctuations in the extractable concentrations of specific mineral elements in these soils, implying potential future variations in soil element composition as well as the loss of total element concentrations/contents in semi-arid Mediterranean ecosystems due to increasing warming. Therefore, these findings enhance our ability to predict ecosystem management strategies and mitigate the observed negative impacts on plant-soil systems and water quality in the context of climate change.

Overlooked drivers of the greenhouse effect: The nutrient-methane nexus mediated by submerged macrophytes

Submerged macrophytes remediation is a commonly used technique for improving water quality and restoring habitat in aquatic ecosystems. However, the drivers of success in the submerged macrophytes assembly process and their specific impacts on methane emissions are poorly understood. Thus, we conducted a mesocosm experiment to test the growth plasticity and carbon fixation of widespread submerged macrophytes (Vallisneria natans) under different nutrient conditions. A refined dynamic chamber method was utilized to concurrently collect and quantify methane emission fluxes arising from ebullition and diffusion processes. Significant correlations were found between methane flux and variations in the physiological activities of V. nantas by the fluorescence imaging system. Our results show that exceeding tolerance thresholds of ammonia in the water significantly interfered with the photosynthetic systems in submerged leaves and the radial oxygen loss in adventitious roots. The recovery process of V. natans accelerated the consumption of dissolved oxygen, leading to increase in the populations of methanogen (153.3 % increase of mcrA genes) and subsequently elevating CH4 emission fluxes (23.7 %) under high nutrient concentrations. Conversely, V. natans increased the available organic carbon under low nutrient conditions by radial oxygen loss, further increasing CH4 emission fluxes (94.7 %). Quantitative genetic and modeling analyses revealed that plant restoration processes drive ecological niche differentiation of methanogenic and methane oxidation microorganisms, affecting methane release fluxes within the restored area. The speciation process of V. natans is incapable of simultaneously meeting improved water purification and reduced methane emissions goals.

Estimating soil mineral nitrogen from data-sparse field experiments using crop model-guided deep learning approach

Sandy soils are susceptible to excessive nitrogen (N) leaching under intensive crop production which is linked with the soil’s low nutrient holding capacity and high-water infiltration rate. Estimating soil mineral nitrogen (SMN) at the daily time-step is crucial in providing fertilizer recommendations balancing plant nitrogen use efficiency (NUE) and N losses to the environment. Crop models [e.g., Decision Support System for Agrotechnology Transfer (DSSAT)] can simulate SMN trend under varied fertilizer application rates and timings but struggle with accuracy in high-water table conditioned sub-irrigated soil. Alternatively, time-series deep learning (DL) models based on a long short-term memory (LSTM) are promising in understanding nonlinearity among complex variables. Yet, purely data-driven DL models for crops are challenging to develop due to limited field data availability and the excessive costs to collect more field data. Hence, a hybrid model (hybrid-LSTM) was developed by leveraging both the DSSAT and LSTM models to estimate daily SMN primarily using daily weather, applied fertilizer rates-timings, and the SMN sparse observations. This study used the observations from field trials conducted between 2011–2014 in Hastings, FL. The first step was to calibrate the DSSAT-SUBSTOR-Potato model to produce reliable SMN of the topsoil for treatments with varied N applied fertilizer rates split among the pre-planting, emergence, and tuber-initiation stages of the potato. Thereafter, the hybrid-LSTM model was trained on the calibrated DSSAT simulated SMN time-series and fine-tuned its predictions using the observed SMN to improve DSSAT simulated SMN. The hybrid-LSTM model was then tested on both calibrated and uncalibrated DSSAT SMN simulations where it outperformed the DSSAT model (improvement ranged ∼18–30 % on comparing the normalized root mean squared error) in providing reliable estimates of SMN across most of the farms and years. This novel hybrid modeling approach could guide stakeholders and farmers to build sustainable N management with improved crop NUE and yield and help in minimizing environmental losses.