Mineral Nitrogen Research Articles

Sources of nutrients fuelling post-flood phytoplankton biomass in a subtropical bay

Extreme rainfall from an ex-tropical cyclone caused a major flood event in the Logan River system in southeast Queensland, Australia. This resulted in a significant flood plume, containing nutrients and sediment, being discharged into the adjacent estuary/Bay system. The spatial extent of higher phytoplankton biomass (Chl a) matched the distribution of higher nutrient and sediment concentrations post-flood, suggesting nutrients fuelled phytoplankton production. Particulate nitrogen (PN) constituted over 50 % of total nitrogen in floodwaters, with lower proportions of dissolved inorganic nitrogen (DIN) and phosphate (PO4-P). Phytoplankton utilised DIN rapidly but may have maintained growth due to the release of ammonia from suspended sediments and microbial mineralisation of particulate organic nitrogen. Ammonia release from intertidal sediments contributed minimally (0.85 %) to daily phytoplankton nitrogen demands. Our study highlights the need to understand the fate of particulate nitrogen in coastal systems and its role in stimulating phytoplankton growth.

Soil mineral nitrogen and winter wheat nitrogen productivity influenced by summer cover crop and nitrogen fertilization

Cover crops and nitrogen (N) fertilization may affect soil mineral N, N uptake, and N productivity (grain yield per unit plant available N) in wheat (Triticum aestivum L.). We evaluated the effect of summer cover crops and N fertilization rates on soil mineral N and winter wheat grain yield, N uptake, and N productivity in the Loess Plateau of China. We measured cover crop aboveground biomass N, soil mineral N (0-20 cm), and winter wheat yield, N uptake, and N productivity for four seasons from 2017-2018 to 2020-2021. Cover crops were soybean (Glycine max L., SB), sudangrass (Sorghum sudanense [Piper] Stapf, SG], soybean and sudangrass mixture (SS), and no cover crop (CK) and N fertilization rates were 0, 60, and 120 kg N ha−1 applied to wheat. The SB increased cover crop biomass N and soil mineral N by 15 to 65%, but SS increased winter wheat yield, protein concentration, and N uptake by 25 to 55% compared to SG and CK at most N fertilization rates and years. Nitrogen fertilization rate had a variable effect on cover crop and wheat parameters. Wheat N productivity was 55 to 85% greater with CK than cover crops, but decreased with increased N fertilization rates. The N fertilizer equivalence of cover crops for wheat yield and N uptake ranged from 31 kg N ha−1 for SG to 150 kg N ha−1 for SS. Overall, SS with 60 kg N ha−1 can sustain winter wheat N uptake and N productivity compared to SG or CK with or without N fertilization.

Reduction in Nitrogen Fertilization Rate for Spring Wheat Due to Carbon Mineralization-Induced Nitrogen Mineralization

Reduction in Nitrogen Fertilization Rate for Spring Wheat Due to Carbon Mineralization-Induced Nitrogen Mineralization

Nitrogen and phosphorus mineralization dynamics in human excreta-derived fertilizers

Growing interest in human-excreta derived fertilizers requires more information on their agronomic relevance. In this study, we measured the nitrogen (N) and phosphorus (P) mineralization from fresh urine, stored urine, urine-enriched biochar prepared with either fresh or stored urine, and feces-derived compost application in a 90-day aerobic loam soil incubation. Soils were extracted for available N at days 0, 5, 10, 20, 30, 60, and 90, while soils were extracted for four biologically relevant P pools at days 0, 30, 60, and 90. We found that N in urine applied alone was immediately bioavailable, supplying nearly all the 200 kg-N ha-1 applied, while urine-enriched biochar supplied approximately half of the N applied. Feces-derived compost application led to a slow release of mineral N. Feces-derived compost application stimulated substantial native soil P mining, while urine-P was likely rapidly immobilized. These results are relevant to container-based sanitation and other source-separated sanitation endeavors, and researchers and producers interested in human excreta-derived fertilizers. Future research should explore, among other things, different urine-enriched biochar preparations and the co-application of urine-based fertilizers and feces-derived compost.

Effect of nitrogen addition on soil net nitrogen mineralization in topsoil and subsoil regulated by soil microbial properties and mineral protection: Evidence from a long-term grassland experiment

Soil net nitrogen mineralization (Nmin), a microbial-mediated conversion of organic to inorganic N, is critical for grassland productivity and biogeochemical cycling. Enhanced atmospheric N deposition has been shown to substantially increase both plant and soil N content, leading to a major change in Nmin. However, the mechanisms underlying microbial properties, particularly microbial functional genes, which drive the response of Nmin to elevated N deposition are still being discussed. Besides, it is still uncertain whether the relative importance of plant carbon (C) input, microbial properties, and mineral protection in regulating Nmin under continuous N addition would vary with the soil depth. Here, based on a 13-year multi-level field N addition experiment conducted in a typical grassland on the Loess Plateau, we elucidated how N-induced changes in plant C input, soil physicochemical properties, mineral properties, soil microbial community, and the soil Nmin rate (Rmin)-related functional genes drove the responses of Rmin to N addition in the topsoil and subsoil. The results showed that Rmin increased significantly in both topsoil and subsoil with increasing rates of N addition. Such a response was mainly dominated by the rate of soil nitrification. Structural equation modeling (SEM) revealed that a combination of microbial properties (functional genes and diversity) and mineral properties regulated the response of Rmin to N addition at both soil depths, thus leading to changes in the soil N availability. More importantly, the regulatory impacts of microbial and mineral properties on Rmin were depth-dependent: the influences of microbial properties weakened with soil depth, whereas the effects of mineral protection enhanced with soil depth. Collectively, these results highlight the need to incorporate the effects of differential microbial and mineral properties on Rmin at different soil depths into the Earth system models to better predict soil N cycling under further scenarios of N deposition.

Root Exudates Promoted Microbial Diversity in the Sugar Beet Rhizosphere for Organic Nitrogen Mineralization

Rhizosphere environments play a vital role in the nutrient cycling of crops and soil organic nitrogen mineralization. Sugar beet is a highly nitrogen (N)-demanding crop, and it is necessary to explore the relationship between the sugar beet root exudates, the microbial community, and nitrogen utilization. In this study, a special separation method was employed to create rhizosphere (H3) and non-rhizosphere (H2 and H1) environments for sugar beet. After 50 d of cultivation in nearly inorganic-free soil, the microbial diversity and its correlation with root metabolites and N were examined. The results showed that in H3, the inorganic N content was over 23 times higher than in H1 and H2, with a 13.1% higher relative abundance of ammonia-oxidizing bacteria compared to H2 and a 32% higher abundance than H1. The relative abundance of nitrite-oxidizing bacteria was also 18.8% higher than in H1. Additionally, a significant positive correlation was observed between inorganic nitrogen content and serine (Ser) and isoleucine (Ile). The organic nitrogen content exhibited positive correlations with glycine (Gly), alanine (Ala), and tyrosine (Tyr) but displayed negative correlations with certain amino acids, organic acids, and glucose. The co-linearity network indicated that the microbial composition in H3 also exhibited higher node connectivity. It can be inferred that under the influence of sugar beet root exudates, the changes in the rhizosphere’s microbial diversity were more intricate, thereby benefiting soil nitrogen cycling and inorganic N accumulation. These findings provide profound insight into sugar beet soil organic nitrogen mineralization and contribute to the sustainable and environmentally friendly development of modern agriculture.

The soil sample conservation method and its potential impact on ammonium, nitrate and total mineral nitrogen measurements

Scientific literature for mineral soil nitrogen content (ammonium and nitrate) measurements usually differs regarding the chosen soil sample conservation method (fresh, frozen or air-dry) before soil extraction and analysis. In addition, most of the commonly used methodologies focus on the definition of the analysis processes, regardless of the previous sample conservation methodology. With the aim to fill this gap, we performed an analysis of the conservation method effect on the nitrate, and ammonium content in frozen or air-dried samples, comparing the results with direct fresh extraction. Moreover, the effects of additional soil parameters, such as soil texture, organic matter content or mineral nitrogen content range were also studied. The results showed that both, frozen and air drying soil samples, were capable of reliably preserving the N content of soil samples in most cases. However, some ammonium losses may occur in frozen samples when a high N content (>30 mg kg−1) is present. It was also observed that air-dried soil samples can reduce the soil nitrate and increase ammonium content in samples with a high N content. It was also observed that significant amounts of organic matter in soil can alter the mineral N measured depending on the conservation method chosen. On the other hand, the soil texture presented small effects on the mineral N measurements. In any case, a broader range of soils conditions (including i.e. pH or different natural organic matter content) should be further tested to confirm our findings.

ACCUMULATION OF SYMBIOTIC NITROGEN BY PERENNIAL LEGUMINOUS CROPS IN THE SOUTHERN STEPPE OF UKRAINE

The use of perennial leguminous crops is an energetically and economically beneficial and ecologically safe measure for improving the nitrogen balance of soils, which implementation requires specification and additional research of certain soil and climatic conditions and farming systems. The work aimed at studying the accumulation of biologically bound nitrogen by alfalfa and Hungarian sainfoin in single-species crops, as well as in wheatgrass-alfalfa and wheatgrass-sainfoin grass mixtures on the dark-chestnut soil of southern Ukraine. Laboratory, field, and statistical research methods were applied. The obtained results showed that the accumulation of nitrogen in the biomass of leguminous perennial grasses in single-species crops of blue hybrid alfalfa, Hungarian sainfoin, and intermediate wheatgrass and their grass mixtures depended on the hydrothermal conditions of the growing season, changes in species botanical composition by the years of grass stand used. During the first and second years of use, the nitrogen content in the biomass of alfalfa was 3,54-3,75%, sainfoin – 3,49-3,65%, and was significantly higher than in single-species crops of intermediate wheatgrass – 2,62-2,77% to dry matter. The removal of total nitrogen by intermediate wheatgrass during this period did not exceed 90 kg/ha; by alfalfa and sainfoin, it was 125-134 kg/ha, including symbiotic nitrogen removed by the alfalfa crop – 35-39 kg/ha and Hungarian sainfoin – 37-44 kg /ha. In the fractional composition of nitrogen in the soil of the experimental field after three years of using alfalfa when inoculating seeds with the complex microbial preparation Ecovital, the nitrogen content was the highest compared to other types of crop rotation, including total nitrogen – 1006,3-1428,8, mineral nitrogen – 24,9-46,3; alkaline hydrolyzed nitrogen – 113,8-186,0 mg/kg of soil. The obtained results allow us to conclude that the creation of highly productive symbiotic systems when using the latest biological preparations will contribute to improving soil nitrogen balance, eliminate the catastrophic decrease in fertility and soil degradation, improve the fodder base for animal production, and reduce the ecological burden on agricultural lands.

Sustainable Methods of Soybean Cultivation in Poland

Many countries in Europe are struggling with a shortage of feed protein; moreover, efforts are being made to limit the import of post-extraction soybean meal, most often from GMO crops. To achieve the above assumptions, varietal progress is necessary and, above all, breeding work should aim at greater adaptation to regional conditions. This study was designed to evaluate the potential for growing Ukrainian soybean ‘Annushka’ in the southeastern Baltic Sea area, in accordance with the application of mineral nitrogen fertilizer and the inoculation of seeds with Bradyrhizobium japonicum. Soybean ‘Annushka’ yielded 0.98–1.68 t ha−1 in the conditions of central Poland. Our experiments have shown significant variations in seed, protein, and fat yields over the years. The maximum amounts of these characteristics were recorded in 2017. Nitrogen fertilization combined with seed inoculation with B. japonicum has proven to be an important factor in improving soybean yields; however, it slightly modified the content of organic compounds in seeds. Improvement in seed and protein yields relative to the control amounted, respectively, to Nitragina + 30 kg N ha−1 (58.8%; 72.6%), HiStick® Soy + 30 kg N ha−1 (57.6%; 68.3%), and Nitroflora + 60 kg N ha−1 (57.6%; 71.9%).

Sewage Sludge Increased Lettuce Yields by Releasing Valuable Nutrients While Keeping Heavy Metals in Soil and Plants at Levels Well below International Legislative Limits

Sewage sludge can be used as an organic amendment as long as it is ensured that there is no risk of environmental contamination or risk to public health. In this study, sewage sludge from two wastewater treatment plants (WWTPs) subjected to two disinfection and stabilization treatments [40% (mass/mass), calcium oxide, and calcium hydroxide] and their respective untreated sewage sludge were used. Three control treatments were also added: conventional farmyard manure (FYM), a nitrogen (N) mineral fertilizer (ammonium nitrate 34.5% N) applied at a rate of 50 kg N ha−1 (N50) (the same rate of all organic amendments), and an unfertilized control (N0), totaling nine treatments. Lettuce (Lactuca sativa L.) was cultivated in pots for two growing cycles. The dry matter yield (DMY) was higher in the N50 treatment (13.5 and 10.6 g plant−1 in the first and second growing cycles, respectively), followed by sewage sludge (10.8 to 12.4 and 8.4 to 8.7 g plant−1), FYM (8.5 and 7.2 g plant−1), and the control (7.7 and 6.0 g plant−1). The DMY was related to the N provided by the different treatments, assessed by the N and nitrate concentrations in tissues, N uptake, and apparent N recovery (ANR). Sewage sludge, due to its high N concentration and low carbon (C)/N ratio, mineralized rapidly, providing a significant amount of N to plants, as well as other nutrients, such as phosphorus (P) and boron (B). FYM, with a higher C/N ratio, provided less N to plants, also due to the short duration of the lettuce growing cycle. Alkalized sewage sludge increased soil pH and calcium (Ca) availability for plants. Fertilizer treatments minimally influenced cationic micronutrients. Heavy metals in the initial sewage sludge were below the threshold values established in international legislation, and the levels in soil and lettuce tissues were generally not higher than those in other treatments. Both of the sewage sludges used in this study showed high fertilizing value and very reactive behavior, making nutrients available much more quickly than FYM. This information is relevant to consider in defining their agricultural use.

Artificial neural networks in soil quality prediction: Significance for sustainable tea cultivation

In today's era artificial intelligence is quite popular, one of the most effective algorithms used is Artificial Neural Networks (ANN). In this study, the determination of soil quality using the Soil Management Assessment Framework (SMAF) model in areas where tea cultivation is carried out at the micro-watershed scale and the predictability of soil quality using ANN were evaluated. According to the results, the soil quality indices of tea-growing areas were generally classified as “medium” between 55 and 70 %. Among the evaluated features for determining soil quality, the highest relative importance value was for soil organic carbon content (13 %) and potential mineralizable nitrogen (13 %), whereas the lowest values were for exchangeable potassium (4 %) and sodium adsorption ratio (SAR) (4 %). In addition, when comparing the actual and predicted values for soil quality prediction using ANN, the Lin's concordance correlation coefficient (LCCC), ratio of performance to deviation (RPD), and R2 values were found to be 0.93, 2.95, and 0.89, respectively. Significant properties for the determined values within a 90 % predicted interval were found to be organic matter, microbial biomass carbon, bulk density, and aggregate stability of the soils. Moreover, the uncertainty values (standard deviation) in the model predictions were determined to be within the range of 1.01–4.56 %. Consequently, the Soil Quality Index (SQI) obtained from the SMAF model using 12 soil properties in tea-growing areas could be accurately predicted using ANN. As a result of this study, digital maps showing the spatial distribution of SQI and the predicted uncertainties can help monitor SQI levels in this area.

Sunflower-nitrogen calibration based on the amount of mineral nitrogen in soil under rainfed conditions in thrace region

Sunflower is grown under both rainfed and irrigated conditions in all regions to meet the vegetable oil needs of Türkiye, however, in the Thrace region, it is the main rotation crop grown under rainfed conditions after wheat. This study was conducted in the Thrace Region between 2013 and 2016 in order to evaluate the parameters that can be used as an index for nitrogen fertilization recommendations for sunflower plant. For this purpose, organic matter and saturation were determined in soil samples taken from 0-20 cm depth before the experiment and ammonium and nitrate contents were determined in soil samples taken from 0-30 cm, 30-60 cm, and 60-90 cm depths. Within the scope of the study, 27 field trials were conducted over four years. Nitrogen levels of 0 (control), 3, 6, 9, and 12 kg da-1 were implemented in the trials conducted in a Latin square experimental design. In this study, log (279.9-y) = log279.9-0.090b1-0.117x Mitscherlich calibration equations were determined based on 0-30 cm ammonium+nitrate content in the soil.

Compost and Mineral Fertilizer Application Affects Soil Microbial Activity and Nutrient Mineralization in an Ultisol

ABSTRACT Organic additions help improve soil biophysical qualities, but they are insufficient to supply nutrient demand and could result in unintentional nutrient immobilization in soils, particularly soils with low fertility status. A 16-week laboratory incubation study was conducted to determine how the method of application of compost and inorganic fertilizers influence microbial respiration, nitrogen (N), and phosphorus (P) mineralization. Topsoil (500 g, 0–15 cm) was amended with compost (0, 5, and 10 g kg−1) and either inorganic N (50 kg N ha−1) or P (30 kg P ha−1). Two soil amendment strategies, applying compost and inorganic fertilizer separately to opposite sides of the soil using a divider and mixing them evenly throughout the soil, were compared for their effects on microbial activity and nutrient mineralization. The cumulative amounts of carbon dioxide (CO2) evolved were measured fortnightly using the static CO2 absorption method and inorganic N and P mineralization. N mineralization was unaffected by the method of compost and inorganic fertilizer application (p > .05), while at the end of day 42, available P in separate applications of compost and mineral N fertilizers was 33% greater than combined applications. Compost and inorganic P fertilizer had favorable N priming effects, but compost and inorganic N had negative effects. The different N priming effects of compost and inorganic N and P fertilizers may be attributable to microbial nutrient demand. The data suggest that composting with conventional fertilizers may change microbial nutrient demand and crop nutrient availability.

Grazing stabilized carbon and nitrogen pools by reducing carbon and net nitrogen mineralization after soil nutrients were added

Nutrient addition and grazing exclusion are effective methods to restore carbon and nitrogen pools in degraded grassland. However, how the combination of nutrient addition and grazing exclusion affect carbon and nitrogen pools through carbon and net nitrogen mineralization is unknown. A 56-day incubation study examined the effect of no additive (control — CK) and, the addition of sucrose (S), urea (U), sucrose + urea (SU), and yak dung (D) to the soil of grazed and fenced alpine grassland on carbon and net nitrogen mineralization. The 15N-tracer technique was used to determine nitrogen utilization by soil microorganisms. Nutrient addition with grazing exclusion increased soil organic carbon, microbial biomass carbon (MBC), inorganic nitrogen, and dissolved organic nitrogen (DON), and promoted carbon and net nitrogen mineralization in early incubation. The 15N recovery rate in soil was 4.5 to 21.7 % and decreased with time. Grazing exclusion altered the drivers of the carbon and net nitrogen mineralization rates, and increased carbon and net nitrogen mineralization rates by enhancing MBC and DON. The results indicated that nutrient addition: (1) decreased soil carbon and nitrogen stability by increasing nutrient availability and enhancing carbon and net nitrogen mineralization rates; and (2) in combination with grazing exclusion promoted carbon and net nitrogen mineralization. Consequently, soil carbon and net nitrogen mineralization depended on nutrient availability, and grazing stabilized soil carbon and nitrogen pools by reducing carbon and net nitrogen mineralization. The results could provide a theoretical basis for alpine grassland management.

Soybean Response to Seed Inoculation with Bradyrhizobium japonicum and/or Nitrogen Fertilization

Seed inoculation with symbiotic bacteria is a commonly employed practice in soybean cultivation. As a result, nodulation proceeds properly and plants self-supply atmospheric nitrogen, requiring either minimal or no additional nitrogen fertilization. The aim of the study was to investigate the response of soybeans to the application of the recommended or double dose of commercial inoculants (HiStick® Soy or TURBOSOY®) and/or mineral nitrogen fertilization compared to the untreated control. It was demonstrated that a double dose of the tested preparations had the most favorable effect on nodulation. However, the impact of weather conditions modified their effectiveness during the study years, which was especially visible in 2022. Sowing seeds without inoculation (control) resulted in the formation of sparse root nodules and consequently the lowest leaf area index (LAI) and soil plant analysis development (SPAD) measurements. In addition, the values of SPAD and LAI indices varied across the years of the study, indicating that weather conditions modified nitrogen uptake by plants. Overall, seed inoculation and/or nitrogen fertilization positively influenced the chemical composition of seeds compared to the control. The only decrease observed was in the oil content, while the double dose of HiStick® Soy preparation reduced the polyphenol content. The double dose of the tested inoculants had the most favorable impact on yield components and seed yield. However, applying inoculation at the recommended dose or in combination with nitrogen fertilization yielded similar or slightly worse results, depending on the year. Therefore, soybean seed inoculation should be recommended, although the effectiveness of the procedure will depend on various factors, including the type of inoculant, dosage, nitrogen fertilization, and weather conditions.

WSTĘPNE OKREŚLENIE MOŻLIWOŚCI REDUKCJI NAWOŻENIA AZOTOWEGO POD WPŁYWEM PREPARATÓW BAKTERYJNYCH W UPRAWIE TRITICUM AESTIVUM L.

The use of microorganisms in agriculture is attracting increasing interest. Thus, the state of knowledge on this issue and biotechnological advances are significantly increasing. A field research was conducted during the 2022–2023 growing season to evaluate the influence of the combined application of bacterial formulation and mineral nitrogen fertilization on grain and straw yield of winter wheat (Triticum aestivum L.) and the structure of the obtained yield. The factors of the conducted field experiment were bacterial formulations: control (no application of bacterial formulations), I – Azotobacter and Arthrobacter, II – Bacillus subtillis, Bacillus megaterium, Bacillus azotofixans, III – Bacillus azotofixans; B – mineral nitrogen fertilization: control (no mineral nitrogen fertilization), 43 kg N·ha−1, 86 kg N·ha−1, 130 kg N·ha−1. Research was conducted demonstrating the most favorable effects after applying a bacterial formulation containing Azotobacter and Arthrobacter bacteria. It was statistically significant increase in grain yield by an average of 17%, number of ears per m2 by 15%, ear length by 5% and thousand grain weight by 3% The application of other formulations also caused an increase in the analyzed traits, but they were lower than those given for Azotobacter and Arthrobacter bacteria. A gradual increase in the level of mineral nitrogen fertilization also had a positive effect on the analyzed traits. The research conducted in the field found a possible reduction in mineral nitrogen fertilization under the conditions of the conducted experiment by about 33% without yield losses when using a bacterial formulation containing Azotobacter and Arthrobacter. Thus, it is appropriate to recommend the use of these bacteria in winter wheat cultivation, but due to the possible variable effectiveness of application under different soil and climatic conditions, the presented research should be continued in different areas both in wheat and other crops.

Biocrusts enhance soil nitrogen mineralization and nitrification under experimental warming in a dryland ecosystem

Nitrogen (N) transformation is essential for soil nitrogen availability and plant growth in drylands, but climate warming may be altering the dynamics of this process. Biological soil crusts (biocrusts) are soil surface communities dominated by cyanobacteria, lichens, and mosses that perform many vital functions in dryland ecosystems. However, their role in regulating soil N transformations under climate warming is uncertain. To explore this, we conducted a one-year field warming experiment in the Tengger Desert of northwestern China to investigate whether and how biocrusts modulate the effects of warming on N transformations, microbial biomass and enzyme activity in the soil underneath them. We found increases in microbial biomass carbon and nitrogen, soil nitrate reductase and urease activities, and net nitrification and mineralization rates in the soil below the biocrusts in response to warming. Our results suggest that biocrusts, acting as a “living skin,” significantly enhance the soil's organic matter and total nitrogen content. Thus, the resultant soil “hot zones” formed by the nutrient increases, help to sustain microbial activity and to mitigate the negative effects of warming on the soil environment. This nutrient enhancement is closely related to microbial biomass and enzyme activity, which are key contributors to N transformation in drylands. Therefore, our study highlights the regulatory role of biocrusts in soil N transformation, emphasizing the necessity to consider their effects to more accurately predict the impact of warming on N cycling in dryland ecosystems.

The Effects of Intercropping Narrowleaf Lupine with Cereals under Variable Mineral Nitrogen Fertilization

Intercropping of legumes and cereals can bring many benefits to agriculture, including an increase in yield and the quality of the crops obtained. In addition, it is possible to reduce mineral fertilization, which can have a positive impact on the environment. The aim of the field research conducted in 2021–2023 in central Poland was to evaluate the yields obtained, the content and yield of total protein and the value of land equivalent ratio in the intercropping of narrowleaf lupine with cereals at different seeding levels of components and variable mineral nitrogen fertilization. The following factors were tested: 1—share of components in the sowing: narrowleaf lupine (NL) 120 seeds m−2; spring barley (SB) 300 seeds m−2; M1—NL 30 + SB 225 seeds m−2; M2—NL 60 + SB 150 seeds m−2; M3—NL 90 + SB 75 seeds m−2; spring triticale (ST) 450 seeds m−2; M4—NL 30 + ST 340 seeds m−2; M5—NL 60 + ST 225 seeds m−2; M6—NL 90 + ST 115 seeds m−2; 2—mineral fertilization with nitrogen 0, 20, 40, 60 kg N ha−1. The most favorable results were obtained with mixtures containing 60 + 150 seeds m2 of narrowleaf lupine + spring barley and 90 + 115 seeds m−2 of narrowleaf lupine + spring triticale. In addition, the favorable results and the lack of significant differences at fertilization of 40 and 60 kg N ha−1 show the possibility of a limited dose of mineral nitrogen fertilization. Sowing narrowleaf lupine with spring barley at a ratio of 60 + 150 seeds m2 or with spring triticale at a ratio of 90 + 115 seeds m−2 and fertilizing with 40 kg N ha−1 can be recommended for agricultural practice. The proposed management technique ensures high yields of good quality and thus can be an interesting solution for sustainable cultivation and be successfully implemented on farms.

Engineering EPS in Halomonas bluephagenesis leads to self-flocculation and filamentation for convenient downstream processing

The halophile Halomonas bluephagenesis has established itself as a cost-effective chassis in industrial bioproduction. However, downstream processing (DSP) expense is a persistent challenge. This study uses genetic knockout of exopolysaccharides (EPS-KO) in six industrially relevant H. bluephagenesis strains, each producing distinct polyhydroxyalkanoate (PHA), to evaluate their impact on reducing DSP costs. Remarkably, EPS-KO cells exhibited an unprecedented filamentous morphology, reaching lengths over 50 times (10–75 μm) that of standard cells. This unexpected behavior initially posed a challenge to industrial applicability due to rapid cell lysis under fermentation agitation. Systematic media supplementation of salt, carbon source, nitrogen, and essential minerals significantly influenced morphology, and tailored nutrient schemes that mitigated filamentation while maintaining production levels were designed. Scaled production in a 5000 L bioreactor demonstrated 85 % PHA and 96 g/L cell dry weight after 40 h fermentation, consistent with non-KO cells. During fermentation, EPS-KO enhanced cell-wall penetrability, reducing the need for high-cost γ-butyrolactone by 40 %. Additionally, a new innovative 5000 L FlipFlow bioreactor design cut rotation speed by 50 % and air input by 25 %. During DSP, centrifugation time decreased tenfold due to rapid cell self-flocculation (15–30 min), and the water and enzyme required for PHA purification was reduced by 30 % and 35 %, respectively. This study highlights the use of EPS-KO cells, a controlled media strategy, and low shear force FlipFlow bioreactor to successfully reduce DSP costs without sacrificing productivity. These novel findings represent a notable advancement in cost-saving strategies while presenting the intriguing discovery of media-controlled filamentous cell behavior.

Effects of Short-Term Tillage on Rhizosphere Soil Nitrogen Mineralization and Microbial Community Composition in Double-Cropping Rice Field.

Soil extracellular enzyme plays a vital role in changing soil nitrogen (N) mineralization of rice field. However, the effects of soil extracellular enzyme activities (EEA) and microbial community composition response to N mineralization of rice field under short-term tillage treatment needed to be further explored. In this study, we investigated the impact of short-term (8-year) tillage practices on rhizosphere soil N transformation rate, soil enzyme activities, soil microbial community structure, and the N mineralization function gene abundances in double-cropping rice field in southern China. The experiment consisted of four tillage treatments: rotary tillage with crop straw input (RT), conventional tillage with crop straw input (CT), no-tillage with crop straw retention (NT), and rotary tillage with all crop straw removed as a control (RTO). The results indicated that the rhizosphere soil N transformation rate in paddy field under the NT and RTO treatments was significantly decreased compared to RT and CT treatments. In comparison to the NT and RTO treatments, soil protease, urease, β-glucosaminidase, and arginase activities were significantly improved by the CT treatment, as were abundances of soil sub, npr, and chiA with CT and RT treatments. Moreover, the overall diversity of soil bacterial communities in NT and RTO treatments was significantly lower than that in RT and CT treatments. Soil chitinolytic and bacterial ureolytic communities were also obviously changed under a combination of tillage and crop straw input practices.