Nitrogen Release Research Articles

Modified Diacetylmonoxime-Thiosemicarbazide Detection Protocol for Accurate Quantification of Urea.

Renewable photo-/electrocatalytic coreduction of CO2 and nitrate to urea is a promising method for high-value utilization of CO2 . However, because of the low yields of the urea synthesis by photo-/electrocatalysis process, the accurate quantification of low concentration urea is challenging. The traditional diacetylmonoxime-thiosemicarbazide (DAMO-TSC) method for urea detection has a high limit of quantification and accuracy, but it is easily affected by NO2 - in the solution, which limits its application scope. Thus, the DAMO-TSC method urgently requires a more rigorous design to eliminate the effects of NO2 - and accurately quantify urea in nitrate systems. Herein, a modified DAMO-TSC method is reported, which consumes NO2 - in solution through a nitrogen release reaction; hence, the remaining products do not affect the accuracy of urea detection. The results of detecting urea solutions with different NO2 - concentrations (within 30ppm) show that the improved method can effectively control the error of urea detection within 3%.

Cellulose-based slow-release nitrogen fertilizers: Synthesis, properties, and effects on pakchoi growth

The application of most slow-release fertilizers is limited by complex preparation processes and short slow-release periods. In this study, carbon spheres (CSs) were prepared by a hydrothermal method using cellulose as the raw material. Using CSs as the fertilizer carrier, three new carbon-based slow-release nitrogen fertilizers were prepared using direct mixing (SRF-M), water-soluble immersion adsorption (SRFS), and co-pyrolysis (SRFP) methods, respectively. Examination of the CSs revealed regular and ordered surface morphology, enrichment of functional groups on the surfaces, and good thermal stability. Elemental analysis showed that SRF-M was rich in nitrogen (total nitrogen content of 19.66 %). Soil-leaching tests showed that the total cumulative nitrogen release of SRF-M and SRF-S was 55.78 % and 62.98 %, respectively, which greatly slowed down the release of nitrogen. Pot experiment results revealed that SRF-M significantly promoted the growth of pakchoi and improved crop quality. Thus, SRF-M was more effective in practical applications than the other two slow-release fertilizers. Mechanistic studies showed that CN, -COOR, pyridine-N and pyrrolic-N participated in nitrogen release. This study thus provides a simple, effective, and economical method for the preparation of slow-release fertilizers, providing new directions for further research and the develop of new slow-release fertilizers.

Brown juice assisted ensiling of straw and press cake for enhanced biogas production and nutrient availability in digestates

The study investigated the effects of ensiling and brown juice-assisted ensiling of wheat straw and press cake from a green biorefinery plant prior to anaerobic co-digestion (Aco-D) with cattle manure on methane yield and nutrient availability in the digestates. Straw was ensiled with and without brown juice at field-scale and lab-scale levels, followed by Aco-D with manure using continuous stirred-tank reactors (CSTR) and batch tests. The digestates from CSTR were incorporated into the soil to study nitrogen and sulphur dynamics and availability over 80 days. Results show that ensiling of straw increased net inorganic nitrogen release in soil and reduced net inorganic sulphur immobilisation compared to the non-ensiled straw. Brown juice-assisted ensiling of straw at the lab-scale level significantly increased methane production by 14 % and increased hydrolysis and methane production rates compared to non-ensiled straw. These results demonstrate that ensiling of straw has the potential as a pre-treatment technique for enhanced biogas production and higher nutrient availability in digestates for crop production and provides an opportunity to valorise brown juice as an ensiling additive.

High contribution of anthropogenic combustion sources to atmospheric inorganic reactive nitrogen in South China evidenced by isotopes

Abstract. Due to the intense release of reactive nitrogen (Nr) from anthropogenic activity, the source layout of atmospheric nitrogen aerosol has changed. To comprehensively clarify the level, sources, and environmental fate of NH4+ and NO3-, their concentrations and stable isotopes (δ15N) in fine particulate matter (PM2.5) were measured in a subtropical megacity of South China. The inorganic nitrogen (NH4+ and NO3-) was an essential part of atmospheric nitrogen aerosol, and the N-NH4+ and N-NO3- contributed 45.8 % and 23.2 % to total nitrogen (TN), respectively. The source contributions of NH4+ and NO3- were estimated by δ15N, suggesting that the dominant sources were from anthropogenic combustion activities, including coal combustion, biomass burning, and vehicles, contributing 63.2 % and 88.3 % to NH4+ and NO3-, respectively. In particular, biomass burning was the predominant source of NH4+ (27.9 %), whereas coal combustion was the dominant source of NO3- (40.4 %). This study emphasized the substantial impacts of human activities on inorganic Nr. With the rapid development of industry and transportation, nitrogen emissions will be even higher. The promotion of clean energy and efficient use of biomass would help to reduce nitrogen emissions and alleviate air pollution.

New Insight into Magnetic Enhanced Methane Production from Oily Sludge via Mesophilic Anaerobic Degradation Processes

Anaerobic digestion is a promising technology for treating and disposing of oily sludge, but the presence of oil in the sludge reduces methane production and sludge volume reduction. To overcome this limitation, this study creatively reports the use of magnetite to enhance methane production in oily sludge mesophilic anaerobic digestion and elucidates the underlying mechanism. Results show that the addition of magnetite increases methane production, with a 5% magnetite content leading to a 1.42-fold increase in cumulative methane output compared to the blank. Mechanistically, magnetite accelerates the release of organic matter, promotes oil degradation, increases volatile fatty acids (VFA) accumulation, and reduces the proportion of propionate. Additionally, magnetite alleviates pH decreases and increases the release of ammonia nitrogen and phosphate, resulting in effective sludge reduction, with volatile suspended solids (VSS) reduction ranging from 26.9% to 32.6%, higher than that of the blank. Moreover, magnetite accelerates electron transfer and increased the relative abundance of microorganisms associated with methane production, with the relative abundance of Methanosarcina increasing to 37.6~38.5% due to the presence of magnetite. This study provides a theoretical framework for effectively utilizing oily sludge through the application of magnetite.

Ammoniacal and Nitrate Nitrogen Release Pattern from Biochar and Biochar Blended Urea Fertilizers in Sandy Soil

Biochar, an organic product of thermal decomposition of biomass in an oxygen limited environment can be used as a nutrient carrier to delay the release of nutrients into the soil, reduce nutrient leaching, and improve the nutrient utilization efficiency of fertilizers. Nutritional enhancement of biochar through fertilizer blending could be a low cost but high efficiency solution compared to non-blended fertilizers. However, the rate of nutrient release from the blended biochar fertilizer in different soils is ambiguous. Hence a 12 month incubation study was conducted in sandy soil (ultisol) of Thiruvananthapuram district of Kerala to elucidate the ammoniacal and nitrate nitrogen release rate and pattern from the produced paddy husk biochar, biochar and biochar bentonite (1:1) each blended with urea fertilizer in different ratios (1:0.5, 1:1, 1:2) including an absolute control. The individual effects of biochar, biochar-bentonite and urea were also studied. Paddy husk biochar was produced by the process of slow pyrolysis and biochar- blended urea fertilizers by the adsorbent process. To evaluate the influence of bentonite clay on the nutrient release pattern of biochar, it was blended with biochar and urea fertilizer. The highest total nitrogen content among the produced fertilizers was recorded in biochar: urea in 1:2 (33.04%) followed by biochar-bentonite: urea in a 1:2 ratio (31.13%). The incubation study revealed that the maximum release of ammoniacal nitrogen from soil+ urea fertilizer was at 30 days (115.73 mg kg-1) followed by a sharp decline, maintaining a low value till the end of incubation, whereas the release was sustained and gradually increased to reach a maximum at the 180th day (117.6 mg kg-1) for soil+ biochar: urea in 1:1 ratio. Nitrate nitrogen also followed the same trend with the maximum release observed for biochar: urea in 1:1 on the 150th day (151.2 mg kg-1). The release of nitrate nitrogen was more than that of ammoniacal nitrogen throughout the incubation period for all the treatments. Among the blended fertilizers, content of both ammoniacal and nitrate nitrogen were comparatively less for biochar –bentonite blended urea fertilizers. Thus, blending of urea with biochar/ biochar-bentonite prolonged the duration of maximum nutrient release.

Oenococcus oeni allows the increase of antihypertensive and antioxidant activities in apple cider

This study aimed to investigate the impact of the malolactic fermentation (MLF) carried out by Oenococcus oeni on antihypertensive and antioxidant activities in cider. The MLF was induced using three strains of O. oeni. The modification in phenolic compounds (PCs) and nitrogen organic compounds, antioxidant, and antihypertensive activities were determined after MLF. Among the 17 PCs analyzed caffeic acid was the most abundant compound and phloretin, (−)-epicatechin, and myricetin were detected only in malolactic ciders, however, (−)-epigallocatechin was not detected after MLF. The evaluation of nitrogen organic compounds revealed a drop in total protein concentration (from 17.58 to 14.00 mg N/L) concomitantly with a significant release of peptide nitrogen (from 0.31 to a maximum value of 0.80 mg N/L) after MLF. In addition, an extracellular proteolytic activity was evidenced in all MLF supernatants. The FRAP activity increased reaching a maximum of 120.9 μmol FeSO4/mL and the ABTS radical-scavenging activity increased until 6.8 mmol ascorbic acid/L. Moreover, the angiotensin I-converting enzyme inhibitory activity reached a maximum value of 39.8%. The MLF conducted by O. oeni in ciders enables the increase of interesting biological activities and this finding could constitute a valuable tool to add value to final product.

Yield- and protein-neutral reduction in fertilizer rate for wheat, maize and rice can reduce the release of reactive nitrogen and greenhouse gas emissions in China

Seeking food security, contemporary Chinese agriculture has followed a trajectory of overfertilization and associated environmental problems, hence the need for nitrogen-balancing practices that do not compromise yield and quality. Here we present a national meta-analysis using 224 studies with 1972 comparisons to quantify the potential to reduce nitrogen (N) fertilization to improve environmental outcomes while maintaining yield and grain protein. We calculated a nitrogen reduction ratio (NRR), as 100 × (N C − N T)/N C; where N is N fertilizer rate and subscripts indicate farmer practice (C) and reduced N rate treatment (T). Our meta-analysis showed that the NRR that maintained yield and grain protein content at the level of current practice was up to 10% in wheat and up to 30% in maize and rice. Larger yield-neutral NRR could be achieved in more fertile, heavier-textured soils, and with practices including enhanced-efficiency N fertilizer, combined application of organic and inorganic N fertilizer, and incorporated straw. Assuming a reduction in N fertilizer usage by 10% for wheat and by 30% for maize and rice in the current cropping area, there is a potential to save 5.7 Mt N yr−1; reduce loss of reactive nitrogen by 1.26 Mt N yr−1, equivalent to 63% of annual total Nr losses for rice in China, reduce N-related greenhouse emissions by 75.2 Mt CO2-eq yr−1, equivalent to 14.5%–25% of the emissions associated with the N fertilizer chain in China; and improve N use efficiency by 23%. Our results highlight the feasibility of maintaining yield and grain protein, and achieving substantial environmental benefits with reduced fertilization rate, and the environmental and agronomic scenarios where these outcomes are more likely.

Effect of Sodium on the Evolution of Nitrogen Functionalities During Coal Pyrolysis : A Quantitative Experimental and Theoretical Investigation

ABSTRACT Understanding the migration and transformation of nitrogen during high-alkali coal pyrolysis and the influence of sodium on the nitrogen-containing components of coal is of great significance for the clean and efficient utilization of coal. In this study, gas chromatography-mass spectrometry (GC-MS), X-ray photoelectron spectroscopy (XPS) and ultraviolet visible spectroscopy (UV-Vis) were used to analyze the conversion of tar-N, char-N and gas-N during coal pyrolysis and the effect of sodium on the nitrogen-containing pyrolysis products of coal. The experimental results were combined with density functional theory (DFT) calculations to investigate the effect of sodium on the internal conversion process of char-N. The results revealed that a large amount of Na (2.5 wt.%, 3.5 wt.%) can reduce the nitrogen content in coal pyrolysis char, promote the formation of amine and amide in tar-N and inhibit the release of gaseous nitrogen. A small amount of Na (0.5 wt.%, 1.5 wt.%) retains nitrogen in char, reducing the total amount of nitrogen-containing species in the gas phase and tar, which is an effective means to inhibit the transformation of nitrogen to volatile matter. In addition, a large amount of Na promotes the conversion of pyrrole nitrogen (N-5) and pyridine nitrogen (N-6) in char to heterocyclic N in tar. A small amount of sodium promotes the hydrogenation and ring opening of heterocyclic-N in tar to HCN. Na promotes the conversion of N-5 and N-6 in char. DFT calculations further confirmed that the addition of Na significantly reduced the energy barrier of the rate determining step by about 36.6 kJ/mol.

Neem and Castor Oil–Coated Urea Mitigates Salinity Effects in Wheat by Improving Physiological Responses and Plant Homeostasis

Soil salinity is abiotic stress of growing concern, whose effects can be potentially mitigated by the use of suitable fertilisers. Based on this, an experiment was conducted to determine the role of vegetable oil–coated urea on the performance of wheat (Triticum aestivum) under salinity. Neem oil–coated urea (NOCU), castor oil–coated urea (COCU), and normal urea (NU) were compared in wheat plants growing in pots at three soil salinity levels (0, 6, and 12 dS m-1). Plant morphology, growth, element contents (Na, Cl, K, and N), and several traits were assessed at the flag leaf stage; biological yield, grain yield, and its components were assessed at maturity. Salinity stunted growth (approximately -50% yield with high salinity vs. control); boosted Na and Cl concentrations while abating K and N concentrations in plant organs; impaired leaf water status; reduced photosynthetic pigments and increased antioxidant activities and osmo-regulating compounds. NOCU and, to a lesser degree, COCU mitigated salinity effects by upgrading antioxidant activities, reducing oxidative stress markers, increasing leaf water status, photosynthetic pigments, and osmo-regulating compounds. However, NOCU under high salinity could only achieve the levels of NU under intermediate salinity. Lastly, NOCU and COCU restricted plant entry of adverse ions (Na and Cl) while increasing K and N accumulation. Vegetable oil–coated urea, namely NOCU, significantly contributed to improving wheat behaviour and final yield under salinity. These outcomes are associated with the two fertilisers’ properties of slow nitrogen release.

Energy production from municipal solid waste in low to middle income countries: a case study of how to build a circular economy in Abuja, Nigeria

The volume of municipal solid waste produced in many cities in low to middle income countries exceeds the capacity of handling facilities causing environmental and health risks. This study provides the most comprehensive analysis to date of municipal solid waste to energy options for Abuja, Nigeria. We use most recently available data on waste generation from Abuja municipal authorities, integrated with secondary data from the literature. This is combined with standard relationships between waste composition and energy production to compare the potential for thermochemical conversion and anaerobic digestion to meet the energy requirement of Abuja. In addition, we use assumptions about digestate production and nitrogen release to estimate the potential production of organic fertilizer from digestate. The organic fraction of municipal solid waste from Abuja [7.1 × 107(±4 × 106) kg y−1] has potential to produce 3.6 × 106(±2 × 105) m3y−1biogas. This could provide 7.8 × 103(±4 × 102) MWh y−1electricity, equivalent to 8% of annual electricity requirement in Abuja, 4.0 × 107(±2 × 106) MJ y−1heat, and 5.3 × 105(±3 × 104) kg y−1digestate use as bio-fertilizer from organic fraction only. Potential power generation by thermochemical conversion for combined heat and electricity is much greater, 7.73 × 104(±4 × 103) MWh y−1, equivalent to 83% of power requirement in Abuja, but does not produce bio-fertilizer. Using the organic fraction for anaerobic digestion and the remaining waste for thermochemical conversion provides combined heat and energy that is 91.5% of Abuja power requirements, while also producing digestate. Barriers to implementation include informal waste recyclers with poor collection and handling procedures, absence of public education, weak environmental policies and lack of funding. There is a need for periodic review of policies and waste legislation to create a circular economy in Abuja.

Quantification of Nutrient Fluxes from Sediments of Lake Hulun, China: Implications for Plateau Lake Management

Dramatic changes in lake water conditions may induce sensitive feedback in sediments, such as the release of phosphate and ammonia. There is a lack of the understanding of sediment nutrient release fluxes and their responses to various environmental factors in plateau lakes. In this study, nutrient contents in the water and sediment, sediment nutrient release rates, and their responses to various influential factors in a steppe shallow plateau lake, Lake Hulun, China, were investigated. Sediment is a large store of nutrients, with bioavailable phosphorus of 555 mg kg−1 in surface lake sediments. If water became anoxic, sediments will release appreciable amounts of phosphate (2.1 mg P m−2 d−1) and ammonia (40.0 mg N m−2 d−1), three times greater than those in oxic conditions. Raised temperatures greatly increased sediment phosphate release rates, while the highest temperature (23 °C) slightly decreased ammonia release rates due to strong nitrification. Assuming a whole year of internal loading, ammonia and dissolved reactive phosphorus concentrations in water column would increase by an estimated 0.22 mg N L−1 and 0.01 mg P L−1, respectively, which is equal to 2 and 0.5 times of their ambient concentrations. A pH increase from 8.4 to 9.4 significantly decreased internal nitrogen and phosphorus release rates by around three times. Overall, dissolved oxygen (DO) and pH had a greater impact on sediment nutrient release from lake sediments compared to temperature, and further increased the eutrophic status in the overlying water when these three parameters varied within the normal seasonal range (temperature: 1.9–23.1 °C, DO: oxic and anoxic; pH: 7.5–9.4). With the periodic low DO and frequency of drought in the future, lake management strategies that mitigate water eutrophication, such as water diversion, may need to be considered.

The response of Tampa Bay to a legacy mining nutrient release in the year following the event

IntroductionCultural eutrophication threatens numerous ecological and economical resources of Florida’s coastal ecosystems, such as beaches, mangroves, and seagrasses. In April 2021, an infrastructure failure at the retired Piney Point phosphorus mining retention reservoir garnered national attention, as 814 million liters of nutrient rich water were released into Tampa Bay, Florida over 10 days. The release of nitrogen and phosphorus-rich water into Tampa Bay – a region that had been known as a restoration success story since the 1990s – has highlighted the potential for unexpected challenges for coastal nutrient management.MethodsFor a year after the release, we sampled bi-weekly at four sites to monitor changes in nutrients, stable isotopes, and phytoplankton communities, complemented with continuous monitoring by multiparameter sondes. Our data complement the synthesis efforts of regional partners, the Tampa Bay and Sarasota Bay Estuary Programs, to better understand the effects of anthropogenic nutrients on estuarine health.ResultsPhytoplankton community structure indicated an initial diatom bloom that dissipated by the end of April 2021. In the summer, the bay was dominated by Karenia brevis, with conditions improving into the fall. To determine if there was a unique carbon (C) and nitrogen (N) signature of the discharge water, stable isotope values of carbon (δ13C) and nitrogen (δ15N) were analyzed in suspended particulate material (SPM). The δ15N values of the discharge SPM were −17.88‰ ± 0.76, which is exceptionally low and was unique relative to other nutrient sources in the region. In May and early June of 2021, all sites exhibited a decline in the δ15N values of SPM, suggesting that discharged N was incorporated into SPM after the event. The occurrence of very low δ15N values at the reference site, on the Gulf Coast outside of the Bay, indicates that some of the discharge was transported outside of Tampa Bay.DiscussionThis work illustrates the need for comprehensive nutrient management strategies to assess and manage the full range of consequences associated with anthropogenic nutrient inputs into coastal ecosystems. Ongoing and anticipated impacts of climate change – such as increasing tropical storm intensity, temperatures, rainfall, and sea level rise – will exacerbate this need.

Amination-modified lignin recovery of aqueous phosphate for use as binary slow-release fertilizer

To address the global phosphorus crisis and solve the problem of eutrophication in water bodies, the recovery of phosphate from wastewater for use as a slow-release fertilizer and to improve the slow-release performance of fertilizers is considered an effective way. In this study, amine-modified lignin (AL) was prepared from industrial alkali lignin (L) for phosphate recovery from water bodies, and then the recovered phosphorus-rich aminated lignin (AL-P) was used as a slow-release N and P fertilizer. Batch adsorption experiments showed that the adsorption process was consistent with the Pseudo-second-order kinetics and Langmuir model. In addition, ion competition and actual aqueous adsorption experiments showed that AL had good adsorption selectivity and removal capacity. The adsorption mechanism included electrostatic adsorption, ionic ligand exchange and cross-linked addition reaction. In the aqueous release experiments, the rate of nitrogen release was constant and the release of phosphorus followed a Fickian diffusion mechanism. Soil column leaching experiments showed that the release of N and P from AL-P in soil followed the Fickian diffusion mechanism. Therefore, AL recovery of aqueous phosphate for use as a binary slow-release fertilizer has great potential to improve the environment of water bodies, enhance nutrient utilization and address the global phosphorus crisis.

Nitrogen and Phosphorus Release Characteristics of Pipeline Sediments on Entering Different Water Bodies

Differences in the physical and chemical properties of reclaimed water (RW) and natural surface water (SW) lead to further differences in nitrogen and phosphorus release when pipeline sediments enter these water bodies. The release kinetics of nitrogen and phosphorus from pipe sediments with different particle sizes have been investigated. The results demonstrated that both SW and RW had a pH buffering effect after sediment addition, and the final pH (approximately 8.1) of RW was lower. The release of total phosphorus (TP) and ammonia nitrogen (NH4+-N) fitted the first-order kinetic model in which the release of TP reached equilibrium. TP release was inhibited in both SW and RW, with RW exhibiting the lowest (by a factor of 1.23~2.44) release (0.002 mg/g). The release of NH4+-N was promoted in both SW and RW; the maximum release in RW was 0.0188 mg/g. The amounts of NH4+-N released in SW and RW were 1.02–1.40 and 1.30–1.80 times that of the control group (CG), respectively. The percentage of TP and NH4+-N release in the three groups was highest in 75–154 μm pipe sediment, reaching 34.53% and 43.51% in SW and RW, respectively. These results can assist in the development of water quality evolution models for specific urban scenarios and provide important guidance for the precise regulation of water recharge quality during and after rainfall.

The influence of polyguanidin on the direction of biochemical processes in wheat (Triti- cum L.) plants.

Modern crop production requires a balance of high and sustainable productivity with maximum safety for the environment, consumers and agricultural workers. The well-known chemical compound polyguanidine, which was previously used as a disinfectant, surfactant and complexing agent, has recently become widely used as a plant growth and development stimulant. Despite the increasing use of polyguanidine preparations as a growth stimulant, there is no data in the literature on its mechanism of action on plants. There are many studies that try to determine whether the effect of biostimulants on plant productivity is a direct or indirect response, for example, through the soil or microbiome. In many cases, biostimulants are considered in terms of their effects on various plant regulatory and functional systems (signaling, metabolic, uptake and transport mechanisms, etc.). But, in general, these modes of action are very diverse and may include activation of nitrogen metabolism or release of phosphorus from soils, general stimulation of soil microbial activity, or stimulation of root growth and increased plant nutrition. The effect of polyguanidin on the physiological parameters of wheat plants was studied under vegetation and laboratory conditions. Seeds of winter wheat variety Bogdana were used for the study. For the determination of flavonoids, a spectrophotometric method based on the measurement of their absorption with aluminum chloride complex was used. It was proved that the treatment of wheat in the tillering and earing phases with polyguanidin had the greatest effect on the protein content in winter wheat grain, which ensured the formation of this indicator at the level of 11.0–13.4% compared to the control. The treatment of wheat seeds with a preparation based on polyguanidine increased the amount of chlorophyll a by almost two times, while the content of chlorophyll b and carotene increased somewhat less. Thus, the use of polyguanidine contributes to the efficient functioning of the photosynthetic apparatus of plants, which will increase their productivity. Since the energy basis of photosynthesis is the absorption of solar radiation by photosynthetic pigments, which are used to form organic matter, there is a direct link between chlorophyll content and plant productivity. Therefore, we decided to check the content of the main photosynthetic pigments in plants after treatment with polyguanidine. At the first stage of our research, plants at the early stages of ontogenesis were analyzed. Thus, we have shown that the treatment of wheat seeds with a polyguanidine-based preparation increases the amount of chlorophyll a almost twice. Evaluation of flavonoid content in wheat plants showed a decrease in their amount after treatment with polyguanidin. That is, after the treatment, the plants, on the contrary, reduced their adaptive potential, because at the biochemical stage it was believed that there were no unfavorable factors in the environment. The analysis of the free proline content showed an increase in its concentration after treatment with the test substance almost doubled both after the first and after the second treatment. Also, it should be noted that reducing the concentration of the drug to 0.15 liters per 200 liters of the working solution increases the level of proline after the first treatment. The increase in proline, in this case, can lead to an increase in stress resistance, which is provided by metabolic and physiological changes. Consequently, its accumulation and conversion into other amino acids due to changes in the activity of proline oxidase contributes to an increase in the protein content in the grain.

Arbuscular mycorrhizae influence raspberry growth and soil fertility under conventional and organic fertilization.

Introducing beneficial soil biota such as arbuscular mycorrhizal fungi (AMF) to agricultural systems may improve plant performance and soil fertility. However, whether bioinocula species composition affects plant growth and soil fertility, and whether fertilizer source influences AMF colonization have not been well characterized. The objectives of this research were to: (1) assess if AMF bioinocula of different species compositions improve raspberry (Rubus idaeus L.) performance and characteristics of soil fertility and (2) evaluate the impact of fertilizer source on AMF colonization. Five bioinocula with different AMF species compositions and three fertilizer sources were applied to tissue culture raspberry transplants in a randomized complete block design with eight replicates. Plants were grown in a greenhouse for 14 weeks and plant growth, tissue nutrient concentrations, soil fertility, and AMF root colonization were measured. Shoot K and Zn concentrations as well as soil pH and K concentration increased in the Commercial Mix 1 treatment (Glomus, Gigaspora, and Paraglomus AMF species) compared to the non-inoculated control. RFI (raspberry field bioinoculum; uncharacterized AMF and other microbiota) increased soil organic matter (SOM), estimated nitrogen release (ENR), and soil copper (Cu) concentration compared to the non-inoculated control. Furthermore, plants receiving the Mix 1 or RFI treatments, which include more AMF species, had greater AMF root colonization than the remaining treatments. Plants receiving organic fertilizer had significantly greater AMF colonization than conventionally fertilized plants. Taken together, our data indicate that coupling organic fertilizers and bioinocula that include diverse AMF species may enhance raspberry growth and soil fertility.

PH-responsive/sustained release nitrogen fertilizer hydrogel improves yield, nitrogen metabolism, and nitrogen use efficiency of rice under alternative wetting and moderate drying irrigation

Rice is challenged by inefficient nitrogen (N) fertilizer and water inputs. However, pH-responsive N fertilizers (pH-RNFs) could improve rice yield and N use-efficiency under water-saving irrigation. Thus, a pot experiment was conducted without N fertilizer (0 mg N/kg, ZNF), with 175 mg/kg mineral N fertilizer (MNF), and with 175 mg/kg pH-responsive N fertilizer (pH-RNF) by using three water regimes: alternate wetting/critical drying (AWCD, 70–60% saturation, 5 cm flooded), alternate wetting/severe drying (AWSD, 80–70% saturation, 5 cm flooded), and alternate wetting/minor drying (AWMD, 100–90% saturation, 5 cm flooded). Under the same alternate wetting/drying regime, the growth traits, yield, and N utilization of rice were found to be higher in pH-RNF than in MNF. The growth attributes and yield and the N efficient use of rice were greater in the AWMD regime than in the AWCD regime under the same N fertilization. The surface area, diameter, length density, oxidation ability, reductase activity, and peroxidase activity of roots were greater in AWMD × pH-RNF than in AWCD × ZNF, because the former treatment increased the total N contents in the rhizosphere, whereas the latter reduced them. In the photosynthesis process, leaf nitrate reductase (41.7 µg/[g.h]) and leaf glutamine synthetase (1158.1 µmol/[g.h]) were larger in AWMD × pH-RNF than in AWCD × ZNF at 22.7 µg/(g.h) and 501.2 µmol/(g.h), respectively, resulting in the amelioration of oxidative leaf cell damage, as revealed by reduced radical oxidative sequence release and lower malonaldehyde level (7.2 µmol/g). Meanwhile, the optimum N nutrition enhanced the leaf mesophyll structure, cell cycle progression, and the development traits of the stem and panicle under the combination AWMD × pH-RNF. Panicle glutamine synthetase (24.35 µmol/[g.h]) and catalase activity (13.86 µg/min) were larger in AWMD × pH-RNF than in AWCD × ZNF at 14.77 µmol/[g.h] and 7.59 µg/min, respectively. The combination AWMD × pH-RNF resulted in the highest N crop removal efficiency (CREN, 49.5%), N agronomic use efficiency (AUEN, 7.97 g/g), N partial factor productivity (PFPN, 18.66 g/g), and N harvest index (HIN, 67.83%). However, the minimum values of CREN (10.3%), AUEN (1.49 g/g), PFPN (7.59 g/g), and HIN (43.48%) were observed in AWCD × MNF. This study suggests that AWMD × pH-RNF could promote root and shoot morpho-physio-biochemical traits, guaranteeing optimal overall plant growth with high yield and adequate N acquisition, and efficient N utilization for sustainable rice production.

Remediate black-odorous sediment by slow-release calcium nitrate: Migration, transformation and microbial succession

Calcium nitrate has been widely used in-situ remediation of black-odorous sediment, which microorganisms mainly utilized nitrate to redox substances through denitrification. However, this technique has the problem that the local nitrate concentration was too high to inhibit the activity of functional microorganisms, which affected the oxidation effect and caused the abnormal release of inorganic nitrogen from the sediment. The slow release of calcium nitrate by tube dosing can effectively solve this disadvantage. However, the specific layout of the dosing method needs further research. Therefore, a method of tube-dosing distribution points was proposed by explored the migration and transformation laws of N-S-Fe in the vertical and horizontal directions of the sediment and the changes in the microbial community structure after the fixed-point dosing of calcium nitrate in this study, which further optimized the calcium nitrate dosing process and provided a new dosing method and idea in practical application. Within one month, nitrate migrated and transformed vertically and horizontally, accompanied by the accumulation of nitrite, oxidation of acid volatile sulfide (AVS) and ferrous iron. Among them, within the nitrate migration distance of 0–6 cm (vertical) and 0–8 cm (horizontal), the removal rate of AVS reached 100% and ferrous iron was effectively oxidized. In addition, in the process of vertical and horizontal migration, bacteria closely related to sulfide and ferrous iron-driven denitrification, such as Thiobacillus, Sulfurimonas and Thioalkalispira, were found to be dominant. These results demonstrate that after exploring the vertical and horizontal migration and transformation laws of nitrate in different contaminated sediments remediated, the reasonable layout of dosing methods can be carried out in practical application.

Network interpenetrating slow-release nitrogen fertilizer based on carrageenan and urea: A new low-cost water and fertilizer regulation carrier

Modern agriculture presents new requirements of low cost, high water retention and degradability for superabsorbent and slow-release fertilizers. In this study, carrageenan (CG), acrylic acid (AA), N, N ‘-methylene diacrylamide (MBA), urea and ammonium persulfate (APS) were used as raw materials. A kind of high water absorption, water retention, nitrogen slow release and biodegradable carrageenan superabsorbent (CG-SA) was prepared by grafting copolymerization. The optimal CG-SA was obtained with a water absorption rate of 680.45 g/g by orthogonal L18(3)7 experiments and single-factor experiments. The water absorption behavior of CG-SA in deionized water and salt solution were studied. The CG-SA was characterized before and after degradation by FTIR, SEM. The nitrogen release behavior and kinetic characteristics of CG-SA were investigated. In addition, CG-SA degraded 58.33 % and 64.35 % in soil at 25 °C and 35 °C after 28 days. All the results indicated that the low-cost and degradable CG-SA can achieve simultaneous slow release of water and nutrients, which is expected to be widely used as a new water-fertilizer integration technology in arid and poor areas.