Low Total Nitrogen Research Articles

Comparative analysis of crop rotation systems: the impact of ginger (Zingiber officinale) and sponge gourd (Luffa aegyptiaca) residues on growth of Chinese cabbage (Brassica rapa var. chinensis).

Continuous cropping in greenhouse cultivation often leads to increased pest and disease problems, reducing crop quality and yield. Crop rotation is a common strategy to address these issues. This study compared the growth of Chinese cabbage (Brassica rapa var. chinensis) following rotations with ginger (Zingiber officinale) and sponge gourd (Luffa aegyptiaca). The Chinese cabbage exhibited normal growth following ginger rotation but showed abnormal growth after sponge gourd rotation. The study investigated the underlying causes by analyzing soil physicochemical properties and rhizosphere microbial communities of Chinese cabbage using 16S rRNA and ITS sequencing. The results revealed that soil from ginger-Chinese cabbage rotation had higher levels of soil organic carbon (SOC) and available phosphorus (AP), but lower total nitrogen (TN) and available potassium (AK). Despite similar alpha-diversity for both bacterial and fungal communities, distinct bacterial and fungal community structures between two rotation cropping systems were observed. This suggests that even if the alpha-diversity does not change, the composition of the microbial community can shift in ways that might influence soil health and plant growth. Furthermore, redundancy analysis revealed a significant correlation between microbial community structures and soil physicochemical properties of two rotation cropping systems. The SOC and TN were revealed to be the most significant of the investigated soil physicochemical parameters with respect to the variation of both bacterial and fungal assemblages, respectively. The identified biomarkers in bacterial community composition further emphasize the potential for specific microbes to influence crop health positively or negatively. We found that the indicator genera of the bacterial community composition of the ginger-Chinese cabbage rotation system were Amycolatopsis (genus), Pseudonocardiales (order), Pseudonocardiaceae (family), and Amycolatopsis mediterranei, which are known as producers of secondary metabolites, such as antibiotics. These findings highlight the importance of crop selection in rotation strategies for optimizing agricultural outcomes.

Selenium availability in tea: Unraveling the role of microbiota assembly and functions

Tea (Camellia sinensis (L.) O. Kuntze) plants have a strong ability to accumulate selenium (Se). However, the question of how tea plants affect Se availability has received little attention. In this study, five tea cultivars, including Soubei (SB), Aolǜ (AL), Longjing43 (LJ), Zhaori (ZR) and Fenglǜ (FL), were chosen for the study. Quantitative Microbial Ecology Chip and high-throughput sequencing were used to explore the effects of five tea cultivars on soil functions, microbial community structures and Se availability. The results showed that the total soil Se content in the FL garden was lower compared to LJ and SB gardens, whereas available Se was highest in the FL garden. Based on the Bray-Curtis distances, tea cultivar was the main factor affecting bacterial and fungal community structures. The abundance of functional genes concerning carbon, nitrogen, phosphorus and sulfur cycling processes varied among tea gardens. The higher soil NH4+ and NO3− contents, and higher abundance of functional genes like nifH, amoA1 and narG, whereas lower total nitrogen in the FL garden than in the AL and LJ tea gardens demonstrated that the FL tea plants induced microbes to accelerate soil nitrogen cycling processes. Dominant microbes that positively related with functional genes like nifH, narG, and amoA1 were also positively related with the available Se content. In conclusion, tea cultivars could regulate soil functions through affecting microbial community structures and then affecting the soil Se availability. The soil nitrogen cycle processes are suggested to be closely related with Se transformation in tea gardens.

NETWORK PERSPECTIVE: BENEFITS OF INTERNATIONAL SCIENTIFIC COLLABORATION

In 2010 Freeman suggested that "the globalization of scientific and engineering knowledge is the most potent aspect of modern globalization". International research collaboration is an activity that is widely pushed globally, at the level of research institutes and universities. Academic world is increasingly interconnected, fostering such international partnerships that represents the globalization of science from the scientific collaboration perspective. These collaborations extend beyond sharing resources. Main goal of those activities is exchanging ideas, cultures, and visions to address complex global challenges. It is evident that from partnering with institutions and researchers worldwide, National Agricultural and Food Centre (NPPC) can be exposed to diverse pools of knowledge and expertise that significantly enhance the academic quality and reputation of our NPPC. This global exchange of ideas leads to more innovative, comprehensive, and impactful research outcomes. Additionally, as the institute's reputation improves, the research centre will attract more funding, students and talented researchers, achieve globalization, creating a cycle of excellence and improvement. In conclusion, the importance and benefits of international co-research agreements are multiple and profound. Collaboration's activities are pivotal in enhancing academic quality, broadening research horizons, preparing young researcher for global challenges, addressing international issues and policy makers, and fostering cultural understanding and global networks. In the second Editorial article of 2024, I am going to introduce the contents of the articles collected and published in the second issue of 2024 year. Atteh reviewed the effects of fiber on nutrition and reproduction in pigs. Author concluded that the reduction of dietary fiber's hemicellulose in a sow's lactation diet can improve the low-birth-weight piglets' health, post-weaning performance and milk composition. While exogenous enzymes and the extrusion of fibrous feedstuffs enhanced nutrient digestibility and utilisation, other processing methods, including fermentation and extrusion, decreased the dietary fiber components and had a beneficial impact on the performance of the pigs. Agro-industrial residues have enormous potential to improve reproductive efficiency and serving as an economically viable dietary fiber feeding strategy in the pig industry. Awodoyin et al. investigated the dietary supplementation of coffee arabica seed powder on performance and meat quality of broiler chicken. Authors ended up that low pathogenic gut microorganisms and total volatile nitrogen base coupled with high sensory acceptability of meat confirm the antioxidant potential of black coffee in broiler chicken diet. Ngige et al. performed a study aimed at screening the internal and external bacteria found in farmed Nile tilapia and African Catfish. According to microbiological investigation, the presence of the microorganisms, some of which are pathogens (Salmonella enteritidis, Enterobacter aerogenes, Klebsiella oxytoca) to humans, is an indication that undercooked fish may pose health risks to susceptible human and an impediment to the rapid intensification of aquaculture because of mortality of fingerings. Busanello reviewed the most common traffic systems in barns for lactating dairy cows milked in automatic milking systems. The study describes the advantages and disadvantages of free, milk-first and feed-first traffic and the differences between forced and guided cow traffic designs. Some research data are also shown to emphasize the theoretical concepts included in this document. Author concluded that guided traffic designs emerge as the most efficient, milking more cows throughout the day while reducing the need to fetch cows and overall labour. When operating at full cow capacity, guided cow traffic designs are recommended. Sudik conducted a study with the aim to determine the nutritional composition of roselle seed cake (Hibiscus sabdarica L.) and its effect on broiler chickens. Author concluded that roselle seed cake is rich in proteins and energy and it can be included up to 50 % in the diet of broilers without negative effects on growth rate and carcass performance. Rajsky et al. described the flexible duodenal monocannula of the National Agricultural and Food Centre design for the determination of intestinal nutrient digestibility in cattle. The innovativeness of the technical design of the NPPC cannula lies in the fact that the cannula is made of one piece of a straight tube with an inner diameter of 22 mm. As a result, the life of cannulated animals can be extended without age limitation. Editorial Team looks forward to evaluating your submitted contributions and providing all necessary support to Authors in order to best serve animal science and the scientific community, with commitment to research integrity and the highest publishing ethics. Enjoy reading!

PERFORMANCE AND MEAT QUALITY OF BROILER CHICKEN FED GRADED LEVELS OF BLACK COFFEE SEED (COFFEE ARABICA) POWDER SUPPLEMENTED DIET

Oxidative degradation is a deleterious condition that affects quality of meat, thereby poses a threat to poultry industry. However, this can be mitigated through feeding with antioxidants, therefore the need for inclusion of high antioxidant compound, such as coffee, in poultry diet. One-day old Ross 308 chicks (n = 200; r = 5) were randomly allotted to four diets containing black coffee seed powder (BCSP): 0.0 g/kg; 1.25 g/kg; 2.50 g/kg and 3.75 g/kg. Birds were fed ad libitum with free access to water for 6 weeks. Total weight gain (TWG) (g/b), total feed intake (TFI) (g), feed conversion ratio (FCR), haematology, oxidative markers, gut microbiology (x105cfu/mL) of birds, sensory characteristics (9-point hedonic scale) and total volatile nitrogen base (TVB-N) (mg/100 g) of broiler meats were assessed. Data were analyzed using ANOVA at P = 0.05. No significant differences in TWG (1873.12 − 1927.58) and FCR (1.55 − 1.71) were observed. However, TFI at 3.75 g/kg of BCSP (3216) was higher (P < 0.05) than at 0 g/kg (3090), 1.25 g/kg 2967 and 2.50 g/kg of BCSP (3072) in the bird diet. Haemoglobin (12.60) at 1.25 g/kg BCSP was higher (P < 0.05) than at 0 g/kg BCSP (10.83), but similar to the groups of 2.50 g/kg (10.97) and 3.75 g/kg (12.13) BCSP in the diet. Creatinine (0.97mg/dL) in the 1.25 g/kg BCSP group was higher (P < 0.05) than those in the 0 g/kg (0.68 mg/dL) and 3.75 g/kg (0.60 mg/dL) groups but similar to the 2.50 g/kg group (0.88 mg/dL). No significant differences in almost all the oxidative markers were recorded. Gut microbiology showed that heterophilic (11.60), Coliform (8.30) and E.coli (13.70) contents in the 0/kg BCSP group were higher (P < 0.05) than those in the 1.25 g/kg group (9.00, 5.58 and 4.48), the 2.50 g/kg group (3.55, 1.83 and 1.28) and 3.75 g/kg group (3.30, 0.53 and 0.25) for heterophilic, coliform and E. coli respectively. Lactobacillus in the 3.75 g/kg group (7.53) was higher (P < 0.05) than that in the 2.50 g/kg (5.63), the 1.25 g/kg (5.70) and 0 g/kg (1.58) groups. With the increase of BCSP inclusion, the TVB-N decreased; aroma and taste of BCSP meat were best and well accepted. Low pathogenic gut microorganisms and total volatile nitrogen base coupled with high sensory acceptability of meat confirm the antioxidant potential of black coffee in broiler chicken diet.

Irons differently modulate bacterial guilds for leading to varied efficiencies in simultaneous nitrification and denitrification (SND) within four aerobic bioreactors

As a novel biological wastewater nitrogen removal technology, simultaneous nitrification and denitrification (SND) has gained increasing attention. Iron, serving as a viable material, has been shown to influence nitrogen removal. However, the precise impact of iron on the SND process and microbiome remains unclear. In this study, bioreactors amended with iron of varying valences were evaluated for total nitrogen (TN) removal efficiencies under aerobic conditions. The acclimated control reactor without iron addition (NCR) exhibited high ammonia nitrogen (AN) removal efficiency (98.9%), but relatively low TN removal (78.6%) due to limited denitrification. The reactor containing zero-valent iron (Fe0R) demonstrated the highest SND rate of 92.3% with enhanced aerobic denitrification, albeit with lower AN removal (84.1%). Significantly lower SND efficiencies were observed in reactors with ferrous (Fe2R, 66.3%) and ferric (Fe3R, 58.2%) iron. Distinct bacterial communities involved in nitrogen metabolisms were detected in these bioreactors. The presence of complete ammonium oxidation (comammox) genus Nitrospira and anammox bacteria Candidatus Brocadia characterized efficient AN removal in NCR. The relatively low abundance of aerobic denitrifiers in NCR hindered denitrification. Fe0R exhibited highly abundant but low-efficiency methanotrophic ammonium oxidizers, Methylomonas and Methyloparacoccus, along with diverse aerobic denitrifiers, resulting in lower AN removal but an efficient SND process. Conversely, the presence of Fe2+/Fe3+ constrained the denitrifying community, contributing to lower TN removal efficiency via inefficient denitrification. Therefore, different valent irons modulated the strength of nitrification and denitrification through the assembly of key microbial communities, providing insight for microbiome modulation in nitrogen-rich wastewater treatment.

Soil Ecological Stoichiometric Characteristics and Influencing Factors of Degraded Alpine Grassland in Northwest Sichuan

Alpine grasslands are important ecosystems providing a variety of ecosystem services. However, alpine grassland degradation poses significant threats impacting soil health, stabilization and soil ecosystem function. This study aims to investigate the soil ecological stoichiometric characteristics and influencing factors in alpine grasslands, to find the primary contributing factors in soil degradation process. Soil samples were collected from alpine grassland areas with varying degrees of degradation, including non-, lightly, moderately and severely degraded (ND, LD, MD, SD). Soil characteristics including soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), available phosphorus (AP), available nitrogen (AN), microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) were measured. The results revealed that soil TN, N:P ratios and C:P ratios were below the average level of China’s soil, while C:N ratio were above the average. With increasing aggravation of grassland degradation, SOC, TP, AN, MBN and MBC significantly decreased. Correlation were observed between SOC and C:N ratios as well as C:P ratios in alpine grassland with different degradation degrees (P < 0.05). The C:N ratios in degraded grasslands were lower than those in ND grasslands but higher than the average level of China’s soil. Additionally, the N:P and C:P ratios of LD and MD were significantly higher than those of ND, but lower than the China’s soil average level. In conclusion, soil degradation in alpine grasslands is associated with lower TN contents, higher C:N ratios, and lower N:P ratios, which can impact soil organic matter decomposition and act as plant growth restriction factor. This study provides comprehensive insights into the ecological stoichiometry of alpine grasslands, understanding these factors is essential for the sustainable management of alpine grasslands and restoration strategies for the ecosystem services.

Management of eutrophication using combined the “flock & sink” mitigation technique and submerged plants restoration: a mesocosm study

Abstract Currently, the issue of eutrophication and cyanobacterial blooms persists in water bodies worldwide, prompting the exploration of various treatment methods. This study conducted a comparative analysis of eutrophic water bodies using ferric chloride-modified zeolite (FMZ) and calcium hydroxide-modified zeolite (CMZ) combined with Elodeanuttallii (E. nuttallii) for removal and purification effects. The results revealed that the addition of E. nuttallii had a sustained inhibitory effect on phosphorus release, maintaining stability with lower Turbidity(Tur) and stabilized pH within the range of 8.5-9. FMZ demonstrated rapid reduction in dissolved phosphorus concentration, achieving a removal rate of 96% within 3 days. The combined plant group of CMZ and FMZ exhibited synergistic effects with E. nuttallii, achieving an impressive total phosphorus (TP) removal rate of 80.13% and a total nitrogen (TN) removal rate of 48.77%. Additionally, chlorophyll a (Chl a) concentration decreased from 100.74 ± 24.72 μg/L to 49.96 ± 2.08 μg/L. The phytoplankton community composition indicated that diatoms thrived in low temperatures and high NH4 conditions. Under the same low Total Nitrogen to Total Phosphorus (TN:TP) ratio, high TP concentrations were associated with cyanobacteria dominance, while green algae dominated in other scenarios. This comprehensive approach demonstrates the potential efficacy of CMZ and FMZ combined with E. nuttallii in addressing eutrophic water bodies and mitigating cyanobacterial blooms.

Enhanced methane recovery from anaerobic membrane bioreactor coupled with cold plasma pretreatment for rapid hydrolysis and nitrogen removal

Research to increase biomethane recovery efficiency from thickened sewage sludge (TSWS) using sustainable anaerobic digestion (AD) in municipal wastewater treatment plants is ongoing. Pretreating substrates is known to increase organic biodegradation and biomethane conversion rates in AD. Cold plasma (CP), a recently adopted advanced oxidation processes (AOP) has emerged as an alternative to accelerate pretreatment times under different operation variables. This study assessed raw and CP-pretreated TSWS in an anaerobic sequencing batch reactor (ASBR) and anaerobic membrane bioreactor (AnMBR). The effects of incremental organic loading rates (OLR) and nitrogenous compounds concentration on enhanced CH4 bioconversion efficiency were evaluated. We found that the AnMBR outperformed the ASBR, with an overall chemical oxygen demand (COD) conversion rate of 67%, lower total nitrogen (T–N) accumulation (594 mg L−1), and an overall methane yield of 0.24 L CH4 g−1 COD. CP pretreatment improved TSWS AD, resulting in more efficient COD removal and methane recovery. This study suggests that CP technology is a promising pretreatment to improve AD when treating TSWS.

Dredging wastewater discharge from shrimp ponds affects mangrove soil physical-chemical properties and enzyme activities

Dredging wastewater discharge is a significant environmental concern for mariculture near mangrove ecosystems. However, little attention has been paid to its effects on the soil physical-chemical properties and enzyme activities in mangrove habitats. This study compared the soil physical-chemical properties and enzyme activities in the polluted area that received dredging wastewater from a shrimp pond with those in the control area without wastewater to explore the effects of wastewater discharge on the soil physical-chemical properties and enzyme activities. Variations in soil physical-chemical properties and enzyme activities across different tidal flat areas and depths were also examined. The polluted area exhibited lower soil salinity (10.47 ± 0.58 vs. 15.64 ± 0.54) and moisture content (41.85 ± 1.03 % vs. 45.81 ± 1.06 %) than the control area. Wastewater discharge increased soil enzyme activities, (acid phosphatase, protease, and catalase), resulting in higher inorganic nitrogen (13.20 ± 0.00 μg g−1 vs. 11.60 ± 0.03 μg g−1) but lower total nitrogen (0.93 ± 0.01 mg g−1 vs. 1.62 ± 0.11 mg g−1) in the contaminated zone. From the control to polluted area, there was an approximate increase of 0.43 and 0.83 mg g−1 in soil total phosphorus and soluble phosphate, driven by increased acid phosphatase. However, soil humus and organic matter decreased by 0.04 and 1.22 %, respectively, because of wastewater discharge. The impact of wastewater discharge on the soil physical-chemical properties and enzyme activities was most pronounced in the landward and surface soil layers (0–5 cm). The results showed that wastewater discharge altered soil physical-chemical properties and enzyme activities, accumulating soil bioavailable nutrients (inorganic nitrogen and soluble phosphate), but at the cost of reduced soil quality, especially organic matter, further adversely affecting the overall health of mangrove ecosystems. Prioritizing the management of wastewater discharged from mariculture adjacent to mangrove forests is crucial for mangrove conservation.

The effect of anthropogenic activities on the spatial distribution of total nitrogen and total phosphate in Lake Maninjau

This study aimed to analyse the effect of anthropogenic activities on the spatial distribution of total nitrogen (TN) and total phosphate (TP) in Lake Maninjau, Indonesia, during the dry season. Sampling was carried out at ten observation locations representative for various activities around the lake. Cluster analysis and ANOVA were used to classify pollutant sources and observe differences between TN and TP at each site. Concentrations of TN and TP are categorised as oligotrophic-eutrophic. The ANOVA showed spatially that some sampling locations, such as the Tanjung Sani River, floating net cages, and hydropower areas have different TN concentrations. At the same time, TP levels were consistently significantly different across sampling sites. ANOVA and cluster analysis confirmed that floating net cages were the first cluster and the primary contributor to TN and TP. The second and third clusters come from anthropogenic activities around the lake, such as agriculture, settlement, and livestock. The fourth cluster with the lowest TN and TP is the river that receives the anthropogenic activity load but has a high flow velocity. The cluster change analysis needs to be conducted when there are future changes in the composition of floating net cages, agriculture, and settlements.

Recovery of lakes from eutrophication: changes in nitrogen retention capacity and the role of nitrogen legacy in 10 Danish lakes studied over 30 years

AbstractUsing data on 23 Danish lakes, we conducted mass balances to develop total nitrogen (TN) models for predicting annual mean TN in lakes based on external TN loading and found high predictability when including lake hydraulic retention time and mean depth in the model. We further used a unique 30-year mass balance data series from 10 Danish lakes with contrasting mean depths and hydraulic retention times to elucidate the effect of external TN loading reduction and N legacy on lake TN. We found that the TN retention percentage during the 30 years was generally not sensitive to an often major reduction in the external TN loading; it overall followed the pattern of the above model predictions, suggesting a low TN legacy effect. Moreover, the TN retention percentage was not affected by changes in TP. Our results, therefore, show a fast response to TN loading reduction, indicating that we can expect an immediate effect on lake water quality in shallow lakes suffering from internal phosphorus loading during re-oligotrophication provided that inorganic N is low enough to become a growth-limiting nutrient.

Optimal Soil, Climate, and Management Factors for Maximizing Crop Yield and Soil Nutrients in a Rice–Oilseed Rotation System with Straw Return

Straw return (SR) has been widely recommended as a conservation agricultural practice in China. However, the effects of SR on crop yield and soil properties are inconsistent across studies of rice–oilseed rape cropping systems in China. This study aimed to investigate the effects of SR on crop yield and soil nutrient content in a rice–oilseed rotation system, and to understand the mechanism of straw return on the difference in yield increases between rice and oilseed rape. Additionally, suitable climate factors, soil properties, and agricultural practices were identified to achieve maximum increases in yield and soil nutrients in a rice–oilseed rotation under SR. This paper is based on a meta-analysis of 1322 observations from 83 peer-reviewed studies to evaluate the effects of climate, initial soil conditions, and agricultural management practices on rice and oilseed rape yields and soil nutrients under SR. The results showed that the responses of oilseed rape and rice yield remained positive, with 12.37% and 6.54% increases, and were significantly higher under SR than the control (no SR). Moreover, SR significantly increased the contents of several soil nutrients (soil organic carbon (SOC), total nutrients, available nutrients) and microbial biomass carbon (MBC) and nitrogen (MBN). Interestingly, the increase in crop yields was attributed to the increase in SOC, total nitrogen, and available potassium. Additionally, the increase in yields was mainly affected by climate factors, initial soil properties, and agronomic practices. For example, both mean annual temperature (MAT) and mean annual precipitation (MAP) had a positive correlation with crop yield increases under SR (p < 0.01). Initial soil conditions such as low SOC and total nitrogen content were more suitable for increased rice yield under SR, while the opposite was true for increased oilseed rape yield. Without fertilization, the SR did not significantly improve crop yield and soil nutrients, while it was more pronounced with N fertilization at 150–180 kg hm−2. The positive effect of SR on crop yields is more evident with plowing tillage, whereas the SR caused the highest increase in soil nutrients with the no-tillage condition. These findings have important implications for further improving crop yield, SOC, and soil nutrients in the Chinese rice–oilseed cropping system through straw return.

Characterization and classification of soils of a paddy field in Badeggi, Niger State, Nigeria

This study was conducted with the aim of characterizing and classifying the soils of a paddy field in Badeggi Katcha local Government Area of Niger State. Two pedons were dug representing upper and lower slopes of the field and were designated as Badeggi 1 and 2 (BDG1 and BDG2) respectively. The pedons were described on the field following the FAO guidelines for soil description. Soil samples were collected from each identified natural horizons and taken to the laboratory for analysis. Results revealed that BDG1 had greyish brown (10YR 5/2) at the topmost horizon and light brownish grey (10YR 6/2) at the subsoil, while BDG2 had light brownish grey (10YR 6/2) overlying light grey (10YR 7/2) at subsoil. Sand content ranged from 840 to 860 g/kg in BDG 1 and 690 to 830 g/kg in BDG 2, silt ranged from 50 to 70 g/kg in BDG 1 and 90 to 210 g/kg in BDG 2 and clay ranged from 90 to 100 g/kg in BDG 1 and 80 to 100 g/kg in BDG 2. Soils from the two pedons were moderately to slightly acidic, low in organic carbon and available phosphorus, while total nitrogen was rated low to medium and irregularly distributed down the two profiles, but exchangeable Calcium, Magnesium, Potassium and Sodium were high across the study area. Using the USDA soil taxonomy system, the soils were classified as Plinthic Petraquepts (BDG 1) and Fluvaquentic Endoaquepts (BDG 2) which corresponded to Petric Plinthosols (Abruptic) and Fluvic Cambisols (Eutric) respectively, under World Reference Base for Soil Classification (WRB). The study has revealed that BDG1 is moderately well-drained while BDG2 is imperfectly drained. The soils are moderate to slightly acid with low inherent fertility as evidenced by low organic carbon, total nitrogen and available phosphorous. The soils were classified as Inceptisols at Soil Order level.

Soil Physicochemical Properties Variation under Annual Crop and Coffee Landuse in the Chentale Watershed, Upper Blue Nile Basin, Ethiopia

A detrimental decline in soil fertility has been attributed to losses in arable land productivity in Ethiopia. In this line, several studies were conducted to enable informed decisions; however, monitoring soil property dynamics in different biophysical, climatic, and cropping systems is yet to be adequate to support and influence decision and policymakers. To this end, this study evaluated soil physicochemical properties on land managed for annual crops and coffee land use in the Chentale watershed, the upper Blue Nile basin, Ethiopia. About 24 soil samples were collected from the two land uses and soil depths (topsoil: 0–15 cm and subsoil: 15–30 cm) with 6 replications for soil properties analysis. The result showed that most of the soil parameters varied significantly with land uses and were higher with coffee landuse (p<0.01) than with cropland. Furthermore, a neutral pH range, clay loam texture, medium level of organic matter (3.93%) and nitrogen (0.18%), high level of available phosphorus (23.35 PPM), and high to very high level of exchangeable base were recorded from coffee landuse than from cropland. Whereas the mean values of organic matter (OM) and total nitrogen (TN) decreased significantly (p<0.05) decreased in the subsoil. However, most of the physical and chemical properties of the soil did not vary significantly with depth. Moreover, low pH, low OM content, and low TN are the main properties of soil considered constraints of soil fertility in cropland at both depths. Therefore, it is recommended to maintain agroforestry practices, reduce the intensity of tilling, and supply organic materials to sustain the productivity of cropland.

Biochar and zero-valent iron alleviated sulfamethoxazole and tetracycline co-stress on the long-term system performance of bioretention cells: Insights into microbial community, antibiotic resistance genes and functional genes

Antibiotics and antibiotic resistance genes (ARGs), known as emerging contaminants, have raised widespread concern due to their potential environmental and human health risks. In this study, a conventional bioretention cell (C-BRC) and three modified bioretention cells with biochar (BC-BRC), microbial fuel cell coupled/biochar (EBC-BRC) and zero-valent iron/biochar (Fe/BC-BRC) were established and two antibiotics, namely sulfamethoxazole (SMX) and tetracycline (TC), were introduced into the systems in order to thoroughly investigate the co-stress associated with the long-term removal of pollutants, dynamics of microbial community, ARGs and functional genes in wastewater treatment. The results demonstrated that the SMX and TC co-stress significantly inhibited the removal of total nitrogen (TN) (C-BRC: 37.46%; BC-BRC: 41.64%; EBC-BRC: 55.60%) and total phosphorous (TP) (C-BRC: 53.11%; BC-BRC: 55.36%; EBC-BRC: 62.87%) in C-BRC, BC-BRC and EBC-BRC, respectively, while Fe/BC-BRC exhibited profoundly stable and high removal efficiencies (TN: 89.33%; TP: 98.36%). Remarkably, greater than 99% removals of SMX and TC were achieved in three modified BRCs compared with C-BRC (SMX: 30.86 %; TC: 59.29%). The decreasing absolute abundances of denitrifying bacteria and the low denitrification functional genes (nirK: 2.80 × 105–5.97 × 105 copies/g; nirS: 7.22 × 105–1.69 × 106 copies/g) were responsible for the lower TN removals in C-BRC, BC-BRC and EBC-BRC. The amendment of Fe/BC successfully detoxified SMX and TC to functional bacteria. Furthermore, the co-stress of antibiotics stimulated the propagation of ARGs (sulI, sulII, tetA and tetC) in substrates of all BRCs and only Fe/BC-BRC effectively reduced all the ARGs in effluent by an order of magnitude. The findings contribute to developing robust ecological wastewater treatment technologies to simultaneously remove nutrients and multiple antibiotics.

Effect of Blended NPSB Fertilizer Rates and Varieties on Productivity of Chickpea (Cicer arietinum L.) in Midland of Guji Zone, Southern Oromia

Low soil fertility comprised of low available phosphorus, total nitrogen and sulphur are the major yield limiting factors for faba bean production in the study area. A field experiment was conducted at Adola Sub-site station of Bore Agricultural Research Centre. The treatments consisted of two varieties namely Dalota and Habru with four levels of NPSB (0, 50, 100 and 150 kg/ha) in randomized complete block design with three replications. The aim of the study conducted to evaluate the effect of application of Blended NPSB fertilizer and to determine economically viable blended NPSB rates that would boost chickpea productivity. Results showed significant effect of various levels of blended fertilizer on all tested parameters except on number of seed per pod and thousand seed weight. Application of 100 kg NPSB kg ha-1 gave highest number of primary branches per plant (3.02), plant height (50.02) and grain yield (2663 kg ha-1), net return (103376.5 ETB) with acceptable MRR (666.0%). Days to flowering (52.62), Days to maturity (108.96), number of pods per plant (40.31) had the highest value with 150 kg/ha with negative agronomic efficiency. Therefore, production of chickpea with the application of 100 kg NPSB ha-1 was most productive for economical production.

2-Hydroxy-1,4-Naphthoquinone: A Promising Redox Mediator for Minimizing Dissolved Organic Nitrogen and Eutrophication Effects of Wastewater Effluent.

Researchers and engineers are committed to finding effective approaches to reduce dissolved organic nitrogen (DON) to meet more stringent effluent total nitrogen limits and minimize effluent eutrophication potential. Here, we provided a promising approach by adding specific doses of 2-hydroxy-1,4-naphthoquinone (HNQ) to postdenitrification bioreactors. This approach of adding a small dosage of 0.03-0.1 mM HNQ effectively reduced the concentrations of DON in the effluent (ANOVA, p < 0.05) by up to 63% reduction of effluent DON with a dosing of 0.1 mM HNQ when compared to the control bioreactors. Notably, an algal bioassay indicated that DON played a dominant role in stimulating phytoplankton growth, thus effluent eutrophication potential in bioreactors using 0.1 mM HNQ dramatically decreased compared to that in control bioreactors. The microbe-DON correlation analysis showed that HNQ dosing modified the microbial community composition to both weaken the production and promote the uptake of labile DON, thus minimizing the effluent DON concentration. The toxic assessment demonstrated the ecological safety of the effluent from the bioreactors using the strategy of HNQ addition. Overall, HNQ is a promising redox mediator to reduce the effluent DON concentration with the purpose of meeting low effluent total nitrogen levels and remarkably minimizing effluent eutrophication effects.

Nutrient status of overlying water and sediment of West Lake, Hangzhou, China

A comprehensive investigation of the physicochemical properties of overlying water and sediments in Hangzhou West Lake, China was conducted. A wide range of crucial physical parameters were analyzed, revealing significant spatial and seasonal differences. Total nitrogen (TN), total phosphorus (TP), and chemical oxygen demand (COD) concentrations in overlying water met the Class III limits (TN ≤2 mg/L, TP ≤0.2 mg/L, COD ≤20 mg/L) of the Environmental Quality Standard for Surface Waters (GB3838–2002), indicating relatively good overall water quality. However, concerns were raised regarding potential eutrophication, particularly evident during summer with explosive chlorophyll-a growth in certain lake areas like WH (266 mg/L) and XLH (239 mg/L). Lakes receiving direct diversion showed lower TN and TP versus non-diverted lakes. This research provides valuable insight into the complex nutrient dynamics and conditions of West Lake, improving understanding of lake ecosystem management and sustainable conservation strategies.

Soil Quality Indicators under Different Smallholder Managed Cropping and Landuse Practices in Abuja, Nigeria

There are limited reports about the impacts of smallholder-managed cropping and land-use practices (CLUPs) on soil quality, especially in developing countries. This study investigates the impact of six different Cropping Land Use Practices (CLUPs) on soil quality parameters in Abuja, Nigeria, focusing on sesame mono-cropping (SM), guinea corn mono-cropping (GCM), yam mono-cropping (YM), maize + yam mixed cropping (MYM), maize mono-cropping (MM), and natural forest (NF). The objectives are to determine Soil Organic Carbon (SOC), Total Nitrogen (TN), and pH values in the six CLUPs and assess differences under various CLUPs and soil depths. The study conducted in the University of Abuja Permanent Site, covers 11,000 hectares and analyzes soil samples from three replicate plots per CLUP, considering topsoil (0-15cm) and subsoil (20-30cm). The results indicate slightly acidic soils with low SOC and TN contents. Significant differences in SOC, TN, and C/N ratio are observed among cropping systems, with mixed cropping (MYM) promoting higher SOC. The C/N ratio is consistently low across CLUPs, indicating accelerated decomposition. While intra-plot soil heterogeneity is low, significant declines in soil quality indicators are noted under cropping systems compared to the natural forest. The study recommends site-specific, sustainable land management practices tailored to each cropping system. Encouraging organic matter additions, such as using animal and farmyard manure, is proposed to enhance soil fertility and reverse degradation trends. The findings contribute to understanding how diverse cropping practices impact soil quality, providing valuable insights for sustainable land management in the Abuja region.

The C/N Ratio’s Effect on a Membrane-Aerated Biofilm Reactor (MABR): COD and Nitrogen Removal, Biofilm Characteristics, and Microbial Community Structure

In this study, a laboratory-scale membrane aerated biofilm reactor system was operated successively through four phases with different C/N ratios (7, 5, 3, and 1) for 15 days each to investigate the C/N ratio’s effect on the COD and nitrogen removal. The COD and NH4+-N removal efficiencies were slightly affected; however, NO3−-N accumulated in the C/N = 1 phase, and slight NO2−-N accumulation was observed in the C/N = 7 phase, leading to lower total nitrogen (TN) removal in the two phases. The TN removal efficiency reached the highest in the C/N = 5 phase at around 70%, and the TN concentration was reduced to 12.3 mg/L on average. Biomass and biofilm thickness had a positive correlation with C/N ratios. The C/N ratio affected not only the generation of extracellular polymeric substances but also their chemical composition. Microbial analysis revealed that a C/N ratio of 5 was the most suitable for both nitrifying and denitrifying bacteria, and a higher C/N ratio favored aerobic denitrifying microbes.