Nitrogen Rates Research Articles

Economic response of potato to nitrogen rate, timing of nitrogen application, cultivar, and irrigation

Three multi-year studies were conducted in Manitoba, Canada to evaluate the effect of nitrogen (N) fertilizer rate (ranging from 0-225 or 0-240 kg N ha-1) and its interactions with timing of N application (pre-plant, split application), cultivar (Russet Burbank (RB), Glacier Fryer (GF), Umatilla Russet (UR)), and moisture regime (irrigated, non-irrigated) on the yield and net revenue (NR) of potato (Solanum tuberosum L.). Based on soil test N, all sites were expected to be N-responsive, with soil test N at most sites ranging from 24 to 45 kg NO3-N ha-1 to 60 cm and measuring 70 and 117 kg NO3-N ha-1 to 60 cm at the remaining two sites. Linear and quadratic coefficients of N and irrigation were significant for yield and NR. However, the NR curves for N inputs were relatively flat, and the NRs were only slightly less than the optimal NR within the vicinity of the optimum. Split N applications performed similarly to pre-plant N, and GF performed better than RB or UR; however, GF optimal economic N rates were about 55% higher than the optimal economic N rates of RB and UR cultivars. Optimal economic N rate for the best potato practices ranged from 157 to 216 kg N ha-1, depending on the studies; or averaging at about 188 kg N ha-1. Adoption of these best N management practices will improve profitability and N use efficiency in potato production and reduce negative environmental impacts.

Shade and Nitrogen Fertilizer Effects on Greenhouse Gas Emissions from Creeping Bentgrass Putting Greens

Climate change mitigation requires creative solutions to reduce greenhouse gases (GHG). Little research has been performed on GHG emissions from shaded turfgrass systems, resulting in a lack of best management practice (BMP) development. The aim of this research was to investigate the soil flux of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) as impacted by shade [shade (98.8%) versus sun (100%)] and differing sources (fast- versus slow-release) and rates (147 versus 294 kg ha−1 yr−1) of nitrogen (N) fertilizers on creeping bentgrass putting greens. The results show that emissions of soil CO2 and soil N2O are significantly lower in shaded plots versus sunny plots. The presence of N fertilizer significantly increased soil CO2 emissions over unfertilized plots. Quick-release N fertilizer fluxed significantly more soil N2O than the slow-release N fertilizers. Turfgrass color was significantly higher on the sunny green versus the shaded green except in late summer. Turfgrass quality was significantly higher for the shaded green versus the sunny green. Milorganite improved turfgrass quality whereas urea decreased turfgrass quality due to fertilizer burn. When N is needed to improve turfgrass color and quality, the use of slow-release N sources should be a BMP for shaded greens.

Maximizing Irrigated Maize Productivity: Evaluating the Impact of Deficit Irrigation and Nitrogen Rates on Growth, Yield, and Water-Use Efficiency in Southwest Ethiopia

Maximizing Irrigated Maize Productivity: Evaluating the Impact of Deficit Irrigation and Nitrogen Rates on Growth, Yield, and Water-Use Efficiency in Southwest Ethiopia

Porous red mud ceramsite for aquatic phosphorus removal: Application in constructed wetlands

Red mud (RM) and spent oyster mushroom substrate (SOMS), by-products of industrial and agricultural production, can be recycled for polluted freshwater purification, bringing about a win-win situation. In this study, unacidified RM and RM acidified with oxalic acid (O-RM) and hydrochloric acid (H-RM), respectively, were mixed with SOMS to produce a porous ceramsite as a potential constructed wetlands (CWs) substrate. The results showed that the O-RM, H-RM, and RM ceramsites displayed fine compressive strengths of 7.75 ± 1.14, 8.40 ± 1.30, and 8.84 ± 0.69 MPa after calcining at 950 °C for 30 min, respectively. The phosphorus adsorption capacities of H-RM, O-RM, and RM ceramsite at a solid-liquid ratio of 25 g/L were 1.18 mg/g, 0.88 mg/g, and 1.06 mg/g, respectively. Toxicity release experiments showed that the ceramsites did not cause secondary environmental pollution, except for arsenic (ranging from 0.210 to 0.238 mg/L). The H-RM ceramsite was tested in a tidal flow-vertical flow CW (TF-VFCW) with Iris pseudacorus L. and Canna indica L plants. In the TF-VFCW, the average chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), total nitrogen (TN), and total phosphorus (TP) removal rates were 81.01, 90.25, 66.90, and 77.32 %, respectively. Plant growth had less impact on COD and NH4-N removal but had greater limited TN and TP removal. Scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction analysis confirmed that acid pretreatment and the incorporation of SOMS significantly increased the surface and interior porous structures of the ceramsite and enhanced phosphate adsorption by the polyhydroxyl aluminum-iron complex ions. Bacteroides and Campylobacter used the energy produced during polyhydroxyalkanoic acid (PHA) catabolism to absorb phosphorus. Therefore, the synergistic effect of the substrate, plants, and microorganisms achieved the removal of phosphorus from CWs and offered effective and environmentally friendly recycling of RM and SOMS.

Response of shallots to different rates of nitrogen grown in the lowland tropics of Cirebon Regency, West Java

Response of shallots to different rates of nitrogen grown in the lowland tropics of Cirebon Regency, West Java

Utilizing auxin dwarf genes to optimize seed yield and lodging resistance in rapeseed

Direct-seeding rapeseed production at high plant density raises the risk of lodging. We investigated the use of dwarf genes to improve rapeseed plant architecture to balance yield and lodging. Three genotypes with different plant architectures (dwarf scaHS5, semi-dwarf +/scaHS5, and tall HS5) were evaluated under varying nitrogen rates (N1, N2, and N3: 120, 240, and 360 kg N/ha) and plant densities (D1, D2, and D3: 15, 45, and 75 plants m−2) from 2019 to 2022. The results showed that increasing N rate positively influenced yield while decreasing lodging resistance in all genotypes. Increasing plant density (D2–D3) enhanced lodging resistance and yield in scaHS5 and +/scaHS5, but reduced yield in HS5. Compared to the two parents, +/scaHS5 exhibited moderate expressions of IAA3, GH3.15, and SAUR30 in stems under N2D3, resulting in reduced plant height and increased compactness. Additionally, +/scaHS5 had a thicker silique layer than HS5 by 14.7 %, and it had a significant correlation between height/angle and yield. Increasing N rate led to increased lignin and pectin contents, while cellulose content decreased. Increasing plant density resulted in greater stem cellulose content and CSLA3/7 expression in scaHS5 and +/scaHS5, but decreased in HS5. Compared to HS5, +/scaHS5 exhibited higher expressions of ARAD1 and GAUT4, along with a 51.1 % increase in pectin content, leading to improved lodging resistance under N2D3. Consequently, +/scaHS5 showed a 46.4 % higher yield and 38.9 % lodging resistance than HS5 under N2D3, while scaHS5 demonstrated strong lodging resistance but lower yield potential. Overall, this study underscores the potential of utilizing auxin dwarf genes to optimize the trade-off between yield and lodging resistance in rapeseed and the possibility of maximizing yield potential by optimizing the plant architecture of +/scaHS5 through nitrogen reduction and dense planting

Effects of Irrigation Amount and Nitrogen Rate on Cotton Yield, Nitrogen Use Efficiency, and Soil Nitrogen Balance under Drip Irrigation

Water and nitrogen (N) are major constraints for cotton growth and yield formation in arid regions. Irrigation and N application have been widely investigated to improve crop yield and water and N use efficiency (NUE). However, further optimization of water and N management is needed because the effects of N application on soil N balance and N loss under different irrigation levels remain unclear. In this study, a field experiment was conducted in 2020 and 2021 to investigate the effects of different irrigation amounts (full irrigation (100% ETc), moderate irrigation (80% ETc), low irrigation (60% ETc)) and N application rates (control (without N application, N0), low N (150 kg ha−1, N150), medium N (225 kg ha−1 and 300 kg ha−1, N225 and N300), and high N (375 kg ha−1, N375)) on cotton yield, NUE, and soil N balance. The 2-year results showed that under the 60% ETc treatment, cotton dry matter accumulation, N uptake, and yield were significantly enhanced by increasing N application. Under the 80% and 100% ETc treatments, these parameters peaked with the N300 treatment; the N375 treatment showed no significant difference or decrease compared to the N300 treatment. The 80% ETc N300 treatment had the highest cotton yield and NUE, which increased by 17.49–106.57% and 12.28–88.78% compared with other treatments, respectively. Residual soil N accumulation (RSNmin), apparent N loss (ANL), and apparent N surplus (ANS) increased as the N application rate increased under the 60% and 100% ETc treatments. While under the 80% ETc treatment, the ANS did not significantly differ between the N225 and N300 treatments, ANL significantly decreased by 43.51–88.56% when the N application rate increased from 150 to 225 and 300 kg ha−1. The ANL of the 80% ETc N300 treatment was the lowest, but ANS did not significantly increase. The regression analysis and spatial analysis results showed that under irrigation of 336–348 mm and N application of 254–327 kg ha−1, cotton yield, NUE, and WPI reached more than 80% of the maximum value, with less apparent N loss, thus maintaining the soil N balance in drip-irrigated cotton fields. This study helps to improve the utilization of water and N resources in cotton production. Future research on optimizing water and N management needs to more fully consider environmental pollution to achieve sustainable development of agricultural ecosystems.

Nitrogen Rate Assessment for Greenhouse Gas Emission Mitigation and Quality Maintenance in Sustainable Turf Management

Nitrogen Rate Assessment for Greenhouse Gas Emission Mitigation and Quality Maintenance in Sustainable Turf Management

Effects of Incubation Temperature and Sludge Addition on Soil Organic Carbon and Nitrogen Mineralization Characteristics in Degraded Grassland Soil

Elucidating the characteristics and underlying mechanisms of soil organic carbon (SOC) and nitrogen mineralization in the context of sludge addition is vital for enhancing soil quality and augmenting the carbon sink capacity of soil. This study examined the chemical properties, enzyme dynamics, and organic carbon and nitrogen mineralization processes of soil from degraded grasslands on the Loess Plateau at various incubation temperatures (5, 15, 25, and 35 °C) and sludge addition rates (0%, 5.0%, 10.0%, and 20.0%) through a laboratory incubation experiment. The results showed that incubation temperature, sludge addition, and their interactive effects significantly altered the soil enzyme C:N, C:P, and N:P stoichiometries. The cumulative mineralization rates of SOC and nitrogen increased significantly with increasing incubation temperature and sludge addition rate. Principal component analysis revealed a significant linear correlation between cumulative SOC and nitrogen mineralization. Random forest analysis indicated that β-1,4-Glucosidase (BG), β-1,4-N-acetyglucosaminidase (NAG), cellobiohydrolase (CBH), ammonium nitrogen (NO3−), enzyme C:P ratio, alkaline phosphatase (ALP), and incubation temperature were crucial determinants of cumulative SOC mineralization. Structural equation modeling demonstrated that sludge addition, NO3−, NAG, ALP, and enzyme C:P positively impacted SOC mineralization, whereas dissolved organic carbon and BG had negative impacts. Conversely, incubation temperature negatively affected soil nitrogen mineralization, whereas NO3−, available phosphorus, and ALP contributed positively. Sludge addition and temperature indirectly modulated soil net nitrogen mineralization by altering soil chemical properties and enzyme activities. These findings underscore the role of SOC and nitrogen mineralization as indicators for evaluating soil nutrient retention capabilities.

Multi-criteria analysis of the continuous operation of a membrane photobioreactor to treat sewage: Modeling and sensitivity analysis

Microalgae-based wastewater remediation is aligned with circular economy principals but successful large-scale facilities are scarce due to the limited knowledge of the interactions between all relevant variables and the scarce development of control and automation systems. Machine learning (ML) methods have the potential predict performance in microalgae photobioreactors, with the aim to optimize it. Some attempts have been performed under controlled lab conditions which prevents the direct application of their results to industrial scale. This study aims to develop ML models for the prediction of nutrient removal, biomass production and photosynthetic efficiency using a database obtained from 1.5-y operation of a pilot-scale membrane photobioreactor (MPBR) that treated sewage. A total of 14 inputs and 6 outputs were selected. Random forests (RF), boosted trees (BT), multilayer perceptron (MLP), support vector machine methods (SVM) were tested. The lowest prediction errors were obtained with the MLP model, allowing the developed tool to be used as an alternative to mechanistic models. Large ranges of data were used, considering the variability of factors in the diurnal cycle whose influence on the variability of the data is usually neglected. Using global sensitivity analysis (GSA), input-output relationships were verified, reflecting relevant number of variables showing significant values of Shapley Indices. Additionaly, partial dependence plots showed both linear and nonlinear depending on the selected inputs and outputs. Finally, using ML models, multi-criteria optimization of operating parameters was performed for two variants: a) optimization of operating parameters (HRT, SRT, and air flowrate (Fair)); and b) optimization of operating parameters and influent nutrient loads (HRT, SRT, Fair, nitrogen and phosphorus loading rates).

Mid-season nitrogen management for winter wheat under price and weather uncertainty

ContextIn-season nitrogen (N) management tools are essential for optimizing N application rates, maximizing farmers’ economic returns and minimizing adverse environmental impacts. The primary limitation to developing such tools is the risk associated with uncertainties in weather forecasts and crop price projections required to estimate yields and returns for different N rates. Therefore, characterizing the risk associated with these uncertainties is crucial for determining optimum N rates in-season. ObjectiveThis study investigated the N application decision-making process for farmers, accounting for risks associated with weather and crop price uncertainties through crop modeling and economic analysis. MethodsWe used field trial data for winter wheat in Kansas to examine how optimal nitrogen rates and economic returns vary over sites, years, and differing farmers’ risk attitudes. First, the Environmental Policy Integrated Climate (EPIC) agroecosystem model was used to simulate the distribution of final yields under different N applications during early spring. Then, an autoregressive moving average (ARMA) model estimated the wheat price distribution at harvest based on historical prices. Finally, optimal N application rates for farmers with different risk appetites were estimated using two risk decision models: the constant-absolute-risk-averse (CARA) expected utility model, which treats upside (higher-than-expected returns) and downside (lower-than-expected returns) deviations equally, and the invariant-preference, generalized-deviation (IPGD) model, which focuses on downside risk. ResultsWe found that optimal N rates vary greatly between sites and years, as well as across farmers with different risk preferences. Due to the positive skewness of economic return distribution, farmers tend to apply lower N rates when considering downside risk. On average, the optimal N rate for farmers with a CARA coefficient of 0.002 is 77 kg/ha in the CARA model and 67 kg/ha in the IPGD model. Compared to the outcome of risk-neutral N usage, risk-averse N usage for a farmer with a CARA coefficient of 0.008 could reduce the uncertainty (standard deviation) of return by 6.2 %, on average, while the expected return decreased by only 1.2 %. ConclusionsBy lowering the N rate, risk-averse farmers would reduce the uncertainty of returns and incur a minor return loss, suggesting the possibility of improving agricultural resilience while also improving N use efficiency. Our analysis also underscores the importance of yearly site-specific N management, given the substantial variation in optimal rates across years and locations. SignificanceThis study provides the foundation for an N application decision framework that considers both weather and price uncertainty. The analysis also demonstrates the potential co-benefit of enhancing agriculture’s climate and market resilience while potentially lowering N losses.

Regulation and microbial response mechanism of nitric oxide to copper-containing swine wastewater treated by Pistia stratiotes

As a signaling molecule, Nitric oxide (NO) has been widely used in abiotic stress mitigation studies.Pistia stratiotes showed a good synergistic removal effect on heavy metals, nitrogen and phosphorus, but the high concentration of copper(Cu) in swine wastewater inhibited the comprehensive removal ability of Pistia stratiotes. At present, it is not clear how the addition of NO regulates the stress resistance mechanism of Pistia stratiotes to copper in swine wastewater, and the microbial response mechanism accompanying this process is not yet clear. Therefore, in the concentration range of 0.31∼4 mg·L−1Cu2+ and NO concentration of 0,0.05 and 0.1 mg L−1, the removal effect of Pistia stratiotes on copper from swine wastewater was studied. The results showed as follows: The treatment of non-available copper in groups M and H increased by 10.67% and 22.31%, respectively, compared with that in group L. The critical point of inhibiting effect of NO on growth rate was 2.03 mg·L−1Cu. By measuring three-dimensional fluorescence spectrum, combined with parallel factor analysis and principal component analysis, it was confirmed that exogenous addition of NO affected the humification degree of dissolved organic matter(DOM) and promoted the chelation of organic matter with copper. With the increase of Cu concentration, the Reyranella and Prosthecobacter with certain copper resistance gradually gained advantages. Redundancy analysis(RDA) showed that Emiticicia had a strong correlation with the removal rates of ammonia nitrogen, total phosphorus and copper in swine wastewater, while hgcI_clade had a strong correlation with the removal rates of total nitrogen. In conclusion, controlling the dosage of NO can effectively improve the tolerance and removal effect of Pistia stratiotes on copper in swine wastewater, which is of great significance for promoting the treatment and resource transformation of swine wastewater.

Characteristics of Novel Heterotrophic Nitrification–Aerobic Denitrification Bacteria Bacillus subtilis F4 and Alcaligenes faecalis P4 Isolated from Landfill Leachate Biochemical Treatment System

Heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria are the key functional microorganisms needed to achieve simultaneous nitrification and denitrification (SND). In this study, 25 strains of HN-AD bacteria were successfully isolated from a stable landfill leachate biochemical treatment system, of which 10 strains belonged to Firmicutes and 15 strains belonged to Proteobacteria. Bacillus subtilis F4 and Alcaligenes faecalis P4 displayed good tolerance at a wide range of ammonia nitrogen (NH4+-N) concentrations. When the C/N ratio was 20, the removal rates of ammonia nitrogen were 90.1% and 89.5%, and the chemical oxygen demand (COD) removal rates were 92.4% and 93.9%, respectively. The napA gene encoding periplasmic nitrate reductase (Nap) and the nirS gene encoding nitrite reductase (Nir) were detected, and nitrogen balance showed assimilation and HN-AD was the main nitrogen metabolism mode in both strains. The use of immobilization materials could increase removal rate of ammonia nitrogen by 21.1% and 29.6%, respectively. The research results of this work can provide theoretical basis and technical support for the practical application of HN-AD bacteria to enhance the treatment of high ammonia nitrogen wastewater with high efficiency and low consumption.

Improving the value of planting and breeding waste compost in agricultural applications: A zucchini cultivation case and circular agricultural models analysis

An important way of utilizing agricultural wastes to improve soil quality is the use of planting and breeding waste compost (PBWC). However, the impact of compost on agricultural production systems is unclear. Therefore, in order to study the effect of PBWC on crop growth, soil environment, and circular agriculture, PBWC [sheep manure (SM): tail vegetable (TV): corn straw (CS) = 6: 3: 1] was used based on chemical fertilizer reduction for zucchini production. In zucchini production systems, R9 (chemical fertilizer reduction by 30 % + 9,000 kg ha−1 PBWC) treatment was most effective in improving the quality and yield of zucchini fruits, mainly by improving the soil microenvironment, manifested in (1) increasing soil alkali-hydrolyzable nitrogen (AN) available potassium(AK), and soil organic matter (SOM), reducing EC, and improving C/N. (2) Increasing the richness and metabolic capacity of bacterial community. (3) Increasing the abundance of Proteobacteria, a phylum with absolute dominance (up to 32.46 %). Then, an optimization model of “summer corn − greenhouse zucchini − fattened sheep” was constructed to analyze the effect of changes in fertilizer dosage usage on the whole model. Compared with the local traditional recycling model, the optimized system reduced the ratio of inorganic to organic nitrogen input from 2.8:1 to 1.4:1, increased the recycling rate of nitrogen (N), phosphorus (P), and potassium (K) by 31.28 %, 50.84 %, and 30.25 %, respectively, and the net energy yield ratio (EYR) increased by 1.04. The optimized recycling system had significant economic and environmental benefits, which would become the basis for moving towards more sustainable farming. Overall, the circular agriculture model with PBWC returning as the core achieves sustainable production by improving material recycling and soil microenvironment. Therefore, chemical fertilizer reduction by 30 % combined with 9000 kg ha−1 PBWC can be used in practical production to improve the productivity of the circular agriculture model and achieve high yield and high quality crops.

Litter decomposition in pure and mixed plantations on the Loess Plateau, China: Lack of home-field advantage

Litter decomposition plays a critical role in the nutrient cycling of terrestrial ecosystems. According to the home-field advantage (HFA) hypothesis, litter decomposes more rapidly in its home habitat (where it originates) compared to other habitats (referred to as away). Although this hypothesis has been widely tested in natural forests, it remains controversial and lacks support for plantations, especially in dry ecosystems where microbial activities are limited. To clarify it, the present study investigated litter mass loss, nutrient dynamics, and decomposer communities in a 549-day reciprocal transplant experiment of litter decomposition in Robinia pseudoacacia (RP) and Hippophae rhamnoides (HR) pure plantations and their mixed plantations (5:5 and 8:2 ratios) on the Loess Plateau, China. The rate of mass, carbon (C), nitrogen (N) and phosphorus (P) loss in litter differed depending on litter type of species component and plantation type they were placed in. HR litter lost mass and released C, N, and P fastest, irrespective of plantation type. The overall mass loss of the four litter types were the fastest under 5:5 mixed plantations. However, litter did not decompose more rapidly in its home soil compared to the away soil. The structural equation modeling revealed that initial litter quality played a significant role in regulating the loss of C and N across decomposition stages, while the climate variations and microbial chemistry also contributed to the process. The similarity in soil microbial communities across plantation types, along with the limited interaction between litter and microbes in arid environments, could help elucidate the lack of HFA, with other factors such as the litter type exerting a minor influence. In summary, this study does not substantiate the hypothesis of home-field advantage but supports its context-dependency. Thus, regional heterogeneity should be taken into account when predicting the carbon cycle of forest ecosystems in future studies.

Optimized electrochemical treatment of semi-coking wastewater for enhanced degradation of biological toxicity using a Ru-Ir-Ti anode and Co-Ti cathode

The Co-Ti cathode was prepared to reduce the biological toxicity of semi-coke wastewater by electrochemical system with commercial ruthenium-iridium titanium (Ru-Ir-Ti) anode. Meanwhile, the removal rate of chemical oxygen demand (COD), volatile phenol (VP) and ammonia nitrogen (NH3-N) in wastewater were also evaluated. Hence, the influence of processing time (A), dilution multiple (B), initial pH (C), electrolyte concentration (D) and current density (D) were systematic explored. After treatment, with the optimized experiment condition of processing time (150 min), dilution multiple (300 times), initial pH (3.2), electrolyte concentration (0.15 mol/L), current density (16 mV/cm2), the B/C value of wastewater was greatly improved from 0.12 to 0.31, the removal rate of COD, NH3-N and VP was 96.82 %, 92.34 % and 97.07 %, respectively. The sequence of significance was B>D>E*E>B*D>A*D>D*D. This most effective degradation was owing to the simultaneously oxidization of both cathode and anode, turning the highly biological toxic wastewater to the biodegradable one. The direct oxidation reaction happened on anode, furthermore, the indirect oxidation reaction would be accelerated near the cathode because of active free radicals generation such as ·OH and O2•– when the cobalt’s valence changed from +2 to +3. It deserve to be mentioned in this research is that the direct and indirect oxidation simultaneously contributed to the degradation of biological toxicity, which is great beneficial for the further bio-chemical processing.

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

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

NPK fertilization for the first years of physic nut cultivated in two regions

The physic nut is an oilseed plant that has stood out as an alternative source for biodiesel. However, using it in this way requires determining the edaphoclimatic conditions and adequate fertilization to guarantee maximum productivity. This study objectived to evaluate and establish adequate rates of Nitrogen (N), Phosphorus (P), Potassium (K) to maximize the growth and productivity of physic nut in two edaphoclimatic conditions. Two experiments were performed over two consecutive years, one under Quartzarenic Neosol in the municipality of Diamantina and the other under Red-Yellow Latosol in the municipality of Governador Valadares. The treatments comprised rates of N: 0, 25, 50, 100 kg ha−1; P: 0, 35, 70, 140 kg ha−1; and K: 0, 40, 80, 160 kg ha−1. Plant growth was evaluated every 30 days until flowering. Seed and oil productivity was also assessed, with one harvest in Diamantina and two harvests in Governador Valadares. The edaphoclimatic condition of Governador Valadares was a determining factor in providing greater growth and productivity of the physic nut when compared to that of Diamantina. The application of N rates was unnecessary for the growth and productivity of the physic nut in Diamantina. Thus, phosphate fertilization was unnecessary in Governador Valadares and potassium fertilization was unnecessary for both regions. In Diamantina, 84 kg ha−1 and 87 kg ha−1 of P is recommended for growth and maximum productivity, respectively. Whereas, in Governador Valadares, 49 kg ha−1 and 55 kg ha−1 of N is recommended for growth and maximum crop productivity, respectively.

Microplastics in granular sequencing batch reactors: Effects on pollutant removal dynamics and the microbial community

This study investigated the relationship between microplastic (MP) presence and pollutant removal in granular sludge sequencing batch reactors (GSBRs). Two types of MPs, polyethylene (PE) and polyethylene terephthalate (PET), were introduced in varying concentrations to assess their effects on microbial community dynamics and rates of nitrogen, phosphorus, and organic compound removal. The study revealed type-dependent variations in the deposition of MPs within the biomass, with PET-MPs exhibiting a stronger affinity for accumulation in biomass. A 50 mg/L dose of PET-MP decreased COD removal efficiency by approximately 4 % while increasing P-PO4 removal efficiency by around 7 % compared to the control reactor. The rate of nitrogen compounds removal decreased with higher PET-MP dosages but increased with higher PE-MP dosages. An analysis of microbial activity and gene abundance highlighted the influence of MPs on the expression of the nosZ and ppk1 genes, which code enzymes responsible for nitrogen and phosphorus transformations. The study also explored shifts in microbial community structure, revealing alterations with changes in MP dose and type. This research contributes valuable insights into the complex interactions between MP, microbial communities, and pollutant removal processes in GSBR systems, with implications for the sustainable management of wastewater treatment in the presence of MP.

Oil-Coated Ammonium Sulfate Improves Maize Nutrient Uptake and Regulates Nitrogen Leaching Rates in Sandy Soil

Ammonium sulfate (AS) has been utilized in agriculture; however, there is a dearth of research on its application in maize cultivation subsequent to the implementation of nitrification inhibitors or coating treatments. This study aimed to analyze the impacts of various combinations of AS fertilizers on soil nutrients, plant nutrient uptake, yield, and fertilizer utilization efficiency in maize cultivation to establish an optimal and stabilized disposal method for AS. A completely randomized design was employed with five treatments (AU, the control using urea; AS, treatment using ammonium sulfate; ASN, treatment using ammonium sulfate with a nitrification inhibitor; ASG, treatment using oil-coated ammonium sulfate; and ASD, treatment using oil–humic acid-coated ammonium sulfate). The results show the following: (1) Compared with AU and AS, ASN, ASG, and ASD decreased the leaching rates of total nitrogen (TN), ammonium nitrogen (NH4+-N), and nitrate nitrogen (NO3−-N), and more residual N had accumulated in the soil. The first-order kinetic equation Nt = N0(1 − e−kt) could better fit the process of N accumulation and release, and the N-release rate constant was in the order of AU > CK > AS > ASG > ASN > ASD. (2) Compared with the AU and AS treatments, the plant dry weight, grain dry weight, spike width, spike length, and yields of maize increased by 8.85–11.08%, 12.98–14.15%, 2.95–3.52%, 5.50–5.65%, and 43.21–51.10%, respectively, under the ASG treatment. A path analysis revealed the main decision coefficient of the effective spike number on the maize yield. Furthermore, the accumulation levels of N, P, and K within above-ground plants significantly increased under the ASG treatment compared with those under the AU and AS treatments. N, P, and K partial factor productivity under the ASG treatment increased by 47.12%, 47.15%, and 73.40% on average, while grain N, P, and K balance increased by 50.45%, 47.10%, 55.61% on average, compared with the AU and AS treatments. Therefore, the ASG treatment exhibited the optimal slow-release effect on nutrients and achieved excellent performance in enhancing the production and efficiency of maize.