Reduce Nitrogen Fertilizer Research Articles

Improving the Microenvironmental of Spring Soybean Culture and Increasing the Yield by Optimization of Water and Nitrogen

Optimizing water and nitrogen management is an effective measure to reduce nitrogen fertilizer loss and environmental pollution risks. This study aims to quantify the impacts of different water and nitrogen management strategies on the soil microenvironment and yield of spring soybeans in southern Xinjiang. In this study, two irrigation quotas were established: W1—36 mm (low water) and W2—45 mm (high water). Three nitrogen application gradients were established: low nitrogen (150 kg·hm−2, N1), medium nitrogen (225 kg·hm−2, N2), and high nitrogen (300 k kg·hm−2, N3). The analysis focused on soil physicochemical properties, enzyme activities, microbial community diversity, soybean yield, and soybean quality changes. The results indicate that the activities of nitrate reductase and urease, as well as total nitrogen content, increased with higher irrigation and nitrogen application rates. The W2N3 treatment significantly increased 0.15 to 4.39, 0.18 to 1.04, and 0.31 to 1.73 times. (p < 0.05). Alkaline protease and sucrase activities increased with higher irrigation amounts, while their response to nitrogen application exhibited an initial increase followed by a decrease. The W2N2 treatment significantly increased by 0.10 to 0.34 and 0.07 to 1.46 times (p < 0.05). Irrigation significantly affected the soil bacterial community structure, while the coupling effects of water and nitrogen notably influenced soil bacterial abundance (p < 0.05). Increases in irrigation and nitrogen application enhanced bacterial diversity and species abundance. Partial least squares path analysis indicated that water–nitrogen coupling directly influenced the soil microenvironment and indirectly produced positive effects on soybean yield and quality. An irrigation quota of 4500 m3 hm−2 and a nitrogen application rate of 300 kg·hm−2 can ensure soybean yield while enhancing soil microbial abundance. The findings provide insights into the response mechanisms of soil microbial communities in spring soybeans to water–nitrogen management, clarify the relationship between soil microenvironments and the yield and quality of spring soybeans, and identify optimal irrigation and fertilization strategies for high quality and yield. This research offers a theoretical basis and technical support for soybean cultivation in southern Xinjiang.

Decarbonization of Nitrogen Fertilizers, from Production to Runoff: A Policy Memo

Decarbonization of agriculture is critical to reshaping the U.S. economy as climate-resilient and less carbon-intensive. Decarbonizing nitrogen fertilizers specifically is increasingly important for the U.S. to achieve its climate targets while feeding a growing population in a changing climate, as around 5% of global greenhouse gas emissions result from nitrogen fertilizers alone. Carbon dioxide equivalent emissions from fertilizer come from non-renewable energy use, chemical processes, transportation, and on-farm applications. These emissions typically take the form of carbon dioxide or nitrous oxide, potent greenhouse gasses. To reduce emissions from nitrogen fertilizers, the United States Department of Agriculture (USDA), Environmental Protection Agency (EPA), and Department of Energy (DOE) should 1) create federal regulations for nitrogen fertilizer use, 2) provide financial incentives for farmers transitioning to less-intensive nitrogen fertilizer use, and 3) create a research grant solicitation focused on regional methods for reducing nitrogen fertilizer use and the creation of green hydrogen.

OsSTP1 mediates sucrose allocation to regulate rice responses to different nitrogen supply levels

Improving the nitrogen use efficiency is an effective way to increase the yield of rice, and maintaining carbon-nitrogen balance is essential for the normal growth and development of rice. To investigate the impact of the sucrose transporter protein OsSTP1 on nitrogen absorption in rice, in this study, we constructed transgenic lines overexpressing the sucrose transporter gene OsSTP1 (OsSTP1-OE1, OsSTP1-OE2) and mutant transgenic lines (osstp1-1, osstp1-2) from the wild type TB309. Further, we conducted a hydroponic experiment with four nitrogen supply levels of free nitrogen (FN, 0 mg/L), low nitrogen (LN, 10 mg/L), normal nitrogen (NN, 40 mg/L), and high nitrogen (HN, 80 mg/L) to study the responses of each line to different nitrogen supply levels during the seedling stage. The results showed that compared with the wild type and mutant lines in the LN group, the OsSTP1-overexpressing lines exhibited significantly increased biomass, root length, and plant height, decreased soluble sugar content in the leaves, and increased soluble sugar content in the roots. The results indicate that the soluble sugars produced by leaf photosynthesis are transported to the roots through the phloem to promote root growth and nitrogen uptake, thus increasing the aboveground biomass. This study has identified that OsSTP1 can affect the long-distance transport of carbohydrates from source to sink to promote root growth, ultimately influencing rice's absorption and accumulation of nitrogen, improving nitrogen use efficiency and providing reference for reducing nitrogen fertilizer application.

Inoculation with Azospirillum brasilense as a Strategy to Reduce Nitrogen Fertilization in Cultivating Purple Maize (Zea mays L.) in the Inter-Andean Valleys of Peru.

Purple maize has gained global significance due to its numerous nutraceutical benefits. However, sustaining its production typically requires high doses of nitrogen fertilizers, which, when applied in excess, can contaminate vital resources such as soil and water. Inoculation with nitrogen-fixing microorganisms, such as those from the Azospirillum genus, has emerged as an alternative to partially or fully replace nitrogen fertilizers. This study aimed to evaluate the inoculation effect with A. brasilense and varying nitrogen fertilization levels on the yield and quality of purple maize. The experiment was carried out using a randomized complete block design (RCBD) with a 2 × 5 factorial arrangement and five replications. Treatments comprised two inoculation levels (control without inoculation and inoculation with A. brasilense) under five nitrogen doses (0, 30, 60, 90, and 120 kg∙ha-1, applied as urea). Inoculation with A. brasilense resulted in a 10.5% increase in plant height, a 16.7% increase in root length, a 21.3% increase in aboveground fresh biomass, a 30.1% increase in root fresh biomass, and a 27.7% increase in leaf nitrogen concentration compared to the non-inoculated control. Regarding yield, the inoculated plants surpassed the control in both purple maize yield (kg∙ha-1) and cob weight by 21.8% and 11.6%, respectively. Across all fertilization levels and parameters assessed, the inoculated treatments outperformed the control. Furthermore, for parameters, namely plant height, leaf nitrogen content, and cob dimensions (length, diameter, and weight), the A. brasilense inoculation treatment with 90 kg N∙ha-1 was statistically equivalent or superior to the non-inoculated control with 120 kg N∙ha-1. These results indicate that inoculation with A. brasilense positively impacted purple maize at all nitrogen levels tested and improved nitrogen use efficiency, enabling a reduction of 30 kg N∙ha-1 without compromising performance in key parameters.

The Effect of Reduced Nitrogen Fertilizer Application on japonica Rice Based on Volatile Metabolomics Analysis.

Nitrogen is critical for rice yield and quality, but its overuse can be detrimental to efficiency and the environment. To identify changes in the quality of rice in response to the reduced application of nitrogen fertilizer, we carried out a comprehensive metabolomics study of SuiJing 18 using volatile metabolomics methods. Our results showed that SuiJing 18 had a total of 358 volatile metabolites, mainly lipids (16.25%), terpenoids (15.41%), heterocyclic compounds (15.13%), and hydrocarbons (13.45%). SuiJing 18 underwent significant changes in response to the reduced application of nitrogen fertilizer. Key sweet volatile compounds such as 4-methyl-benzeneacetaldehyde, hexyl acetate, and 2-methylnaphthalene were present at significantly higher levels when nitrogen fertilizer was applied at a rate of 68 kg of pure nitrogen per hectare, and their flavor characteristics also differed significantly from the compounds resulting from the other two treatments. Focusing on 16 differential volatile metabolites, we further investigated their effects on flavor and quality, thus laying the foundation for a greater understanding of the biomarkers associated with changes in rice quality. This study contributes to a better understanding of the mechanisms underlying changes in rice quality after reduced nitrogen fertilizer application.

Rational Nitrogen Reduction Helps Mitigate the Nitrogen Pollution Risk While Ensuring Rice Growth in a Tropical Rice–Crayfish Coculture System

The incorporation of aquaculture feed within a rice–crayfish coculture system significantly enhances nitrogen cycling, thereby diminishing the reliance on chemical fertilizers. However, this benefit is often overlooked in practice, and farmers continue to use large quantities of chemical fertilizers to maximize production, resulting in excessive soil fertility and water nitrogen pollution. Thus, avoiding nitrogen pollution in rice–crayfish coculture systems has become a pressing issue. In this study, we conducted a two-year experiment with two rice cultivars, and a 33.3% reduction in nitrogen fertilizer in a rice–crayfish coculture system (RC), to systematically analyze the overall nitrogen balance, rice nitrogen nutrition, and soil fertility, as compared with a rice monoculture system (RM). Our findings revealed the following: (1) Under the 33.3% reduction in nitrogen fertilizer, the nitrogen surplus in the rice–crayfish coculture system was comparable to that in the rice monoculture, and was controlled at an environmental safety level. (2) Nitrogen utilization efficiency and the accumulation of nitrogen in the rice–crayfish coculture were comparable to those in the rice monoculture. The nitrogen cycle in this system was able to provide the nitrogen required for rice growth after nitrogen fertilizer reduction. (3) The rice–crayfish coculture significantly improved the overall soil fertility and the effectiveness of soil nitrogen nutrition. Furthermore, cutting off the application of nitrogen fertilizer after the mid-tillering stage effectively controlled the total nitrogen content in soil after rice maturity. In conclusion, reducing nitrogen fertilizer in a rice–crayfish coculture system is feasible and beneficial. It ensures rice production, reduces the risk of excessive nitrogen surplus and surface pollution, and promotes a greener, more environmentally friendly paddy field ecosystem.

Fulvic Acid Enhances Nitrogen Fixation and Retention in Paddy Soils through Microbial-Coupled Carbon and Nitrogen Cycling.

Fulvic acid, the most soluble and active humic substance, is widely used as an agent to remediate contaminated soils and improve soil fertility. However, the influence of fulvic acid (FA), as a microbial carbon source, on carbon and nitrogen cycles in paddy soils remains elusive. Therefore, to investigate it, an incubation experiment was conducted. Gas analyses indicated that the carbon dioxide and methane emissions were enhanced in FA treatment, which increased up to 94.08-fold and 5.06-fold, respectively. 15N-labeling experiments revealed that nitrogen fixation capability was promoted (1.2-fold) to reduce the carbon and nitrogen imbalance due to fulvic acid amendment. Metagenomic analysis further revealed that gene abundances of degradation of lignin-like compounds, gallate degradation, methanogenesis, nitrogen fixation, and urea hydrolysis increased, while the bacterial ammonia oxidation and anaerobic ammonium oxidation decreased, caused by FA application. Metabolic reconstruction of metagenome-assembled genomes revealed that Azospirillaceae, Methanosarcinaceae, and Bathyarchaeota, with higher abundance in FA treatment, were the key microorganisms to maintain the carbon and nitrogen balance. The metabolic pathways of fulvic acid degradation and coupled nitrogen fixation and retention were constructed. Collectively, our results provided novel insights into the theoretical basis of the use of humic substances for reducing nitrogen fertilization and climate change.

Growth-Promoting Bacteria, Silicon Supply and Nitrogen Fertilization in Zoysia Grass Production Area

ABSTRACT One of the alternatives for reducing nitrogen fertilization is the use of plant growth-promoting bacteria (PGPB), such as Pseudomonas fluorescens and Azospirillum brasilense, which can provide a sustainable form of production, with increased profitability for rural producers, because bacteria are a low-cost technology compared to fertilizer. In view of the above, the objective of this study was to evaluate the effect of inoculation with plant growth-promoting bacteria (P. fluorescens and A. brasilense) combined with the supply or not of Si and doses of nitrogen (N) in zoysia grass sod production area. The experimental design was in randomized blocks with 12 treatments arranged in a 3 × 2 × 2 factorial scheme, with four replications, in plots of 9 m2. The treatments were: two inoculations with PGPB (A. brasilense and P. fluorescens) and non-inoculated, combined with two doses of N, with or without supply of Si through fertilization (through the commercial fertilizer known as Potasil). There was an increase in the shoot dry matter with the supply of Si, the standard dose of N and the inoculation with PGPB. The standard dose of N promoted an increase in the content of nitrogen (N), phosphorus (P) and potassium (K) in the shoot of Zoysia japonica. There was an effect of inoculation with plant growth-promoting bacteria combined with the supply of silicon and N rates in the zoysia grass production area, where the use of Pseudomonas combined with the application of Si with 75% of the N dose is recommended.

Quantifying the impact of an abrupt reduction in mineral nitrogen fertilization on crop yield in the European Union

Contemporary crop production in Europe relies on nitrogen (N) fertilization. Fertilizer prices soared in 2021–2022, and remained at historical high levels in 2023. These high prices invoked an immediate concern on the possible consequences for Europe's food production.In this study, we use a biogeochemical model framework to estimate the impact of reducing mineral N fertilization on crop yields in the European Union (EU). First, crop yields simulated with the biogeochemical DayCent model are evaluated against subnational yield data averaged for 2015–2018 reported by Eurostat and National Statistical Institutes in the EU for soft wheat, barley, grain maize and rapeseed. Then, we simulate three different scenarios where mineral N fertilization across the EU is abruptly reduced by respectively 5, 15 and 25 %, and compare yields to the projected baseline for contemporary conditions (2019–2022).The model evaluation gives r2 values ranging from 0.28 (rapeseed) to 0.61 (soft wheat) and root mean square errors (RMSE) ranging from 0.6 (rapeseed) to 1.95 t ha−1 (maize). The model shows a reduction in yield per crop at the EU level up to 2.1, 6.4 and 11.2 % with the 5, 15 and 25 % reduction scenario, respectively. Different crops show different percentage reduction in yield following a reduction in mineral N fertilization, showing a legacy effect over the years and depending on the availability of organic fertilizer. The strongest relative yield reduction occurs for soft wheat for all three scenarios. Even with 25 % drop in mineral N fertilization, maize yield in the Netherlands, Belgium and Denmark is not significantly reduced, because of the high N surplus and large share of organic fertilization in these countries.This process-based modelling study provides spatially explicit, high resolution information on the response of crop yields to N fertilizer input reductions, helping policy-makers in decision-making on food security and environmentally-friendly food systems.

Effect of sward species diversity combined with a reduction in nitrogen fertilizer on the performances of spring-calving grazing dairy cows

The objective of this study was to evaluate the impact of sward diversification combined with a reduction of chemical nitrogen (N) fertilizer on the performance of spring calving grazing dairy cows within a farm systems experiment. Three farmlets were created; a monoculture of perennial ryegrass (Lolium perenne L.; PRG) fertilized with 250 kg N/ha (PRG-250N), a PRG - white clover (Trifolium repens; WC) sward fertilized with 125 kg N/ha (PRGWC-125N) and a multispecies sward (MSS) comprising of grasses, legumes and herbs also fertilized with 125 kg N/ha (MSS-125N). Each farmlet had its own herd of dairy cows on a total area of 18.7 ha divided into 20 paddocks. Each herd was comprised of pure Holstein-Friesian (HF) and HF Jersey crossbred (JFX) animals and randomly assigned through the 3 treatments. For 3 years (2021 to 2023), the performances of both swards (grass yield, botanical composition, nutritive value) and grazing animals (milk production and composition, body weight (BW) and body condition score (BCS)) were recorded. There were no significant differences in pasture production or sward nutritive value between sward systems and grazing season length was also similar (264 d). On average over the 3 years, PRGWC-125N contained 150 g/kg DM of legumes and the MSS-125N contained 160 g/kg DM legumes, 130 g/kg DM plantain and 40 g/kg DM chicory. Both individual cow milk and fat plus protein (Milk solids; MS) yield were lower for PRG-250N (5,018 and 452 kg, respectively), intermediate for PRGWC-125N (5,139 and 463 kg, respectively) and highest for MSS-125N (5,297 and 476 kg, respectively) while milk and MS production per hectare from grazing were similar during the study period (11,523 and 1,016 kg/ha, respectively). Breed also had a significant effect with the JFX having lower milk yield but higher fat and protein concentration compared with HF. This resulted in higher MS production per kg of BW for the JFX compared with HF (0.96 and 0.87 kg MS/kg BW, respectively). The results of this study highlight the possibility for more diverse pastures to reduce chemical N fertilizer input requirements and maintain pasture productivity while increasing animal performance within pasture-based spring calving systems.

Reducing nitrogen fertilizer usage coupled with organic substitution improves soil quality and boosts tea yield and quality in tea plantations.

The utilization of chemical fertilizers is a key measure for maintaining tea yield and quality, but excessive use has negative environmental impacts. The substitution of chemical fertilizer with organic fertilizer has been promoted to sustain crop yield and soil quality. However, knowledge gaps regarding the effects of organic substitution on soil quality and tea yield in tea plantations still exist. A field experiment was conducted to investigate the influence of organic substitution treatments (i.e. 25% partial substitution: biogas slurry + green manure + formula fertilizer, BFG; sheep manure + formula fertilizer, OFF; 100% complete substitution: sheep manure + green manure, OG) on the soil quality, tea yield and quality, and nitrogen utilization efficiency in southwestern China. Results showed that all organic substitution treatments slightly increased soil pH, and significantly increased soil organic matter by 13.22-14.88% compared to conventional fertilization (CF). The BFG treatment was the most effective in enhancing the soil quality index, showing increases of 16.80%, 8.37% and 24.87% higher than the CF, OFF and OG treatments, respectively. Tea yield significantly increased under the BFG, OFF and OG treatments by 11.97%, 13.58% and 5.90% compared to CF, respectively. The BFG treatment increased the amino acid content by 7.78% and decreased the tea polyphenol/amino acid ratio by 6.87%. Additionally, the BFG, OFF and OG treatments greatly increased the nitrogen utilization efficiency of young sprouts by 70.71%, 82.54% and 34.28%, respectively. Overall, partial organic substitution could effectively improve soil quality while maintaining tea yield. © 2024 Society of Chemical Industry.

Optimum management strategy for improving maize water productivity and partial factor productivity for nitrogen in China: A meta-analysis

China’s agricultural production suffers significant constraints due to low water productivity (WP) and partial factor productivity for nitrogen (PFPN). The pivotal solution to enhance maize yield, WP, and PFPN is through optimizing field management practices. However, previous studies primarily focused on the effects of individual or coupled field management practices on maize yield, WP, or PFPN in an area or land mass, so it is necessary to conduct a comprehensive quantitative analysis of various field management practices on maize yield, WP, and PFPN at the national scale. In this study, we compiled 286 studies encompassing 6959 pairs of experimental data spanning from 1990 to 2023. Meta-analysis was conducted to observe the variations in maize yield, WP, and PFPN across diverse field management practices (straw returning, nitrogen fertilizer application, irrigation practice, and tillage practice) on a national scale. The results showed that nitrogen fertilizer application (215 kg N ha−1) was the most effective in enhancing maize yield and WP by 68.1 % and 54.8 %, respectively. Additionally, irrigation had the most substantial impact on PFPN, enhancing 16.8 %. Straw mulching, application of slow and controlled release fertilizers, drip irrigation, and subsoiling were identified as the most effective practices in increasing maize yield, WP, and PFPN by Random forest model. Maize straw returning could reduce nitrogen fertilizer application by 20 kg ha−1, while increasing WP and PFPN by 4.2 % and 11.6 %, respectively. Moreover, straw returning could reduce water consumption by 23–60 mm, while increasing WP and PFPN by 2.9 % and 6.8 %, respectively. These findings can provide a reference for the formulation of comprehensive management strategies for sustainable maize production in China and globally.

Precision Nutrient Management Amid Climate Change Challenges: A Review

Increasing food demand and climate change present significant challenges to sustainable food production systems and environmental health. Nitrogen, crucial for plant metabolism and growth, also poses risks such as water pollution through nitrate leaching and the emission of nitrous oxide (N<sub>2</sub>O), a potent greenhouse gas contributing to global warming. Despite ongoing efforts to reduce nitrogen fertilizer application, inefficient use persists. Precision agriculture emphasizes optimizing nitrogen application to mitigate climate change and enhance productivity, sustainability, profitability, and climate resilience. While soil testing has historically improved grain production, focusing on crop nutrient demands rather than soil nutrient levels is gaining traction. This approach synchronizes nutrient supply with plant needs more effectively, ensuring nutrients are applied when and where they are most beneficial. Implementing precision nutrient management enhances efficiency, maintains or increases yields, and minimizes nutrient runoff, safeguarding water supplies. This strategy adheres to the principles of the "4 Rs" – Right rate, Right source, Right application method, and Right timing – to deliver nutrients effectively. Advances in technologies like optical sensors and leaf color charts enable real-time nitrogen application adjustments during the growing season, supporting cost-effective and farmer-friendly practices. While developed countries lead in adopting precision nutrient management for nitrogen and other nutrients, developing nations are increasingly exploring similar strategies. Effective policies and programs are essential to address nitrogen fertilizer use and mitigate its impact on climate change in agriculture.

基于实时光谱信息的小麦变量施肥效率分析与评价

Studying the effect of variable fertilization during the jointing stage on winter wheat production in the rice-wheat rotation area is critical for evaluating the application effect and economic benefits of variable fertilization technology. The variable fertilization experiment of wheat was carried out in Jiangsu province by using the self-developed fertilizer applicator. Three fertilization methods were used to conduct a comparative analysis of the fertilization amount, population structure, and yield of winter wheat during the jointing stage. On this basis, the economic feasibility of variable fertilization during the jointing stage was evaluated. The experimental results showed that the control accuracy of variable-rate fertilization with fertilization equipment was greater than 95%. After variable fertilization, the coefficient of variation of NDVI values in the winter wheat canopy spectral data remained between 0.076 and 0.125, and the Christensen uniformity coefficient remained between 0.901 and 0.940. Compared with the traditional empirical balance method for quantitative fertilization of plots, the real-time variable fertilization plot used 13.6 kg/hm2 less fertilizer during the jointing stage. The findings validate that implementing variable fertilization can help reduce nitrogen fertilizer input, improve nitrogen fertilizer utilization efficiency, reduce environmental pollution, and enhance the sustainability of agricultural production.

Reducing nitrogen fertilizer applications mitigates N2O emissions and maintains sugarcane yields in South China

Fertilizer N application combined with crop residue retention and a warm and humid climate increases nitrous oxide (N2O) emissions from sugarcane systems. However, the effects of high fertilizer N application rates on N2O emissions from sugarcane fields in China and the N2O reduction potential are still unclear. This study measured N2O emissions, the δ15N values for N2O and soil mineral N (NH4+ and NO3–), and yields during three continuous growing seasons in a sugarcane field in subtropical South China when four fertilizer N application rates: 0 (N0), 300 (N300), 400 (N400), and the local conventional rate of 500 kg N ha–1 (N500), were applied. The results showed that N2O emissions peaked in the first 4 weeks after fertilizer N application and the peak amplitude was highest after applying the N500 rate. The greatest soil N2O fluxes occurred when soil NH4+ and NO3– contents were high, the soil pore spaces contained large amounts of water (around 60 %), and there was a high soil surface temperature (around 35°C). The cumulative N2O emissions over the whole season (1.3–64.8 kg N ha–1) and emission factor values (2.6–11.1 %) both strongly increased with fertilizer N rate. The δ15N values for N2O and soil NH4+ and NO3– indicated that N2O production after N fertilization was dominated by denitrification and the microbial types varied with time and N fertilization rate. The principal component analysis showed that the factors associated with denitrification and nitrification explained 53.53 % and 30.53 % of the variation in N2O fluxes, respectively. Sugarcane yields, N uptake, and sugar contents were not affected by the reduced fertilizer N rates (N400 and N300) compared to that of N500. A reasonable N fertilizer rate of around 340 kg N ha–1 could reduce N2O emissions by more than 65 % compared to the conventional N500 rates while maintaining sugarcane yields. This study quantified the N2O emissions induced by different fertilizer N rates in a sugarcane system in China and highlighted the considerable potential for reducing N2O emissions through optimization of the fertilizer N application rate.

Impact of Agricultural Activities on Climate Change: A Review of Greenhouse Gas Emission Patterns in Field Crop Systems.

This review paper synthesizes the current understanding of greenhouse gas (GHG) emissions from field cropping systems. It examines the key factors influencing GHG emissions, including crop type, management practices, and soil conditions. The review highlights the variability in GHG emissions across different cropping systems. Conventional tillage systems generally emit higher levels of carbon dioxide (CO2) and nitrous oxide (N2O) than no-till or reduced tillage systems. Crop rotation, cover cropping, and residue management can significantly reduce GHG emissions by improving soil carbon sequestration and reducing nitrogen fertilizer requirements. The paper also discusses the challenges and opportunities for mitigating GHG emissions in field cropping systems. Precision agriculture techniques, such as variable rate application of fertilizers and water, can optimize crop production while minimizing environmental impacts. Agroforestry systems, which integrate trees and crops, offer the potential for carbon sequestration and reducing N2O emissions. This review provides insights into the latest research on GHG emissions from field cropping systems and identifies areas for further study. It emphasizes the importance of adopting sustainable management practices to reduce GHG emissions and enhance the environmental sustainability of agricultural systems.

Regional quality analysis of the hydrological environment with an improved random forest model based on the chimpanzee algorithm.

High-precision evaluations of water environment quality are highly important for improving the accuracy of early warning systems of regional water pollution risk and improving the regional water environment. This paper employs the chimp optimization algorithm (ChOA) to enhance the traditional random forest model, resulting in the chimp optimization algorithm-random forest (ChOA-RF) water quality assessment model for evaluating the Jiansanjiang area in Heilongjiang Province, China. The results show that the overall water environment in Jiansanjiang has the following characteristics: "The water quality of farms in the northwest is poor, and the quality of groundwater is better than that of surface water." Total nitrogen (TN) and total phosphorus (TP) in surface water and ammonium nitrogen (NH3-N), ferrum (Fe), and manganese (Mn) in groundwater are the main pollutants. The TP and TN in surface water and the NH3-N in groundwater exceeded the relevant standards, likely due to the excessive application of chemical fertilizers, especially nitrogen fertilizers. Additionally, Fe and Mn are harmful native substances. According to these findings, targeted improvement strategies, such as reducing nitrogen fertilizer application, plugging well, and increasing the surface water utilization rate, are proposed. Moreover, the ChOA-RF model is compared with the traditional empirical value model and the particle swarm optimization-random forest (PSO-RF) model. The results show that the ChOA-RF model can effectively reduce the root mean square error and mean absolute percentage error and improve the coefficient of determination. The running time and convergence ability are also better than those of the PSO-RF model, which is a more accurate and efficient machine learning model. The model can be used not only for high-precision evaluation of regional water environment quality but also for other machine learning fields.

Green manure combined with reduced nitrogen reduce NH3 emissions, improves yield and nitrogen use efficiencies of rice

Background Green manure is an important source of organic fertilizer. Exploring green fertilizer and nitrogen fertilizer reduction is important for agricultural production. However, few studies have been conducted, especially on the effects of different green fertilizers along with reduced nitrogen fertilizer application on soil ammonia volatilization emissions, rice yield, and nitrogen fertilizer uptake and utilization. Methods In this study, the effects of different types of green manure and reduced nitrogen fertilizer application on soil ammonia volatilization emissions, aboveground population characteristics of rice, and nitrogen fertilizer uptake and utilization were explored. This study was based on a field-positioning experiment conducted between 2020 and 2022. Six treatments were established: no nitrogen fertilizer application (CK), conventional fertilization in wheat-rice (WR), villous villosa-rice (VvR), vetch sativa-rice (VsR), rapeseed seed-rice (RR), and milk vetch-rice (GR), with a 20% reduction in nitrogen fertilizer application. The amounts of phosphorus and potassium fertilizers remained unchanged. The characteristics of ammonia volatilization loss in rice fields, agronomic traits of rice, yield traits, and nitrogen uptake and utilization were investigated. Results The results indicated a significant difference (P < 0.05) in the impact of different treatments on ammonia volatilization emissions from rice in the two-year experiment. Compared with WR treatment, VvR, VsR, RR, and GR treatments reduced the total ammonia volatilization loss by 23.58 to 39.21 kg ha−1, respectively. Compared with the conventional WR treatment, other treatments increased rice yield by 0.09 to 0.83 t ha−1. GR treatment was significantly higher than other green fertilizer treatments, except for VsR (P < 0.05). It increased the nitrogen uptake of rice by an average of 4.24%–22.24% and 13.08%–33.21% over the two years, respectively. The impact of different types of green manure on the nitrogen uptake and utilization of rice varied greatly, indicating that the combination of green manure and fertilizer is a sustainable fertilization model for crops to achieve high yields. In particular, the Chinese milk vetch as green manure was more beneficial for ammonia volatilization reduction in paddy field and stable grain production of rice.

The impact of bacillus sp. NTLG2-20 and reduced nitrogen fertilization on soil properties and peanut yield

The excessive use of nitrogen (N) fertilizers has led to farmland degradation and reduced crop yields. To address this drawback, reducing the amount of nitrogen fertilizer and Bacillus sp. NTLG2-20 inoculant are the optimal cultivation method. The impact of different N rates (0, 20, and 40 kg ha-1) combined with the Bacillus sp. NTLG2-20 inoculant on soil chemical properties, growth, development, and peanut yield was designed in the field in Phuoc Hung commune, An Phu district from May to August 2023. The field experiment was designed with 6 treatments and 4 replications. The research results showed that different N rates adequately augmented soil chemical traits such as pH, cation exchange capacity (CEC), soil organic matter (SOM), total N, available phosphorous (AP), and exchangeable potassium (EK). Furthermore, different N fertilizers rates combined with Bacillus sp. NTLG2-20 inoculant adequately augmented plant height, number of leaves, total chlorophyll, nodulous number and weight per groundnut plant. Reducing N fertilizer application by 50% (20 kg N ha-1) was the optimal N reduction rate when combined with the Bacillus sp. NTLG2-20, which resulted in 17.6% higher peanut yield compared to no N application and no difference compared to 100% of recommended N application (P<0.01)). Bacillus sp. NTLG2-20 inoculant increased peanut yield by 19.6% when compared to no Bacillus sp. NTLG2-20 inoculant (P<0.01). Nitrogen – fixing ability of Bacillus sp. NTLG2-20 promoted peanut yield and reduced fifty percentage of the N fertilizer application. Bacillus sp. NTLG2-20 is the promising species for the production of biological fertilizer in the future.

Reducing Application of Nitrogen Fertilizer Increases Soil Bacterial Diversity and Drives Co-Occurrence Networks.

Reducing nitrogen fertilizer application highlights its role in optimizing soil bacterial communities to achieve sustainable agriculture. However, the specific mechanisms of bacterial community change under these conditions are not yet clear. In this study, we employed long-term field experiments and high-throughput sequencing to analyze how varying levels of nitrogen application influence the soil bacterial community structure and co-occurrence networks. The results show that reducing the nitrogen inputs significantly enhances the diversity and evenness of the soil bacterial communities, possibly due to the diminished dominance of nitrogen-sensitive taxa, which in turn liberates the ecological niches for less competitive species. Furthermore, changes in the complexity and stability of the bacterial co-occurrence networks suggest increased community resilience and a shift toward more mutualistic interactions. These findings underline the potential of reduced nitrogen application to alleviate competitive pressures among bacterial species, thereby promoting a more diverse and stable microbial ecosystem, highlighting the role of competitive release in fostering microbial diversity. This research contributes to our understanding of how nitrogen management can influence soil health and offers insights into sustainable agricultural practices.