Nitrogen Management Strategies Research Articles

Effects of Grain Sprout Fertilizer Application Rate on Yield and Its Composition of Hybrid Middle Rice–Ratoon Rice System

Enhancing yield and achieving environmental goals represent challenges for the future of agriculture. Rational nitrogen (N) management is one of the most promising ways to meet this challenge. However, complicated nitrogen management strategies and considerable input requirements still exist in rice–ratoon rice production. To address this issue, field experiments were conducted with two main high-yield rice crop genotypes and five fertilization treatments at six sites in Southwest China from 2018 to 2020. The results showed the following: (1) the yield of the main rice crop was extremely significantly affected by the year, location, and fertilization, but not by genotype; (2) the yield of the ratoon rice was extremely significantly affected by year, genotype, location, and fertilization; and (3) the total plant N content (TPN) and leaf SPAD value at the full heading stage of the main crop were significantly positively correlated with the total soil N content (TSN) and soil available N (SAN) content of the basic soil. The highly efficient N application rate of grain- and bud-promoting fertilizer for ratoon rice was 60–120 kg ha−1. The TSN, SAN, TPN, and SPAD values higher than 0.247 kg N kg−1, 298 mg N kg−1, 2.159 kg N kg−1, and 49.94 were, respectively, considered the reference values when not applying grain- and bud-promoting fertilizer. A regression equation was established to predict the amount of high-efficiency grain- and bud-promoting fertilizer based on the TSN and SPAD. Overall, the yield of rice–ratoon rice was significantly affected by year, genotype, location, fertilization, and their interactions. The use of the predicted grain- and bud-promoting fertilizer regression equation can achieve high yields under simplified and reduced N input practices in the rice–ratoon rice systems.

Oilseed Radish: Nitrogen and Sulfur Management Strategies for Seed Yield and Quality—A Case Study in Poland

Oilseed Radish: Nitrogen and Sulfur Management Strategies for Seed Yield and Quality—A Case Study in Poland

Field and simulation studies on yield, water and nitrogen dynamics and use efficiency in rice-wheat crops in sequence

ContextThe dominant rice-wheat cropping system in the Indo-Gangetic plain faces challenges of water depletion and nitrogen pollution of groundwater as well as declining productivity caused by over irrigation and nitrogen fertilization by the farmers. To appreciate the apt use of irrigation water and nitrogen fertilizer in rice and wheat crops it is essential to explore the water and nitrogen balances as well as dynamics in these crops, involving complex interaction between weather, soil, irrigation water and nitrogen fertilizer management. ObjectiveThe objective of the study is to quantify yield, field water balance components, water use efficiency, water productivity, water footprint, and water and nitrogen dynamics of rice and wheat crops in relation to season, varieties, irrigation regimes and nitrogen levels. MethodsField experimentations were conducted in double split plot design along with calibrated and validated HYDRUS 1D model use for two years comprising of treatments in rice i.e. two varieties (PR122-V1 and PR126-V2), two irrigation regimes (2-days drainage period-I1 and soil water suction 16 kPa-I2) and two nitrogen levels (120-N1 and 90-N2 kg N ha−1); and in wheat, two varieties (Unnat PBW343-V1 and Unnat PBW550-V2), two irrigation (1.2 IW/CPE-I1 and 0.9 IW/CPE-I2) regimes and two nitrogen levels (120-N1 and 90-N2 kg N ha−1). ResultsThe highest grain yield recorded was 7.6 t ha−1 in treatment combination of V1I2N1 in rice and 5.4 t ha−1 in V1I1N1 in wheat owing to better plant growth and yield attributes (biomass production, number of effective tillers, panicle length, and 1000 grain weight). Total water footprints were lower in the treatment combination of V1I1N1 in rice and V1I2N1 in wheat. The water budget revealed a higher percent contribution of the total water input to drainage (62 %) in rice ensuing restoration of water in the soil profile; and to evapotranspiration (ET) (100 %) in wheat ensuing water depletion. Modeling water and nitrogen dynamics showed higher root water uptake in I2 treatment in rice and with I1 treatment in wheat; and leaching losses of NO3-N under rice than wheat; and under I2 treatment than I1 as well as in N1 than N2. ConclusionsThe V1I2N1 treatment in rice and V1I1N1 treatment in wheat demonstrated superior grain yield, soil water storage, and root water uptake. Conversely, V1I1N1 treatment in rice and V1I2N1 treatment in wheat showed higher water use efficiency and lower water footprint. SignificanceIt helps to evaluate the effectiveness of irrigation and nitrogen management strategies in maximizing crop productivity while minimizing environmental impacts.

Severe nitrogen leaching and marked decline of nitrogen cycle-related genes during the cultivation of apple orchard on barren mountain

Limited available lands have led to the widespread practice of establishing orchards on barren mountains to expand apple cultivation in China. However, improper nitrogen (N) management strategies in intensive orchards escalate costs and also contribute to environmental contamination. A long-term field experiment was conducted in a representative apple-producing area in Shandong Province, China, to assess the environmental risks associated with newly established orchards. This research utilized lysimeters and soil metagenomic sequencing to investigate N leaching loss and the functional microbial profiles associated with the N cycle during apple cultivation on barren mountains. Five treatments were implemented: no inorganic N fertilizer, traditional farmer's fertilization, drip irrigation with a water-soluble fertilizer, resin-coated urea, and grass interplanting. Among treatments involving inorganic N, the total N leaching rate ranged from 16.5% to 30.7% of the total N fertilizer input. Notably, in treatments with equivalent N fertilizer applications, the water-soluble fertilizer treatment exhibited the highest N leaching loss rate -(20.2–29.0%), while the grass interplanting and resin-coated urea treatments showed significantly lower rates of N leaching loss (17.0–24.9% and 15.2–24.5%, respectively). The abundance of N cycle-related genes experienced a marked decline (17.1–18.8%) during the cultivation of orchards on barren mountains. The water-soluble fertilizer treatment displayed the highest potential for nitrification, contributing to elevated N leaching. Both resin-coated urea and traditional farmer's fertilization treatments exhibited the highest abundance of genes associated with N2O emission risk to the atmosphere. However, the grass interplanting treatment, while effectively reducing N leaching, also triggered the most pronounced soil acidification. Spearman correlation analysis revealed that the decline in pH, coupled with an increase in soil NO3--N concentration and electrical conductivity (EC), were the primary factors contributing to the reduction in the abundance of key N cycle functions. In summary, excessive use of inorganic N fertilizer in orchard environments led to increased N leaching, altered soil physicochemical properties, and significant impacts on N cycle-related genes. The elevated ionic strength in soils might be responsible for both the high N leaching loss and the decrease in N cycle function abundance. In intensive orchard cultivation, each N fertilization strategy mentioned above comes with its environmental drawbacks. Further investigation is warranted to achieve a balance between productivity and environmental protection.

Effect of Nitrogen Management Strategies on Yield, Quality and Nitrogen Uptake by Wheat (Triticum aestivum L.)

There is little knowledge among farmers on the rate of nitrogen-fertilizer application. Therefore, there is a need to determine optimal rate of nitrogen-fertilizer application on growth and yield of wheat. Accordingly, an field experiment was conducted during the winter (Rabi) season at Crop Research Centre the Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut, Uttar Pradesh, to study the impact of different nitrogen level and splitting modules on quality, yield and nitrogen uptake by wheat (Triticum aestivum L.) crop. The main object of investigation was to find out the optimum dose and splitting of nitrogen for wheat in irrigated system under integrated nitrogen management approach. The experiment consisting of four nitrogen levels viz. control i.e. 0 kg N ha-1 , 90 kg N ha-1, i.e 120 kg N ha-1 and 150 kg N ha-1 as main plots and four splitting modules M1- 50% N as basal through VC, + 25% at CRI + 25% booting stage through urea, M2-50 % N as basal through FYM + 25% at tillering + 25% at booting stage through urea, M3 -50% N as basal through VC+FYM (1:1), + 25% at tillering + 20% at booting stage and 5 % N as foliar spray at pre flowering stage through urea, M4 -50% N as basal through VC+FYM (1:1), rest based on SPAD reading through urea as sub-plots. The experimental results revealed that the plot which fertilized with 150 kg N ha-1 gave higher yield-attributing characters and yield (grain, straw and biological yield). The application of 150 kg N ha-1 resulted in 0.44, 15.25 and 80.8 per cent during 2016-17 and 0.41, 13.05 and 79.2 per cent during 2017-18 produced the higher grain yield over 120, 90 and 0 kg N ha-1. The content and uptake of nitrogen by grain, straw and total uptake as well as protein content and protein yield were obtained with 150 Kg N ha-1 but differences between 120 and 150 kg N ha-1 were non-significant, during both the year 2016-17 and 2017-18. Among different splitting modules M3 resulted significantly higher entire yield attributes, yield (grain and straw yield), nitrogen content and uptake by grain, straw and total uptake as well as content and yield of protein. The M3 module produced higher grain yield by 7.9, 14.7 and 24.8 per cent during 2016-17 and 8.1, 14.89 and 25.2 per cent during 2017-18 over M4, M1 and M2 splitting modules, respectively.

Enhancing Maize Yield Simulations in Regional China Using Machine Learning and Multi-Data Resources

Improved agricultural production systems, together with increased grain yield, are essential to feed the growing global population in the 21st century. Global gridded crop models (GGCMs) have been extensively used to assess crop production and yield simulation on a large geographical scale. However, GGCMs are less effective when they are used on a finer scale, significantly limiting the precision in capturing the yearly maize yield. To address this issue, we propose a relatively more advanced approach that downsizes GGCMs by combining machine learning and crop modeling to enhance the accuracy of maize yield simulations on a regional scale. In this study, we combined the random forest algorithm with multiple data sources, trained the algorithm on low-resolution maize yield simulations from GGCMs, and applied it to a finer spatial resolution on a regional scale in China. We evaluated the performance of the eight GGCMs by utilizing a total of 1046 county-level maize yield data available over a 30-year period (1980–2010). Our findings reveal that the downscaled models created for maize yield simulations exhibited a remarkable level of accuracy (R2 ≥ 0.9, MAE < 0.5 t/ha, RMSE < 0.75 t/ha). The original GGCMs performed poorly in simulating county-level maize yields in China, and the improved GGCMs in our study captured an additional 17% variability in the county-level maize yields in China. Additionally, by optimizing nitrogen management strategies, we identified an average maize yield gap at the county level in China ranging from 0.47 to 1.82 t/ha, with the south maize region exhibiting the highest yield gap. Our study demonstrates the high effectiveness of machine learning methods for the spatial downscaling of crop models, significantly improving GGCMs’ performance in county-level maize yield simulations.

Bactérias diazotróficas aumentam produtividade e rentabilidade no cultivo orgânico do feijão comum

ABSTRACT The symbiosis of common beans with nitrogen-fixing bacteria provides an efficient approach to sustainable and economical food production. Therefore, this study aimed to evaluate the application of cost-effective nitrogen management strategies in organic common bean cultivation, including the application of poultry manure and organic liquid fertilizer, seed and co-inoculation with diazotrophic bacteria (Azospirillum brasilense and/or Rhizobium tropici), and supplementary Rhizobium tropici inoculation. The study spanned three years in a well-established organic cultivation field (2018) and an initial organic cultivation area (2019 and 2020) in Brazil. It was arranged in a randomized blocks design in a 2 × 5 (2018) and 2 × 6 (2019 and 2020) factorial scheme, with four replicates. The most profitable strategy involves seed inoculation with Azospirillum brasilense and additional inoculation with Rhizobium tropici at stage V4-5 (fifth trifoliate leaf fully expanded), while the most costly strategy was the application of poultry manure at the V3 stage (first trifoliate leaf fully expanded). Thus, the use of diazotrophic bacteria for seed inoculation and co-inoculation (Azospirillum brasilense and/or Rhizobium tropici) ensured financial returns and system profitability in common bean cultivation.

Optimized nitrogen fertilizer application strategy improves grain yield and quality of high-quality late indica rice under field ambient warming

Post-heading high temperatures occurred frequently in late indica rice regions in southern China recently, but the effects of high post-heading temperature on rice yield and quality under nitrogen application including nitrogen management (NM) and panicle fertilizer (NPF) were still unclear. Therefore, the grain yield and quality of late indica rice cultivars were compared in 2020 (ambient temperature) to 2019 (warming 2.3 °C) and 2021 (warming 3.5 °C). The results showed that moderate NPF can increase the yield, protein content (PC) and brown rice rate, and reduce the chalkiness and amylose content (AC) under naturally high temperatures. The proportion and application of NPF values higher than 22.5%, 36 kg·ha−1 effectively improved grain yield, processing and appearance qualities, and PC, while reducing AC of late indica rice under natural warming. The temperature parameters, AC and PC during the total growth period could explain 81.7%, 90.7% and 89.6% of the variation in rice processing qualities, appearance qualities and gel consistency, respectively. The finding demonstrated that the optimum Tmean of improving rice yield and quality was 29.0 °C before heading and 21.1 °C after heading under NM, and 28.6 °C before heading, and 22.9 °C after heading under NPF. This study suggested that optimizing nitrogen management strategies under future climate warming conditions can synergistically increase indica rice yield and quality.

Interannual variability of atmospheric ammonia over the Sichuan Basin, southwestern China: Trend, sources, and implications on particle matter control

Atmospheric ammonia (NH3) is an important constituent of biogeochemical cycle and excessive NH3 in the environment results in detrimental effects on ecosystems, air quality, and human health. However, interannual variability and emission changes of NH3 remain highly uncertain, particularly for NH3 hotspot areas. Here, we identify the emission hotspots of NH3 and reveal the trend of NH3 emissions over the Sichuan Basin (SCB) based on a high-resolution map from infrared Atmospheric Sounding Interferometer (IASI) satellite observations in combination with the MEIC inventory from 2008 to 2019. IASI observations indicate that NH3 columns persistent increase over time while MEIC inventory suggests that the past increase in NH3 emissions has indeed ended in 2017 and exhibit decreasing trend afterwards. The NH3 hotspots derived from IASI mainly concentrate in the Chengdu Plain and southern SCB city cluster, which mostly agrees with MEIC emission inventory. CMAQ model simulations well reproduce PM2.5 and ammonia loading and capture observed patterns of NH3. We find that ammonium makes up 15–35% of inorganic fine PM2.5 mass in winter over the SCB. Regulation efforts focused on joint reducing 30% of NOx, SO2, and NH3 emissions could lead to basin-wide wintertime PM2.5 reduce by 10.0 μg/m3, while cutting 30% emissions of NH3 or NOx alone only yield PM2.5 reduced by 0.8 and 5.0 μg/m3, respectively. This work contributes insights on the trend and spatial pattern of NH3 source over the SCB and reveals the critical role of regulating NH3 emissions in mitigating PM2.5 pollution, shedding insights on nitrogen management strategies

Can the Blended Application of Controlled-Release and Common Urea Effectively Replace the Common Urea in a Wheat-Maize Rotation System? A Case Study Based on a Long-Term Experiment.

The one-time application of blended urea (BU), combining controlled-release urea (CRU) and uncoated urea, has proven to be a promising nitrogen (N) management strategy. However, the long-term sustainability of blending urea remains largely unexplored. To assess whether a single application of blended urea could effectively replace split uncoated urea applications, a long-term field experiment was conducted in the North China Plain (NCP). The results indicated that, when compared to common urea (CU) at the optimal N rate (180 kg N ha-1), BU achieved comparable grain yields, N uptake and NUE (61% vs. 62). BU exhibited a 12% higher 0-20 cm soil organic nitrogen stock and a 9% higher soil organic carbon (C) stock. Additionally, BU reduced life-cycle reactive N (Nr) losses and the N footprint by 10%, and lowered greenhouse gas (GHG) emissions and the C footprint by 7%. From an economic analysis perspective, BU demonstrated comparable private profitability and a 3% greater ecosystem economic benefit. Therefore, BU under the optimal N rate has the potential to substitute split applications of common urea in the long-term and can be regarded as a sustainable N management strategy for wheat and maize production in the NCP.

Optimizing Water Use Efficiency and Yield of Wheat Crops through Integrated Irrigation and Nitrogen Management: A Comprehensive Review

Achieving sustainable agricultural productivity is critical due to the rising worldwide demand for food and the growing scarcity of water. This comprehensive review investigates the complex interrelations where integrated irrigation and nitrogen management are used as a strategic method to improve wheat crop yields and water use efficiency (WUE). The study synthesizes current research findings, methodologies, and technological advancements related to optimizing water and nitrogen inputs in wheat cultivation. A number of factors can affect WUE in wheat, including climate, soil, crop management practices, and genetic factors. There are a number of irrigation and nitrogen management practices that can be used to improve WUE in wheat, including deficit irrigation, mulching, and split applications of nitrogen fertilizer. The review underscores the significance of tailored irrigation and nitrogen management strategies in mitigating water stress, reducing nutrient runoff, and promoting sustainable agricultural practices. Insights from this comprehensive analysis aim to guide policymakers, agronomists, and farmers in making informed decisions for optimizing wheat production while conserving water resources and minimizing environmental impact. Future research on WUE can help to ensure that wheat production remains sustainable in the face of future challenges such as climate change and water scarcity.

Effect of water and nitrogen coupling on energy balance and production efficiency in rice production

This study evaluated the effects of water-nitrogen coupling on the energy balance and production efficiency of rice production in Hainan Province, a region of China with tropical climatic. Results showed that the effects of water and nitrogen fertilizer on the total energy output (Eo), net energy (NE), and energy production efficiency (EPE) of rice were coupled. The total energy input (Ei) for rice production increased with irrigation water and nitrogen fertilizer application. Rice production currently depends heavily on indirect and nonrenewable Eis. Diesel, machinery, and nitrogen fertilizer Eis accounted for more than 75 % of the total Eis for rice production. The highest total Eo and NE were observed in rice treated with F-N100 and AWD-N150, respectively. Except for the F-N150 treatment, the total Eo and NE of rice increased with nitrogen fertilizer application. Higher EPE was observed for rice treated with R-N100. In conclusion, the AWD-N150 treatment is suitable for rice production areas with good irrigation conditions, while the R-N100 treatment should be adopted as the preferred water and nitrogen management strategy in rice production areas with high rainfall. Furthermore, research on reducing Eis for irrigation, tillage, and nitrogen fertilizer application for rice production should be strengthened in the future.

The Relationship of Soil Organic Carbon and Nutrient Contents to Maize Yield as Affected by Maize Straw Return Modes

Returning crop residues to the field after harvesting is a proven effective strategy for improving soil fertility, carbon sequestration, and crop productivity. However, the relationships between crop residue return modes, SOC and nutrient contents, and crop yields are still unclear. In this study, a field trial was conducted to investigate the effects of different maize straw return modes, i.e., straw mulching (SMU), straw deep ploughing (SDP), and control without straw return (CK), on soil organic carbon (SOC) and nutrient contents in soil layers of 0–40 cm in a Mollisol. The relationships between straw return modes, SOC and nutrient contents, and maize yield were evaluated. Compared with CK, SMU and SDP significantly increased SOC, total nitrogen (N), available N, total phosphorus (P), and available P contents in all soil layers. Relative to SMU, SOC, total N, available N, total P, and available P contents were significantly lower in soil layers of 0–10 cm, but they were significantly higher in soil layers of 20–40 cm in SDP. Redundancy analysis indicated that total N, available N, and SOC were major factors controlling maize yield. Structural equation modeling further showed that straw return modes indirectly affected maize yield by directly and preferentially affecting total N and available N contents. The results indicated that SMU and SDP were beneficial for increasing SOC and nutrient contents at the surface and subsurface soils, respectively. Optimizing a nitrogen management strategy is important to achieve high maize yield with straw return.

Evaluating Nitrogen Management Practices for Greenhouse Gas Emission Reduction in a Maize Farmland in the North China Plain: Adapting to Climate Change.

Quantification of the trade-offs among greenhouse gas (GHG) emissions, yield, and farmers' incomes is essential for proposing economic and environmental nitrogen (N) management strategies for optimizing agricultural production. A four-year (2017-2020) field experiment (including four treatments: basic N fertilizer treatment (BF), suitable utilization of fertilization (SU), emission reduction treatment (ER), and high fertilization (HF)) was conducted on maize (Zea mays L.) in the North China Plain. The Life Cycle Assessment (LCA) method was used in this study to quantify the GHG emissions and farmers' incomes during the whole maize production process. The total GHG emissions of BF, SU, ER, and HF treatments in the process of maize production are 10,755.2, 12,908.7, 11,950.1, and 14,274.5 kg CO2-eq ha-1, respectively, of which the direct emissions account for 84.8%, 76.8%, 74.9%, and 71.0%, respectively. Adding inhibitors significantly reduced direct GHG emissions, and the N2O and CO2 emissions from the maize fields in the ER treatment decreased by 30.0% and 7.9% compared to those in the SU treatment. Insignificant differences in yield were found between the SU and ER treatments, indicating that adding fertilizer inhibitors did not affect farmers' incomes while reducing GHG emissions. The yield for SU, ER, and HF treatments all significantly increased by 12.9-24.0%, 10.0-20.7%, and 2.1-17.4% compared to BF, respectively. In comparison with BF, both SU and ER significantly promoted agricultural net profit (ANP) by 16.6% and 12.2%, with mean ANP values of 3101.0 USD ha-1 and 2980.0 USD ha-1, respectively. Due to the high agricultural inputs, the ANP values in the HF treatment were 11.2%, 16.6%, and 12.4% lower than those in the SU treatment in 2018-2020. In conclusion, the combination of N fertilizer and inhibitors proved to be an environmentally friendly, high-profit, and low-emissions production technology while sustaining or even increasing maize yields in the North China Plain, which was conducive to achieving agricultural sustainability.

Modeling of The Nitrogen Requirement of Winter Wheat for Protein Content Using Optical Sensor in Central Anatolia Region of Türkiye

Chlorophyll meters manage both the amount and duration of nitrogen fertilizer application based on the principle that the chlorophyll or nitrogen content of plants should be maintained throughout their development. For smallholders in developing countries, the use of a hand-held meter to manage nitrogen fertilizer in rice and wheat is the most popular method. The adoption of nitrogen management strategies based on close sensing using chlorophyll meters and optical sensors will largely depend on the inclusion of specific economic analysis in future research. The importance of using sensors and chlorophyll meters for nitrogen fertilizer management depends on how successful current practices have been. In this study, five different nitrogen rates (0, 80, 120, 160, 200 kg N ha-1) were applied to two different wheat varieties, and the effect of these different nitrogen rates on wheat protein content was investigated in a randomized block design. A quadratic polynomial model described the relationship between protein content and nitrogen rates.

Mixed application of controlled-release urea and normal urea can improve crop productivity and reduce the carbon footprint under straw return in winter wheat-summer maize cropping system

An important goal of sustainable agriculture is reducing the environmental risk while also ensuring food security. The mixed application of controlled-release urea and normal urea (CRUNU) is a potential nitrogen (N) management strategy for achieving this goal. However, few studies have focused on whether optimizing the N application rate of CRUNU can balance crop yield and greenhouse gas emissions, especially when straw is returned. Thus, we conducted a five-year field experiment in a winter wheat–summer maize planting system in Northwest China to determine the effects of different N fertilizer types (NU: normal urea; CRUNU) and N application levels (low N, 135 kg ha–1; medium N, 180 kg ha–1; high N, 225 kg ha–1) with straw return on the crop yield and stability, N fertilizer partial factor productivity (NFPF), and soil organic carbon (SOC). Life cycle assessment was also conducted to quantify the GHG emissions from farmland and carbon footprint (CF). Compared with NU, CRUNU improved the winter wheat and summer maize grain yield, biomass, and NFPF at all three N application levels. The crop grain yields increased significantly as the N application level increased under NU, but the crop grain yields did not differ significantly between the medium and high N application levels under CRUNU (P > 0.05). The SOC contents increased as the duration of straw return increased. Compared with NU, CRUNU significantly increased the SOC content, and correlation analysis showed that this increase was related to the increased amount of returned straw. Compared with NU, CRUNU increased the GHG emissions in the production process but reduced the GHG emissions in the application process, as well as increasing soil CO2 fixation to ultimately reduce the total GHG emissions. CRUNU increased the crop grain yield while also reducing the total GHG emissions, and thus the CF decreased significantly by 14.53–23.03% compared with NU, especially at the medium N application level. Therefore, this comprehensive analysis of the crop productivity and GHG emissions indicates that CRUNU combined with an appropriate N application level can be used as a nitrogen fertilizer management strategy for sustainable winter wheat–summer maize cropping in Northwest China.

Characteristics of Ammonia Emissions from the use of Compost manure and Composite Fertilizer in Upland Field

Objectives : This study aimed to monitor ammonia volatilization in upland fields under different nitrogen fertilizer applications, comparing compost manure (CM) and composite fertilizer (CF) and investigate the environmental factors influencing ammonia volatilization.Methods : Ammonia was collected using the static chamber method in upland fields, and the soil analyses were conducted before and after ammonia volatilization monitoring. Pearson's correlation analysis and machine learning were utilized to determine the relationship between ammonia volatilization and environmental factors. Growth characteristics of harvested crops were analyzed, and Duncan analysis confirmed significant differences between nitrogen fertilizer treatments.Results and Discussion : In both CM and CF fertilized fields, there was no significant difference in ammonia volatilization. However, more ammonia volatilization was observed in the potato field compared to the Chinese cabbage field, attributed to higher NH<sub>4</sub><sup>+</sup>-N content in the soil of the potato field. Machine learning identified soil temperature and moisture as significant factors affecting ammonia volatilization. The analysis of crop growth revealed a positive effect of increased nitrogen fertilizer application. The result showed that single CM application was insufficient to meet crop nutrient demands.Conclusion : This study quantified ammonia emissions, identified influencing factors, and provided valuable data for enhancing fertilizer use efficiency and nitrogen management strategies in agriculture.

Impact of SPAD chlorophyll meter based nitrogen management strategy on N uptake and soil properties in direct seeded rice

The present investigation was emphasized to evaluate the precision nitrogen management using SPAD meter in improving N uptake as well as soil fertility status in rice crop under direct seeded condition.The experiment was conducted at Agriculture Research Farm, Bihar Agricultural University, Sabour, Bhagalpur, Bihar, India during the monsoon season, 2018 including twelve treatment combinations of three rice cultivars (Sabour Ardhjal, Shushk Samrat, Shabhagi Dhan) and four N management levels (Control, Fixed time nitrogen management (FTNM), Real time nitrogen management (RTNM), Adjustable dose of nitrogen management (ADNM)). Results revealed that Shushk Samrat among the cultivars and FTNM among N management practices have recorded highest leaf N content as well as N uptake. There is no major difference observed in soil properties and it might take few years to observe the impact of nitrogen management strategies on soil properties.

Mitigating ammonia volatilization in rice cultivation: The impact of partial organic fertilizer substitution

Optimizing water and nitrogen management to minimize NH3 volatilization from paddy fields has been extensively studied. However, there is limited research on the combined effect of different rates of organic fertilizer substitution (OFS) and irrigation methods in rice cultivation, exploring an effective water and nitrogen combination is beneficial to mitigate NH3 volatilization. To address this gap, we conducted a two-year field experiment to investigate NH3 volatilization under different OFS rates (0%, 25%, and 50%) combined with continuous flooding irrigation (CF) and alternate wet and dry irrigation (AWD). Our findings revealed that NH3 fluxes exhibited similar emission patterns after each fertilization event and significantly decreased with increasing rates of OFS during the basal stage. Compared to no substitution (ON0), the low (ON25) and high (ON50) rates of OFS reduced cumulative NH3 emissions by 18.9% and 16.6%, and lowed NH3 emission factors (EFs) by 26.7% and 23.3%, respectively. Although OFS resulted in a slight reduction in rice yield, yield-scaled NH3 emissions were significantly reduced by 11.9% and 6.5% under the low and high substitution rates, respectively. This reduction was mainly attributed to the slight yield reduction observed at the low substitution rate. Furthermore, when combined with ON0, AWD irrigation had the potential to increase NH3 volatilization. However, this increase was not observed when combined with ON25 and ON50. During each fertilization stage, floodwater + concentration emerged as the prominent environmental factor influencing NH3 volatilization, showing a stronger and more positive correlation compared to other factors such as floodwater pH, soil pH, and NH4+ concentration. Based on our findings, we recommend implementing effective water and nitrogen management strategies to minimize NH3 volatilization in rice cultivation. This involves applying a lower rate of organic fertilizer substitution during the basal stage, maintaining high water levels during fertilization, and implementing mild AWD irrigation during non-fertilization periods.

Optimizing water and nitrogen management strategies to improve their use efficiency, eggplant yield and fruit quality.

With improvement in living standards, consumer preferences for vegetables are changing from quantity- to quality-oriented. Water and nitrogen supply, as two major determinants of vegetable crop yield and quality, can be optimally managed to improve the yield and quality. To evaluate the response in yield, fruit quality, and water and nitrogen utilization of eggplant to different water and nitrogen management strategies, a 2-year (2021 and 2022) field trial under mulched drip irrigation was conducted. The growth period was divided into seedling, flowering and fruit set, fruit development, and fruit ripening stages. Three irrigation levels were applied during the flowering and fruit set stage: W0, adequate water supply (70%-80% of field water capacity, FC); W1, mild water deficit (60%-70% FC); and W2, moderate water deficit (50%-60% FC). In addition, three nitrogen application rates were applied: N1, low nitrogen level (215 kg ha-1); N2, medium nitrogen level (270 kg ha-1); and N3, high nitrogen level (325 kg ha-1). The irrigation and nitrogen rates were applied in all combinations (i.e., nine treatments in total). Adequate water supply throughout the reproductive period in combination with no nitrogen application served as the control (CK). The yield of the W1N2 treatment was significantly increased by 32.62% and 35.06% in 2021 and 2022, respectively, compared with that of the CK. Fruit soluble protein, soluble solids, and vitamin C contents were significantly higher under W1 than W2. Fruit quality was significantly higher under the N2 rate compared with the other nitrogen rates. The W1N2 treatment showed the highest water productivity, with a significant increase of 11.27%-37.84% (2021) and 14.71%-42.48% (2022) compared with that under the other treatments. Based on the average water-deficit degree and nitrogen application rate, W0 and N1 had the highest partial factor productivity of nitrogen. Assessment of the results using the TOPSIS (technique for order preference by similarity to an ideal solution) method indicated that mild water deficit in combination with the medium nitrogen application rate (W1N2) was the optimal water and nitrogen management strategy for cultivated eggplant. The present findings contribute novel insights into the sustainable cultivation of eggplant in an oasis arid environment.