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【Objective】 Soil water and nitrogen are the most important abiotic factors influencing plant growth and final yields. This paper aims to investigate the applicability of the Richards' equation for modeling growth, dry matter accumulation and yield formation of sunflower under different fertilizations and irrigations. 【Method】 The field experiment was conducted in 2021 in a dry area in the northern foot of Yinshan Mountain, Inner Mongolia. The variety Long Kui 27 used as the model plant; the field was mulched by plastic films. The split-plot experiment had three irrigation treatments: rain-fed plus irrigating 300 m3/hm2 of water just after the drilling to ensure seed germination (W1), replenishing irrigation by irrigating 900 m3/hm2 of water at seedling and budding stage, following the 300 m3/hm2 of pro-drilling irrigation (W2), and normal irrigation by irrigating a total 1 500 m3/hm2 of water at seedling, budding, flowering, and grain filling stages, respectively. In each irrigation treatment, there were three nitrogen fertilizations: 0 (N0), 135 (N1) and 270 kg/hm2 (N2). For each treatment, we used the Richards’ model to quantitatively analyze the changes in dry matter accumulation (DMA) and the impact of fertilization and irrigation on yield and yield formation. 【Result】 The Richards model was able to describe the dynamics of DMA. The impact of water and nitrogen on DMA and sunflower yield was obtained by the path analysis and the decision coefficient calculation. Optimized fertilization made the period of quick increase in DMA occur early, while excessive fertilization not only delayed the start of the quick increase in DMA but also shortened its duration. It was found that nitrogen application expedited the occurrence of the quick dry matter accumulation period, compared to no nitrogen application, while excessive nitrogen application not only brought the rapid growth period ending earlier, but also shortened it. Irrigation in the early growth stage delayed the onset of the rapid growth but increased the dry matter accumulation rate. In contrast, irrigation in the late growth stage delayed the end of the rapid growth period. 【Conclusion】 Our results provide guidance for optimal regulation of irrigation and fertilization to achieve high yield and improve water and nitrogen use efficiency of sunflower production in arid areas.

IntroductionIn recent decades, the need for increased food production has resulted in the expansion of intensified agriculture practices characterized by high consumption of inputs, thereby reducing agricultural sustainability. The agricultural sector's contribution to the world's energy consumption, ecological footprint, and greenhouse gas emissions has grown substantially. Emissions of greenhouse gases have negative ecological effects, including climate change, global warming, and diminished sustainable development. In this sector, energy analysis and greenhouse gas emissions in ecosystems are the most common methods for assessing sustainability. This study was conducted to evaluate the sustainability of canola agroecosystems by analyzing energy consumption, carbon footprint, and greenhouse gas emissions.Methods and MaterialsThe study was conducted using a questionnaire in Kalaleh County, in Golestan province, and gathering information from Golestan Agricultural Jihad Organization, during 2018-2019. The number of samples was determined by the Cochran formula. Accordingly, 50 farms were selected for canola cultivation. The questionnaire's reliability was determined to be 0.81. To calculate the energy indices, carbon footprint, and greenhouse gas emissions, after determining the most important inputs and output, first, their amounts were determined in each of the 50 farms and then their average was calculated. The energy equivalent of each input and output was calculated by multiplying its raw value by the corresponding energy conversion factor. The carbon footprint of the canola system was calculated as the amount of land required to absorb the environmental pollution caused by input and resource consumption. Carbon uptake in canola agroecosystems served as the basis for evaluating the carbon footprint and consequently the sustainability of this study. Also, the amount of greenhouse gases produced was determined by multiplying the raw values of the consumed inputs by their emission coefficient. Results and DiscussionIn canola agroecosystems, the total energy input was calculated to be 13,200 MJ ha-1, the total energy output was 63,400 MJ ha-1, the energy use efficiency was 4.8, and the energy productivity was 0.17 kg MJ-1. In addition, the ecological footprint and global warming potential were 0.99 gha and 779.03 CO2e ha−1, respectively. In canola production, fossil fuel and nitrogen fertilizer inputs contributed the most to ecological footprint and global warming potential respectively. Reducing the number of machines entering the farm through the application of conservation tillage methods and the modernization of machines can be effective in reducing the consumption of this input. Due to the non-renewability of this input, reducing its consumption is effective in reducing both economic costs and environmental pollution. Consuming as much livestock manure (cattle) as possible and implementing crop rotations with legumes such as soybeans that can grow well in this area is effective in supplying soil nitrogen and reducing the need for chemical fertilizers. ConclusionAnalysis of energy indices, such as energy efficiency and net energy, revealed that energy loss in the canola farming ecosystem is low and that the system's sustainability is adequate. Evaluation of carbon footprint revealed that the value of this index for canola production in the county of Kalaleh was less than the ecological capacity of each hectare of land used for canola production, indicating the environmental sustainability of canola production in the county of Kalaleh. In general, canola agroecosystems in the county of Kalaleh were sustainable based on terms of all three indices: net energy, carbon footprint, and global warming potential. Due to the large proportion of two inputs, fossil fuel, and nitrogen fertilizer, in these indices and their significant impact on production sustainability, consumption management of these inputs and training and justification of farmers are recommended to increase production sustainability.

Nitrogen (N) fertilization affects grain quality in common buckwheat (Fagopyrum esculentum Moench). But the effects of N fertilizer on various buckwheat protein parameters are not fully understood. This study aimed to investigate the synthesis, accumulation, and quality of buckwheat protein under four N application rates in the Loess Plateau, China. Optimal N application (180 kg N ha−1) improved yield, agronomic traits, and N transport and increased protein yield and protein component accumulation. Prolamin and glutelin accumulation first increased and then decreased with increasing N application. The relationships between the contents of protein components and the amount of applied N generally followed quadratic functions. Nitrate reductase and glutamine synthetase activities first increased and then decreased with increasing N levels. Optimal N fertilizer increased the waterholding capacity and thermal stability of buckwheat protein and reduced its emulsification capacity, but negligibly changed its oil-absorption capacity. Hydrophobic amino acids and glutelin content were the main factors affecting protein quality.

Abstract Many agricultural regions in China are likely to become appreciably wetter or drier as the global climate warming increases. However, the impact of these climate change patterns on the intensity of soil greenhouse gas (GHG) emissions (GHGI, GHG emissions per unit of crop yield) has not yet been rigorously assessed. By integrating an improved agricultural ecosystem model and a meta‐analysis of multiple field studies, we found that climate change is expected to cause a 20.0% crop yield loss, while stimulating soil GHG emissions by 12.2% between 2061 and 2090 in China's agricultural regions. A wetter‐warmer (WW) climate would adversely impact crop yield on an equal basis and lead to a 1.8‐fold‐ increase in GHG emissions relative to those in a drier‐warmer (DW) climate. Without water limitation/excess, extreme heat (an increase of more than 1.5°C in average temperature) during the growing season would amplify 15.7% more yield while simultaneously elevating GHG emissions by 42.5% compared to an increase of below 1.5°C. However, when coupled with extreme drought, it would aggravate crop yield loss by 61.8% without reducing the corresponding GHG emissions. Furthermore, the emission intensity in an extreme WW climate would increase by 22.6% compared to an extreme DW climate. Under this intense WW climate, the use of nitrogen fertilizer would lead to a 37.9% increase in soil GHG emissions without necessarily gaining a corresponding yield advantage compared to a DW climate. These findings suggest that the threat of a wetter‐warmer world to efforts to reduce GHG emissions intensity may be as great as or even greater than that of a drier‐warmer world.

Abstract In Senegal, agriculture is an important sector underpinning the socioeconomic fabric of the populace. Notably, the agricultural production in this region exhibits heightened sensitivity to climatic perturbations, particularly droughts and heat waves. This study aims to determine the resilience of different agronomic interventions for farmers practicing mixed farming that produce both crops (i.e., groundnut (Arachis hypogaea L.) and pearl millet (Pennisetum glaucum (L.) R. Br.)) and raise animals in the Groundnut Basin in Senegal, which holds historical and socioeconomic significance. To understand the current situation regarding demographics, economics, consumption behavior, and farm operations for smallholder farmers, data were comprehensively collected from government and nongovernment organizations (NGO) reports, scientific papers, organization databases, and surveys. Additionally, the Agricultural Production Systems sIMulator (APSIM) was used to understand how combinations of three planting dates, three plant densities, and six urea nitrogen (N) fertilizer rates affected the yield of pearl millet, which were used as the alternative scenarios to the baseline in the farm modeling and analyses. All the collected and generated data were used as inputs into the Farm Simulation Model (FARMSIM) to generate economic, nutritional, and risk data associated with mixed farming systems. The generated data were then used to determine the resilience of the alternative scenarios against the baseline. Initially, a multi‐objective optimization was employed to meet nutritional needs while maintaining a healthy diet at the lowest cost. Then, the scenarios that met the population's nutritional requirements were evaluated based on four economic indicators: net cash farm income (NCFI), ending cash reserves (EC), net present value (NPV), and internal rate of return (IRR). Lastly, those that passed the economic feasibility test were ranked based on risk criteria certainty equivalent (CE) and risk premium (RP). The analyses found N fertilizer rates of 0, 20, and 100 kg N ha−1 were generally economically not feasible. Additionally, medium (early‐July to late‐August) and late (late‐July to mid‐September) planting dates generally performed better than early (early‐June to late‐July) planting dates, while plant densities of 3.3 and 6.6 pL m−2 performed better than 1.1. The robust resilience approach introduced in this study is easily transferable to other regions.

Abstract Biochar is promoted as a means of improving soil fertility. Yet, few experiments have investigated its potential to improve nitrogen (N) use efficiency for high‐yielding maize production in the U.S. Midwest. We tested the hypothesis that biochar application increases inorganic soil N availability during maize growth, leading to higher grain yields and N recovery efficiency while reducing the risk of N leaching following harvest. Four N fertilizer rates (0, 90, 179, and 269 kg ha−1 as urea ammonium nitrate [UAN] solution) were applied with or without biochar (10 Mg ha−1) before planting in a two‐year field study. Inorganic soil N concentration was measured during the growing season (0–15 cm), and deep soil cores were obtained following harvest (0–90 cm). Results show that biochar did not affect maize yield, crop N uptake, or N recovery efficiency (by the difference method) across N rates, and there was no biochar by N rate interaction. While biochar lowered soil inorganic N concentrations on several sampling dates, this did not translate into seasonal differences in cumulative soil N availability, although grain yields in the unfertilized control were ~10% lower with biochar, suggesting net N immobilization. Biochar partially reduced the risk of N leaching following harvest by decreasing soil N concentrations at 30–60 cm, but mean concentrations for 0–90 cm were not different. Compared to previous work highlighting the benefits of biochar in arid climates with low soil fertility, we found no evidence of increased crop yield, NRE, or reduced risk of N leaching on Mollisols in a temperate climate.

AbstractThis study determined the most effective plating density (PD) and nitrogen (N) fertilizer rate for well-adapted BH540 medium-maturing maize cultivars for current climate condition in north west Ethiopia midlands. The Decision Support System for Agrotechnology Transfer (DSSAT)-Crop Environment Resource Synthesis (CERES)-Maize model has been utilized to determine the appropriate PD and N-fertilizer rate. An experimental study of PD (55,555, 62500, and 76,900 plants ha−1) and N (138, 207, and 276 kg N ha−1) levels was conducted for 3 years at 4 distinct sites. The DSSAT-CERES-Maize model was calibrated using climate data from 1987 to 2018, physicochemical soil profiling data (wilting point, field capacity, saturation, saturated hydraulic conductivity, root growth factor, bulk density, soil texture, organic carbon, total nitrogen; and soil pH), and agronomic management data from the experiment. After calibration, the DSSAT-CERES-Maize model was able to simulate the phenology and growth parameters of maize in the evaluation data set. The results from analysis of variance revealed that the maximum observed and simulated grain yield, biomass, and leaf area index were recorded from 276 kg N ha−1 and 76,900 plants ha−1 for the BH540 maize variety under the current climate condition. The application of 76,900 plants ha−1 combined with 276 kg N ha−1 significantly increased observed and simulated yield by 25% and 15%, respectively, compared with recommendation. Finally, future research on different N and PD levels in various agroecological zones with different varieties of mature maize types could be conducted for the current and future climate periods.

Paddy rice cultivation is a vital food source but also a significant contributor to greenhouse gas (GHG) emissions, particularly methane. Management measures such as improved water management and fertilization are being pursued to sustain rice production while cutting down the emissions. However, climate change may pose further challenges for sustainable rice agriculture by either impacting rice production or GHG emissions. Based on a database consisting of 1216 observations across China, we established machine learning models predicting rice yield and GHG emissions, taking into account climate, soil, and management variables. We tested three machine learning methods including random forest, support vector machine and artificial neural networks. The models were trained on 70% of the dataset with the remaining 30% used to evaluate the model performance. Random forest performed best with R2 of 0.59 to 0.72 and modelling efficiency of 52% to 72%. Farmland management emerged as the most important variable to the model prediction, followed by climate and soil variables. Rice production and GHG emissions were estimated to be 245.36 Tg and 218.95 Tg CO2-eq in 2018, respectively. By the year 2050, rice yield was expected to experience a modest decrease ranging from 0.6% to 1.2% due to the combined effects of global change variables, but GHG emissions were projected to increase by 2.1% to 4.9% under different climate change scenarios (Representative Concentration Pathways) in China. A large spatial variability in the impact of climate change was observed, and climate change will have the most significant impact in the Northeast agricultural region of China due to the warming effect. Through the analysis of region-specific farmland management scenarios, this study underscores a “Code Red” situation, signifying that future climate change could pose unprecedented risks to the sustainability of rice production in China, despite ongoing management improvements.

Straw return (SR) plus nitrogen (N) fertilizer has become a practical field management mode to improve soil fertility and crop yield in North China. This study aims to explore the relationship among organic waste, mineral nutrient utilization, and crop yield under SRN mode. The fertilizer treatments included unfertilized (CK), SR (straws from wheat and corn), N fertilizer (N), and SR plus N fertilizer (SRN). SRN treatment not only significantly increased the grain yield, net photosynthetic rate, and transpiration rate but also enhanced the contents of chlorophyll, soluble sugar, and soluble protein and increased the activities of antioxidant enzymes but reduced intercellular CO2 concentration and malondialdehyde (MDA) content when compared to other treatments. There were 2572, 1258, and 3395 differentially expressed genes (DEGs) identified from the paired comparisons of SRvsCK, NvsCK, and SRNvsCK, respectively. The transcript levels of many promising genes involved in the transport and assimilation of potassium, phosphate, and nitrogen, as well as the metabolisms of sugar, lipid, and protein, were down-regulated by straw returning under N treatment. SRN treatment maintained the maximum maize grain yield by regulating a series of genes' expressions to reduce nutrient shortage stress and to enhance the photosynthesis of ear leaves at the maize grain filling stage. This study would deepen the understanding of complex molecular mechanisms among organic waste, mineral nutrient utilization, crop yield, and quality. [ABSTRACT FROM AUTHOR]

The soil microbial community diversity of wheat rhizosphere was affected by the amount of nitrogen fertilizer. In addition to bacterial community, ammonia-oxidizing archaea, nitrogen-fixing bacteria and denitrifying bacteria also play important roles in nitrogen cycle. At present, the microecological mechanism of its response to nitrogen application is still unclear. In this study, the rhizosphere soil microorganisms of winter wheat were used as the research object. The changes of soil bacteria, ammonia-oxidizing archaea, nitrogen-fixing bacteria and denitrifying bacteria communities under five nitrogen rates of 0—N(0), 90—N(6), 180—N(12), 240—N(16), 300—N(20) kg N ha–2 were studied by high-throughput sequencing technology. Under N(12) treatment, the Alpha diversity index of bacteria, AOA and nifH nitrogen-fixing bacteria and the Shannon and Simpson indices of nirK denitrifying bacteria were significantly increased. N(12) treatment significantly increased the relative abundance of Proteobacteria, but no significant difference was found at the nifH and nirK bacterial phyla levels. Under the high nitrogen treatment of N(16) and N(20), the dominant bacteria of nirK-type denitrifying bacteria increased significantly compared with N(12) treatment, there was no significant difference in microbial community distribution between N(20) and the control group. Therefore, the nitrogen addition under N(12) treatment was most conducive to the absorption and utilization of nitrogen fertilizer by soil microorganisms. The effect of nitrogen addition on microbial community was weaker than that of soil properties and wheat yield, and nitrogen addition was significantly correlated with yield, reaching the highest yield at 300 kg ha–2. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The nitrogen leaching of agricultural non-point source pollution is the key factor of eutrophication pollution in plateau lakes, and it is important to study the seasonal nitrogen leaching in growing region to alleviate the nitrogen contamination of agricultural non-point source pollution to groundwater and surface water in plateau lake deposit areas. In this study, the nitrogen leaching characteristics of a new type of water-soluble nitrogen fertilizer (calcium nitrate ammonium) and traditional urea under different fertilization and rainfall conditions were studied through indoor column experiments. The results indicate that during the fertilization period, the new nitrogen fertilizer (T1) releases more NO3--N, but its cumulative emissions of NH4+-N and TN are much smaller than urea (T2). Seasonal precipitation has a certain impact on T1 nitrogen leaching, The total nitrogen content lost during fertilization and rainfall simulation periods accounts for 76.60% and 81.97% of the total nitrogen application in rainy seasons and the dry season, respectively. However, it has a significant impact on T2 nitrogen leaching, with leaching rates of 93.18% and 87.95%, respectively. In the rainy season with strong and frequent rainfall in Erhai Lake, the replacement of traditional urea by new nitrogen fertilizer will have a certain mitigation effect on agricultural non-point source pollution, and the denitrification in lake sediments has a retention effect on nitrogen in the shallow vadose zone. This study has certain guiding significance for the timing and methods of agricultural planting and fertilization in the lake deposit areas around plateau lakes. [ABSTRACT FROM AUTHOR]

This review article explores the impact of nitrogen fertilizers on the symbiotic relationship between Rhizobium bacteria and legume plants. Nitrogen fixation has the potential to address the global protein shortage by increasing nitrogen supply in agriculture. However, the excessive use of synthetic fertilizers has led to environmental consequences and high energy consumption. To promote sustainable agriculture, alternative approaches such as biofertilizers that utilize biological nitrogen fixation have been introduced to minimize ecological impact. Understanding the process of biological nitrogen fixation, where certain bacteria convert atmospheric nitrogen into ammonia, is crucial for sustainable agriculture. This knowledge helps reduce reliance on synthetic fertilizers and maintain soil fertility. The symbiotic relationship between Rhizobium bacteria and leguminous plants plays a vital role in sustainable agriculture by facilitating access to atmospheric nitrogen, improving soil fertility, and reducing the need for chemical fertilizers. To achieve optimal nitrogen fixation and plant growth, it is important to effectively manage nitrogen availability, soil conditions, and environmental stressors. Excessive nitrogen fertilization can negatively affect the symbiotic association between plants and rhizobia, resulting in reduced soil health, altered mutualistic relationships, and environmental concerns. Various techniques can be employed to enhance symbiotic efficiency by manipulating chemotaxis, which is the ability of rhizobia to move towards plant roots. Plant-specific metabolites called (iso)flavonoids play a crucial role in signaling and communication between legume plants and rhizobia bacteria, initiating the symbiotic relationship and enhancing nitrogen fixation and plant growth. Excessive nitrogen fertilizer application can disrupt the communication between rhizobia and legumes, impacting chemotaxis, root exudation patterns, nodulation, and the symbiotic relationship. High levels of nitrogen fertilizers can inhibit nitrogenase, a critical enzyme for plant growth, leading to reduced nitrogenase activity. Additionally, excessive nitrogen can compromise the energy demands of nitrogen fixation, resulting in decreased nitrogenase activity. This review discusses the disadvantages of using nitrogenous fertilizers and the role of symbiotic biological nitrogen fixation in reducing the need for these fertilizers. By using effective rhizobial strains with compatible legume cultivars, not only can the amounts of nitrogenous fertilizers be reduced, but also the energy inputs and greenhouse gas emissions associated with their manufacturing and application. This approach offers benefits in terms of reducing greenhouse gas emissions and saving energy. In conclusion, this paper provides a comprehensive overview of the current understanding of the impact of nitrogen fertilizers on the symbiotic relationship between Rhizobium and legume plants. It also discusses potential strategies for sustainable agricultural practices. By managing nitrogen fertilizers carefully and improving our understanding of the symbiotic relationship, we can contribute to sustainable agriculture and minimize environmental impact. [ABSTRACT FROM AUTHOR]

In order to find out the optimal nitrogen application rate and suitable number of basic seedlings for Shenliangyou 19, we studied the changes of tillering dynamics, dry matter accumulation, yield composition and rice quality of Shenliangyou 19 under different basic seedlings and nitrogen levels with fixed P and K fertilizer levels. Results showed that the number of tillers increased firstly and then decreased with time. With the increase of nitrogen application rate, tillering dynamics increased firstly and then decreased except for the control. Dry matter accumulation could be increased by increasing nitrogen application rate and basic seedling number within a certain range. In terms of yield, it increased with the increase of nitrogen application rate under the condition of low basic seedling, and increased first and then decreased with the increase of nitrogen application rate under the condition of medium and high basic seedling. In terms of the quality of rice, in the case of the same basic seedlings, with the increase of N application rate, rate of brown rice, white rice, rice rate and rate of the whole white rice except 66.7×104 plants / hm² +225 kg / hm² N treatment presents the downward trend after rising first, reach maximum when basic seedlings 50.0× 104 plants / hm² +150 kg / hm² N treatment, but evil whiteness and white rate with the increase of N application, showing a trend of increase the lower first, when basic seedlings 50.0×104 plants / hm² +150 kg / hm² N treatment minimum value, Under the same nitrogen application level, brown rice rate and white rice rate increased with the increase of basic seedlings. The amylose content under the same basic seedling decreased firstly and then increased with the increase of nitrogen application rate. Under the same nitrogen application level, there was a trend of decrease with the increase of basic seedlings under both blank and low nitrogen levels, and a trend of first decrease and then increase under high nitrogen level. The gel consistency was between 68. 7-85. 0 mm, and increased first and then decreased with the increase of nitrogen application rate under the same basic seedling. In conclusion, basic seedlings 50. 0×104 plants / hm² +150 kg / hm² N treatment has a reasonable yield structure, the highest yield, higher population quality, better rice quality and better comprehensive benefit. [ABSTRACT FROM AUTHOR]

Intensive irrigation and nutrient management practices in agriculture have given rise to serious issues in aquifer water depletion and groundwater quality. This review discusses the effects of irrigation and nitrogen management practices on potato growth, yield, and quality, and their impacts on water and nitrogen use efficiencies. This review also highlights the economics and consequences of applying deficit irrigation strategies in potato production. Many researchers have demonstrated that excessive irrigation and nitrogen application rates negatively impact potato tuber yield and quality while also increasing nitrate leaching, energy consumption, and the overall costs of production. An application of light-to-moderate deficit irrigation (10–30% of full irrigation) together with reduced nitrogen rates (60–170 kg/ha) has a great potential to improve water and nitrogen use efficiencies while obtaining optimum yield and quality in potato production, depending on the climate, variety, soil type, and water availability. There is an opportunity to reduce N application rates in potato production through deficit irrigation practices by minimizing nitrate leaching beyond the crop root zone. The best irrigation and nitrogen management techniques for potato production, as discussed in this review, include using sprinkle and drip irrigation techniques, irrigation scheduling based on local crop coefficients, soil moisture content, and crop modeling techniques, applying slow-release nitrogenous fertilizers, split nitrogen application, and applying water and nitrogenous fertilizers in accordance with crop growth stage requirements. [ABSTRACT FROM AUTHOR]

Although straw is an abundant and useful agricultural byproduct, it, however, exhibits hardly any decomposition and transformation. Despite the successful application of chemical and biological substrates for accelerating straw decomposition, the co-effects and mechanisms involved are still unknown. Herein, we performed a 120 day field trial to examine the co-effects of a nitrogen fertilizer (N) and a straw-decomposing microbial inoculant (SDMI) on the straw mass, nutrient release, and the straw chemical structure of composted wheat straw in the Chaohu Lake area, East China. For this purpose, four treatments were selected with straw: S (straw only), NS (N + straw), MS (SDMI + straw), and NMS (N + SDMI + straw). Our results indicated that NMS caused a higher straw decomposition rate than S, NS, and MS (p < 0.05) after 120 days of composting. The N, P, and K discharge rates in treating with NMS were higher than other the treatments at 120 days. The A/OA ratios of the straw residues were gradually increased during the composting, but the treatment of NMS and MS was lower than the CK at the latter stage. The RDA showed that the decomposition rate, nutrient release, and the chemical structure change in the straw were cumulative, while respiration was strongly correlated with lignin peroxidase, manganese peroxidase, and neutral xylanase. In conclusion, nitrogen fertilizer or straw-decomposing microbial inoculant application can improve the decomposition rate and nutrient release with oxidase activity intensified. However, the co-application of nitrogen fertilizer and a straw-decomposing microbial inoculant promoted straw decomposition and enzyme activity better than a single application and showed a lower decomposition degree, which means more potential for further decomposing after 120 days. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to clarify the expression pattern and molecular regulation mechanism of genes related to sugar, lipid and protein metabolism in maize ear leaves under different fertilization in field conditions. [ Method] Maize cultivar 'Luyu 16' was used as the material and five treatments were set up: No fertilizer (CK), nitrogen fertilizer ( N), N + P fertilizer (NP), N + K fertilizer ( NK) and N + P + K fertilizer ( NPK). At grain filling stage, the upper part of ear leaves was harvested for transcriptome analysis using RNA-Seq techniques. The differentially expressed genes ( DEGs) under different fertilizer treatments were analyzed by Hisat2 software. [Result]GO(Gene ontology)analysis showed that DEGs related to sugar, lipid and protein metabolism were enriched in Biological process ( BP), Cell components( CC) and Molecular function( MF). Although the enriched items were the same, the number of DEGs varied under different combinations. KEGG ( Kyoto encyclopedia of genes and genomes) analysis exhibited that more DEGs were enriched in carbon metabolism, starch and sucrose metabolism, and amino acid synthesis pathways. The total number of DEGs with both I log2 FC I > 1 and P < 0. 05 involved in sugar, lipid and protein metabolism under different fertilizer treatments was 82, 29 and 84, respectively. Among them, the total number of DE Gs with I log2 FC I > 2 was 6, 24 and 17. The number of DE Gs showed the maximum in comparisons of NPvsCK and NPKvsCK but the minimum in NvsCK comparison. Further analysis of DEGs with I log2 FC I showed that these DEGs had significant differences in the expression level and expression patterns. [ Conclusion] The combined of nitrogen, potassium and phosphorus fertilizer significantly affected the transcription levels of genes related to sugar, lipid and protein amino acids metabolism in maize ear leaves. Some key genes participating in the three organic substances' metabolism were identified. The results provided molecular basis for improving the photosynthetic efficiency of maize leaves by rational fertilization in the future. [ABSTRACT FROM AUTHOR]

Copyright of Acta Agronomica Sinica is the property of Crop Science Society of China and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The frequent occurrence of extreme weather in recent years poses a significant threat to food production. Ensuring food production and rationalizing the use of agricultural resources require addressing the problem of the improper application of chemical fertilizers. Several effective measures have been implemented in China to reduce agricultural non-point source pollution. Among them, the reduction of excessive nitrogen fertilizer application proves to be the most effective approach in controlling surface pollution from cultivation. Currently, it is crucial to clarify and quantify crop nutrient fertilizer requirements while evaluating the potential for reducing nitrogen fertilizer usage in China. Nitrogen requirements for major crops grown in China were assessed based on the theory of crop nutrient balance, assuming constant grain production as a guarantee. In this paper, we analyze the potential for nitrogen reduction through short-term, medium-term, and long-term scenario predictions. The results show that in the next 3 years, China has a reduction potential of 34.98%, but this potential is not sustainable. Over the next 10 years, there is a reduction potential of 15.04%, with most provinces experiencing a balanced state of soil nitrogen cycling. Hainan, Beijing, Shaanxi, and Fujian have higher reduction potential, with possible reductions of 69.95%, 64.14%, 60.72%, and 54.10%, respectively. However, there are still provinces in China where nitrogen fertilizer is insufficient, leading to soil nitrogen consumption. Specifically, Heilongjiang, Jiangxi, and Shandong Provinces need to increase their nitrogen fertilizer applications by 87.00%, 35.97%, and 8.31%, respectively. The long-term scenario analysis over the next 30 years shows a reduction potential of 40.96%. Among the regions analyzed, Hainan, Beijing, Shaanxi, Fujian, and Ningxia have higher nitrogen fertilizer reduction potentials, with values of 78.97%, 78.48%, 74.25%, 67.87%, and 67.72%, respectively. However, Heilongjiang Province still needs to increase nitrogen fertilizer application by 44.20% to address soil nitrogen depletion. Conversely, Tibet and Qinghai, with high organic fertilizer yields, lower chemical fertilizer usage, and low nitrogen loss coefficients, are well-suited for organic agriculture development. For areas with high organic fertilizers usage and a risk of fertilizer loss, we recommend implementing the organic-inorganic mixed fertilization planting mode. [ABSTRACT FROM AUTHOR]

Background and Objective: In order to make optimal use of available soil resources, preserve paddy lands for rice cultivation, prevent them from changing their use, and on the other hand, improve the living conditions of farmers, it is necessary to turn to the second cultivation of plants such as clover after rice harvesting as one of the ways to increase The income, while creating employment, will increase the production and stability of the income of paddy lands. Materials and Methods: This experiment was carried out in 2018 in the Lundville region of Astara for rice crop rotation, different amounts of nitrogen and potassium fertilizers, and varieties and dates of clover planting in the Guilan region. The experiment was evaluated in the form of s split-split plot with a completely randomized block design in three replications. The main factor includes nitrogen fertilizer with potassium at three levels (50, 100, and 150 kg per hectare) and the spreading of clovers in three different stages of rice growth, including after flowering, before harvest, and after harvest as split plot and secondary factors. the split split plot also included species of clovers (Barsim and Iranian). The rice variety used in this experiment was the Hashemi cultivar. Results:: The results of comparing the average effects of treatments showed that the highest plant height (154.5 cm) was obtained when 150 kg ha-1 of nitrogen fertilizer with potassium was used in the stage of spreading clovers before rice harvest for the Iranian clover variety. The total number of claws per square meter (779.56) in the spreading stage of clovers before harvesting rice and Iranian clover variety was more than other treatments. The number of clusters per square meter (235.44) and the total number of seeds per cluster (116.21) in the spreading phase of clovers after flowering of rice and Barsim clover cultivars were significantly higher than other treatments. The highest weight of thousand seeds under 100 kg ha-1 of fertilizer was obtained in the stage of spreading clovers after rice flowering (34.44 g) and also in the stage of spreading clovers after rice flowering and from the Barsim clover variety (35.78 g). The yield of paddy (550.67 g m2) was the highest under 100 kg ha-1 of fertilizer in the stage of spreading clovers after rice harvesting and from the Iranian clover variety. The harvest index (51.94%) was significantly higher in the spreading phase of clovers after rice harvest and from the variety of Bersim clover compared to other treatments. Conclusion: The use of nitrogen and potassium fertilizers along with crop rotation of rice and clover due to nitrogen stabilization and improvement of the soil substrate increased the height of the plant, increased the number of claws, spike length, the weight of 1000 seeds, and finally increased the yield of the rice plant. [ABSTRACT FROM AUTHOR]

Background and aims: In agriculture, biochar (BC) and nitrogen (N) fertilizers are commonly used for improving soil fertility and crop productivity. However, it remains unclear how different levels of BC and N fertilizer affect soil fertility and crop productivity. Methods: This study elucidates the impact of different application rates of BC (0, 600, and 1200 kg/ha) and N fertilizer (105 and 126 kg/ha) on biomass accumulation, soil microbial biomass of carbon (SMC) and nitrogen (SMN), and soil biochemical properties, including soil organic carbon (SOC), total nitrogen (TN), soil nitrate nitrogen (NO3--N), ammonium nitrogen (NH4 +-N), urease (UE), acid phosphatase (ACP), catalase (CAT), and sucrase (SC) of tobacco plants. In addition, a high throughput amplicon sequencing technique was adopted to investigate the effect of different application rates of BC/N on rhizosphere bacterial communities of tobacco plants. Results: The results confirm that high dosages of BC and N fertilizer (B1200N126) significantly enhance dry matter accumulation by 31.56% and 23.97% comparedwith control B0N105 and B0N126 under field conditions and 23.94% and 24.52% under pot experiment, respectively. The soil biochemical properties, SMC, and SMN significantly improved under the high application rate of BC and N fertilizer (B1200N126), while it negatively influenced the soil carbon/nitrogen ratio. Analysis of rhizosphere bacteriome through amplicon sequencing of 16S rRNA revealed that the structure, diversity, and composition of rhizosphere bacterial communities dramatically changed under different BC/N ratios. Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, and Acidobacteria were highly abundant bacterial phyla in the rhizosphere of tobacco plants under different treatments. Co-occurrence network analysis displayed fewer negative correlations among rhizosphere bacterial communities under high dosages of biochar and nitrogen (B1200N126) than other treatments, which showed less competition for resources among microbes. In addition, a redundancy analysis further proved a significant positive correlation among SMC, SMN, soil biochemical properties, and high dosage of biochar and nitrogen (B1200N126). Conclusions: Thus, we conclude that a high dosage of BC (1200 kg/ha) under a high application rate of N fertilizer (126 kg/ha) enhances the biomass accumulation of tobacco plants by improving the soil biochemical properties and activities of rhizosphere bacterial communities. [ABSTRACT FROM AUTHOR]

The application of nitrogen (N) fertilizer aggravates the nutrient runoff loss from paddy, causing serious agricultural non-point source pollution, and leading to a serious decline in water quality. The global area of saline-alkali paddy has expanded, but the response of nutrient loss via runoff to N-fertilizer applications in saline-alkali paddy is still unclear. This study conducted a 147-day field experiment to evaluate the nutrient runoff loss from saline-alkali paddy with different N-fertilizer application strategies in Songnen Plain of Northeast China. Regardless of N-fertilizer types, the nutrient loss via rainfall runoff in the entire rice-growing season was significantly (p < 0.05) higher than that via artificial drainage. The N and phosphorus (P) concentrations in runoff water were correlated with salinity and alkalinity. Especially, pH had a significant positive correlation with total-P (TP) (r = 0.658, p < 0.01). In the entire rice-growing season, the TN runoff losses in urea (U), microbial fertilizer (MF), and inorganic compound fertilizer (ICF) treatments were significantly (p < 0.05) lower compared with carbon-based slow-release fertilizer (CSF) and organic–inorganic compound fertilizer (OCF), respectively. Meanwhile, the TP runoff losses in OCF and ICF treatments were significantly (p < 0.05) lower than U and MF, respectively. Overall, the application of ICF is a better choice to avoid N and P losses via runoff from saline-alkali paddy fields. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China Agricultural University is the property of Gai Kan Bian Wei Hui and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective: In order to present a new, non-destructive, accurate, and fast method for estimating the nitrogen content of corn, Unmanned Aerial Vehicle (UAV) multispectral sensing technology was used. Methods: The experiments were performed based on a randomized complete block design in four levels of nitrogen fertilizer (zero, 50, 100, and 150%) in Varamin in 2018. Sampling was carried out in two stages of fertilization (8-leaf Stage and Tasseling Stage). Multispectral aerial imaging and ground sampling was performed one week after each fertilizer application. After processing aerial imagery, vegetation indices were calculated and their correlation with the results of ground sampling was determined. Results: Based on the results obtained from the correlation coefficients (r) and best subsets regression, among the spectral vegetation indices, Normalized Difference Vegetation Index (NDVI), Nitrogen Reflectance Index (NIR), and Modified Triangular Vegetation Index2 (MTVI2) indices in both eight leaf collar (V8) and tasseling (VT) of maize growth stage was identified as the best indicator to estimate the nitrogen content of forage maize. At VT, a positive and significant relationship was obtained between NDVI (R²= 0.86, P≤0.001), NRI (R²= 0.70, P≤0.001) and MTVI2 (R²= 0.46, P≤0.01) indices with maize nitrogen content. Conclusion: It can be concluded that UAV multispectral imaging provides acceptable accuracy in determining the nitrogen content of maize. This technology can help farmers to determine the appropriate time of fertilization. [ABSTRACT FROM AUTHOR]

Abstract Storing manure is an essential aspect of nutrient management on dairy farms. It presents the opportunity to use manure efficiently as a fertilizer in crop and pasture production. Typically, the manure storages are constructed as earthen, concrete, or steel-based structures. However, storing manure can potentially emit aerial pollutants to the atmosphere, including nitrogen and greenhouse gases, through microbial and physicochemical processes. We have characterized the composition of the microbiome in two manure storage structures, a clay-lined earthen pit and an aboveground concrete storage tank, on commercial dairy farms, to discern the nitrogen transformation processes, and thereby, inform the development of mitigation practices to preserve the value of manure. First, we analyzed the 16S rRNA-V4 amplicons generated from manure samples collected from several locations and depths (0.3, 1.2, and 2.1–2.75 m below the surface) of the storages, identifying a set of Amplicon Sequence Variant (ASVs) and quantifying their abundances. Then, we inferred the respective metabolic capabilities. These results showed that the manure microbiome composition was more complex and exhibited more location-to-location variation in the earthen pit than in the concrete tank. Further, the inlet and a location with hard surface crust in the earthen pit had unique consortia. The microbiomes in both storages had the potential to generate ammonia but lacked the organisms for oxidizing it to gaseous compounds. However, the microbial conversion of nitrate to gaseous N2, NO, and N2O via denitrification and to stable ammonia via dissimilatory nitrite reduction seemed possible; minor quantities of nitrate was present in manure, potentially originating from oxidative processes occurring on the barn floor. The nitrate-transformation linked ASVs were more prevalent at the near-surface locations and all depths of the inlet. Anammox bacteria and archaeal or bacterial autotrophic nitrifiers were not detected in either storage. Hydrogenotrophic Methanocorpusculum species were the primary methanogens or methane producers, exhibiting higher abundance in the earthen pit. These findings suggested that microbial activities were not the main drivers for nitrogen loss from manure storage, and commonly reported losses are associated with the physicochemical processes. Finally, the microbiomes of stored manure had the potential to emit greenhouse gases such as NO, N2O, and methane.

Coffee is one of the productive agro-industries in Indonesia, so care needs to be taken to use varieties and doses of fertilizers based on plant needs and environmental conditions. This study aimed to determine the clone, dose of urea, and the interaction between the clone and the dose for Robusta coffee plants in the mother planting stock farm. This study used a split-plot design with coffee clones as the main plot and doses of urea fertilizer as subplots. The study showed no significant difference between clones in the growth of robusta coffee plants, where clone BP 534 was the best clone for plant growth. In addition, based on the study's results, the best interaction was obtained where the best interaction for increasing the number of leaves was between clone BP 936 and a dose of 15 g.plant-1. The interaction between clones and the best dose for increasing the height and number of branches was between clone BP 936 and dose 20 g.plant-1, and the interaction between clones and the best dose for plant stem diameter was between clone BP 358 and a dose of 20 g.plant-1.

Due to a scarcity of freshwater resources, agriculture is dependent on the use of poor quality water for irrigation in arid and semi-arid regions. Hence, the effective use of poor quality water requires pioneering water management and nitrogen fertilizer practices for increasing yield and resource efficiency. This study aimed to investigate the effect of saline water levels, nitrogen fertilizer, and irrigation methods on eggplant yield, water productivity, NPK uptake, and nitrogen use efficiency. The experiment was conducted in 2019 and 2020 under drip (IM1) and surface flood irrigation (IM2). The treatments included three saline water levels i.e. canal water (SW1), ECiw=2.5 dS/m (SW2), and ECiw=5.0 dS/m (SW3) along with the three nitrogen levels of 75% (N1), 100% (N2), and 125% (N3) of the recommended dose of nitrogen. Application of saline water using IM1 reduced the ECe by 41.8% (SW2) and 34% (SW3) over IM2. The fruit yield, water productivity (WP), NPK uptake, and nitrogen use efficiency (NUE) was increased by 22%, 127.6%, 39.8%, 16.6%, 11.8%, and 23.8% under IM1 over IM2, respectively. A high saline water level under IM2 can cause more reduction in fruit yield, NPK uptake, and water use. Applying saline water through IM1 improves fruit yield, WP, and NUE by 13-32.8%, 104.1-147.3%, and 10.5-35.2% as compared to IM2. We found that saline water and N applied by drip improved eggplant yield, water productivity, and NPK uptake. It is concluded that irrigation water and nitrogen fertilizer consumption are optimized when saline water is applied through drip irrigation.

The objective of this study was to investigate how nitrogen and slow-release fertilizers affect the traits of leaf senescence and quinoa production in order to explore the optimal slow-release fertilizer and nitrogen fertilizer ratios suitable for quinoa production, as well as to provide theoretical references for the planting of quinoa fertilization methods and fertilizer amount. In this experiment, the main local strain Quinoa 77 was selected as the experimental material, and six treatments were set up: CK: no nitrogen fertilizer; T1: 100% urea (N); T2: 100% slow-release fertilizer (C); T3: 5:5 (C5N5); T4: 3:7 (C3N7); and T5: 7:3 (C7N3). This was done in order to investigate how various treatments affect the activities of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD); malondialdehyde (MDA) content; and yield of quinoa leaves. The findings revealed the following: (1) As the reproductive period progressed, the activities of CAT, POD, and SOD in quinoa leaves treated differently showed a tendency to increase and subsequently decrease, and they reached the peak value at the early stage of filling. The activity of CAT, POD, and SOD in the T3 treatment was the highest, and the average activities were 3148.74 U·g−1, 2197.84 U·g−1, and 118.51 U·g−1, respectively, which increased by 78.90%, 101.99%, and 108.14%, respectively, compared with CK. The content of MDA continued to increase with the progress of fertility. The average T3 treatment was 36.41 nmol·g−1, which was 46.87% lower than that of CK. (2) Out of all the treatments, T3 had the highest yield with an average of 3829.43 kg·hm−2, T5 the second with an average of 3313.52 kg·hm−2, and T4 the third with 2847.47 kg·hm−2, which increased yields by 96.18%, 69.75%, and 45.87%, respectively, compared with CK. (3) Yield was highly significantly and positively correlated with thousand kernel weight; number of grains per spike per plant; and the early filling stages of CAT, POD, and SOD sports, and it had a negative, extremely significant correlation with MDA content. Comprehensive analysis showed that slow-release fertilizer and nitrogen fertilizer can improve the antioxidant enzyme activity of quinoa leaves, inhibit MDA content, improve the physiological characteristics of quinoa, and delay the purpose of leaf senescence, with a better effect of yield and income, of which the T3 treatment had the high-quality impact of increasing yields and was a more scientific and reasonable fertilization method.

Quinoa (Chenopodium quinoa Willd.) is gaining recognition as a pseudocereal due to its nutritional attributes and adaptability to challenging conditions and marginal soils. However, understanding the optimal fertilization for quinoa growth remains a challenge. This study investigates the effects of nitrogen fertilization (0, 90, 120, and 150 kg using urea) on quinoa phenology, growth, and photosynthesis in the Loess Plateau region of China, a critical area facing soil erosion and ecological degradation. The results showed that nitrogen fertilization significantly influenced quinoa phenology, prompting early flowering and shorter growth at an optimum rate of 120 kg ha−1. Nitrogen application enhanced growth traits such as plant height, stem diameter, and chlorophyll content, particularly at the heading and flowering stages. Photosynthesis-related parameters, including net photosynthesis rate, transpiration rate, stomatal conductance, and intercellular CO2 concentration, were affected by nitrogen application, with higher values observed at 120 kg ha−1. Non-photochemical quenching was significantly increased by nitrogen application, indicating the efficient dissipation of excess energy. The study demonstrated a positive correlation between grain yield and growth traits, photosynthesis-related traits, and chlorophyll content. In conclusion, quinoa yield could be significantly improved at the Loess Plateau region under rainfed conditions by an optimal nitrogen fertilizer rate of 120 kg ha−1, which reduces the growth duration while increasing photosynthesis traits.

The intercropping of peanuts and sugarcane is a sustainable planting model that deserves in-depth research. For this study, two variables, i.e., intercropping status (peanut monocropping or sugarcane/peanut intercropping) and the level of nitrogen fertilization (low, medium, or high), were evaluated to analyze the effects of intercropping and nitrogen application on soil fertility and microbial communities in peanut rhizosphere soil. These analyses revealed that higher nitrogen application led to increased total nitrogen (TN), available nitrogen (AN), and soil organic matter (OM) levels in rhizosphere soil for both monocropped and intercropped peanuts, with a decrease in pH. Monocropped peanuts had higher TN, total phosphorus (TP), and total potassium (TK) levels compared to intercropped peanuts at the same nitrogen level but lower AN content and pH levels. The diversity of microbial communities in the rhizosphere soil of intercropped peanuts was significantly higher than that of monocropped peanuts under high levels of nitrogen fertilizer application. Higher levels of Gemmatimonadetes abundance were observed in intercropping rhizosphere soil, compared to that associated with peanut monocropping under low, middle, and high levels of nitrogen fertilizer application, whereas the opposite trend was observed for Chloroflexi abundance. Nitrospira abundance levels rose gradually in the monocropping treatment group, whereas the opposite trend was evident under intercropping conditions. Further analyses of nitrogen cycle-related genes demonstrated higher levels of nitrogen conversion cycle activity in intercropping peanut rhizosphere soil under low nitrogen levels, whereas nitrogen transformation cycle activity levels were higher in monocropping peanut rhizosphere soil under high levels of nitrogen amendment. It can be concluded that intercropping and nitrogen fertilizer application change the physical and chemical properties of soil, thus affecting the diversity and function of soil microbial communities in the peanut rhizosphere. These results offer a theoretical foundation for more efficient sugarcane/peanut intercropping systems.

This study was conducted to determine the effect of nitrogen (N) doses (0, 40, 80, 120, 160, 200, and 240 kg ha-1) and bacterial inoculation on macro- (N, P, K, Ca, Mg, and Na) and micro- (Fe, Cu, Zn, Mn, and B) element contents of the Halisbey peanut variety. The nutrient requirements, specific nutrient management strategies, and adaptation of the variety to the regions where it was grown were also assessed. According to the average results of the N applications, different doses affected the levels of N (240N+B: 1.76%) alongside the content of other macro-elements, as well as sodium (200N: 0.09 mg kg-1), iron (80N: 32.39 mg kg-1), and copper (40N: 14.11 mg kg-1) among the micro-elements. The bacterial application was not found to significantly increase N content (240N+B: 1.76%), calcium content (0.08%) and zinc content (49.68 mg kg-1). At the same time, (240N+B) bacteria and N application increased the N ratio.

Reactive nitrogen gas (Nr) originating from the soil is highly susceptible to the influence of agricultural water and fertilizer management practices, making it a critical gas that can substantially contribute to atmospheric pollution. Understanding the emission patterns of Nr in the surface soil under reclaimed water (RW) irrigation is essential for guiding RW irrigation practices and informing policies aimed at reducing Nr emissions. In this study conducted in Beijing, North China, field sites were selected with different irrigation management strategies and corresponding fertilizer application methods. The two types of irrigation water quality comprised RW irrigation and groundwater (UW) irrigation, whereas the two fertilizer types utilized were calcium ammonium nitrate with a high nitrate nitrogen content and ammonium sulfate with ammonium nitrogen. Nr emissions and concentrations in the soil profile (0–30 cm depth) were monitored throughout key agricultural events, including cultivation, irrigation, fertilization, and harvest, spanning the period from 2020 to 2021. It is observed that RW irrigation effectively reduces cumulative ammonia (NH3) emissions compared to groundwater (UW) treatment. However, it results in increased concentrations of nitrous oxide (N2O) (12.33%−73.82%) and nitric oxide (NO) (13.74%−36.59%) in the soil within the depth range of 0–30 cm. Of particular importance is the notable increase in the abundance of soil denitrifying and ammonia-oxidizing archaea (AOA-amoA) genes due to RW irrigation, indicating the potential for elevated N2O and NO emissions. Furthermore, it is noteworthy that the soil Nr emissions and concentrations are more strongly affected by nitrogen type rather than water quality. Conversely, the inclusion of nitrate has proven to be effective in mitigating N2O and NO emissions in RW-irrigated farmland.

Background and aimsIn agriculture, biochar (BC) and nitrogen (N) fertilizers are commonly used for improving soil fertility and crop productivity. However, it remains unclear how different levels of BC and N fertilizer affect soil fertility and crop productivity.MethodsThis study elucidates the impact of different application rates of BC (0, 600, and 1200 kg/ha) and N fertilizer (105 and 126 kg/ha) on biomass accumulation, soil microbial biomass of carbon (SMC) and nitrogen (SMN), and soil biochemical properties, including soil organic carbon (SOC), total nitrogen (TN), soil nitrate nitrogen (NO3−−N), ammonium nitrogen (NH4+−N), urease (UE), acid phosphatase (ACP), catalase (CAT), and sucrase (SC) of tobacco plants. In addition, a high throughput amplicon sequencing technique was adopted to investigate the effect of different application rates of BC/N on rhizosphere bacterial communities of tobacco plants.ResultsThe results confirm that high dosages of BC and N fertilizer (B1200N126) significantly enhance dry matter accumulation by 31.56% and 23.97% compared with control B0N105 and B0N126 under field conditions and 23.94% and 24.52% under pot experiment, respectively. The soil biochemical properties, SMC, and SMN significantly improved under the high application rate of BC and N fertilizer (B1200N126), while it negatively influenced the soil carbon/nitrogen ratio. Analysis of rhizosphere bacteriome through amplicon sequencing of 16S rRNA revealed that the structure, diversity, and composition of rhizosphere bacterial communities dramatically changed under different BC/N ratios. Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes, and Acidobacteria were highly abundant bacterial phyla in the rhizosphere of tobacco plants under different treatments. Co-occurrence network analysis displayed fewer negative correlations among rhizosphere bacterial communities under high dosages of biochar and nitrogen (B1200N126) than other treatments, which showed less competition for resources among microbes. In addition, a redundancy analysis further proved a significant positive correlation among SMC, SMN, soil biochemical properties, and high dosage of biochar and nitrogen (B1200N126).ConclusionsThus, we conclude that a high dosage of BC (1200 kg/ha) under a high application rate of N fertilizer (126 kg/ha) enhances the biomass accumulation of tobacco plants by improving the soil biochemical properties and activities of rhizosphere bacterial communities.

Vegetable growers on the central coast of California are under regulatory pressure to reduce nitrate loading to ground and surface water supplies. California also implemented legislation that limits agricultural pumping in regions such as the central coast where the aquifers have been over-extracted for crop irrigation. Growers could potentially use less N fertilizer, address water quality concerns, and conserve water by improving water management and matching nitrogen applications to the N uptake pattern of their crops. Two tools available to growers, the soil nitrate quick test (SNQT) and reference evapotranspiration (ETo) data have been previously shown to improve the management of water and fertilizer nitrogen in vegetable production systems. However, adoption of these practices has not been widespread. These techniques can be time consuming to use, and vegetable growers often have many crops to manage. To address such time constraints, the CropManage online application (cropmanage.ucanr.edu) was developed to facilitate implementation of the SNQT and evapotranspiration-based irrigation scheduling. CropManage additionally helps growers account for plant available N from background levels of nitrate in irrigation water. Trials were conducted in commercial vegetable fields in the Salinas Valley during 2012–2019 to evaluate CropManage fertilizer and irrigation recommendations relative to the grower practice. Results demonstrated that in many cases fertilizer or irrigation reductions could be attained by following CropManage recommendations without jeopardizing yield. In lettuce, the total fertilizer N applied under CropManage guidance was reduced by an average of 31 % compared to the grower standard practice. Lettuce yield within the CropManage treatment averaged 107 % of the grower practice. CropManage guidance in broccoli reduced N and applied water by 24 % and 27 %, respectively, compared to the grower standard practice, while average yield was similar between treatments. Management tools such as CropManage can support operational efficiencies and compliance with regulatory targets designed to improve groundwater quality.

Ridge-furrow film mulching (RFFM) and nitrogen (N) fertilization have been widely used in semi-arid regions, it is particularly important to clarify the mechanism of crop physiological indicators in response to RFFM. A two-year (2018 and 2019) field experiment was conducted on summer maize under RFFM (including biodegradable film mulching (B) and plastic film mulching (P)) at N fertilizer application rate of 0 (N0), 90 (N1), 180 (N2) and 270 (N3) kg N ha–1. The aims of this research were to 1) explore the effects of different film mulching and N application rates under RFFM on photosynthesis, water utilization, and yield; 2) identify key factors and their contribution to yield. The results showed that RFFM and nitrogen application significantly improved net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), intrinsic water use efficiency (WUEi) (grain-filling stage), the maximum quantum yield of PSII photochemistry (Fv/Fm), energy transformation potential activities of PSII (Fv/Fo), the effective quantum yield of PSII photochemistry (ΦPSII), photochemical quenching of variable chlorophyll fluorescence (qP), non-photochemical chlorophyll fluorescence quenching (NPQ), chlorophyll ab (Chl ab), evapotranspiration (ET) and yield, but decreased chlorophyll a/b (Chl a/b) and soil water storage (SWS). The maximum Pn, Tr, Gs, WUEi, Fv/Fm. Fv/Fo, ΦPSII, qP, and Chl ab (anthesis stage) all appeared in N2. At the same N application rate, the positive effects on photosynthetic and chlorophyll fluorescence (ChlF) of the plastic film were better than biodegradable film, especially in water use efficiency (WUE). Nitrogen deficiency had significantly negative effects on various parameters (Photosynthetic parameters, ChlF, Chl ab, grain yield), while nitrogen application (N > N1) had strong positive effects. Photosynthetic parameters, Fv/Fm, Fv/Fo, NPQ, Chl ab, ET, and WUE had strong positive effects on yield. The grain yield of the plastic film were slightly better (5.03% on average) than biodegradable film, but from the perspective of sustainable development, we recommend that biodegradable film and N2 should be used in the semi-arid regions of China.

Long-term excessive application of chemical fertilizers can cause many problems, such as soil degradation and environmental pollution. Therefore, we reduced conventional nitrogen fertilization and added organic fertilizers in some cases to investigate the response of photosynthetic characteristics, root nodules and yield on reduced nitrogen fertilization. Compared to conventional nitrogen fertilization, the 25% and 35% nitrogen reduction treatments reduced the leaf area index, net photosynthetic rate, 100-fruit weight, 100-kernel weight and the yield of peanut, but had no significant effect on the kernel rate. With constant N fertilizer, adding organic fertilization alone increased leaf area index, chlorophyll, net photosynthetic rate and yield of peanut. In compounded treatments of nitrogen and organic fertilizer, the highest yields were achieved in the 25% N reduction with the 3000 kg/hm−2 organic fertilizer treatment (T3) and the 4500 kg/hm−2 organic fertilizer treatment (T4); furthermore, the net photosynthetic rate, leaf area index, yield and fertilizer contribution were significantly higher in these two treatments than in the conventional fertilizer treatments. Nitrogen fertilizer had significant effects on the quantity and fresh weight of root nodules. Concretely, nitrogen reduction increased the quantity and fresh weight of root nodules of peanut in the early stage of fertility but decreased them in the harvest stage. Nitrogen reduction with an additional organic fertilizer in the late stage of fertility increased the quantity and fresh weight of root nodules of peanut. Considering the property of root nodules was significantly positively correlated with net photosynthetic rate and yield, the arguments above may be the mechanism of the highest yields found in T3 and T4. This work can provide empirical and instructional support for a balanced fertilization strategy in peanut agriculture and high-yielding and efficient cultivation of peanut. [ABSTRACT FROM AUTHOR]

Organic fertilizer applications and subsurface drainage are two important measures for improving coastal saline soil; however, nitrous oxide (N2O) emissions from saline soil under a combination of these two measures are seldom evaluated. In this study, saline soil cultivated with sunflowers (Helianthus annuus L.) was employed as an experimental system. Prior to the experiment, the saline soils were buried with three different spacings (10 m (S1), 15 m (S2), and 20 m (S3)) of subsurface drainage pipes. The nitrogen nutrients that are needed by sunflowers came from two different nitrogen sources (organic and inorganic fertilizer), including six application schemes of either 100% organic fertilizer (100%OF), 75% organic fertilizer combined with 25% inorganic fertilizer (75%OF), 50% organic fertilizer (50%OF), 25% organic fertilizer (25%OF), 0% organic fertilizer (0%OF), and no fertilizer (CK). The results show that the cumulative N2O emissions from the treatments under S1, S2, and S3 throughout the entire growth period were 8.9–15.8, 9.5–17.5, and 10.1–17.6 kg ha−1, respectively. A smaller spacing between adjacent drainage pipes or a higher replacement proportion of organic fertilizer reduced the accumulative N2O emissions. The increased replacement of organic fertilizer decreased the soil salinity, whereas it increased the C/N ratio and total carbon content. The fertilization treatments significantly increased the nitrogen uptake of sunflower plants, with increase ranges of 18.1–47.2%, 8.6–40.5%, and 8.8–34.5% under S1, S2, and S3, respectively, compared with CK. The highest yield of sunflowers was achieved under S2 combined with 25%OF, reaching 3.82 t ha−1. Correlation analysis showed that the N2O emission flux was positively correlated with the soil salinity, crop yield, and crop nitrogen uptake, whereas it was negatively correlated with the total carbon, C/N ratio, and organic carbon content. We concluded that using 25% organic fertilizer instead of inorganic fertilizer was beneficial for reducing N2O emissions while maintaining the crop yield under subsurface drainage. [ABSTRACT FROM AUTHOR]

The overuse of nitrogen fertilizers has led to environmental pollution, which has prompted the widespread adoption of biochar as a soil conditioner in agricultural production. To date, there has been a lack of research on the effects of biochar and its combination with nitrogen fertilizer on the quality of broomcorn millet (Panicum miliaceum L.) starch. Thus, this study examined the physicochemical characteristics of starch in two types of broomcorn millet (waxy and non-waxy) under four different conditions, including a control group (N0), nitrogen fertilizer treatment alone (N150), biochar treatment alone (N0+B), and a combination of biochar and nitrogen fertilizer treatments (N150+B). The results showed that, in comparison to the control, all the treatments, particularly N150+B, decreased the content of amylose and gelatinization temperature and enhanced the starch transparency gel consistency and swelling power. In addition, biochar can improve the water solubility of starch and the gelatinization enthalpy. Importantly, the combination of biochar and nitrogen fertilizer increased the proportion of A-granules, final viscosity, starch content, and the average degree of amylopectin in polymerization. Thus, this research indicates that the combinations of biochar and nitrogen fertilizer result in the most significant improvement in the quality of starch produced from broomcorn millet. [ABSTRACT FROM AUTHOR]

China uses 7% of the world's arable land to consume 35% of the world's chemical fertilizer, and a large amount of unreasonable chemical fertilizer inputs lead to increased planting costs. With the introduction of the policy of double reduction of pesticides and fertilizers, how to reduce the nitrogen fertilizer input while ensuring the stable yield of potato crops has become the main problem to be solved urgently for the sustainable development of the potato industry. Breeding and popularizing potato varieties with efficient nitrogen absorption and utilization are an important way to realize the sustainable and healthy development of potato production in China. In this experiment, 'Dongnong 310', 'Xingjia 2', 'Muyushu 3', 'Zaodabai', 'Zhongshuzao 35', and 'Innovator' were used as test materials, and three fertilizer gradients were set as nitrogen free (0), low nitrogen (90 kg/ha), and regular nitrogen (180 kg/ha), to comprehensively analyze the differences in nitrogen accumulation and nitrogen efficiency. The dry matter accumulation and plant height of most potato varieties were significantly increased with the application of nitrogen fertilizer in the tuber formation and tuber bulking stages. Under the treatment of low nitrogen, the yields of 'Xingjia 2' and 'Zhongshuzao 35' were significantly higher than that of the other four varieties (except 'Innovator', which was not significantly different from 'Xingjia 2'). Under the treatments of low nitrogen and regular nitrogen application, the nitrogen recovery efficiency of 'Dongnong 310' was higher, which was 7.26% and 7.49%, respectively, but its nitrogen agronomic efficiency and partial factor productivity of applied nitrogen were lower. Furthermore, its yield did not have a significant advantage compared with other varieties. Its dry matter accumulation was higher, possibly due to the accumulation of nitrogen mainly transported to above- ground part of plants. The nitrogen agronomic efficiency of 'Muyushu 3' and 'Zhongshuzao 35' under N 90 kg/ha treatment was higher, 75.42 and 96.38 kg/kg, respectively, indicating that these two varieties had a significant increase in yield with the application of nitrogen fertilizer. The partial factor productivity of applied nitrogen of 'Zhongshuzao 35' was the highest, 219.36 kg/kg, under N 90 kg/ha treatment. The study on photosynthetic pigments found that the content of photosynthetic pigments in tuber formation stage was higher than that in tuber bulking stage, and 'Innovator' had a longer duration of photosynthesis. Therefore, under the condition of reducing nitrogen fertilizer application, 'Xingjia 2' and 'Zhongshuzao 35' could achieve higher yield, and 'Dongnong 310' has a stronger nitrogen absorption efficiency, but its yield is relatively low. [ABSTRACT FROM AUTHOR]

We investigated the variations in metabolites associated with the quality of rice consumption when exposed to varying nitrogen fertilizer levels, as well as the regulatory role of pivotal metabolites within metabolic pathways. This research employed Hongyang 5 as the subject of experimentation, examining the metabolites of Hongyang 5 at three different nitrogen levels using non-targeted metabonomic analysis. The findings indicated that the overall assessment of the eating quality/palatability (CEQ) and amylose contents (AC) of Low nitrogen (D1: 180 kg·ha−1) was notably greater than that of Medium nitrogen (D2: 270 kg·ha−1) and High nitrogen (D3: 315 kg·ha−1). Conversely, the amylopectin (APC), total starch (SC), and protein contents (AP) of D1 were remarkably lower than those observed in D2 and D3. The starch debranching enzyme (DBE) and granule-bound starch synthetase (GBSS) of D1 were remarkably higher than those of D2 and D3. The soluble starch synthase (SSS) of D1 was the lowest. The ADP-glucose pyro-phosphorylase (AGP) and starch branching enzyme (SBE) of D3 were remarkably higher than that of D1 and D2. We identified 76 differential metabolites (DMs) between D1 and D2 (20 up-regulated and 56 down-regulated). A total of 88 DMs were identified between D3 and D1 (42 up-regulated and 46 down-regulated). A total of 57 DMs were identified between D3 and D2. Most of the DMs related to rice-eating quality were involved in the lipid metabolic pathway and amino acid metabolic pathway. The essential metabolites within the metabolic pathway are classified as lipid metabolites and are (13(S)-hydroperoxylinolenic acid, PGB2, 3-phosphocholine, 7-epijasmonic acid, 20-carboxyleukotriene B4 and 11-dehydro-thromboxane B2), amino acid metabolites (4-guanidinobutanoic acid, (3R, 5S)-1-pyrroline-3-hydroxy-5-carboxylic acid, citric acid, (S)-2-Acetolactate, L-glutamine, L-2, 4-aminobutyric acid and putrescine). These key metabolites may be affected by nitrogen fertilizer conditions and play critical regulatory roles in the metabolic pathway, resulting in differences in rice eating quality. [ABSTRACT FROM AUTHOR]

A field experiment on sorghum (Sorghum bicolor L.) with diverse levels of fertilization, carried out in the spring of 2022 in a randomized complete block design (RCBD) with factorial arrangement, had three replications and two factors at the field of Ibn-Al-Bitar Vocational Preparatory School, District Al-Hussainiya, Kerbala, Iraq. The first factor comprised three sorghum cultivars (V1 = Al-Khair, V2 = Rabeh, and V3 = Bohuth-70), while the second was combinations of nitrogen and bio-fertilizers (F0 = recommended dose of N 320 kg ha-1, F1 = 3/4 of the recommended amount of N with Azotobacter, F2 = 1/2 of the recommended dosage of N + Aotobacter, F3 = 1/4 of the recommended dose of N + Azotobacter, and F4 = Azotobacter + No nitrogen fertilizer). The results showed that the sorghum cultivar Bohuth-70 was significantly superior for enhanced plant height (204.63 cm), number of leaves plant-1 (9.807), 1000-grain weight (35.27 g), and the grain yield (6.192 Mg.ha-1). However, cultivar Al-Khair produced the highest mean leaf area (4,929 cm2) and grains per head (4,428 grains.head-1). Cultivar Rabeh excelled in performance, with the highest mean value for stem diameter (24.67 mm) and head length (31.29 cm). The F0 treatment recommended dose of N 320 kg ha-1 was considerably superior in the number of leaves (9.867 leaves plant-1), stem diameter (24.8 mm), and grain yield (6.145 Mg.ha-1). The F1 treatment of 3/4 of the recommended dose of N with Aotobacter excelled in plant height (166.57 cm), leaf area (4,936 cm2), and number of grains (3,916 grain head-1). However, the F2 treatment 1/2 of the recommended dose of N + Aotobacter was notably superior in head length (30.18 cm) and 1000-grain weight (29.93 grains). As for the interaction, the sorghum cultivar Bohuth-70 with F0 treatment excelled in the number of leaves plant-1 (10.33 leaves) and the grain yield (7.157 Mg.ha-1), while the cultivar Al-Khair with F1 treatment excelled in stem diameter (26.70 mm) and leaf area (5,164 cm2). [ABSTRACT FROM AUTHOR]

The commercial organic fertilizer was applied with different amounts of inorganic fertilizer in the field experiment. The result showed that the combined application of organic and inorganic fertilizers could improve the field growth of tobacco plants, promote the growth and development of tobacco plants, and reduce the occurrence of diseases to a certain extent. Under the same organic fertilizer level, the yield and output value decreased with the decrease of nitrogen application. From the comprehensive analysis of field performance, agronomic characters, stress resistance and economic indicators, B3 (chemical fertilizer pure nitrogen 97.5 kg/hm2+organic fertilizer 1 800.0 kg/hm2) treatment performed best, followed by B2 (chemical fertilizer pure nitrogen 97.5 kg/hm2), B4 (chemical fertilizer pure nitrogen 90.0 kg/hm2+organic fertilizer 1 800.0 kg/hm2) treatment and B1 (fertilization according to local tobacco farmers habits, chemical fertilizer pure nitrogen 105.0 kg/hm2) ,B5 (chemical fertilizer pure nitrogen 82.5 kg/hm2+organic fertilizer 1 800.0 kg/hm2) showed the worst performance.  [ABSTRACT FROM AUTHOR]