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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.)

【Objective】 Overuse of nitrogen fertilizer is a major source of nonpoint pollution in agricultural production. Reducing nitrogen application and improving nitrogen use efficiency are essential for developing sustainable agriculture. We investigate in this paper the impact of reduced nitrogen fertilization and nitrogen topdressing on physiological traits of buckwheat. 【Method】 The field experiment consisted of six nitrogen fertilizations: applying 100 kg/hm2 of nitrogen as base fertilizer (CK1), applying 70 kg/hm2 of nitrogen as base fertilizer and 30 kg/hm2 of nitrogen for topdressing (CK2), applying 70 kg/hm2 of nitrogen as base fertilizer and 0.25 kg/hm2 of nitrogen in dissolved urea (concentration 1%) for spray-topdressing (CK3), applying 70 kg/hm2 of nitrogen as base fertilizer and 0.25 kg/hm2 of nitrogen in dissolved urea (1% concentration) for spray-topdressing using UAV (T4), applying 70 kg/hm2 of nitrogen as base fertilizer and 0.5 kg/hm2 of nitrogen in dissolved urea (concentration 2%) for spray-topdressing using UAV (T5), applying 70 kg/hm2 of nitrogen as base fertilizer and 1 kg/hm2 of nitrogen in dissolved urea (concentration 4%) for spray-topdressing using UAV (T5). In each treatment, we measured dry matter accumulation, photosynthetic traits, and antioxidant enzyme activity of the crop. 【Result】 ① Aboveground dry matter accumulation increased over time, with the accumulation rate initially increasing and then declining. At the maturity stage, T5 had the highest dry matter accumulation, surpassing other treatments by 16.03%-82.88% in total accumulation and 34.05%-132.05% in accumulation rate. ② Chlorophyll content and net photosynthetic rate varied with treatments, with T5 showing the highest values at maturity stage and CK1 the lowest. ③ Antioxidant enzyme activity exhibited a single-peak trend as the crop matured. At the post-bloom stage, T5 increased superoxide dismutase activity by 1.16%-19.16%, peroxidase activity by 0.49%-35.49%, and catalase activity by 11.89%-51.76%, compared to other treatments, while antioxidant activity in T4 and T5 was comparable. Malondialdehyde content increased with leaf senescence, but their values in T4 and T5 were similar at the maturity stage, 10.99%-19.00% lower than that in other treatments. ④ Compared to other treatments, T5 significantly increased grain number, grain weight per plant, and 1 000-grain weight by 9.65%-80.67%, 5.15%-59.17%, and 9.77%-17.01%, respectively, resulting in a yield increase of 21.66%-140.30%. 【Conclusion】 Applying 70 kg/hm2 of nitrogen as a basal fertilizer combined with a 1%-2% urea solution applied via UAV for foliar spraying is the optimal nitrogen fertilization strategy for buckwheat; it increases dry matter accumulation, enhances antioxidant enzyme activity, prolonges leaf functionality, and improvs photosynthetic efficiency, thereby boosting crop yield.

【Objective】The effects of nitrogen fertilizer reduction on the growth and development, nutrient utilization, yield and quality of flue-cured tobacco were studied, and the feasibility of nitrogen fertilizer reduction was preliminarily clarified, which provided a theoretical basis for the sustainable production of flue-cured tobacco.【Method】Five treatments were set up, including no fertilization (control), conventional nitrogen application, 10% reduction of nitrogen fertilizer, 20% reduction of nitrogen fertilizer and 30% reduction of nitrogen fertilizer. The agronomic traits, economic traits, chemical composition and fertilizer utilization rate of tobacco plants in each treatment were compared and analyzed.【Result】An appropriate amount of nitrogen fertilizer reduction could shorten the growth period of flue-cured tobacco, and significantly increased the plant height, effective leaf number and maximum leaf width. In terms of chemical composition of tobacco leaves, the indexes of reducing sugar content, total nitrogen content and nicotine content of flue-cured tobacco leaves treated with nitrogen fertilizer reduction by 10% were all within the requirements of conventional chemical composition indexes of high-quality flue-cured tobacco in Yunnan. In terms of appearance quality of tobacco leaves, the color of flue-cured tobacco leaves treated with nitrogen fertilizer reduction of 10% and 20% was orange, the structure was loose or still loose, the oil was sufficient, and the appearance quality of tobacco leaves was better. In terms of nitrogen nutrient distribution, the nitrogen content of each part of tobacco plants showed the rule of leaf > stem > root, and the nitrogen content of tobacco leaves was significantly increased under the treatment of 10% nitrogen reduction. In terms of nitrogen use efficiency, after reducing nitrogen application by 10% and 20%, the nitrogen fertilizer utilization rate, agronomic efficiency and partial productivity of nitrogen fertilizer increased by 10.15%, 9.31%, 3.66%, 5.22%, 5.22%, 8.72%, respectively. After reducing nitrogen application by 30%, there was no significant difference between nitrogen fertilizer utilization rate and conventional nitrogen application rate. In terms of economic traits, the yield and output value of flue-cured tobacco increased by 6.47% and 16.18% after reducing nitrogen fertilizer by 10%.【Conclusion】The reduction of nitrogen fertilizer by 10% and 20% significantly affected the agronomic traits, nutrient distribution, chemical composition and economic traits of tobacco plants, however, the reduction of nitrogen fertilizer by 30% had no significant effect on the agronomic traits and economic traits of tobacco plants. The appropriate reduction of nitrogen fertilizer application promoted the growth of flue-cured tobacco, and improved the yield and quality as well as fertilizer utilization rate of flue-cured tobacco.

In order to explore the impact of nitrogen fertilizer reduction on greenhouse gas emissions in paddy fields under the condition of continuous straw return, an eight-year positioning experiment was carried out in the Qianjin Farm Science and Technology Demonstration Park in Heilongjiang Province in 2022. In the experiment, there were seven treatments:straw-free and nitrogen fertilizer application, nitrogen fertilizer application, straw application, straw application and routine nitrogen application, straw application and 10% nitrogen fertilizer reduction, straw application and 20% nitrogen fertilizer reduction, straw application and 30% nitrogen fertilizer reduction, and the greenhouse gas emissions during the rice growing period were compared with straw-free and nitrogen fertilizer application. The results showed that compared with straw and conventional nitrogen fertilizer treatment, the cumulative CO2 emissions were significantly reduced by 20. 00%, 40. 00% and 49. 43%, respectively, in the treatments of straw application and 10% nitrogen fertilizer reduction, straw application and 20% nitrogen fertilizer reduction, straw application and 30% nitrogen fertilizer reduction, the cumulative emissions of CH4 were significantly reduced by 16. 30%, 20. 21% and 28. 80%, and the cumulative emissions of N2O were significantly reduced by 48. 76%, 60. 03% and 67. 74% respectively; The global warming potential was significantly reduced by 37. 75%, 46. 90% and 54. 93%, and the greenhouse gas emission intensity was significantly reduced by 32. 59%, 39. 79% and 51. 51%, respectively. Under the condition of straw return, nitrogen fertilizer reduction will reduce rice yield, and under this experimental condition, nitrogen fertilizer reduction by 10% will reduce greenhouse gas emissions and rice yield will not be greatly affected. [ABSTRACT FROM AUTHOR]

【Objective】The effects of nitrogen fertilizer reduction on the growth and development, nutrient utilization, yield and quality of flue-cured tobacco were studied, and the feasibility of nitrogen fertilizer reduction was preliminarily clarified, which provided a theoretical basis for the sustainable production of flue-cured tobacco.【Method】Five treatments were set up, including no fertilization (control), conventional nitrogen application, 10% reduction of nitrogen fertilizer, 20% reduction of nitrogen fertilizer and 30% reduction of nitrogen fertilizer. The agronomic traits, economic traits, chemical composition and fertilizer utilization rate of tobacco plants in each treatment were compared and analyzed.【Result】An appropriate amount of nitrogen fertilizer reduction could shorten the growth period of flue-cured tobacco, and significantly increased the plant height, effective leaf number and maximum leaf width. In terms of chemical composition of tobacco leaves, the indexes of reducing sugar content, total nitrogen content and nicotine content of flue-cured tobacco leaves treated with nitrogen fertilizer reduction by 10% were all within the requirements of conventional chemical composition indexes of highquality flue-cured tobacco in Yunnan. In terms of appearance quality of tobacco leaves, the color of flue-cured tobacco leaves treated with nitrogen fertilizer reduction of 10% and 20% was orange, the structure was loose or still loose, the oil was sufficient, and the appearance quality of tobacco leaves was better. In terms of nitrogen nutrient distribution, the nitrogen content of each part of tobacco plants showed the rule of leaf > stem > root, and the nitrogen content of tobacco leaves was significantly increased under the treatment of 10% nitrogen reduction. In terms of nitrogen use efficiency, after reducing nitrogen application by 10% and 20%, the nitrogen fertilizer utilization rate, agronomic efficiency and partial productivity of nitrogen fertilizer increased by 10.15%, 9.31%, 3.66%, 5.22%, 5.22%, 8.72%, respectively. After reducing nitrogen application by 30%, there was no significant difference between nitrogen fertilizer utilization rate and conventional nitrogen application rate. In terms of economic traits, the yield and output value of flue-cured tobacco increased by 6.47% and 16.18% after reducing nitrogen fertilizer by 10%.【Conclusion】The reduction of nitrogen fertilizer by 10% and 20% significantly affected the agronomic traits, nutrient distribution, chemical composition and economic traits of tobacco plants, however, the reduction of nitrogen fertilizer by 30% had no significant effect on the agronomic traits and economic traits of tobacco plants. The appropriate reduction of nitrogen fertilizer application promoted the growth of flue-cured tobacco, and improved the yield and quality as well as fertilizer utilization rate of flue-cured tobacco. [ABSTRACT FROM AUTHOR]

[Objective] This study was aimed to test the applicability of the AquaCrop model for simulating the growth and production of drip-irrigated cotton under nitrogen-reducing conditions in the northern border, and to investigate the optimal nitrogen-reducing and irrigation regimes during the reproductive period of cotton. [Methods] Through the field trials in 2022 and 2023, we clarified the effects of four nitrogen application levels (conventional nitrogen application, nitrogen reduction of 10%, nitrogen reduction of 20%, and nitrogen reduction of 30%), and three irrigation schedules (488, 444, and 400 mm) on cotton yield, water and nitrogen use efficiency, and soil nutrient content; we used measured data from the treatments to determine and validate the parameters of the model, and then simulated the model with the calibrated model. Cotton yield and water and nitrogen use efficiencies were simulated with the calibrated model under six combinations of nitrogen application levels (conventional nitrogen application, nitrogen reduction of 6%, nitrogen reduction of 12%, nitrogen reduction of 18%, nitrogen reduction of 24%, and nitrogen reduction of 30%), and six combinations of irrigation levels (300, 360, 420, 480, 540, and 600 mm), and the optimal water and nitrogen combinations were screened out by the comprehensive evaluation method. [Results] Nitrogen reduction and irrigation quota together had a significant effect on cotton yield, water and nitrogen use efficiency and soil nutrients. Nitrogen fertilizer reduction can be achieved by appropriately increasing the irrigation quota to stabilize cotton yield; Under the same nitrogen application, appropriately reducing the irrigation quota improved water use efficiency; Under the same irrigation quota, appropriately reducing the nitrogen application improved nitrogen fertilizer bias productivity; A 10% increase in the conventional irrigation quota (W1N1) when applying conventional nitrogen effectively improved the nutrient content of the tillage layer of the soil. The simulation and measurement results showed that each evaluation index of canopy cover and above-ground biomass of the 2-years experimental treatments satisfied the coefficient of determination (R2)≥ 0.936, the root mean square error (NRMSE) ≤ 40.58%, and the Nash coefficient (ENS)≥ 0.72; And each evaluation index of yield and water-use efficiency satisfied the coefficient of determination R2≥0.87, NRMSE ≤ 4.29%, and ENS≥0.81; The model achieved a better simulation effect. [Conclusion] Based on the scenario simulation under 36 combinations of nitrogen reduction and irrigation, and considering the yield, water and nitrogen utilization efficiency and the actual production cost, the nitrogen reduction irrigation system with 12% nitrogen reduction and 360 mm irrigation quota is recommended to be adopted in the northern border region. The study can provide experience for the application of the AquaCrop model under different fertilizer and irrigation regimes in the future and provide a theoretical basis and scientific guidance for the improvement of water and nitrogen fertilizer use efficiency during cotton cultivation in arid regions.

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board 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.)

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

High-quality japonica rice, distinguished by its unique flavor and enriched nutritional value, has attracted significant attention across Asia. The over-application of nitrogen (N) fertilizers, however, is a growing concern, threatening both the rice quality and the environmental sustainability of its production. This situation calls for a reevaluation and modification of traditional agricultural practices. Our study investigates the effects of reduced N fertilizer use, complemented by foliar fertilizer application, on the physiological attributes and yield of high-quality japonica rice. The aim is to achieve efficient N use and enhanced crop productivity. The experiment employed 'Sujing 1180', a high-quality japonica rice cultivar, utilizing urea as the N source and a comprehensive macronutrient-rich water-soluble fertilizer for foliar application. Five treatments were established: conventional N application (270 kg ha− 1, N100), 10% N reduction (N90), 10% N reduction with foliar application (N90 + FF), 20% N reduction (N80), and 20% N reduction with foliar application (N80 + FF). These treatments were meticulously examined throughout various growth stages. Photosynthetic parameter analysis indicated that N90 + FF significantly boosted the net photosynthetic rate during the heading stage. N80 + FF maintained higher stomatal conductance at the maturity stage, suggesting that foliar fertilizer is effective in enhancing photosynthetic efficiency and stomatal conductance. In terms of N metabolism, N90 + FF notably increased the accumulation of nitrate N during the jointing stage, surpassing other treatments. While N90 and N80 showed reductions in both nitrate and ammonium N levels compared to N100, N90 + FF was particularly effective in elevating nitrate and ammonium N as well as free amino acid concentrations. Regarding N fertilizer efficiency, N90 + FF surpassed N100 across several critical parameters, specifically total N absorption, N recovery efficiency, N agronomic efficiency, and N physiological efficiency. Significantly, N90 + FF showed marked improvements in both N agronomic efficiency and N partial factor productivity. In examining yield and its components, the N90 + FF treatment achieved a higher yield of 9872.48 kg ha− 1, surpassing the 9383.75 kg ha− 1 of N100. N90 + FF had better results in seed-setting rate and average grain number per panicle, with its 1000-grain weight similar to that of N100. The N90 and N80 treatments, however, were less effective in terms of yield and its components. The integrated study findings demonstrate that a strategy incorporating moderate N reduction and foliar fertilizer application markedly optimizes rice photosynthesis, augments N metabolism, and enhances utilization efficiency, leading to increased yields. These insights are valuable for advancing precision agriculture, enhancing japonica rice production efficiency, and promoting sustainable farming. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Soil & Water Conservation (1009-2242) is the property of Institute of Soil & Water Conservation 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] To assess the effects of nitrogen fertilizer reduction and substitution on potato field soil physicochemical properties, potato yield and potato quality in the north foot of Yinshan Mountains in Inner Mongolia. (Methods] The experiment was carried out in Wuchuan dryland experiment station of Inner Mongolia Academy of Agricultural and Animal Husbandry Sciences. Seven treatments were set up, including conventional fertilization (NPK, CK), no nitrogen fertilization (PK), reduced nitrogen fertilization (RN), reduced nitrogen fertilization+water-soluble fertilizer (RN+WF), reduced nitrogen fertilization+ decomposed sheep manure organic fertilizer (RN+SM), reduced nitrogen fertilization+bio-organic fertilizer (RN+BM), and reduced nitrogen fertilization+controlled release urea (RN+RUN). The impacts of reduced nitrogen fertilization and partial substitution of nitrogen fertilizer with different fertilizers on soil bulk density, total porosity, available nutrients, organic matter as well as potato yield and quality were evaluated. [Results] The soil bulk density and total porosity of RN+BM treatment were significantly (P<0.05) higher than other treatments. In comparison with NPK treatment, RN+RUN treatment significantly (P<0.05) elevated the available nitrogen, available phosphorus, and available potassium content in the 10-20 cm soil layer by 1.62%, 2.38% and 1.54%, respectively. RN+BM treatment had the highest increase of organic matter content in the 0-10 cm soil layer, with an increase of 2.45% compared with NPK treatment. RN+BM treatment significantly (P<0.05) improved the potato yield and quality. In comparison with NPK treatment, the potato yield improved by 16.95%, VC, starch, crude protein and reducing sugar content increased by 15.92%,2.96%, 16.26% and 6.67% respectively, and nitrate content decreased by 7.89%. [Conclusion] Reduced nitrogen fertilization+bio-organic fertilizer effectively improved potato field soil physicochemical properties, improved potato yield and quality, was the suitable fertilization pattern for potato cultivation in the north foot of Yinshan Mountains in Inner Mongolia [ABSTRACT FROM AUTHOR]

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

In order to study the comprehensive effects of nitrogen reduction combined with different fertilizer applications on greenhouse gas emissions, nitrogen use efficiency and potato yield, seven treatments were set up: balanced application of nitrogen, phosphorus and potassium fertilizer (NPK, control), no nitrogen fertilizer (PK, blank), reduction of nitrogen application rate by 20% (RN, application rate of phosphorus and potassium fertilizer is the same as NPK), reduction of nitrogen application rate by 20% + water-soluble fertilizer instead of 20% of total nitrogen application rate (RN + WF), reduction of nitrogen application rate by 20% + decomposed sheep manure instead of 20% of total nitrogen application rate (RN + SM), reduction of nitrogen application rate by 20% + bio-organic fertilizer instead of 20% of total nitrogen application rate (RN + BM), reduction of nitrogen application rate by 20% + slow-release urea instead of 20% of total nitrogen application rate (RN + RUN) from 2020 to 2021. Effects of the seven treatments on greenhouse gas emissions from potato fields, global warming potential, yield and nitrogen use efficiency during the potato growing season were researched. The results showed that the reduction of nitrogen fertilizer and the combined application of different fertilizers could obviously affect the emission of greenhouse gases in farmland. In 2020 and 2021, the average emission fluxes of CO2 and N2O in RN + SM treatment were 10.97%-22.70% and 7.86%-14.66% higher than those in NPK treatment. The cumulative emissions of CO2, N2O and CH4 in RN + SM treatment were the largest, which were 9 299.77-11 401.35, 3.65-3.77 and -1.35- -1.20 kg/ha, respectively. The global warming potential (GWP) in RN + SM treatment was 36.10%- 79.66% higher than that in NPK treatment. Nitrogen fertilizer reduction and combined application of different fertilizers could significantly increase potato yield and nitrogen use efficiency (P < 0.05). Compared with NPK treatment, the partial factor productivity of applied nitrogen (PFPN) and nitrogen agronomic efficiency (NAE) in RN + BM treatment were significantly different (P < 0.05), which increased by 46.19%-47.26% and 150.51%-236.38%, respectively, and the yield of potato increased by 16.95%- 17.77% . Therefore, organic manure (sheep manure) could increase greenhouse gas emissions from farmland; biological organic fertilizer replacing part of nitrogen fertilizer could improve nitrogen use efficiency and potato yield, which should be recommended to be popularized and applied in potato production. [ABSTRACT FROM AUTHOR]

Conservation tillage is an important management practice to guarantee soil fertility in degraded Mollisols. It is still unclear, however, whether the improvement and stability of crop yield under conservation tillage can be sustainable with increasing soil fertility and reducing fertilizer-N application. Based on a long-term tillage experi¬ment initiated in Lishu Conservation Tillage Research and Development Station by Chinese Academy of Sciences, we conducted a 15N tracing field micro-plot experiment to investigate the effects of reducing nitrogen application on maize yield and fertilizer-N transformation under long-term conservation tillage agroecosystem. There were four treat¬ments, including conventional ridge tillage (RT), no-tillage with 0% (NT0), 100% (NTS) maize straw mul¬ching, and 20% reduced fertilizer-N plus 100% maize stover mulching (RNTS). The results showed that after a complete cultivation round, the average percentages of fertilizer N recovery in soil residues, crop usage, and gaseous loss were 34%, 50%, and 16%, respectively. Compared with conventional ridge tillage, no-tillage with maize straw mulching (NTS and RNTS) significantly increased the use efficiency of fertilizer N in current season by 10% to 14%. From the perspective of N sourcing analysis, the average percentage of fertilizer N absorbed by crop parts (including seeds, straws, roots, and cobs) to the total N uptake reached nearly 40%, indicating that soil N pool was the main source of N for crop uptakes. In comparison with conventional ridge tillage, conservation tillage significantly increased total N storage in 0-40 cm by reducing soil disturbance and increasing organic inputs, and thus ensured the expansion and efficiency increment of soil N pool in degraded Mollisols. Compared with conven¬tional ridge tillage, NTS and RNTS treatments significantly increased the maize yield from 2016 to 2018. In all, by improving fertilizer nitrogen utilization efficiency and maintaining the continuous supply of soil nitrogen, long-term management of no-tillage with maize straw mulching could achieve a stable and increasing maize yield in three con-secutive growing seasons and simultaneously reduce environmental risks derived by fertilizer-N losses, even under the condition of 20% reduction of fertilizer-N application, and thus actualize the sustainable development of agricul¬ture in Mollisols of Northeast China. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences 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】The effects of different nitrogen application treatments on soil microbial diversity under rice-vegetable rotation were analyzed to provide theoretical support for reducing nitrogen application.【Method】Four treatments of total application of nitrogen fertilizer（T1）, reduced application of nitrogen fertilizer（T2）, combined application of nitrogen fertilizer with organic fertilizer（T3） and no application of nitrogen fertilizer（CK） were set up, and their effects on the structure and diversity of soil fungal and bacterial communities were studied by using high-throughput sequencing technology and bioinformatics methods.【Result】The diversity analysis of soil bacterial and fungal community Alpha showed that the Chao1 index and Observed index of the bacterial community in T1 treatment were lower than that in CK treatment, while the Observed index in T2 and T3 treatments were higher than that in CK treatment, but the difference among treatments was not significant. The bacterial Shannon index and Simpson index of T1, T2 and T3 were higher than those of CK, and the difference was not significant; The Chao1 index and Observed index of the fungal community in T1, T2 and T3 were higher than those in CK, while the Shannon index and Simpson index were lower than those in CK, with no significant difference. The microbial community Beta diversity analysis showed that the soil bacterial community composition of the four treatments was basically similar, but the difference between treatments was not significant.Compared with CK, T1 and T2 treatment, the species composition of fungi in T3 treatment was different to some extent.The four dominant bacteria groups were Proteobacteria, Actinobacteria, Chloronexi and Acidobacteria. The relative abundance of Chloronexi in T2 treatment was the highest, and that of Proteobacteria in T3 treatment was the highest. The relative abundance of Acidobacteria, Actinobacteria and Nitrospira was decreased by nitrogen application.The species composition of fungi was different to some extent.The dominant phyla were Ascomycota, Mortierellomycota and Basidiomycota.T1 treatment increased the relative abundance of Basidiomycota, T2 treatment increased the relative abundance of Mortierellomycota, and T3 treatment was the highest relative abundance of Ascomycota.T2 treatment significantly reduced the relative abundance of Marmoricola; T3 treatment significantly increased the relative abundance of Humicola and Penicillium. Nitrogen treatment significantly reduced the relative abundance of Alternaria.【Conclusion】Under the rice-stemon mustard rotation mode, nitrogen reduction fertilization and nitrogen combined with organic fertilizer both increased the richness of soil bacterial community and decreased the richness of soil fungal community compared with total nitrogen application. There was no significant difference in soil microbial community structure between treatments, and the differences in microbial community diversity were mainly reflected in the significant changes in the relative abundance of Marmoricola, Humicola, Penicillium and Alternaria. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology 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] Under the control measures of biochar and nitrogen reduction, the physical and chemical properties of soil were studied in order to clarify the effect of biochar and nitrogen reduction on the physical and chemical properties of soil. [ Method] Split plot experiments were designed, and with nitrogen fertilizer was the main area; The different magnitude with biological carbon and nitrogen were set up, the breed as the varieties of nitrogen efficiency and inefficiency, Zheng 958 respectively (lh-zd) and jade 508 (XY) first, was deputy district, the soil organic matter content, total nitrogen, available phosphorus and available potassium, conductivity, cation exchange capacity and other indicators were determined. [Result] Under the control measures of biochar combined with nitrogen reduction, the soil total nitrogen, available phosphorus, available potassium, electrical conductivity and soil quality index could be significantly improved, but their effect had no significance on cation exchange. C1 and C3 treatments were beneficial to the accumulation of total nitrogen in the soil, and the total nitrogen content in the rhizosphere soil of high-efficiency nitrogen varieties was more abundant The total nitrogen content of ClZD958 and C3ZD958 were significantly higher than that of the low-efficiency nitrogen varieties of the corresponding treatments (4. 90% and 8. 15% respectively). The content of available phosphorus in ZD958 treated by C2 was significantly higher than that of NHlOl with low nitrogen efficiency, which was 125. 30%, and the content of available phosphorus in ZD958 treated by Cl was significantly higher than that of NH101 with low nitrogen efficiency, which was 25. 23%. The effect of C2 treatment on the accumulation of available potassium in soil was more significant, and the content of available potassium in ZD958 treated by C2 treatment was significantly higher than that of NH101 with low nitrogen efficiency. After biochar application, the electrical conductivity of each treatment was significantly increased, and that of C2 treatment was the most significant Moreover, the rhizosphere soil conductivity of nitrogen efficient cultivars had some advantages over that of nitrogen inefficient cultivars. The electrical conductivity of rhizosphere soil treated with C2ZD958, and ClZD958 were higher than that of ClZD958 6. 87%. The regulation of biochar and nitrogen fertilizer reduction had no significant effect on increasing the cation exchange capacity of soil. [Conclusion] Biochar and nitrogen fertilizer reduction control measures can effectively improve soil quality. The soil quality index of C2 and Cl was the highest, with 0. 746 and 0. 643, respectively. The short-term regulation measures of biochar and nitrogen fertilizer reduction were adopted, which still had a significant effect on soil quality improvement. The combination of biochar 3000 with pure N 300 and 255 kg/hm2 had the most significant effect. [ABSTRACT FROM AUTHOR]

Background Excessive nitrogen (N) application rate with low N use efficiency (NUE) caused a considerable amount of N losses, especially ammonia volatilization (AV). Proper N fertilizer reduction (RN) could significantly reduce AV. However, continuous RN led to a nutrient deficiency in the soil and therefore negatively impacted the NUE and rice yield. Paddy Azolla, a good green manure, is considered as a promising measure to decrease AV and improve NUE and grain yield of rice. However, there is limited information on the integrated effects of RN and Azolla cover on the AV, NUE, and rice yield, especially in the highly fertilized rice-growing systems. Methods The experiment was conducted including eight treatments: the control (without N fertilizer and Azolla cover), Azolla cover without N fertilizer (A), farmer’s N application rate (FN), FN + Azolla cover (FNA), 15% RN from FN (RN15), RN15 + Azolla cover (RN15A). 30% RN from FN (RN30), RN30 + Azolla cover (RN30A). The integrated effects of N fertilizer reduction and Azolla cover on AV, NUE, and rice grain was evaluated. Results RN15A and RN30A substantially reduced total AV by 50.3 and 66.9% compared with FN, respectively, primarily due to the lower surface water ammonia concentrations and pH. RN improved the efficiency of Azolla cover on reducing AV, with 4.1–9.9% higher than for FN. Compared with the FN, RN15A and RN30A enhanced apparent N recovery efficiency (ANRE) by 46.5 and 39.1%, which might be responsible for the lower NH3 emission and the increased total N uptake / total chemical N applied. Furthermore, RN15A and RN30A reduced yield-scaled volatilization by 52.3 and 64.3% than for FN, respectively. Thus, combining 15–30% RN with Azolla cover may be a way to reduce AV and improve ANRE without decreasing rice grain yield.

Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology 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 Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology 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.)

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Fertilizer is extremely essential to increasing the yield of vegetables. However, excessively using fertilizers has had a negative impact on the yield and quality of vegetables as well as soil environment in recent years. Non-heading Chinese cabbage ‘yellow rose’ was applied to determine the influence of organic manure and inorganic fertilizer on the character of rhizosphere soil, the growth and quality of plants. There were five treatments: conventional fertilization (NF), a total nitrogen reduction of 20% (NF20), a total nitrogen reduction of 30% (NF30), a total nitrogen reduction of 20% with 100 kg·667 m−2 bio-organic fertilizer (BNF20) and a total nitrogen reduction of 30% with 200 kg·667 m−2 bio-organic fertilizer (BNF30). The results show that the content of nitrate nitrogen, organic matter in rhizosphere soil treated by BNF20 and BNF30, was significantly enhanced compared with NF. The yield, Vc and soluble protein of plants treated by BNF20 and BNF30 increased by 30.11%, 17.26%, 5.66% and 15.90%, 16.02%, 5.37%, respectively, compared with NF. On the contrary, the nitrate content significantly decreased in plants of BNF20 and BNF30 by 47.87% and 40.98% compared with NF. The significantly positive correlation was observed between nitrate nitrogen content in rhizosphere soil and the yield (p < 0.05). In conclusion, reduced nitrogen with bio-organic fertilizer can improve the yield and quality of ‘yellow rose’ cabbage by improving the quality of rhizosphere soil.

Methane (CH 4) emissions are primarily dependent on the net balance between the activities of methanogens and methanotrophs. Straw returning (straw residue incorporation) and nitrogen (N) fertilizer applications are two of the most frequent agronomic practices applied to ensure rice yield, and they also profoundly affect the behavior of methanogens and methanotrophs. However, the effect of rice straw or its biochar combined with N fertilizer on the activities and compositions of methanogens and methanotrophs is still not well understood, especially in rice root zone soil in coastal saline paddy fields. Moreover, only few studies linking communities and functions of methanogens and methanotrophs are available, resulting in a lack of adequate indicators to predict methane production potential (MPP) or methane oxidation potential (MOP), for improving fertilizer strategies. Here, through quantitative PCR (qPCR), high-throughput sequencing, network analysis and linear regression model, we investigated the response of the abundances, compositions and activities of methanogens and methanotrophs to rice straw or its biochar combined with N fertilizer in rice root zone soil in coastal regions, and explored the relationships between MPP and methanogenic compositions as well as MOP between methanotrophic compositions, respectively. Therefore, a combination of pot and mesocosm experiment was conducted including seven fertilizer treatments: CK, without N fertilizer and rice straw return; SN100, 100 % N plus straw return; SN80, 80 % N plus straw return; SN60, 60 % N plus straw return; BN100, 100 % N plus rice biochar return; BN80, 80 % N plus biochar return; and BN60, 60 % N plus biochar return. Results showed that irrespective of MPP, MOP, or methanogenic and methanotrophic abundance, they all decreased significantly (P < 0.05), with the reduction of N application under the condition of combined straw or biochar with N fertilizer in coastal saline paddy soils. Moreover, compared with straw, biochar could significantly (P < 0.05) reduce MPP and methanogenic abundances, whereas improve MOP and methanotrophic abundances under the same N application rate. The models incorporating mcrA gene copy and soil dissolved organic carbon (DOC) could accurately predict MPP, while MOP was best predicted by a model incorporating pmoA gene copy and NO 3 −-N. The family Methanobacteriaceae and Methanosarcinaceae were dominant in the methanogenic co-occurrence and keystone patterns. Correspondingly, the genera Methylocystis and Metilomonas were dominant in the methanotrophic co-occurrence pattern, and genus Methylocystis was also the keystone members in coastal saline root zone soil of rice. Soil DOC and salinity were the key factors in shaping the methanogenic co-occurrence and keystone patterns, whereas the methanotrophic co-occurrence and keystone patterns were mainly regulated by NO 3 −-N. Furthermore, methanogenic keystone taxa were more suitable for predicting MPP than their co-occurrence pattern. Our findings provide insights into the possibility of key microbial taxa for predicting MPP or MOP for low-carbon production fertilizer application strategies in coastal saline paddy soils. • Fertilization affected the activities, abundances and compositions of methanogens and methanotrophs. • Methanogenic keystone taxa were suitable for predicting MPP. • Combined biochar with N fertilizer facilitated to strengthen associations of methanogens or methanotrophs. • Soil DOC and salinity were the key factors in shaping the methanogenic co-occurrence and keystone patterns. • Methanotrophic co-occurrence and keystone patterns were mainly regulated by NO 3 —N. [ABSTRACT FROM AUTHOR]

Aims: Rhizosphere metabolomics can potentially help us to better understand belowground root-environment interactions that are mediated by root exudation in the rhizosphere. The main goals of the present work were to characterize the pattern of maize root exudation in response to straw-derived biochar (BC) addition and chemical nitrogen (N) fertilizer reduction and to explore the underlying mechanisms.Methods: Two sets of pot experiments were performed independently that involved planting maize in aquic brown soil to which BC was added at dosages of 0 or 5% (w/w, equivalent to 112.5 t ha−1) combined with urea N application at rates of 150 kg ha−1 (100%) or 105 kg ha−1 (70%) for a total of four treatments. Samples containing root exudates were analyzed using nuclear magnetic resonance, and quantitative real-time reverse transcription-PCR (qRT-PCR) was performed to analyze gene expression in maize roots.Results: The 5% BC addition significantly influenced the global rhizosphere metabolome of the maize seedlings regardless of the N application level, but without BC addition, the rhizosphere metabolome was not significantly affected by a 30% reduction in N. The effects of N reduction on the metabolite profiling of the native root exudates were stronger than those of BC addition and an obvious interaction was observed between BC addition and N reduction. BC addition combined with N reduction significantly changed the levels of some amino acids (e.g., causing a 1.75-fold increase in isoleucine) and organic acids (e.g., causing a 2.16-fold increase in malonate and a 2.15-fold increase in acetate) in the root exudates. Soil environmental factors, including the size of NH4+-N pool and total P content, had a strong positive correlation with rhizosphere metabolome. The decrease in root biomass caused by N reduction was partially mitigated by BC addition, and the expression of ZmMATE1 (for multi-drug and toxic compound extrusion transporter) in root was significantly up-regulated (P < 0.05) by BC addition and N reduction.Conclusions: Maize roots can reshape their rhizosphere metabolome under BC addition combined with N reduction and its underlying mechanism may involve the synergistic effects of soil environmental factors, root growth, and the expression of transport-associated genes. [ABSTRACT FROM AUTHOR]

Nitrogen reduction combined with organic fertilizer is of considerable significance for the sustainable development of agriculture. A pot experiment using nitrogen reduction combined with organic fertilizer was conducted to explore the effects of different treatments on matter accumulation, physiological resistance, and fertilizer nitrogen fate in banana seedlings. Compared with conventional fertilization, a 20% reduction of nitrogen did not affect the dry weight, chlorophyll content, physiological resistance, and fertilizer utilization rate of banana seedlings, but significantly reduced the nitrogen leaching loss and increased the nitrogen soil residue. Compared with conventional fertilization, organic nitrogen substituting 20% or 30% of the nitrogen reduced by 20% significantly promoted dry matter accumulation and physiological resistance. Organic nitrogen substituting 30% of the 20% reduction of nitrogen increased the dry matter of the whole plant by 24.94%, the nitrogen uptake in the root by 30.87%, the chlorophyll content by 6.05%, the soluble sugar content by 16.88%, Peroxidase (POD) activity by 26.35%, Catalase (CAT) activity by 27.48%, and Super Oxide Dismutase (SOD) activity by 22.97%. Compared with conventional fertilization, all organic substitution treatments significantly reduced fertilizer nitrogen leaching loss, apparent loss, and increased nitrogen soil residue. Compared with the 20% reduction of nitrogen, organic nitrogen substituting 30% of the 20% reduction of nitrogen significantly increased nitrogen utilization by 16.34% and soil residue rate by 13.26%, and reduced nitrogen leaching loss by 35.46%. The results of the present study revealed that a 20% reduction of nitrogen fertilizer with a 30% organic substitution application promoted matter accumulation, enhanced the physiological resistance of banana seedlings, increased the utilization and residue of nitrogen fertilizer, and reduced nitrogen pollution. • Nitrogen reduction with organic fertilizer increased nitrogen availability. • Nitrogen reduction with organic fertilizer promoted matter accumulation of banana. • Nitrogen reduction with organic fertilizer improved the physiological resistance. • Nitrogen reduction with organic fertilizer reduced nitrogen loss and pollution. [ABSTRACT FROM AUTHOR]

Conservation tillage is an important management practice to guarantee soil fertility in degraded Mollisols. It is still unclear, however, whether the improvement and stability of crop yield under conservation tillage can be sustainable with increasing soil fertility and reducing fertilizer-N application. Based on a long-term tillage experiment initiated in Lishu Conservation Tillage Research and Development Station by Chinese Academy of Sciences, we conducted a 15 N tracing field micro-plot experiment to investigate the effects of reducing nitrogen application on maize yield and fertilizer-N transformation under long-term conservation tillage agroecosystem. There were four treatments, including conventional ridge tillage (RT), no-tillage with 0% (NT0), 100% (NTS) maize straw mul-ching, and 20% reduced fertilizer-N plus 100% maize stover mulching (RNTS). The results showed that after a complete cultivation round, the average percentages of fertilizer N recovery in soil residues, crop usage, and gaseous loss were 34%, 50%, and 16%, respectively. Compared with conventional ridge tillage, no-tillage with maize straw mulching (NTS and RNTS) significantly increased the use efficiency of fertilizer N in current season by 10% to 14%. From the perspective of N sourcing analysis, the average percentage of fertilizer N absorbed by crop parts (including seeds, straws, roots, and cobs) to the total N uptake reached nearly 40%, indicating that soil N pool was the main source of N for crop uptakes. In comparison with conventional ridge tillage, conservation tillage significantly increased total N storage in 0-40 cm by reducing soil disturbance and increasing organic inputs, and thus ensured the expansion and efficiency increment of soil N pool in degraded Mollisols. Compared with conventional ridge tillage, NTS and RNTS treatments significantly increased the maize yield from 2016 to 2018. In all, by improving fertilizer nitrogen utilization efficiency and maintaining the continuous supply of soil nitrogen, long-term management of no-tillage with maize straw mulching could achieve a stable and increasing maize yield in three consecutive growing seasons and simultaneously reduce environmental risks derived by fertilizer-N losses, even under the condition of 20% reduction of fertilizer-N application, and thus actualize the sustainable development of agriculture in Mollisols of Northeast China.

Fertilizer is extremely essential to increasing the yield of vegetables. However, excessively using fertilizers has had a negative impact on the yield and quality of vegetables as well as soil environment in recent years. Non-heading Chinese cabbage 'yellow rose' was applied to determine the influence of organic manure and inorganic fertilizer on the character of rhizosphere soil, the growth and quality of plants. There were five treatments: conventional fertilization (NF), a total nitrogen reduction of 20% (NF20), a total nitrogen reduction of 30% (NF30), a total nitrogen reduction of 20% with 100 kg·667 m−2 bio-organic fertilizer (BNF20) and a total nitrogen reduction of 30% with 200 kg·667 m−2 bio-organic fertilizer (BNF30). The results show that the content of nitrate nitrogen, organic matter in rhizosphere soil treated by BNF20 and BNF30, was significantly enhanced compared with NF. The yield, Vc and soluble protein of plants treated by BNF20 and BNF30 increased by 30.11%, 17.26%, 5.66% and 15.90%, 16.02%, 5.37%, respectively, compared with NF. On the contrary, the nitrate content significantly decreased in plants of BNF20 and BNF30 by 47.87% and 40.98% compared with NF. The significantly positive correlation was observed between nitrate nitrogen content in rhizosphere soil and the yield (p < 0.05). In conclusion, reduced nitrogen with bio-organic fertilizer can improve the yield and quality of 'yellow rose' cabbage by improving the quality of rhizosphere soil. [ABSTRACT FROM AUTHOR]

Background: Excessive nitrogen (N) application rate with low N use efficiency (NUE) caused a considerable amount of N losses, especially ammonia volatilization (AV). Proper N fertilizer reduction (RN) could significantly reduce AV. However, continuous RN led to a nutrient deficiency in the soil and therefore negatively impacted the NUE and rice yield. Paddy Azolla , a good green manure, is considered as a promising measure to decrease AV and improve NUE and grain yield of rice. However, there is limited information on the integrated effects of RN and Azolla cover on the AV, NUE, and rice yield, especially in the highly fertilized rice-growing systems., Methods: The experiment was conducted including eight treatments: the control (without N fertilizer and Azolla cover), Azolla cover without N fertilizer (A), farmer's N application rate (FN), FN + Azolla cover (FNA), 15% RN from FN (RN 15 ), RN 15 + Azolla cover (RN 15 A). 30% RN from FN (RN 30 ), RN 30 + Azolla cover (RN 30 A). The integrated effects of N fertilizer reduction and Azolla cover on AV, NUE, and rice grain was evaluated., Results: RN 15 A and RN 30 A substantially reduced total AV by 50.3 and 66.9% compared with FN, respectively, primarily due to the lower surface water ammonia concentrations and pH. RN improved the efficiency of Azolla cover on reducing AV, with 4.1-9.9% higher than for FN. Compared with the FN, RN 15 A and RN 30 A enhanced apparent N recovery efficiency (ANRE) by 46.5 and 39.1%, which might be responsible for the lower NH 3 emission and the increased total N uptake / total chemical N applied. Furthermore, RN 15 A and RN 30 A reduced yield-scaled volatilization by 52.3 and 64.3% than for FN, respectively. Thus, combining 15-30% RN with Azolla cover may be a way to reduce AV and improve ANRE without decreasing rice grain yield., Competing Interests: The authors declare there are no competing interests., (©2021 Yang et al.)

We explored the impacts of nitrogen (N) reduction and biochar application on soil fertility and nutrient uptake of rice in early and late seasons of 2018 with a field experiment. There were six treatments, including control (no N application, CK), conventional N application (N 100 ), 20% N reduction (N 80 ), 20% N reduction plus biochar application (N 80 +BC), 40% N reduction (N 60 ), 40% N reduction plus biochar application (N 60 +BC). Our results showed that 20% and 40% N reduction and/or with biochar application did not affect soil pH, organic matter, total N, total phosphorous (P), total potassium (K), ammonium N, available P and K in comparison with N 100 treatment. N 80 +BC and N 60 +BC substantially increased soil cation exchange capacity (CEC) at tillering stage and electrical conductivity (EC) at heading stage in late season, respectively. Compared with the treatment with single N reduction, N 80 +BC significantly increased soil available K in early and late seasons and soil pH and total N in late season, while N 60 +BC increased soil total K at mature stage in early season. Soil nitrate content was decreased along with the growth stages for all treatments in early season. Compared with tillering stage, soil nitrate N content in conventional N application at heading stage and mature stage was decreased by 50.0% and 71.6%, respectively. Soil nitrate content in biochar treatment only was decreased by 6.3%-45.5%. N application along with biochar application had no significant effects on plant N uptake and utilization in early season. However, N reduction with biochar application significantly increased plant N uptake and N utilization rate by 34.8%-52.4% in late season, compared to conventional N application and single N reduction. Our findings suggest that adequate N reduction along with biochar application could maintain soil health and improve plant N uptake and utilization efficiency.