Use Of Nitrogen Fertilizers Research Articles

Enhanced growth performance of abi5 plants under high salt and nitrate is associated with reduced nitric oxide levels

Numerous environmental stresses have a significant impact on plant growth and development. By 2050, it is anticipated that high salinity will destroy more than fifty percent of the world's agricultural land. Understanding how plants react to the excessive use of nitrogen fertilizers and salt stress is crucial for enhancing crop yield. However, the effect of excessive nitrate treatment on plant development is disputed and poorly understood; so, we evaluated the effect of excessive nitrate supply and high salinity on abi5 plant growth performance. We demonstrated that abi5 plants are tolerant to the harmful environmental conditions of excessive nitrate and salt. abi5 plants have lower amounts of endogenous nitric oxide than Arabidopsis thaliana Columbia-0 plants due to their decreased nitrate reductase activity, caused by a decrease in the transcript level of NIA2, a gene encoding nitrate reductase. Nitric oxide appeared to have a critical role in reducing the salt stress tolerance of plants, which was diminished by an excess of nitrate. Discovering regulators such as ABI5 that can modulate nitrate reductase activity and comprehending the molecular activities of these regulators are crucial for the application of gene-editing techniques. This would result in the appropriate buildup of nitric oxide to increase the production of crops subjected to a variety of environmental stresses.

Optimum nitrogen improved stem breaking resistance of intercropped soybean by modifying the stem anatomical structure and lignin metabolism

Excessive use of nitrogen fertilizers enhanced the stem lodging, leading to serious threats to environmental sustainability. As the maize-soybean intercropping system is eco-friendly, however, soybean micro-climate hinders soybean growth and caused lodging. Since the relationship between nitrogen and lodging resistance under the intercropping system is not widely studied. Therefore, a pot experiment was conducted with the application of different nitrogen concentrations referring to low nitrogen (LN) = 0 mg/kg, optimum nitrogen (OpN) = 100 mg/kg, and high nitrogen (HN) = 300 mg/kg. To evaluate the optimum nitrogen fertilization under the maize-soybean intercropping system, two soybean cultivars were selected Tianlong 1 (TL-1), (lodging resistant) and Chuandou 16 (CD-16), (lodging susceptible). The results revealed that under the intercropping system, the OpN concentration significantly improved the lodging resistance of soybean cultivars by reducing the plant height of TL-1 and CD-16 by 4 and 28% as compared to LN, respectively. Following OpN, the lodging resistance index for CD-16 was also increased by 67% and 59% under the respective cropping systems. In addition, we found that OpN concentration prompted the lignin biosynthesis by stimulating the enzymatic activities of lignin biosynthetic enzymes (PAL, 4CL, CAD, and POD), which was reflected at the transcriptional levels (GmPAL, GmPOD, GmCAD, Gm4CL), too. Henceforth, we proposed that optimum nitrogen fertilization boosts soybean stem lodging resistance by modulating the lignin metabolism in the maize-soybean intercropping system.

Does Azospirillum brasilense mitigate water stress and reduce the use of nitrogen fertilizers in maize?

Does Azospirillum brasilense mitigate water stress and reduce the use of nitrogen fertilizers in maize?

Evaluating the use of nitrogen and phosphorous fertilization as crop management options for maize adaptation to climate change in the Nigeria savannas

Poor soil fertility and climate variability are major constraints to maize production in the Nigeria savannas. The application of nitrogen (N) and phosphorus (P) as adaptation strategy may enhance maize yield under climate change. In this study, the already calibrated and validated CERES-maize model in DSSAT was used to simulate the response of maize varieties to N and P in three agroecological zones. Similarly, the model, coupled with data for representative concentration pathways (RCP4.5 and RCP8.5) scenarios, was applied to simulate maize yields for mid-century and end-of-century periods and to estimate the effect of use of N and P as a strategy for maize adaptation to climate change. Results of a 30-year sensitivity analysis showed that the optimum grain yields were obtained with application of 150 kg N + 30 kg P ha–1 to the two varieties in Kano and Zaria. In Abuja, the optimum grain yields were obtained with the application of 150 kg N ha–1 + 30 kg P ha–1 to SAMMAZ–15 and 120 kg N ha–1 + 30 kg P ha–1 to SAMMAZ–16. When P is not applied, the simulation results show that across all N rates, maize yield would decrease by 25%–52% and 32%–52% for the mid- and end-of-century, respectively, under RCP4.5 for both varieties. There would be a greater reduction under RCP8.5, with a decrease of 32%–59% and 52%–69% under mid- and end-of-century scenarios, respectively. When P is applied at 30 kg ha−1, the reduction in yield due to climate change is lower. Under RCP4.5, the yield would decrease by 9%–15% and 11%–21% for the mid- and end-of-century, respectively. There would be a reduction of 12%–21% and 32%–41% for mid-century and end-of-century, respectively, under RCP8.5 scenario. This suggests that the application of optimum P could reduce the impact of yield loss due to climate change.

Response of nitrogen use efficiency, N-assimilating enzymes and growth in Cyclocarya paliurus seedlings to different nitrogen nutrition

Cyclocarya paliurus has been used as tea production and medicine in China. In order to identify C. paliurus preference for absorption of nitrogen (N) nutrition and the relationship between C/N ratio and growth, effects of five NO3 −/NH4 + ratio treatments on growth, N absorption and metabolism of C. paliurus seedlings were investigated. Compared to NH4 + as a sole N source, the seedlings supplied with a sole NO3 − source had higher growth rate, percent of nitrogen derived from nitrogen fertilizer (NDFF), N content and nitrogen use efficiency (NUE). However, mixed nitrate-ammonium nutrition improved growth and NUE in C. paliurus seedling, while an equal mixed ratio nutrition induced the highest NDFF and seedling growth. Nitrate reductase (NR) and nitrite reductase (NiR) activities in leaves and roots showed a decreased trend with decreasing NO3 − in growth medium, whereas the highest glutamine synthetase (GS) and glutamate synthase (GOAGT) activities were detected at the equal mixed ratio of NO3 −/NH4 +. Regression analysis showed that activities of the N-assimilated enzymes were positively correlated with NUE and N content in C. paliurus seedlings, but the seedling growth was negatively and significantly correlated with C/N ratio. Our study demonstrated that C. paliurus preferred NO3 − over NH4 + in N nutrition, but an equal mixed ratio of NO3 −/NH4 + would best improve seedling growth and nitrogen use efficiency. This study would provide a basis for manipulating nitrogen fertilization in C. paliurus plantations.

Interaction between nitrogen doses and alfalfa (Medicago sativa L.) incorporation in lettuce (Lactuca sativa L.) production

Objective: To determine the optimal nitrogen dose combined with alfalfa in the growth, yield, and ion concentration in the sap of the lettuce leaf. Design/Methodology/Approach: We used a completely randomized experimental design, with a 2×5 factorial arrangement and nine repetitions in each treatment. The treatments consisted of five nitrogen doses (200, 250, 300, 350, and 400 kg ha-1) and two soil conditions (with and without alfalfa). Results: Aerial fresh weight (AFW), aerial dry weight (ADW), end-to-end diameter of the shoot (EDS), maximum diameter of the shoot (MDS), shoot weight (SW), and yield were higher when a 200-300 kg ha-1dose of N was applied along with alfalfa. This application had a similar effect to the 300 kg dose of N ha-1, applied without the addition of alfalfa. The concentration of nitrates (NO3-) in the sap decreased with the addition of alfalfa and 200 kg of N ha-1. The concentration of potassium (K+) was higher with or without the addition of alfalfa and 250 kg of N ha- 1. The concentration of calcium (Ca2+) was higher in the plants that received a 400-kg dose of N ha-1, whether alfalfa was included or not. Study Limitations/Implications: The lack of equipment prevented the determination of the nitrogen available in the soil. Findings/Conclusions: The incorporation of alfalfa into the soil is a good alternative to improve lettuce production and reduce the use of nitrogen fertilizers.

Highly Sensitive Graphene-Based Electrochemical Sensor for Nitrite Assay in Waters.

The importance of nitrite ions has long been recognized due to their extensive use in environmental chemistry and public health. The growing use of nitrogen fertilizers and additives containing nitrite in processed food items has increased exposure and, as a result, generated concerns about potential harmful health consequences. This work presents the development of an electrochemical sensor based on graphene/glassy carbon electrode (EGr/GC) with applicability in trace level detection of nitrite in water samples. According to the structural characterization of the exfoliated material, it appears as a mixture of graphene oxide (GO; 21.53%), few-layers graphene (FLG; 73.25%) and multi-layers graphene (MLG; 5.22%) and exhibits remarkable enhanced sensing response towards nitrite compared to the bare electrode (three orders of magnitude higher). The EGr/GC sensor demonstrated a linear range between 3 × 10-7 and 10-3 M for square wave voltammetry (SWV) and between 3 × 10-7 and 4 × 10-4 M for amperometry (AMP), with a low limit of detection LOD (9.9 × 10-8 M). Excellent operational stability, repeatability and interference-capability were displayed by the modified electrode. Furthermore, the practical applicability of the sensor was tested in commercially available waters with excellent results.

Usage of agricultural inputs in sugarcane producers of the ejido Jaeros, state of veracruz, México

Objective: in this research, we assessed the level of organic inputs usage in contrast to chemical inputs in sugarcane producers at the ejido Jareros, Veracruz, in the municipality of Ursulo Galvan.
 Design/methodology/approach: Through surveys, a descriptive statistical analysis was conducted on the main socioeconomic aspects of the sugarcane producers in the ejido and an analysis of the means significance of the level of usage of agricultural inputs (chemical / organic) divided into five variables: pesticides, fungicides, acaricides, fertilizers and weed control.
 Results: The significance value of the five variables analyzed was: pesticides (p=0.1774); fungicides (P = 0.2090); acaricides (0.3625); fertilizers (P = 0.0005) and weed control (P = 1.0000).
 Limitations on study/implications:
 Findings/conclusions: Based on the significance values and mean difference of the five assessed variables, it is concluded that the excessive use of nitrogenous fertilizers is the factor with the greatest potential to negatively impact the environmental and edaphic deterioration of arable soils in the Jareros ejido, State of Veracruz, Mexico.

Improving nitrogen fertilizer use efficiency and minimizing losses and global warming potential by optimizing applications and using nitrogen synergists in a maize-wheat rotation

Nitrogen (N) is the key nutrient for crop growth in most agricultural systems, but excessive N fertilizer applications have led to very large ammonia (NH3) and greenhouse gas (GHG), especially nitrous oxide (N2O), emissions, resulting in severe air pollution and making a major contribution to global warming. To clarify the effects of improved N management on NH3 and N2O emissions and crop production, a 2-year field experiment was carried out in a maize-wheat rotation in the North China Plain (NCP), testing four optimized N management practices including reducing the fertilizer (urea) N rate and using N ‘synergists’ with the fertilizer. NH3 emissions were significantly reduced only by the urease inhibitor (UI) LIMUS®, with an average reduction of 66.9 % relative to emissions from the untreated urea. At the same N rate, N2O emissions were reduced by 30.8–76.7 % by all the synergists (UI, a nitrification inhibitor DMPP (NI) and urea with a bacterial agent (UB)), and crop yields were improved by 14.4 % and 15.2 % under the UI and UB treatments, respectively. An 15N tracer experiment showed that using N synergists decreased the total N loss by 10.9–58.7 %, and significantly increased the recovery efficiency of N (REN) by 16.9–44.8 % over the whole rotation. Reducing the N rate reduced the GWP and yield-scaled GWP (GHGI) by 10.6 % and 8.4 %, respectively. Using the N synergists, GHGI was significantly decreased by 19.2–26.7 % (P < 0.05), while GWP was reduced by 13.2–18.1 % only by the application of DMPP or LIMUS®. Overall, the study showed that reducing N2O and NH3 emissions is important for increasing N utilization and mitigating global warming. Reducing N rate and using synergists can address the joint problems of environmental pollution and agricultural efficiency. In particular, the application of the optimal amount of urea (33% reduction over rates typically applied by farmers) amended with the urease inhibitor LIMUS® to maize-wheat rotations in the NCP proved to be the most effective method for the ‘green’ and sustainable development of agriculture and the mitigation of global warming in that region of China.

Quantitative Analysis of Source-Sink Relationships in Two Potato Varieties under Different Nitrogen Application Rates

Nitrogen is an essential nutrient for plant growth. However, the excessive use of nitrogen fertilizers not only increases production cost, but also has negative a impact on the environment. The purpose of this study was to quantify the source-sink characteristics and length of each growth stage in two potato varieties under different nitrogen application rates. This clarifies the source-sink coordination characteristics of the nitrogen-efficient variety and the source-sink coordination mechanisms of high nitrogen use efficiency (NUE). Field experiments were conducted in 2019, 2020, and 2021 using a split-plot design, with a nitrogen application rate of (0; 150 kg·ha−1; 300 kg·ha−1) as the main plot and variety (J, nitrogen-efficient variety Jizhang 12; Y, nitrogen-inefficient variety Youjia 70) as the subplot. The results showed that the yield and NUE of Jizhang 12 at 300 kg·ha−1 were, on average, 90.73% and 75.15% higher than those of Youjia 70, respectively. The NUE and nitrogen utilization efficiency of Jizhang 12 increased on average, with decreasing N application at 68.66% and 24.53%, which were higher than those of Youjia 70 at 62.89% and 10.86%. Quantitative analysis of the source and sink showed that the Jizhang 12 had a higher source and sink capacity of 23.45 g and 51.85 g, respectively, and the maximum source and sink activity was on average 0.28 g·plant−1·d−1 and 1.47 g·plant−1·d−1 higher, and the growth period of the source and sink was on average 24 days and 7 days longer, respectively. On the basis of these results, the nitrogen-efficient varieties had a higher yield base and a smaller reduction in NUE with reduced N application. In terms of source-sink growth, N-efficient varieties lasted longer at the seedling and tuber initiation stages, when potatoes grew above ground and source organs grew for longer periods, providing a solid foundation for later sink growth, as evidenced by their higher source-sink activity, capacity, and growth time than N-inefficient varieties.

Grain yield and protein content in different ripening varieties of soft winter wheat using various types and doses of fertilizers

Purpose. To study of yield formation and protein content in the grain of different ripening varieties of soft winter wheat under the condition of using various types and doses of fertilizers. Methods. Field and laboratory (determination of protein content), calculation (collection of protein), mathematical and statistical. Results. It was found that different fertilization systems reliably increased the grain yield of soft winter wheat. The use of N75 increased this indicator by 1.2 times and N150 by 1.4 times in the varieties studied, compared with the no-fertilizer variant. Yield with incomplete return of phosphorus-potassium fertilizer was only 2–3% lower than with complete mineral fertilizer. With the nitrogen-phosphorus and nitrogen-potassium fertilization systems, the yield was 5–7% higher than with the nitrogen system. At the same time, this indicator was 6% lower than in the full mineral fertilizer version of the trial. The use of 75 kg/ha nitrogen fertilizer per year increased the protein content to 13.5%, or by 10% compared to the control. In the double dose nitrogen fertilizer variant, the protein content increased to 14.2% or by 15%. The use of nitrogen fertilizers with phosphorus-potassium only contributed 2–4% to the increase of this indicator. Cultivation of winter wheat under the condition of application of N75 increased the collection of protein up to 724 kg/ha or by 33%, and with a double dose of nitrogen fertilizer – up to 848 kg/ha or by 55% compared to the option without fertilizer. In the N75P30K40 variant, protein yield increased by 10% compared to the nitrogen system. The application of a complete mineral fertilizer (N150P60K40) increased this indicator by 12%. Conclusions. It was found that the use of N75P30K40 increased the grain yield of soft winter wheat by up to 5.9 t/ha, or 7%, compared to the option where only 75 kg/ha of nitrogen fertilizer was applied. Yield development in soft winter wheat varies considerably from variety to variety. For example, this indicator was 35% higher in the ‘KWS Emil’ variety than in the ‘Prino’ line. In addition, the grain yield of both varieties is reliably influenced by the weather conditions during the growing season. The protein content of soft winter wheat varies considerably depending on the variety and the weather conditions. When growing soft winter wheat varieties, the protein content can vary by 12.8–15.1%. Weather conditions during the growing season can change this indicator by 13.1–14.7%. The protein content index in the grain of the ‘Prino’ line is significantly higher than that of the ‘KWS Emil’ variety. According to the protein yield per hectare indicator, the ‘KWS Emil’ variety (896 kg/ha) has a significant advantage over the ‘Prino’ line (774 kg/ha).

Dynamics of phytoplankton functional groups in river-connected lakes and the major influencing factors: A case study of Dongting Lake, China

Identifying the drivers that impact phytoplankton biomass and dynamics of functional groups (FGs) is crucial to the management of lake aquatic systems. To explore the interactive effects of hydrological characteristics, physicochemical parameters and phytoplankton FGs in the largest river-connected lake, a case study was carried out at Dongting Lake, China. We analyzed the changes in the hydrological characteristics of the lake as well as in the phytoplankton biomass throughout the year to explore the driving factors that influence phytoplankton FGs. Four periods were defined in our study based on water level (WL) fluctuations including the rising periods (RⅠ and RⅡ) and the falling periods (FⅠ and FⅡ). The phytoplankton biomass in Dongting Lake was the highest in RⅡ, followed by RⅠ, FⅠ, and FⅡ. And the trend of FGs dominance through the four periods were P/MP/D (RⅠ) → P/MP/J (RⅡ) → MP (FⅠ) → MP/P/Y (FⅡ). Changes in phytoplankton biomass and FGs were the result of a combination of hydrological characteristics and physicochemical parameters. Throughout the water period, the hydrological characteristics did not directly influence phytoplankton, instead exerting a more indirect effect on phytoplankton biomass and FGs by affecting the water’s physicochemical parameters, e.g., permanganate index (CODMn), nitrogen nutrients, dissolved oxygen (DO), water temperature (WT), and conductivity (Cond). CODMn might be a significant predictor of phytoplankton biomass and FGs in all water periods, explaining 36.6% of the variability, followed by Cond, WT, ammonia nitrogen (NH4+-N), and DO explaining 17.6%, 12.3%, 11.3%, and 7.2%, respectively. However, according to each water phase analysis, the WL was the key factor for phytoplankton growth in RⅡ. Nitrogen nutrients, WT and Cond had more pronounced effects on phytoplankton in RⅠ, FⅠ and FⅡ, respectively., Based on the findings of our study, we suggest that increased control of organic matter input into the lake and nitrogen fertilizer use at nearby agricultural surface sources are effective actions that are needed to prevent and control algal blooms in Dongting Lake.

A better use of fertilizers is needed for global food security and environmental sustainability

The massive use of fertilizers during the last decades allowed a great increase in the global capacity of food production. However, in the last years, several studies highlight the inefficiency and country asymmetries in the use of these fertilizers that generated environmental problems, soil nutritional imbalances and not optimal food production. We have aimed to summarize this information and identify and disentangle the key caveats that should be solved. Inadequate global management of fertilization produces areas with serious nutrient deficits in croplands linked with insufficient access to fertilizers that clearly limit food production, and areas that are overfertilized with the consequent problems of environmental pollution affecting human health. A more efficient use of nitrogen (N), phosphorus (P) and potassium (K) fertilizers for food security while preserving the environment is thus needed. Nutrient imbalances, particularly the disequilibrium of the N:P ratio due to the unbalanced release of N and P from anthropogenic activities, mainly by crop fertilization and expanding N-fixing crops that have continuously increased the soil N:P ratio, is another issue to resolve. This imbalance has already affected several terrestrial and aquatic ecosystems, altering their species composition and functionality and threatening global biodiversity. The different economic and geopolitical traits of these three main macronutrient fertilizers must be considered. P has the fewest reserves, depending mostly on mineable efforts, with most of the reserves concentrated in very few countries (85% in Morocco). This problem is a great concern for the current and near-future access to P for low-income countries. N is instead readily available due to the well-established and relatively low-cost Haber–Bosch synthesis of ammonium from atmospheric N2, which is increasingly used, even in some low-income countries producing an increasing imbalance in nutrient ratios with the application of P and K fertilizers. The anthropogenic inputs of these three macronutrients to the environment have reached the levels of the natural fluxes, thereby substantially altering their global cycles. The case of the excess of N fertilization is especially paradigmatic in several areas of the world, where continental water sources have become useless due to the higher nitrate concentrations. The management of N, P and K fertilizers is thus in the center of the main dichotomy between food security and environmentally driven problems, such as climate change or eutrophication/pollution. Such a key role demands new legislation for adopting the well-known and common-sense 4R principle (right nutrient source at the right rate, right time and right place) that would help to ensure the appropriate use of nutrient resources and the optimization of productivity.

Nitrogen and potassium in biomass production and water use efficiency of irrigated wheat cv. BRS 394 in Cerrado

The objective of this study was to evaluate the influence of nitrogen and potassium levels in biomass production and efficiency in water consumption of wheat BRS 394 in brazilian Cerrado. The experiment consisted of fractioned factorial combination of five levels of (N): (0, 70, 140, 210 and 280 kg ha−1) and five levels of potassium (K): (0, 50, 100, 150 and 200 kg ha−1), randomized block design and four replications. The shoot biomass, the number of spikelets per ear and the efficiency of water use for biomass production were evaluated as a function of the N and K levels used in the present study. Analysis of variance at 5% and 10% was performed using F test for the surface response model and when not significant to the first and second degree regression using the R software. The combination of N(238 kg ha−1) and K(97 kg ha−1) increased spikelet yield per spike (15.5), during 2019 harvest. The fertilization with N(115 and 125 kg ha−1) in an isolated way guaranteed maximum shoot biomass yield(5827 kg ha−1) and wheat water use efficiency (32.9 g L−1), during 2018 harvest, respectively. The N provided isolated increases in number of spikelets per spike in 2018 harvest, as well as for shoot biomass and water use efficiency in 2019. The main use of nitrogen fertilization and its combination with potassium provide gains in the production of shoot biomass and water use efficiency of wheat BRS 394 in brazilian Cerrado.

Using spatially variable nitrogen application and crop responses to evaluate crop nitrogen use efficiency

Low nitrogen use efficiency (NUE) is ubiquitous in agricultural systems, with mounting global scale consequences for both atmospheric aspects of climate and downstream ecosystems. Since NUE-related soil characteristics such as water holding capacity and organic matter are likely to vary at small scales (< 1 ha), understanding the influence of soil characteristics on NUE at the subfield scale (< 32 ha) could increase fertilizer NUE. Here, we quantify NUE in four conventionally managed dryland winter-wheat fields in Montana following multiple years of sub-field scale variation in experimental N fertilizer applications. To inform farmer decisions that incorporates NUE, we developed a generalizable model to predict subfield scale NUE by comparing six candidate models, using ecological and biogeochemical data gathered from open-source data repositories and from normal farm operations, including yield and protein monitoring data. While NUE varied across fields and years, efficiency was highest in areas of fields with low N availability from both fertilizer and estimated mineralization of soil organic N (SON). At low levels of applied N, distinct responses among fields suggest distinct capacities to supply non-fertilizer plant-available N, suggesting that mineralization supplies more available N in locations with higher total N, reducing efficiency for any applied rate. Comparing modelling approaches, a random forest regression model of NUE provided predictions with the least error relative to observed NUE. Subfield scale predictive models of NUE can help to optimize efficiency in agronomic systems, maximizing both economic net return and NUE, which provides a valuable approach for optimization of nitrogen fertilizer use.

Isotopic tracing of nitrogen source and interaction between surface water and groundwater of a small valley plain in the Zhangxi watershed

Identifying the mechanism for circulation of nutrient elements in the hydrological cycle is crucial for protection of water resource quality. In this study, 72 surface water and 21 groundwater samples were collected in three seasons for hydrochemical and multiple isotopic (δD-H2O, δ18O–H2O, δ15N–NO3−, and δ18O–NO3−) analysis in the Zhangxi watershed, a small valley plain in the southeastern Yangtze River Delta. The hydrochemical type in surface water and shallow groundwater was Ca–HCO3, and the δD and δ18O isotope values were similar. Thus, the hydraulic connection and its material interaction were similar. Quantitative evaluation of the mass balance model showed that shallow groundwater accounted for more than 90% of surface water in the dry season but only 33.0% in the wet season. On the average, nitrate in shallow groundwater was mainly derived from organic fertilizer, whereas nitrate in surface water was mainly sourced from soil nitrogen and chemical fertilizer carried by surface runoff. At the time scale, the nitrogen sources of surface water showed seasonal variation owing to the interaction between surface water and groundwater. The contribution of organic fertilizer in the wet season was approximately 16.2%, but in the dry season increased to 32.3% and exceeded that of chemical fertilizer (24.6%). Shallow groundwater contributed more to surface water in the dry season, and transferred more nitrogen from organic fertilizer to surface water, so that they had similar nitrate sources. At the space scale, nitrate sources of surface water differed significantly with the land use types. The NO3− and δ15N–NO3− concentrations of the surface water in the mid-valley plain and downstream were significantly higher than in the natural forest area upstream, indicating the increased contribution of organic fertilizer. Agricultural activities and the interaction between surface water and groundwater in the valley plain area have a significant impact on nitrogen pollution. Reduction in nitrogen fertilizer use and establishment of a riparian protection zone are crucial to protect the water resource quality.

Availability of Nitrogen in Soil for Irrigated Cotton Following Application of Urea and 3,4-Dimethylpyrazole Phosphate-Coated Urea in Concentrated Bands.

Low nitrogen (N) fertilizer use efficiency for irrigated cotton has been attributed to the limited ability of tap roots to access N from concentrated subsurface bands, or the preferential root uptake of microbially-mineralized dissolved organic N. This work investigated how applying high-rate banded urea affects the availability of N in soil and the capacity of cotton roots to take up N. Soil was analyzed for water-extractable total dissolved N and inorganic N species after urea or urea coated with 3,4-dimethylpyrazole phosphate (DMPP) was applied at concentrations of 261, 455, 461, and 597 mg N kg-1 of (air-dry) soil (mean bulk density: 1.01 g cm-3). A mass balance was used to compare N applied as fertilizer and in unfertilized soil (supplied N) with the N recovered from soil within the cylinders (recovered N) at five plant growth phases. Root uptake was estimated by comparing ammonium-N (NH4-N) and nitrate-N (NO3-N) in soil sampled from within cylinders with soil sampled from immediately outside. Recovered N was up to 100% above supplied N within 30 days of applying urea above 261 mg N kg-1 of soil. Significantly lower NO3-N in soil sampled from immediately outside the cylinders suggests urea application stimulates cotton root uptake. The use of DMPP-coated urea prolonged high NH4-N in soil and inhibited the mineralization of released organic N. These results imply the release of previously sequestered soil organic N within 30 days of applying concentrated urea enhances the availability of NO3-N in the rhizosphere, reducing N fertilizer use efficiency.

Organic fertilizer substitutions maintain maize yield and mitigate ammonia emissions but increase nitrous oxide emissions.

Organic fertilizer can improve soil structure and enhance the nutrient content in soil and is beneficial to sustainable agricultural development. However, the influence of organic fertilizer substitutions on NH3 and N2O emissions from farmland is unclear. Thus, we set up an organic substitution field experiment in Northeast China. The experiment included six treatments: single application of chemical fertilizers (NPK: 250kg N ha-1); NO10, 10% reduction in chemical nitrogen fertilizers (225kg N ha-1) + chicken manure (25kg N ha-1); NO20, 20% reduction in chemical nitrogen fertilizers (200kg N ha-1) + chicken manure (50kg N ha-1); NO30, 30% reduction in chemical nitrogen fertilizers (175kg N ha-1) + chicken manure (75kg N ha-1); NO40, 40% reduction in chemical nitrogen fertilizers (150kg N ha-1) + chicken manure (100kg N ha-1); and no-nitrogen fertilizer (CK). This experiment investigated the effects of partial substitution of chemical nitrogen fertilizer with organic fertilizer on NH3 and N2O emissions and nitrogen use efficiency in a maize field. The results showed that, compared with chemical N, organic fertilizer mitigated NH3 volatilization but promoted the soil N2O total emissions during the whole growth stage. NH3 cumulative volatilization decreased with the increase in the substitution rate of organic fertilizer. Compared with the NPK treatment, the cumulative volatilization of NH3 in the NO30 and NO40 treatments decreased by 15.24 and 17.92%, respectively. The NO40 treatment had the highest N2O emission in the whole growth stage, and the N2O emission of the NO40 treatment increased by 10.72% compared to the NPK treatment. Moreover, the yield, partial factor productivity (PFP), nitrogen harvest index (NHI), and apparent nitrogen recovery efficiency (NRE) of NO30 treatment were the highest of all treatments, and the yields, PFP, plant N accumulation, grain N accumulation, and the cumulative emissions of NH3 and N2O were similar to N20 treatment. In conclusion, nitrogen fertilizer use efficiency was enhanced, decreasing environmental pollution from livestock under organic fertilizer substitution conditions. We suggested 20% or 30% substitution rates of organic fertilizer were proper.

Effect of Nitrogen Fertilization on Tree Growth and Nutrient Content in Soil and Cherry Leaves (Prunus cerasus L.)

Nitrogen fertilization ensures the proper growth of trees. The aim of the study was to evaluate the impact of differentiated nitrogen fertilization on selected parameters. It was assumed that such analysis is an indirect picture of the needs of cherries grown in herbicide fallow. The content of minerals in two layers of the soil, in leaves, and its influence on tree growth, and the content of chlorophyll in leaves were assessed. The experiments were carried out in three different cherry orchards. Three levels of fertilization were applied in each orchard: 0 kg, 60 kg, and 120 kg N ha−1. As expected the fertilization resulted in an increase in the content of nitrate and ammonium forms of nitrogen in the soil, however, their content was also dependent on precipitation and temperature. Additionally, high nitrogen fertilization increased the content of phosphorus and potassium and decreased the magnesium in the topsoil layer. High nitrogen fertilization caused the decreased content of phosphorus and potassium in the leaves. The level of calcium and magnesium in leaves increased with fertilization of 60 kg N ha−1 but decreased with the dose to 120 kg N ha−1. The use of nitrogen fertilization increased the vegetative growth of trees measured by leaf area and trunk cross-sectional area. However, the chlorophyll content was not dependent on the amount of nitrogen fertilization. Based on the results, it can be concluded that 60 kg N ha−1 is the optimal dose, ensuring proper nutrition of cherry trees.

Chinese Violet Cress (Orychophragmusviolaceus L.) Yield and Nitrogen Balance in Response to Coupling Effects of Water–Nitrogen Application—A Case Study Using 15N Tracing Technique

The accurate and efficient management of water and nitrogen is of significance for the intensive production of field-cultivated flowers. To investigate the effects of different irrigation and nitrogen application modes on the growth, development, and nitrogen use of Orychophragmus violaceus, three nitrogen application doses of 120, 160, and 200 kg/ha and three irrigation treatments of 50 + 30 mm (overwintering water and regreening water), 75 + 45 mm, and 100 + 60 mm were implemented. The 15N isotope tracing technique was used to investigate the fertilizer nitrogen use, soil nitrogen residue, and nitrogen balance of Orychophragmus violaceus, and the entropy weight coefficient evaluation model was employed to optimize the water and nitrogen strategy. Results showed that after the application of water and nitrogen, the fresh yield of Orychophragmus violaceus increased by 21.4–49.3%, W2N3 possessed the most obvious effect on promoting yield increase, and the fresh yield reached 31.1 t/ha. The highest plant nitrogen use efficiency (39.1%) was detected in W2N2, but no significant (p &gt; 0.05) difference of nitrogen use efficiency was found between W2N2 andW3N2. After the peak flowering period, 23.8–39.1% of the fertilizer nitrogen was absorbed by the plants, 44.3–59.2% remained in the soil, and 13.7–21.6% was lost via deep seepage, a gaseous state, or other unknown ways. A higher application amount of water or nitrogen increased the risk of nitrogen loss. Among the treatments, W2N2 treatment has the highest entropy weight coefficient evaluation value of 0.905, indicating that W2N2 was the water–nitrogen coupling mode with optimal comprehensive benefits. It was recommended that 75 mm of overwintering water and 45 mm of regreening water combined with a 160 kg/ha nitrogen application amount is the suitable water and nitrogen regulation scheme for Orychophragmus violaceus.