Losses Of Fertilizer Nitrogen Research Articles

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

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

The dynamic relation between fertilization, precipitation and the diffusion of agricultural non-point pollution in Hainan Island

With the increasing demand for crops, the excessive application of fertilizers has gradually become a significant factor affecting water quality. Therefore, studying the relationship between agricultural fertilizer runoff and water quality is crucial for the sustainable development of agricultural production. The present study sets up a new dynamic model of nitrogen fertilizer loss, introducing variables such as precipitation, fertilization application during dry and rainy seasons, and their lagged and interaction terms. The paper analyzed the issue of fertilizer runoff under the complex interactions of various factors, including spatial and temporal scales and climatic conditions, and explored the relationship between agricultural activities and water quality changes in the context of sustainable development. Due to Hainan Island’s independent river system, which is free from transboundary pollution, and its low level of industrial pollution, it provides an excellent sample for assessing the impact of agricultural non-point source pollution on water quality. Based on watershed monitoring data from Hainan Island, this study draws the following conclusions: 1. Precipitation exhibits a pronounced seasonal influence on total nitrogen concentration. 2. Nitrogen fertilizer enters into water bodies through precipitation, resulting in a lag effect on total nitrogen concentration. 3. The influence of grain and tropical crops on nitrogen loss is less significant, while cash crops will trigger the nitrogen overloading of rivers in scenarios where they account for a high proportion of the planting structure of the sown area.

Effect of ridge-furrow with plastic mulching and organic amendment on fertilizer-N fate in maize-soil system: A 15N isotope tracer study

The implementation of ridge-furrow with plastic film mulching has the potential to enhance crop yields and water productivity, particularly in black soil regions. However, the synergistic impacts of combining ridge-furrow with plastic mulching alongside with various organic amendments on maize yield and nitrogen fertilizer utilization efficiency remain unclear. Using 15N-labeled tracing technology, we investigated fertilizer-N recovery of maize, distribution, fertilizer-N residual in soil, and nitrogen fertilizer loss across six treatments: non-mulched flat with non-organic amendment (FN), non-mulched flat with straw amendment (FS), non-mulched flat with biochar amendment (FBC), ridge-furrow with plastic mulching without organic amendment (RN), ridge-furrow with plastic mulching with straw amendment (RS), and ridge-furrow with plastic mulching with biochar amendment (RBC). The results revealed that ridge-furrow with plastic mulching in comparison to non-mulched flat, led to a significant increase in maize dry biomass accumulation, yield, and the rate of fertilizer-N recovery in maize (NRE) by 8.57%–12.36%, 10.08%–15.13%, and 2.22%–3.18%, respectively. The rate of fertilizer-N residual in soil (NSR) and fertilizer-N loss (NLS) decreased by 0.5%–2.04% and 0.78%–3.21%, respectively. In addition, the straw and biochar amendments under different planting methods promoted NRE in plants and NSR in soil, reducing NLS. Compared with non-organic amendment treatments, the inclusion of straw and biochar amendments resulted in increased NRE and NRS by 1.64%–6.20% and 0.12%–2.18%, while NLS decreased by 1.76%–7.78%. Biochar amendment treatment exhibited significantly higher nitrogen accumulation and NRE compared to the straw amendment treatment. Overall, ridge-furrow with plastic mulching combined with biochar amendment proved to be an effective method to enhance nitrogen fertilizer utilization of maize in the black soil regions, improving both yield and nitrogen fertilizer utilization efficiency.

Modeling canopy water content in the assessment for rainfall induced surface and groundwater nitrate contamination: The Bilate cropland sub watershed

Nitrate contamination in surface and groundwater remains a widespread problem in agricultural watersheds is primarily associated to high levels of percolation or leakage from fertilized soil, which allows easy infiltration from soil into groundwater. This study was aimed to predict canopy water content to determine the nitrate contamination index resulting from nitrogen fertilizer loss in surface and groundwater. The study used Geographically Weighted Regression (GWR) model using MODIS 006 MOD13Q1-EVI Earth observation data, crop information and rainfall data. Satellite data collection was synchronized with regional crop calendars and calibrated to plant biomass. The average plant biomass during observed plant growth stages was between 0.19 kg/m2 at the minimum and 0.57 kg/m2 at the maximum. These values are based on the growth stages of crops and provide a solid basis for monitoring and validating crop water productivity data. The simulation results were validated with a high correlation coefficient (R2 = 0.996, P < 0.0005) for the observed rainfall in the growing zone compared to the predicted canopy water content. The nitrate contamination index assessment was conducted in 2004, 2008, 2009, 2010, 2011, 2013, 2014, 2015, 2018 and 2020. Canopy water content and root zone seasonal water content were measured in (%) per portion as indicators of the NO−3-N-nitrate contamination index in these years (0.391, 0.316, 0.298, 0.389, 0.380, 0.339, 0.242, 0.342 and 0.356).

Rapid and Inexpensive Assay for Testing the Efficiency of Potential New Synthetic Nitrification Inhibitors

The microbial conversion of ammonia to nitrite in soils involves three enzymatic steps. Nitrification inhibitors (NIs) are designed to inhibit ammonia monooxygenase (AMO), the enzyme performing the initial oxidation of ammonia to hydroxylamine, to mitigate excessive nitrogen fertilizer losses in agricultural systems. Because the efficiency of the current commercial NIs is highly unreliable, novel, better performing compounds need to be developed. Previously, time-consuming soil incubation studies were required as the first step to test new potential NIs. We present here a simple and cost-efficient colorimetric assay that has been developed for the rapid assessment of the efficiency of new synthetic NIs to identify the most promising compounds for subsequent soil studies. This protocol enables screening of the inhibitor activity of multiple compounds at the same time with high reproducibility and can be manipulated to determine pH and temperature-dependent effects on NIs.

Effects of Synthetic Nitrogen Fertilizer and Compost Chicken Manure on Ammonia (NH3) Volatilization in Winter Wheat System

The volatilization of ammonia is an important nitrogen (N) loss path in agricultural production, which not only results in a loss of economy, but also represents a significant atmospheric pollutant. Volatized ammonia (NH 3 ) from livestock manure and cropping field is associated with ecosystem and public health and can also be an indirect source of greenhouse gases. The rate of ammonia volatilization after application of fertilizers is strongly affected by many factors such as soil properties, temperature as well as the type, application time and mode of nitrogen fertilizers. This work aimed to quantify the losses of N by volatilization of ammonia from synthetic nitrogen fertilizer and composted chicken fertilizer in the volatilization of ammonia (NH 3 ) in winter wheat system by the calibrated Dräger-Tube method. An experiment of four treatments Control (CK), Farmer’s compound fertilizer-NPK (CF), Chicken manure compost (25%) + Urea (75%) (MF) and Chicken manure compost (CM) was conducted, with wheat culture in Baizhai County, Quzhou County, Hebei province, following a delineation of casualized blocks, with three repetitions. The daily variation of the ammonia volatilization flow was not dramatically influenced by the type of fertilizer and its combination, ranging from 0.01 to 0.23 mg N m -2 h -1 in base fertilization and 0.03 to 0.44 mg N m -2 h -1 in topdressing fertilization. The results showed that the cumulative losses of volatilization of NH 3 were significantly affected (P≤ 0.05) by the type of fertilizer and its combination. The cumulative volatilization losses of NH 3 in the treatments CM, CF, MF were 14.30 kg N/ha, 21.58 kg N/ha and 25.79 kg N/ha corresponding to 5.72 %, 8.63%, 10.32 % of the total application rates of N, respectively. Emissions factors of Ammonia were highly variable depending on the type of fertilizer or combination of fertilizer. The results showed that wheat yield has been substantially improved by the application of fertilizers alongside organic fertilizers, with the maximum yield achieved in the combination of synthetic and organic fertilizer of about 10.79 t/ha, whereas the isolated organic and synthetic fertilizer (NPK) was not significantly different at around 10.3 t/ha and 10.4 t/ha respectively. Synthetic and organic fertilizers combined proportions with chemical fertilizers have significantly different performance in the volatilization of ammonia, emissions factors and crop yields. Chicken manure can be applied alone or in combination with 75% chemical nitrogen (urea) to achieve the yield of the similar crop or more as with chemical fertilizer alone, and thus reducing the excessive use of chemical fertilizer and the gaseous loss of nitrogen fertilizer, thus being economically beneficial and environmentally sound. Keywords: Manure; Synthetic fertilizer; Winter wheat; Yield; Ammonia DOI: 10.7176/JBAH/12-10-02 Publication date: May 31 st 2022

Effects of drought at different growth stages and nitrogen application on nitrogen absorption and utilization in peanut

<p id="C3">The aim of this study was to clarify the effects of drought at different growth stages and nitrogen application on nitrogen absorption and utilization of peanut. We investigated the effects of nitrogen application on nitrogen absorption and utilization efficiency under different water conditions in peanut by the ¹⁵N-label technique. The residue and loss rate of nitrogen in soil after peanut harvest were also studied. The soil water treatments were three levels of well-watered conditions (WW, 75%-80% of field capacity), slight water stress at flowering-pegging stage (FD, 55%-60% of field capacity), and slight water stress at pod-setting stage (PD, 55%-60% of field capacity). Nitrogen treatments were three levels of no nitrogen application (LN), moderate nitrogen (MN, 90 kg hm^-2), and high nitrogen (HN, 180 kg hm^-2). The results showed that peanut yield was decreased under drought stress at different growth stages and the reduction of drought stress at flowering-pegging stage was greater than that at pod-setting stage. Nitrogen accumulation of peanut kernel accounted for 68.42%-77.67% of the total nitrogen accumulation of the whole plant. Compared with the well-watered condition, nitrogen accumulation of peanut plants was decreased under drought stress at both flowering-pegging and pod-setting stages. Compared with WWMN treatment, FDMN treatment significantly increased the accumulation of Ndff and ¹⁵N in different organs and promoted the transport of nitrogen to seed kernel in peanut. However, ¹⁵N accumulation in kernel was significantly decreased under PDMN treatment. The recovery rate of ¹⁵N labeled nitrogen fertilizer was 30.20%-38.42%, the residue rate was 37.12%-48.83%, and the loss rate was 12.75%-32.68%. The recovery rate of nitrogen fertilizer was the highest and the loss rate was the lowest under FDMN treatment. In summary, nitrogen application level of 90 kg hm^-2could promote the yield and nitrogen absorption and utilization under drought stress, and reduce the loss of fertilizer nitrogen in peanut.

Drip Irrigation Reduced Fertilizer Nitrogen Loss from Lettuce Field—A Case Study Based on 15N Tracing Technique

Nitrogen losses under different irrigation modes have been evaluated by many studies, yet it is not very clear whether the lost N sources are from the soil or fertilizer. In order to quantitatively investigate the effects of different irrigation modes on fertilizer N loss, we used the 15N-labeledurea (15N abundance of 19.6%) as fertilizer and the lettuce (Lactuca sativa var. angustana iris) as the plant material to conduct a field experiment under three different lower limits of drip irrigation, including 75% (DR1), 65% (DR2) and 55% (DR3), accounting for the field water capacity. A furrow irrigation treatment (FI) with the same irrigation regime as DR2 was used as the control. The fate and balance of 15N under these treatments were studied. The results showed that, after the lettuce harvest, 36.9–48.8% of the applied fertilizer 15N remained in 0–80-cm soil, 32.6–39.4% was absorbed by plants, and 18.6–26.3% was lost via pathways such as volatilization or leaching. Under the same irrigation regime, 15N loss caused by FI (26.3%) was significantly (p &lt; 0.05) higher than that byDR2 (18.9%). Moreover, FI increased the amount of total 15N, mineral 15N and organic 15N in the deeper soil layers (60 cm depth and below), leading to a potential risk of 15N leaching. The soil 15N residue was relatively lower under DR1, while the crop-absorbed 15N or 15N loss was atthe highest level among the three drip irrigation treatments. The correlation analysis results showed that increasing the total irrigation amount or increasing the irrigation frequency might increase the 15N loss. We concluded that using drip irrigation instead of furrow irrigation with controlling the lower irrigation limit at 65% is conducive to improving crop 15N utilization and reducing 15N loss from lettuce fields.

Impact of a transformation from flood to drip irrigation on groundwater recharge and nitrogen leaching under variable climatic conditions

The sustainability of agriculture in the Mediterranean climate is challenged by high irrigation water demands and nitrogen fertilizer losses to the environment, causing significant pressure on groundwater resources and groundwater-dependent ecosystems. Advanced irrigation technologies and improved fertilizer management have been promoted as key solutions to reduce the agricultural impact on aquatic systems. However, it remains unclear how different irrigation-fertilizer practices perform on the long-term under a highly variable climate, such as the Mediterranean one. Here, we conduct hydrological simulations over a fifty-year period to quantify the magnitude and dynamics of groundwater recharge and nitrogen leaching under five real-case irrigation-fertilizer practices observed in Valencia (eastern Spain). The Valencian Region is the largest citrus-producing region of Europe and current irrigation-fertilizer practices reflect the ongoing transformation of irrigation systems from flood to drip irrigation. Our simulations highlight three major implications of the irrigation transformation for groundwater resources. First, the transformation from flood to drip irrigation reduces the recharge fraction (19% vs. 16%) and especially the nitrogen leaching fraction (33% vs. 18%) on the long term. Second, the long-term performance of the two irrigation practices is subject to substantial inter-annual differences controlled by precipitation variability. The sensitivity of recharge and nitrogen leaching to annual meteorological conditions is stronger in drip irrigation, which eventually leads to a similar performance of flood and drip irrigation in wet years if fertilizer inputs are similar. Third, we identify a pronounced year-to-year nitrogen memory in the soil, whereby an enhanced (decreased) nitrogen leaching is observed after anomalously dry (wet) years, affecting the performance of irrigation-fertilizer practices. Overall, the study demonstrates the highly variable nature of the performance of irrigation-fertilizer practices, and the major findings can guide future efforts in designing sustainable water management strategies for agricultural areas with a Mediterranean climate.

Effects of free air temperature increase on nitrogen utilization of rice in northeastern China

<p id="C3">Northeastern China is one of the regions where are experiencing the most significant global warming trend. Revealing the effects of anticipated warming on nitrogen absorption and utilization of rice in northeastern China can provide reference for regional sustainable production of rice and optimal management of nitrogen fertilizer. In this study, the field and pot experiments were setup based on free air temperature increase (FATI) system in Harbin, Heilongjiang province during 2019 to 2020, combined with ¹⁵N isotope tracer technique, to investigate the effects of anticipated warming (+1.5℃) on rice yield, nitrogen utilization, and the fate of fertilizer nitrogen. The results showed that warming treatment (W) promoted rice above-ground dry-matter accumulation. The mean grain yields in field and pot experiments during 2019 and 2020 under warming treatment were higher by 10.4% and 10.8% than those under control (CK), respectively. Compared with CK, the mean total nitrogen uptake of two years under W treatment significantly increased by 21.3%, however, the nitrogen utilization efficiency of rice grains showed a decreased trend. Under W treatment, the nitrogen absorbed from fertilizer decreased significantly, while the nitrogen absorbed by rice from soil increased by 31.1%, resulting in the reduction of 12.5% in fertilizer nitrogen recovery rate and the increase of 14.2% in fertilizer nitrogen loss rate. Overall, warming tended to increase rice grain yield, but decreased the proportion of fertilizer nitrogen uptake by plant, which leading to the decrease in nitrogen use efficiency and the significant increase in nitrogen loss rate. Under the background of climate warming, it was suggested to reasonably increase the transplanting density of rice to make full use of the positive effect of global warming on rice yield, as well as appropriately reduce the amount of nitrogen fertilizer application and optimize the management of nitrogen fertilizer operation to improve the nitrogen use efficiency of rice.

Application of biochar-coated urea controlled loss of fertilizer nitrogen and increased nitrogen use efficiency

BackgroundThe use of biochar-based N fertilizers have been considered among the most effective strategy for reducing nitrogen loss and improving nitrogen use efficiency (NUE). However, effect and mechanism of biochar-coated urea (BCU) controlling the loss of nitrogen from soil and NUE are rarely reported.MethodologyIn this study, a 65-d culture pot experiment of oilseed rape was used to investigate the impact of BCU on nitrogen leaching, ammonia volatilization, soil nitrogen concentrations, soil pH, nitrogen uptake, NUE and oilseed rape biomass as compared with urea and urea combined with biochar at same nitrogen level.ResultsResults showed that the application of BCU could minimize nitrogen loss mainly by reducing nitrate leaching loss; which could be attributed to the slow-release performance of BCU, followed by biochar induced adsorption/fixation of nitrogen due to the porous nature and surface functional groups of biochar. However, the application of BCU enhanced ammonia volatilization due to the increase of soil NH4+–N concentration and pH value of microenvironment around urea by BCU. The application of BCU increased NUE by about 20% when compared with urea, since BCU reduced losses of nitrogen fertilizer and increased concentration of nitrogen in the soil as well as nitrogen uptake in oilseed rape. Furthermore, the reduction of nitrogen application by 20% when BCU served as a nitrogen source not only reduced nitrogen loss but significantly improved NUE, with no negative effect on the biomass of oilseed rape.ConclusionBCU can serve as a promising control release nitrogen fertilizer for reducing loss of nitrogen and increasing NUE. However further investigations are required to validate the dosage-effect relationship of BCU on crop yield at the field scale.

The fate of urea

Context Organic amendments (OAs) from agricultural and non-agricultural industries provide an alternative source of nitrogen (N) and other nutrients for crop production, especially with increasing costs of synthetic fertilisers. Aims This study examined the fate of urea in combination with OA in the form of raw mill mud, composted mill mud and high N compost in a maize field experiment on a sandy loam soil in a rain-fed subtropical environment. Methods OAs (346 kg N ha−1) were incorporated at sowing with 15N labelled urea (200 kg N ha−1) applied 28 days later, including a no OA control. Key results Grain yield, aboveground biomass and roots were not significantly different across all treatments, averaging 8.1, 17.4 and 1.3 t ha−1 at harvest. Total N uptake was 249.1 kg N ha−1 (on average) with fertiliser, native soil N and OAs sources accounting for 49.5, 44 and 6.5% of the total N uptake respectively. There was no significant difference in N fertiliser recovery between the OA treatments and the unamended control, with 61.7 and 3.7% of the applied N recovered in the plant and soil (to 100 cm), respectively, at harvest. Nitrogen fertiliser losses were equivalent to 33.6% of the applied N and were attributed to N leaching after extensive rainfall events late in the growing season. Conclusions OAs with high mineral and/or organic N content at time of application can supply significant amounts of plant available N but high levels of soil mineral N at sowing may hinder their full potential. Implications Reducing N loss and cost, and improving overall soil fertility by replacing synthetic N fertilisers with OAs may contribute to more environmentally sustainable crop production.

Nitrogen Uptake and Use Efficiency of Wheat (&amp;lt;i&amp;gt;Triticum aestivum &amp;lt;/i&amp;gt;L.) Varieties as Influenced by Combined Application of Vermicompost and Nitrogen Fertilizer Rate

Crop management strategies that improve nitrogen use efficiency and increase profits while reducing the detrimental effects on the environment due to loss of nitrogen fertilizer. A study was conducted in 2019 cropping season to evaluate effectiveness of vermicompost, N fertilizer and their combinations in improving nitrogen uptake and nitrogen use efficiency at Holeta Agricultural Research Center. The experiment was designed in a split- split-plot combination with wheat varieties (Wane and Danda’a) as main plots, four vermicompost rates (0, 2.5, 5 and 7.5 t ha^-1) as sub-plot and four N fertilizer rates (0, 23, 46 and 69 kg N ha^-1) as sub-sub plot with three replications. Synergistic nutrient interaction effect sourced from vermicompost and urea fertilizer brought positive influence on wheat nitrogen uptake and use efficiency. The highest (154.33 kgha^-1) total nitrogen uptake was obtained from combined application of Wane variety together with 5 t ha^-1 vermicompost and 46 kgha^-1 of nitrogen fertilizer while the lowest value (33.21kgha^-1) was obtained from control plot. Maximum grain nitrogen use efficiency (93.45 kg kg^-1) was recorded from plot that received Wane variety with 23 kg N ha^-1 and the value decreased as vermicompost and N fertilizer level increased while the lowest (29.63 kg kg^-1) value was obtained when Danda’a variety used with vermicompost at 7.5t ha^-1 and 69 kg ha^-1nitrogen fertilizer. Similarly, the highest nitrogen apparent recovery efficiency (111.42%) and agronomic efficiency (42.59 kg kg^-1) were observed in treatment that received Wane variety with combined application of vermicompost at 5 t ha^-1 and nitrogen at 46 kg ha^-1 while the lowest value was respectively obtained from Danda’a variety with nitrogen at 69 kg ha^-1 and Danda’a variety with vermicompost at 2.5t ha^-1. The maximum (72.64%) N harvest index was recorded from variety Wane when applied with combination of vermicompost at 2.5t V ha^-1 and nitrogen at 46kgha^-1, but the minimum (61.98%) value was recorded from application of vermicompost at 7.5tha^-1. Therefore, integrated use of variety, vermicompost and nitrogen fertilizer is found to be better in enhancing nitrogen fertilizer efficiency and reducing environment problems.

Comparison of Novel and Established Nitrification Inhibitors Relevant to Agriculture on Soil Ammonia- and Nitrite-Oxidizing Isolates.

Nitrification inhibitors (NIs) applied to soil reduce nitrogen fertilizer losses from agro-ecosystems. NIs that are currently registered for use in agriculture appear to selectively inhibit ammonia-oxidizing bacteria (AOB), while their impact on other nitrifiers is limited or unknown. Ethoxyquin (EQ), a fruit preservative shown to inhibit ammonia-oxidizers (AO) in soil, is rapidly transformed to 2,6-dihydro-2,2,4-trimethyl-6-quinone imine (QI), and 2,4-dimethyl-6-ethoxy-quinoline (EQNL). We compared the inhibitory potential of EQ and its derivatives with that of dicyandiamide (DCD), nitrapyrin (NP), and 3,4-dimethylpyrazole-phosphate (DMPP), NIs that have been used in agricultural settings. The effect of each compound on the growth of AOB (Nitrosomonas europaea, Nitrosospira multiformis), ammonia-oxidizing archaea (AOA; “Candidatus Nitrosocosmicus franklandus,” “Candidatus Nitrosotalea sinensis”), and a nitrite-oxidizing bacterium (NOB; Nitrobacter sp. NHB1), all being soil isolates, were determined in liquid culture over a range of concentrations by measuring nitrite production or consumption and qPCR of amoA and nxrB genes, respectively. The degradation of NIs in the liquid cultures was also determined. In all cultures, EQ was transformed to the short-lived QI (major derivative) and the persistent EQNL (minor derivative). They all showed significantly higher inhibition activity of AOA compared to AOB and NOB isolates. QI was the most potent AOA inhibitor (EC50 = 0.3–0.7 μM) compared to EQ (EC50 = 1–1.4 μM) and EQNL (EC50 = 26.6–129.5 μM). The formation and concentration of QI in EQ-amended cultures correlated with the inhibition patterns for all isolates suggesting that it was primarily responsible for inhibition after application of EQ. DCD and DMPP showed greater inhibition of AOB compared to AOA or NOB, with DMPP being more potent (EC50 = 221.9–248.7 μM vs EC50 = 0.6–2.1 μM). NP was the only NI to which both AOA and AOB were equally sensitive with EC50s of 0.8–2.1 and 1.0–6.7 μM, respectively. Overall, EQ, QI, and NP were the most potent NIs against AOA, NP, and DMPP were the most effective against AOB, while NP, EQ and its derivatives showed the highest activity against the NOB isolate. Our findings benchmark the activity range of known and novel NIs with practical implications for their use in agriculture and the development of NIs with broad or complementary activity against all AO.

Characteristics of uptake, residual and loss of nitrogen fertilizer in winter wheat after rice stubble

To promote the rational application of nitrogen fertilizer in winter wheat after rice stubble, the effects of nitrogen application rate (0, 150, 225, 300 kg·hm-2, expressed as N0, N150, N225, N300) on nitrogen recovery, residue, loss and grain yield were examined using field 15N tracer technology. The results showed that with the increases of application rate, nitrogen accumulation from different sources significantly increased while nitrogen recovery significantly decreased. The accumulation of basal nitrogen in plants reached the peak during overwintering stage to jointing stage, while the accumulation of topdressing nitrogen peaked between jointing to flowering stage. At maturity, nitrogen accumulation of the top fertilizer was higher than that of the base fertilizer. Plant nitrogen accumulation from soil under N150 was higher than that from nitrogen fertilizer, but with an opposite tendency under N225 and N300. With the increases of nitrogen application rate, the residual nitrogen in the 0-100 cm soil layer in the maturing stage significantly increased, while the residual nitrogen ratio in the 60-100 cm soil layer gradually increased. In the whole growth period of wheat, both nitrogen loss and loss ratio were positively correlated with nitrogen application rate. The nitrogen loss of base fertilizer reached the highest during sowing to overwintering stage, while the nitrogen loss of top fertilizer was at the peak from jointing to flowering period. Taking grain yield into consideration, N225 treatment was the proper application rate for winter wheat after rice stubble, with grain yield being 6735 kg·hm-2, and the nitrogen fertilizer recovery rate, soil residue rate and loss rate being 42.6%, 34.0% and 23.3%, respectively.

Nitrogen transformation and losses in soil: A cost-effective review study for farmer

Environmental and economic issues have increased the necessity to know better understand the role and fate of nitrogen (N) in crop production systems. Nitrogen is the nutrient most often deficient for crop production in India, and its use can result in substantial economic return for farmers. Losses of nitrogen from the soil and plant system not only reduce soil fertility and plant yield but can also create adverse impacts on the environment. Nitrogen fertilizer useful to crops is partially lost through different mechanisms, including ammonia volatilization, de-nitrification, and leaching. These losses may cause environmental problems like polluting the atmosphere, aquatic systems, and groundwater. However, losses can be reduced a considerable extent by various techniques. Research has been conducted in whole world to minimalize nitrogen fertilizer losses. This paper reviews this information on nitrogen fertilizer losses, indicating management practices for minimizing these losses from the soil‐water system.

Losses of fertilizer nitrogen after a winter fertilization in three managed pine plantations of the southeastern United States

AbstractLosses of fertilizer nitrogen (N) were compared between urea and urea treated with the urease inhibitor N‐(n‐Butyl) thiophosphoric triamide (urea + NBPT) after a surface application in winter at three thinned mid‐rotation (age 15–20 years) loblolly pine plantations in Virginia, South Carolina, and Florida. Treatments were labeled with 15N and applied to open chamber microcosms in January and February 2016. Fifteen days after application, microcosms were removed from the field to determine fertilizer N lost from each microcosm. Losses following fertilization with urea (24% to 50%) were greater (p ≥ .05) at all sites compared to urea + NBPT (12% to 22%). Fertilizer N losses were greater in Florida than in SC and Virginia although N loss following urea fertilization was still 25% in Virginia. The loss of fertilizer N was consistently lower on beds compared to interbeds for both urea (bed = 25%, interbed = 40%) and urea + NBPT (bed = 12%, interbed = 23%). This research highlights the value of using urea + NBPT to reduce fertilizer N losses after a winter application and the greater potential loss in the interbed on wetter sites.

Variability in Winter Wheat (Triticum aestivum L.) Grain Yield Response to Nitrogen Fertilization in Long-Term Experiments

ABSTRACTCrop nitrogen (N) use is always affected by the variability in production environment. Dataset (2001 to 2014) from long-term winter wheat (Triticum aestivum L.) experiments at Lahoma and Stillwater, Oklahoma was used. Both experiments have a randomized complete block design with four replications, and fertilizer N was applied as urea pre-plant. Responsiveness of grain yield to maximum fertilizer N rate (112 kg ha−1 – Lahoma; 135 kg ha−1 – Stillwater) was compared with that from check plot (0 kg ha−1). The objective was to determine the relative influence of environment, management, and variety on winter wheat grain yield. The combined analysis of variance indicated that the main effect of year, treatment, location, and variety accounted for 29.3%, 21.2%, 3.1%, and 22.6%, respectively of the variance terms. Over the study period, the non-responsiveness of winter wheat to fertilizer N accounted for 29% and 23% of grain yield at Lahoma and Stillwater, respectively where yield at maximum N rate did not significantly differ from check plot. This highlights the importance of random changes in a crop production environment and its influence in dictating the response to applied N fertilizer. Nitrogen fertilizer losses could be reduced by adopting in-season variable N application techniques.

Crop production kept stable and sustainable with the decrease of nitrogen rate in North China Plain: An economic and environmental assessment over 8 years

In pursuit of maximum grain yield farmers in the North China Plain usually apply excessive N fertilizer, resulting in wasted resources and environmental pollution. To assess the economic and environmental performances of different nitrogen rates will be conductive to sustain cleaner crop production. An 8-year field experiment was carried out with four treatments, N0 (0 kg ha−1 for winter wheat and summer maize), N1 (168 kg ha−1 for winter wheat and 129 kg ha−1 for summer maize), N2 (240 kg ha−1 for winter wheat and 185 kg ha−1 for summer maize) and N3 (300 kg ha−1 for winter wheat and summer maize), on the double cropping at Dawenkou research field (36°11’N, 117°06’E), Shandong Province, China. The crop production, soil physical-chemical parameters, and greenhouse gas emission are measured and the economic and environmental performances are assessed. The optimal nitrogen rate obtained the highest grain yield of summer maize in 4 of 8 year and was equivalent to conventional N rate in the other years. The nitrogen partial factor productivity and agronomic efficiency of optimal nitrogen rate was 63% and 58% higher than that of conventional nitrogen rate. The optimal nitrogen rate effectively decreased soil bulk density and increased weight percentage of water-stable aggregate and activities of urease and invertase compared to conventional nitrogen rate, which improved soil productivity. The fertilizer nitrogen loss and global warming potential of optimal nitrogen rate reduced by 76% and 35% compared to conventional nitrogen rate. The annual greenhouse gas intensity of optimal nitrogen rate decreased by 14–35% compared to others. The net ecosystem economic budget under optimal nitrogen rate is 252–604 $ ha−1 yr.−1 higher than other addition levels. The optimal nitrogen rate produces more grains and obtains higher economic and environmental benefits.

High temporal resolution measurements of ammonia emissions following different nitrogen application rates from a rice field in the Taihu Lake Region of China

Ammonia emission is one of the dominant pathways of nitrogen fertilizer loss from rice fields in China. It is difficult to measure ammonia emissions by high-frequency sampling with the chamber methods widely used in China, which is of great significance for investigating the environmental effects on the ammonia emissions. The chamber methods also can not accurately determine the ammonia emissions. In this study, the backward Lagrangian stochastic dispersion model, with ammonia concentrations continuously measured by the open-path tunable diode laser absorption spectroscopy technique, was used to determine ammonia emissions from a rice field after fertilizer application at excessive (270 kg N ha−1) and appropriate (210 kg N ha−1) rates in the Taihu Lake Region of China. High temporal resolution measurements of ammonia emissions revealed that high intraday fluctuations of ammonia emissions were significantly affected by the meteorological conditions. Multiple regression analysis showed a dominant solar radiation dependence of intraday ammonia emission cycles, especially during the rice panicle formation stage. The NH4+-N concentrations of the surface water of the rice field were found to be the decisive factor that influenced interday dynamics of ammonia emissions. Accurate quantifications of ammonia emissions indicated that the total ammonia losses under appropriate nitrogen application rate were 27.4 kg N ha−1 during the rice tillering stage and 11.2 kg N ha−1 during the panicle formation stage, which were 29.4% and 17.0% less than those under traditional excessive nitrogen application rate used by the local farmers, respectively. The ammonia loss proportions during the rice panicle formation stage were significantly lower than those of the tillering stage, which might be due to different nitrogen application rates and environmental effects during the two stages. This study indicated that the open-path tunable diode laser absorption spectroscopy technique could facilitate the investigation of high temporal resolution dynamic of ammonia emissions from farmland and the environmental influence on the ammonia emissions.