Search Results (35)

Nitrogen (N) fertilizer management in winter wheat production faces challenges from volatilization losses and sub-optimal application strategies. This is particularly problematic in the Southern Great Plains, where environmental conditions during top-dressing periods favor N losses. This study evaluated the effects of a fertilizer placement method, enhanced-efficiency fertilizers, and application timing on grain yield and protein concentration (GPC) across six site-years in Oklahoma (2016–2018). Treatments included broadcast applications of untreated urea and SuperU^® (urease/nitrification inhibitor-treated urea). These were compared with subsurface placement using single-disc and double-disc drilling systems, applied at 67 kg N ha⁻¹ during January, February, or March. Subsurface placement increased the grain yield by 324–391 kg ha⁻¹ compared to broadcast applications at sites with favorable soil conditions. However, responses varied significantly across environments. Enhanced-efficiency fertilizers showed limited advantages over untreated urea. Benefits were most pronounced during February applications under conditions favoring volatilization losses. Application timing effects were more consistent for GPC than for the yield. Later applications (February–March) increased GPC by 0.8–1.2% compared to January applications. Treatment efficacy was strongly influenced by soil pH, equipment performance, and post-application environmental conditions. This indicates that N management benefits are highly site-specific. These findings demonstrate that subsurface placement can improve nitrogen use efficiency (NUE) under appropriate conditions. However, success depends on matching application strategies to local soil and environmental factors rather than adopting universal recommendations. Full article

There are discrepancies regarding the effectiveness of enhanced efficiency nitrogen (N) fertilizer (EENF) products on ammonia loss from unincorporated, surface applications of urea-based fertilizers. Soil properties and management practices may account for the differences in the performance of EENF. However, few studies have investigated the performance of urea- and urea ammonium nitrate (UAN)-based EENF on soils with contrasting properties. Controlled-environment incubation experiments were conducted on two soils with different properties to evaluate the efficacy of urea and UAN forms of EENF to minimize ammonia volatilization losses. The experiments were set up as a completely randomized design, with seven treatments replicated four times for 16 days. The N treatments, which were surface-applied at 134 kg N ha⁻¹, included untreated urea, untreated UAN, urea+ANVOL^TM (urease inhibitor product), UAN+ANVOL^TM, environmentally smart nitrogen (ESN^®), SUPERU^® (urease and nitrification inhibitor product), and urea+Excelis^® (urease and nitrification inhibitor product). In this study, urea was more susceptible to ammonia loss (24.12 and 26.49% of applied N) than UAN (5.24 and 16.17% of applied N), with lower ammonia volatility from soil with a pH of 5.8 when compared to 7.0. Urea-based EENF products performed better in soil with a pH of 5.8 compared to the soil with pH 7.0, except for ESN, which was not influenced by pH. In contrast, the UAN-based EENF was more effective in the high-pH soil (7.0). Across both soils, all EENFs reduced cumulative ammonia loss by 32–91% in urea and 27–70% in UAN, respectively, when compared to their untreated forms. The urea-based EENF formulations containing both nitrification and urease inhibitors were the least effective among the EENF types, performing particularly poorly in high-pH soil (pH 7.0). In conclusion, the efficacy of EENF is dependent on soil pH, N source, and the form of EENF. These findings underscore the importance of tailoring EENF applications to specific soil conditions and N sources to optimize N use efficiency (NUE), enhance economic returns for producers, and minimize environmental impacts. Full article

The denitrification process is the main process of the soil nitrogen (N) cycle in paddy fields, which leads to the production of large amounts of nitrous oxide (N₂O) and increases N loss in paddy soil. Plant-derived bio denitrification inhibitor procyanidins are thought to inhibit soil denitrification, thereby reducing N₂O emissions and soil N loss. However, the denitrification inhibition effect of procyanidins in paddy soils with high organic matter content remains unclear, and their high price is not conducive to practical application. Therefore, this study conducted a 21-day incubation experiment using low-cost proanthocyanidins (containing procyanidins) and paddy soil with high organic matter content in Northeast China to explore the effects of proanthocyanidins on N₂O emissions and related microorganisms in paddy soil. The results of the incubation experiment showed that the application of proanthocyanidins in paddy soil in Northeast China could promote the production of N₂O in the first three days but inhibited the production of N₂O thereafter. Throughout the incubation period, proanthocyanidins inhibited the enzyme nitrate reductase (NaR) activity and the abundance of nirS and nirk denitrifying bacteria, with a significant dose-response relationship. Although the application of proanthocyanidins also reduced the soil nitrate nitrogen (NO₃⁻-N) content, the soil NO₃⁻-N content increased significantly with increasing incubation time. In addition, the application of proanthocyanidins increased soil microbial respiration, ammonia-oxidizing archaea (AOA) amoA gene abundance, and soil ammonium nitrogen (NH₄⁺-N) content. Therefore, the application of proanthocyanidins to paddy soil in Northeast China can effectively regulate denitrification. However, in future studies, it is necessary to explore the impact of proanthocyanidins on the nitrification process and use them in combination with urease inhibitors and/or nitrification inhibitors to better regulate soil N transformation and reduce N₂O emissions in paddy soil. Full article

Improving nitrogen use efficiency (NUE) is critical to advancing sustainable cereal production, particularly under Mediterranean conditions where environmental pressures challenge input-intensive practises. This study evaluates NUE in Tritordeum, a climate-resilient wheat–barley hybrid, using a holistic experimental approach that integrates pre- and post-harvest soil analyses, including an electrical conductivity (EC) assessment, plant and seed nutrient profiling, and an evaluation of yield performance and nitrogen ratio dynamics. Four treatments were tested: conventional urea (T1), urea with an urease inhibitor (NBPT) (T2), urea with a nitrification inhibitor (DCD) (T3), and an unfertilised control (C). While conventional urea achieved the highest yield (1366 kg ha⁻¹), enhanced-efficiency fertilisers (EEFs) improved nutrient synchronisation and seed nutritional quality. Specifically, EEFs increased seed zinc (T2: 34.93 mg/kg), iron (T1: 33.77 mg/kg), and plant potassium (T2: 1.66%; T3: 1.61%) content, and also improved nitrogen remobilisation (elevated Nplant/Nseed ratios). EEFs also influenced soil properties, increasing organic matter (T3: 2.75%) and EC (T3: 290.78 μS/cm). These findings suggest that while EEFs may not always boost yield in the short term, they contribute to long-term soil fertility and nutrient density in grain. This study underscores the importance of synchronising nitrogen availability with Tritordeum’s phenological stages and highlights the crop’s suitability for sustainable, low-input agriculture under climate variability. Full article

Nitrogen (N) fertilizer incorporation of efficiency enhancer is a well-established practice aiming at reducing N loss while enhancing crop yield. However, the effect of different kinds of fertilizer efficiency enhancer on N use efficiency (NUE) and gas loss are rarely compared and poorly comprehended. Here, we conducted a field experiment involving the combination of urease and nitrification inhibitor (NI), the biological inhibitor eugenol (DE) and the bioploymer poly-glutamic acid (PG) and their combinations (NI + PG, NI + DE, PG + DE) to evaluate their effects on crop yield, NUE, NH3 volatilization and greenhouse gas emissions (GHGs). Results indicated that NI, DE, PG and their combinations significantly enhanced the crop yield, N uptake and NUE. NI, DE and PG are all effective in reducing NH₃ volatilization and N₂O emission, averagely decreased by 11.13%, 6.83%, 8.29%, respectively, and by 11.15%, 4.32%, 8.35%, respectively, while have no significant effects on CO₂-C and CH₄-C fluxes, except PG significantly increases CO₂-C emission and thus global warming potential. The combination of these three efficiency enhancers has no multiply effect on maize yield, NUE and gas loss. These findings help to screen the fertilizer efficiency enhancer that can be more effectively utilized in agricultural practices and contribute to their application strategies within agricultural systems. Full article

Urease and nitrification inhibitors represent ways to reduce nitrogen losses; their presence modifies microbial and enzymatic activity in the soil, affecting pH and organic matter (OM), which in turn affects the mobility of heavy metals. To evaluate the effect of urea with inhibitors, pH, OM content, and pseudo-total and mobile metal content (Cu, Cd, Ni, Pb, Cr, Zn, and Mn) were determined in soil samples fertilized with six different urea variants with inhibitors. The modification in the pseudo-total content of heavy metals following fertilization (%) was as follows: Cu (−39.26 ÷ −8.82), Cd (10.74 ÷ 15.40), Ni (5.76 ÷ 18.84), Pb (−13.30 ÷ 12.46), Cr (−15.55 ÷ 11.60), Zn (35.10 ÷ 162.76), and Mn (−1.32 ÷ 12.17). The pH was situated in the range of 7.05 to 7.17, while OM content showed an average increase of 16%. The determined pollution indicators revealed an accumulation of Zn in the soil. The results showed a trend of accumulation of bioavailable heavy metals, with the greatest increase for Mn (43%). Only in the case of Zn, there was a decrease in mobile content with the lowest value when applying two urease inhibitors and one nitrification inhibitor. Inhibitors modify the OM content and soil pH, influencing the mobility and bioavailability of heavy metals. Full article

While previous studies have suggested that biochar, nitrification inhibitors, and urease inhibitors may reduce soil greenhouse gas emissions, their effectiveness in soils irrigated with alternative water resources remains unclear. To compensate for this, reclaimed water and livestock wastewater were utilized as alternative water resources alongside groundwater control. Nitrapyrin and N-(n-butyl) thiophosphoric triamide and biochar were applied to the soil either individually or in combination, and a no-substance treatment (NS) was included for comparison. The results revealed that reclaimed water and livestock wastewater irrigation exacerbated the global warming potential. Compared to the NS, all exogenous substance treatments suppressed nitrous oxide (N₂O) emissions while increasing carbon dioxide (CO₂) emissions, and affecting methane (CH₄) emissions varied across treatments irrespective of the water types. Interestingly, the additional biochar reduced the inhibitory effect of the inhibitors on the greenhouse effect. Using nitrification inhibitors reduced the global warming potential by 48.3% and 50.1% under reclaimed water and livestock wastewater irrigation, respectively. However, when nitrification inhibitors were applied in combination with biochar, the global warming potential was increased by 52.1–83.4% compared to nitrification inhibitors alone, and a similar trend was also observed in the scenario of urease inhibitors, with increases ranging from 8.8 to 35.1%. Therefore, the combined application of biochar and inhibitors should be approached cautiously, considering the potential for increased greenhouse gas emissions. Full article

Processing tomato (Lycopersicon esculentum Mill.) is regarded amongst the most dominant horticultural crops globally. Yet, due to its elevated water and fertilization needs, its environmental footprint is significantly high. The recent efforts to reduce the footprint of agriculture have rekindled the search for optimized fertilization regimes in tomato. The aim of the present study was to assess the effect of different urea fertilizers and tomato pomace-based composts on the performance and quality traits of processing tomato. A two-year field experiment was conducted in the Larissa region, Central Greece, during 2018–2019. The experiment was set up in a randomized complete block design (RCBD), with five treatments: control, urea (Urea), urea with nitrification and urease inhibitors (Urea + NI + UI), processing tomato pomace with farmyard manure (TP + FM), and processing tomato pomace with compost from plant residues (TP + CM). Measurements included soil total nitrogen (STN), soil organic matter (SOM), root length density (RLD), arbuscular mycorrhiza fungi (AMF) colonization, dry weight per plant, fruit yield (number per plant, total yield, weight, diameter), fruit firmness, total soluble solids (TSS), titratable acidity (TA), lycopene content and yield, and fruit surface color (L*, a*, b*, CI). Overall, the best results in soil properties and quality traits were reported in the organic fertilization treatments (STN, SOM, AMF, TSS, TA, lycopene content, L*, a*, b*) and the differences among TP + FM and TP + CM were insignificant in their majority. On the contrary, fruit yield and its components were significantly improved in Urea + NI + UI. Full article

Carbon and nitrogen compounds in agroecosystems have attracted much attention in recent years due to their key roles in crop production and their impacts on environment quality and/or climate change. Since fertilization profoundly disrupted the C and N cycles, several mitigation and/or adaptation strategies, including the application of farmyard manure (FYM) and/or urease and nitrification inhibitors (UI and NI), have been developed. The aim of this study was to evaluate the contents of soil organic carbon and its fractions, the total and mineral forms of nitrogen, as well as CO₂ and N₂O emissions under mineral and organic fertilization with and without urease and nitrification inhibitors in a maize agroecosystem. A two-year field study was carried out on Cambisols (silt) in Poland. The experiment scheme included nine treatments: C (the control without fertilization), UAN (Urea Ammonium Nitrate), UAN+UI, UAN+NI, UAN+UI+NI, FYM with N mineral fertilizer base, FYM with N mineral fertilizer base+UI, FYM with N mineral fertilizer base+NI, and FYM with N mineral fertilizer base+UI+NI. It was found that treatments fertilized with cattle FYM were higher sinks and sources of C and N compounds in comparison to the UAN plots. The organic carbon, humic and humin acid, and total nitrogen concentrations, in contrast to ammonium and nitrate nitrogen, were not affected by the inhibitors added. Nitrification and urease inhibitors were effective in decreasing N₂O emissions only in treatments that were exclusively applied with UAN and had no significant influence on CO₂ emissions. Full article

The excessive application of nitrogen fertilizer aggravated the loss of nitrogen in farmland and exerted detrimental effects on the soil and water environment. Examining the effects of N-(n-Butyl)thiophosphoric triamide (NBPT) and nitrification inhibitor dicyandiamide (DCD) on nitrification and crop yield in wheat-corn double cropping systems would provide valuable insights for improving nitrogen efficiency and ensuring a rational application of inhibitors. A field experiment lasting one and a half years was performed in the winter wheat–summer maize double agroecosystem in North China. The four treatments that were applied included (I) conventional fertilization without inhibitors (CK), (II) conventional fertilization with 0.26 g/m² NBPT (NBPT), (III) conventional fertilization with 1.00 g/m² DCD (DCD), and (IV) conventional fertilization with 0.26 g/m² NBPT and 1.00 g/m² DCD (NBPT + DCD). The results demonstrated that the combined use of NBPT and DCD exerted better effects in reducing NO₃⁻-N leaching. Nitrification could be inhibited for up to 95 days by combining NBPT and DCD, while 21 days by DCD. Ammonia-oxidizing archaea (AOA) (R² = 0.07159, p < 0.01) along with ammonia-oxidizing bacteria (AOB) (R² = 0.09359, p < 0.01), rather than a complete ammonia oxidizer (comammox), were significantly and positively correlated with NO₃⁻-N content, which indicated that the ammoxidation process was mainly regulated by AOA and AOB, instead of comammox in the winter wheat–summer maize double agroecosystem in North China. Full article

A better understanding of the factors that reduce bundle-sheath cell leakage to CO₂ (Փ), enhance 13C carbon isotope discrimination, and enhance the photosynthetic capacity of barley leaves will be useful to develop a nutrient- and water-saving strategy for dry-land farming systems. Therefore, barley plants were exposed to a novel nitrification inhibitor (NI) (3,4-dimethyl-1H-pyrazol-1-yl succinic acid) (DMPSA) and a urease inhibitor (UI) (N-butyl thiophosphorictriamide (NBPT)) with mulched drip fertigation treatments, which included HF (high-drip fertigation (370 mm) under a ridge furrow system), MF (75% of HF, moderate-drip fertigation under a ridge furrow system), LF (50% of HF, low-drip fertigation under a ridge furrow system), and TP (traditional planting with no inhibitors or drip fertigation strategies). The results indicated that the nitrification inhibitor combined with mulched drip fertigation significantly reduced bundle-sheath cell leakage to CO₂ (Փ) as a result of increased soil water content; this was demonstrated by the light and CO₂ response curves of the photosynthesis capacity (An), the apparent quantum efficiency (α), and the ¹³C-photosynthate distribution. In the inhibitor-based strategy, the use of the urease and nitrification inhibitors reduced Փ by 35% and 39% compared with TP. In the NI-HF strategy, it was found that barley could retain the maximum photosynthesis capacity by increasing the leaf area index (LAI), An, rubisco content, soluble protein, dry matter per plant, and productivity. The CO₂ and light response curves were considerably improved in the NI-HF and NI-MF treatments due to a higher 13C carbon isotope (Δ‰), respiration rate (Rd), and Ci/Ca, therefore obtaining the minimum Փ value. With both inhibitors, there was a significant difference between HF and LF drip fertigation. The NI-MF treatment significantly increased the grain yield, total chlorophyll content, WUE, and NUE by 52%, 47%, 57%, and 45%, respectively. Collectively, the results suggest that the new nitrification inhibitor (DMPSA) with HF or MF mulched drip fertigation could be promoted in semi-arid regions in order to mitigate bundle-sheath cell leakage to CO₂ (Փ), without negatively affecting barley production and leading to the nutrient and water use efficiency of barley. Full article

One-time fertilization with controlled-release urea (CRU) is a research hotspot for its lower labor cost and stability of nitrogen (N) supply for rice growth. Yet the fertilizer formulation needs to be further improved to better adjust the N supplement to meet the demand of rice plants and obtain a higher grain yield. Therefore, the effects of novel fertilizer formulations composed of CRU, urease inhibitor (UI) and nitrification inhibitor (NI) on the rice growth and photosynthetic characteristics as well as high-yield formation were tested through a two-year field experiment. The result indicated that the combined use of CRU and UI treatment can achieve higher yields than with CRU at the same N application level. Meanwhile, with a 20% reduction of N use, one-time application of CRU + UI can obtain the same high yield as the conventional split application of urea. Compared with conventional fertilization and CRU treatment, the CRU + UI treatment had suitable leaf area and biomass accumulation at the vegetative growth stage and high effective stem tiller rate. More post-anthesis dry matter accumulation, higher net photosynthesis rate and low senescence rate were guaranteed for its high yield and nitrogen agronomic efficiency. Full article

Large nitrogen (N) losses during fertilization in agricultural production may result in energy wastage, soil and water contamination, and potentially influence crop development. Thus, with the help of a ¹⁵N-labeled tracer, we carried out a field monitoring analysis of NH₃ emissions in a long-term (9-year) conservation tillage agroecosystem of Mollisols in northeast China, in order to determine whether a no-tillage regime and four levels of stover mulching (0%, 33%, 67%, and 100%), combined with urease and nitrification inhibitors, could improve fertilizer utilization efficiency in agricultural systems by reducing ammonia volatilization. Our results showed that in comparison with ridge tillage, no-tillage with stover mulching levels of 33%, 67%, and 100% significantly reduced NH₃ emission rates and cumulative volatilization from 159.67 to 130.42 g N ha⁻¹ and ¹⁵N-NH₃ cumulative volatilization emission by 26% (on average). Furthermore, the application of urease and nitrification inhibitors significantly reduced ¹⁵N-NH₃ volatilization levels from 1.19 to 0.98 g N ha⁻¹. Our research results demonstrate that a long-term no-tillage regime and straw mulching can significantly reduce NH₃ volatilization in fertilizers. Furthermore, when combined with the use of urease and nitrification inhibitors, these practices further enhance the reduction in NH₃ volatilization. Although the volatilization of ¹⁵N-NH₃ is minimally studied in Mollisols, these findings provide a solid foundation for improving fertilizer utilization efficiency, reducing crop production costs and mitigating subsequent environmental pollution. Full article

The addition of fertilizers is indispensable in agricultural production, and currently, there is a wide variety of new types of fertilizers available. For example, commonly used are stabilized fertilizers with inhibitors and coated slow-release fertilizers, among others. However, the long-term effects of these fertilizers, when applied continuously are still uncertain. This study will provide scientific and theoretical support for the development and promotion of these fertilizers. A 16-year paddy field with brown soil treated with different urease and nitrification inhibitors, sulfur-coated urea (SCU), and resin-coated urea (PCU) was studied. The study showed that long-term use of conventional urea nitrogen fertilizer resulted in a significant reduction in soil total phosphorus (TP). Long-term application of NBPT and conventional urea significantly increased soil organic matter (SOM). Moreover, except for HQ and NBPT+DMPP, the prolonged application of new urea fertilizers also significantly enhanced soil total potassium (TK). Application of SCU fertilizer in brown soil type paddy fields resulted in a significant decrease in soil pH over time. However, changes in pH had no effect on the abundance of ammonia-oxidizing bacteria (AOB), as AOB was mainly affected by soil-available N. DMPP, HQ+DCD, NBPT+DMPP, SCU, and PCU significantly reduced the 16S rRNA gene copy number of soil bacteria, with the greatest effect of coated urea fertilizer (SCU and PCU). Long-term application of stable urea fertilizer with HQ significantly reduced the bacterial community in paddy soil. Conversely, HQ+DCD-stabilizede urea fertilizer significantly increased the population structure and abundance of Basidiomycota fungi while decreasing the population structure and abundance of Rozellomycota fungi. DMPP-stabilized urea fertilizer notably increased the population structure and abundance of Ascomycota fungi while decreasing the population structure and abundance of Rozellomycota and Chytridiomycota fungi. Furthermore, HQ-stabilized urea fertilizer significantly reduced the population structure and abundance of Chytridiomycota fungi. Full article

Optimizing nitrogen (N) availability to plants is crucial for achieving maximum crop yield and quality. However, ensuring the appropriate supply of N to crops is challenging due to the various pathways through which N can be lost, such as ammonia (NH₃) volatilization, nitrous oxide emissions, denitrification, nitrate (NO₃⁻) leaching, and runoff. Additionally, N can become immobilized by soil minerals when ammonium (NH₄⁺) gets trapped in the interlayers of clay minerals. Although synchronizing N availability with plant uptake could potentially reduce N loss, this approach is hindered by the fact that N loss from crop fields is typically influenced by a combination of management practices (which can be controlled) and weather dynamics, particularly precipitation, temperature fluctuations, and wind (which are beyond our control). In recent years, the use of urease and nitrification inhibitors has emerged as a strategy to temporarily delay the microbiological transformations of N-based fertilizers, thereby synchronizing N availability with plant uptake and mitigating N loss. Urease inhibitors slow down the hydrolysis of urea to NH₄⁺ and reduce nitrogen loss through NH₃ volatilization. Nitrification inhibitors temporarily inhibit soil bacteria (Nitrosomonas spp.) that convert NH₄⁺ to nitrite (NO₂⁻), thereby slowing down the first and rate-determining step of the nitrification process and reducing nitrogen loss as NO₃⁻ or through denitrification. This review aims to provide a comprehensive understanding of urease and nitrification inhibitor technologies and their profound implications for plants and root nitrogen uptake. It underscores the critical need to develop design principles for inhibitors with enhanced efficiency, highlighting their potential to revolutionize agricultural practices. Furthermore, this review offers valuable insights into future directions for inhibitor usage and emphasizes the essential traits that superior inhibitors should possess, thereby paving the way for innovative advancements in optimizing nitrogen management and ensuring sustainable crop production. Full article