N-butyl Thiophosphoric Triamide Research Articles

The Combined Use of Liquid Fertilizer and Urease/Nitrification Inhibitors on Maize Yield, Nitrogen Loss and Utilization in the Mollisol Region

Nitrification inhibitor (NI) and urease inhibitor (UI) with fertilizer have the potential to reduce nitrogen (N) loss as well as improve grain yields. Urea-ammonium nitrate (UAN) solution as liquid fertilizer is superior to conventional solid nitrogen (N) fertilizer in terms of fertilizer efficiency, energy savings, environmental pollution reduction and economic benefits. However, comprehensive assessments of UAN with inhibitors from an environmental and agronomy perspective, including insights into the mechanisms of UAN with inhibitors, are lacking. In a field trial, three single-inhibitor and two double-inhibitor (DI) treatments were set to quantify the grain yield, the N losses and the N recovery efficiency of maize treated with urea supplemented with dicyandiamide (DCD), 3,4-dimethylpyrazole phosphate (DMPP) and N-(n-butyl) thiophosphoric triamide (NBPT). Compared with the UAN treatment, the supply of urease inhibitors reduced NH3 emission by 13.0% but increased N2O emission by 13.0%. The supply of nitrification inhibitors delayed the conversion of ammonium N to nitrate N and improved NH3 emission by 23.5-28.7%, but reduced N2O emission by 31.4% and significantly increased the maize yield by 21.3%. The combined use of NBPT and DCD were not compatible in UAN and cannot achieve the maximum potential for optimizing yields and reducing nitrogen losses. Considering the grain yield, the N use efficiency and the N losses, the combined use of NBPT and DMPP in maize production system significantly improved the grain yield and N use efficiency, as well as reduced N losses.

The win-win effects of nitrification inhibitors on soil-crop systems: Decreasing carbendazim residues but promoting soil bacterial community diversities and stabilities and crop yields

Applying nitrogen (N)-cycling inhibitors is an effective measure to improve N fertilizer utilization efficiency, but the effects of N-cycling inhibitors on fungicide residues in soil-crop systems are unclear. In this study, nitrification inhibitors dicyandiamide (DCD) and 3, 4-dimethylpyrazole phosphate (DMPP) and urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) were applied into agricultural soils with fungicide carbendazim applications. The soil abiotic properties, carrot yields, carbendazim residues, bacterial communities and their comprehensive relationships were also quantified. Compared to the control treatment, the DCD and DMPP significantly decreased soil carbendazim residues by 96.2% and 96.0%, and the DMPP and NBPT significantly reduced carrot carbendazim residues by 74.3% and 60.3%, respectively. The nitrification inhibitor applications also generated significant and positive effects on carrot yields and soil bacterial community diversities. The DCD application significantly stimulated soil Bacteroidota and endophytic Myxococcota and modified soil and endophytic bacterial communities. Meanwhile, the DCD and DMPP applications also positively stimulated the co-occurrence network edges of soil bacterial communities by 32.6% and 35.2%, respectively. The linear correlation coefficients between soil carbendazim residues and pH, ETSA and NH4+-N contents were − 0.84, − 0.57 and − 0.80, respectively. The nitrification inhibitor applications generated win-win effects on the soil-crop systems by decreasing carbendazim residues but promoting soil bacterial community diversities and stabilities and crop yields.

Rational utilization of urease and nitrification inhibitors improve the ammonia-oxidizing bacteria community, nitrogen use efficiency and peanut growth

ABSTRACT Peanuts (Arachis hypogaea L.) is an important oil and nitrogen (N) fixing crop. Urease inhibitors (UIs) and nitrification inhibitors (Nis) can mitigate the release of N and reduce the harmful effects of excessive N concentrations. However, the effect of these inhibitors on the soil nutrient-microbial activity-plant growth system is unknown in peanut. The purpose of this study was to investigate the effects and mechanism of N-(n-butyl) thiophosphoric triamide (NBPT), 3,4-dimethylpyrazole phosphate (DMPP) and sulfur-coated urea (SCU) on peanut. The results showed that comparing with urea alone, adding NBPT + DMPP inhibited the urea hydrolysis better and decreased the concentration of NH4 +-N + NO3 −-N by 20.8% in soil. Therefore, it increased the net photosynthetic rate, promoted the development of roots even the absorption of N by peanut, with N use efficiency (NUE) up to 20.8%. The effect of NBPT + DMPP on microorganism was better than that of NBPT alone, which considerably impacted the structure and abundances of aonia oxidizing bacteria (AOB) but not ammonia-oxidizing archaea (AOA). Specifically, g_Nitrosospira and g_Nitrosomonas decreased by 46.9% and 2.2% respectively, and g(c) Betaproteobacteria increased. Furthermore, when combined with SCU on this basis, the overall effect was clearer.

Investigation of Soil Microbial Communities Involved in N Cycling as Affected by the Long-Term Use of the N Stabilizers DMPP and NBPT

Both, 3,4-dimethylpyrazole phosphate (DMPP) and N-(n-butyl) thiophosphoric triamide (NBPT) are commonly used as nitrogen (N) stabilizers, and are often used in agriculture to reduce nitrogen (N) loss from soils by inhibiting soil nitrification and by slowing down urea hydrolysis, respectively. The current knowledge gap concerns how soil microbial communities involved in N cycling are affected by the long-term use of DMPP and NBPT. The present field study explored the inter-annual variation of nitrous oxide (N2O) emissions and the responses of ammonia oxidizers (AOA, AOB encoded by the amoA gene), nitrite-oxidizing bacteria (NOB, encoded by the nxrA and nxrB genes), and denitrifier (encoded by the narG and nosZ genes) populations following a long-term (8 years) addition of DMPP and NBPT. The results showed that the reduction in N2O emissions by DMPP and NBPT increased year on year. The AOB population diversity significantly increased (p < 0.05) after a long-term urea application but decreased after DMPP addition. The long-term application of urea increased the potential nitrification rate (PNR) by the enrichment of the genera with a high ammonia oxidation capacity in the AOB population. In contrast, DMPP addition weakened this effect and formed a population with a low ammonia oxidation capacity. Variations in the NOB population were mainly associated with fertilizer-induced changes in substrate NO2−, whereas DMPP and NBPT had minor impacts on the NOB population. Additionally, the change in the denitrification population was indirectly affected by the soil ammonium (NH4+) content with a long-term N stabilizer application. These findings provide a new interpretation related to the response mechanisms of the nitrifier and denitrifier populations for the long-term use of N stabilizers in soils.

Effect of Natural Liquid Hydroabsorbents on Ammonia Emission from Liquid Nitrogen Fertilizers and Plant Growth of Maize (Zea Mays L.) under Drought Conditions.

The use of mineral nitrogen (N) fertilizers is associated with significant nitrogen loss through the volatilization. Ammonia (NH3) emissions are common from fertilizers with amide (NH2) and ammonium (NH4) nitrogen forms applied to the soil surface without incorporation. The objective of the laboratory and greenhouse pot experiments was to verify the hypothesis that liquid mineral fertilizers and fertilizer solutions containing N-NH2 and N-NH4 applied to the soil surface in combination with natural hydroabsorbents (NHAs) will reduce the volatilization of nitrogen. The effect of NHAs addition to urea ammonium nitrate (UAN) fertilizer and urea, ammonium nitrate (AN) and ammonium sulphate (AS) solutions was evaluated in a laboratory experiment. The effect of the two types of NHAs (acidic and neutral) was compared with the control (UAN) and its mixture with the commercially used urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT). The proportion of volatilized NH3 of the total N from the examined fertilizers applied to the soil surface was determined by the titration method. Subsequently, the effect of fertilization with UAN and its mixture with NHAs and NBPT on the growth of maize under the drought conditions was verified in a greenhouse pot experiment. While the addition of NBPT resulted in a reduction of NH3 emission for the fertilizers containing NH2 (UAN, urea solution), a decrease in volatilization after the addition of both acidic and neutral NHA was observed especially for UAN. A reduction in ammonia emission was also observed for AS after the addition of acidic NHA. The addition of both NHAs and NBPT to UAN increased the utilization of nitrogen from the applied fertilizer, which was reflected by an increase in chlorophyll content and increased CO2 assimilation by maize plants grown under the drought stress. UAN fertilizer combined with acidic NHA and NBPT significantly increased aboveground biomass production and root system capacity of maize. Significant increases in UAN nitrogen recovery were observed for all examined additives (UI and both types of NHAs). In addition to the known effects of hydroabsorbents, especially their influence on soil physical and biological properties and soil water retention, the effect of NHAs application in combination with UAN and AS solutions on the reduction of gaseous N loss, maize plant growth and fertilizer nitrogen recovery was found.

Dynamics of ammonia volatilization from NBPT-treated urea in tropical acid soils

The urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) reduces NH3 losses from urea (UR) surface-applied to soils, but its efficacy may be lower in acidic soils. The period when urease inhibition occurs efficaciously may change with soil pH. This needs to be clarified in tropical soils which are commonly acidic. This study evaluated the effectiveness of NBPT-treated urea to delay and reduce ammonia volatilization in two soils at three pH levels. Two experiments were conducted under laboratory conditions in soils with different textures (sandy-clay and clay). The treatments consisted of three soil pH levels and two N sources (UR and UR + NBPT), with five replicates. The soil pH values were adjusted and reached values of 4.5, 5.6, and 6.4 in the sandy-clay, and 4.5, 5.4, and 6.1 in the clay soil. Ammonia volatilization was measured using glass chambers (1.5 L). In the sandy-clay soil, NH3 losses were 40-47 % of the UR-N. In the clay soil, losses were 26-32 %. The addition of NBPT to UR reduced the NH3 volatilization by 18-53 %; the inhibitor decreased the N losses under all soil pH conditions but was significantly less efficient in acidic soils (pH 4.5). The lower efficiency of the inhibitor under acidic conditions was more evident in the first few days: 50 % of the total NH3 losses occurred in less than four days in soils with pH 4.5, but in 8-11 days in soils with pH above 5.4. The rapid loss in efficiency in more acidic soils is a drawback. Using NBPT in severely acidic soils showed a relatively small advantage over untreated UR as the inhibitor did not provide extra time for fertilizer incorporation and further reduction of NH3 losses.

Nitrogen stabilizers mitigate nitrous oxide emissions across maize production areas of China: A multi-agroecosystems evaluation

N stabilizers such as urease and nitrification inhibitors are potential tools for mitigating N2O emissions and improving maize yield. However, the efficacy of N stabilizers is inconsistent across a broad range of agroecosystems. To enable the large-scale use of N stabilizers for sustainable agricultural development, it is necessary to identify the benefits of N stabilizers and the driving factors that regulate their efficiency. Here, we evaluated the efficiencies of 3,4-dimethylpyrazole phosphate (DMPP) and N-(n-butyl) thiophosphoric triamide (NBPT) in four typical ecological sites with contrasting climatic and soil conditions in the maize production area of China (Gongzhuling, Wuqiao, Xinxiang, and Wenzhou). Disparate ecological sites significantly influenced the N2O emissions (0.2–19.0 kg N2O-N ha−1) and maize yields (7.5–13.9 Mt ha−1). Also, N stabilizers reduced N2O emissions by 1.3–93.9 % across the four sites. Compared to NBPT, DMPP showed higher efficiency, but the joint inhibitor (NBPT+DMPP) had non-significant effects compared to DMPP. Although N stabilizers did not significantly increase maize yield, they reduced yield-scaled N2O emissions (YSNEs) by 3.1–83.4 % (p < 0.05) across study sites. Hotspots of N2O emission occurred within two weeks after N fertilization, and the mitigation of N stabilizers on N2O emissions was strongly reduced over time. This implies the degradation velocity of N stabilizers was critical for emissions mitigation efficiency. Meanwhile, environmental factors obviously influenced N stabilizers efficiency. Random forest and correlation analyses indicated that soil pH and sand content showed positive correlations and high importance for the N2O mitigation efficiencies of N stabilizers, whereas water-filled pore space and salt content showed negative correlations and high importance. In addition, N2O mitigation efficiencies of different N stabilizers showed a different response to environmental changes, wherein higher environmental sensitivity and easy invalidation under unsuitable conditions were observed in NBPT than in DMPP. In conclusion, DMPP effectively mitigated YSNEs in all study sites, and its efficiency was closely regulated by soil pH, water-filled pore space, and soil texture. Therefore, amending soil quality may enhance the benefits of DMPP and might decrease future N2O emissions in the maize fields of China.

The efficient recovery of molybdenite fines using a novel collector: Flotation performances, adsorption mechanism and DFT calculation

In this work, a novel collector N-(N-butyl) thiophosphoric triamide (NBPT) was explored to improve the flotation of molybdenite fines. The flotation performance was evaluated through micro-flotation tests, and the interaction mechanism was investigated through Zeta potential, Fourier Transform Infrared Spectrometer (FTIR), adsorption capacity, Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), Atomic Force Microscopy (AFM) and density functional theory (DFT) calculations. Flotation results manifested NBPT could greatly improve the flotation of molybdenite fines. Zeta potential, FTIR, adsorption capacity and AFM measurements proved NBPT was more inclined to adsorb on molybdenite surface. XPS and ToF-SIMS analysis showed NBPT chemically adsorbed on molybdenite surface via the bonding between PS groups with Mo atoms. DFT calculations reconfirmed NBPT had much stronger affinity towards edges (Eads = -657.69 kJ/mol) than faces (Eads = -39.96 kJ/mol). Moreover, NBPT strongly interacted with molybdenite edges through the hybridization of the S 3p orbital of NBPT with the Mo 4d orbital of molybdenite to form strong covalence bond. As a result, NBPT could be utilized as a potential collector to enhance the flotation of molybdenite fines.

Urease inhibitor and biochar independently affected N&lt;sub&gt;2&lt;/sub&gt;O emissions from Camellia oleifera soils

Nitrous oxide (N2O) is a long-lived greenhouse gas that impacts climate change. Agricultural soils with intensive nitrogen (N) application are the main source of N2O emissions. Reducing N2O emissions from N-fertilised soils is, therefore, important for climate change mitigation. The application of urease inhibitor and/or biochar provides the potential for mitigating N2O emissions. However, the interactive effect of urease inhibitor and biochar on N2O emissions remains limited. In this study, an incubation experiment was performed to investigate the gradients of urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) (0, 0.08, 0.16, and 0.24%) and biochar additions (0, 2.5, and 5%) on N2O emissions from urea-fertilised Camellia oleifera soils. Results showed that urease inhibitor decreased, but biochar increased cumulative N2O emissions. No significant interactive effects were observed between urease inhibitor and biochar on the cumulative N2O emissions, but cumulative N2O emissions were decreased by NBPT under a 2.5% biochar addition rate. Soil N2O emission rates were negatively correlated with net ammonification and N mineralisation rates and positively correlated with net nitrification rates. This study indicates that NBPT, with the characteristic of delaying urea hydrolysis, can be better than biochar in mitigating N2O emissions from urea-fertilised soils of C. oleifera plantations.

Major metabolites of NBPT degradation pathways contribute to urease inhibition in soil.

Urea is the most commonly used nitrogen fertilizer worldwide. However, depending on soil and environmental conditions, high nitrogen losses can occur due to gaseous ammonia emissions. Urease inhibitors like N-(n-butyl)thiophosphoric triamide (NBPT) reduce these losses by blocking the urease enzyme, which catalyzes urea hydrolysis. With the increasing use of NBPT its environmental fate and features of urease inhibition become increasingly important. This study aimed to further elucidate major NBPT degradation pathways and related urease inhibition in soil. This was investigated in a 14-d incubation experiment using practice-relevant application rates of NBPT and four of its metabolites N-(n-butyl)phosphoric triamide (NBPTO), diamido phosphoric acid (DAP), diamido thiophosphoric acid (DATP) and rac-N-(n-butyl)thiophosphoric diamide (NBPD), covering three postulated degradation pathways. Additionally, the urease inhibition by these compounds was determined and further investigated in 2-h tests. The latter provided dose-response curves, showing that all substances inhibited urease, with NBPTO being the most effective. Inhibition of urease in NBPT-spiked soil was also largely, but not completely, attributed to NBPTO formed within the test period. In 14-d incubation tests, all investigated compounds dissipated quickly by >90% within 6d (NBPTO), 3d (NBPT) and ≤1d (DAP, DATP and NBPD). Extensive oxidation of NBPT to NBPTO and subsequent minor formation of DAP was identified as the preferred degradation pathway. Abiotic degradation processes in sterile soil corresponded to 65-90% of total degradation in microbial active soil. Furthermore, pseudo-first order dissipation kinetics were retarded in sterile soil. Urease activity, calculated as a percentage of activity in the urea-fertilized control, was lowest after about 2d when NBPTO was spiked to soil (17.9%), followed by NBPT (35.7%), DATP (51.3%), NBPD (54.0%), and DAP (54.4%). This shows that urease inhibition depends on the interplay of NBPT and its degradation products.

Disponibilidad de forraje en praderas de pasto Xaraés en respuesta a fuentes de nitrógeno convencionales y tratadas con N-(n-butil) triamida tiofosfórica (NBPT)

The N-(n-butyl) thiophosphoric triamide (NBPT), a urease inhibitor, has been reported as one of the most promising compounds to reduce losses by volatilization, and to maximize the use of urea nitrogen (N) in agricultural systems. A field study was carried out to examine urease inhibitors' potential about volumetric density and forage mass grass (Brachiaria brizantha cv. Xaraés) to N application. The experiment was carried out from September 2017 to September 2018. The experimental design used was complete randomized blocks in the 3×2×4 factorial array, considering: three periods of the year (wet season, dry season, and the transition), two sources of urea (conventional urea and NBPT–treated urea), and four N rates (0, 80, 160 and 240 kg N ha-1 yr-1), replicated three times. Nitrogen sources promoted a positive effect (P&lt;0.0001) on bulk density, forage mass, and in the grazing stratum during the wet season and the transition season, with increasing N rates in pastures. The leaf: stem ratio decreased linearly (P&lt;0.0045) as increased N rates, and the higher ratio during the wet season and lower in the dry season of the year. For the rates of 80 kg N ha-1 yr-1, there was a significant difference (P=0.0042) between sources, with greater (P=0.0006) forage mass of 0–30 cm, post-grazing forage mass (P=0.0042) and forage volumetric density (P=0.0006), when utilized the conventional urea. The application of N, regardless of the source, provides an increase in forage mass and volumetric density in Xaraés grass pastures up to a dose of 240 kg N ha-1 yr-1, in the transition season and wet season.

Induced CaCO3 mineral formation based on enzymatical calcification for bioremediation under different pressure conditions

Enzymatically induced carbonate precipitation (EICP) is widely studied as a promising technique for soil stabilization and consolidation. Most of the studies of biomineralization are carried out at a normal pressure. However, several practical application fields are in high-pressure environmental conditions, which affect treatment effects. In this study, a new high-pressure research apparatus has been constructed and used to provide a maximum confining pressure of 20 bar for sand solidification. In addition, the N-(n-butyl) thiophosphoric triamide (NBPT) addition was proposed to improve the solidification homogeneity at higher pressures. The formed sand columns demonstrated the feasibility of the constructed apparatus for high-pressure sand solidification. The permeabilities of EICP or EICP-NBPT treated specimens both decreased during the treatment regardless of different confining pressures. The increase of confining pressure decreased pore sizes, eventually leading to smaller CaCO3 contents in specimens. With the confining pressure increasing from 0 to 12 bar, the increasing rate of strength for the sample with EICP treatment was 75%, while decreased to 35% and 12% at 16 bar and 20 bar, respectively. The NBPT addition resulted in smaller differences of sonic time values and CaCO3 contents at different parts, achieving higher strengths. The sample with EICP-NBPT treatment had the largest strength at 16 bar. In this study, the difference of strength was attributed to the combined effects of solidification homogeneity and confining pressure. The results demonstrated that the EICP or EICP-NBPT treatments in this study had several promising applications potentials: improving wellbore integrity, reducing near-wellbore pressure loss, and enhancing CO2 sequestration, which benefit the petroleum industry.

Assessing the long-term impact of urease and nitrification inhibitor use on microbial community composition, diversity and function in grassland soil

Reductions in ammonia (NH3) and nitrous oxide (N2O) emissions from agricultural systems are critical for achievement of sustainability targets that underpin international efforts on climate and biodiversity. Urease inhibitors (UI) such as N-(n-butyl) thiophosphoric triamide (NBPT) and nitrification inhibitors (NI) such as dicyandiamide (DCD) slow down microbial and chemical N transformation rates in soil, resulting in decreased environmental N losses. To date there has been minimal assessment of the long-term non-target impacts of UI and NI on soil microbial communities and biological function in grasslands. Utilising a temperate grassland field experiment where fertilisers (with or without inhibitors) were repeatedly applied over a five year period, we assessed the impact of individual or combined inhibitor use on microbial community composition, abundance and function via a combination of functional assays, quantitative polymerase chain reaction (qPCR) assays and amplicon sequence analysis. We also investigated the effect of N inhibitor use on the N functional community, and whether the form of applied N fertiliser (i.e. calcium ammonium nitrate (CAN) or Urea) affected microbial community composition and function. Treatments included a Control (no N); CAN; Urea; Urea + NBPT (UI); Urea + DCD (NI); and Urea + DCD + NBPT (NI & UI). There was no impact of either UI or NI use on non-target microbial community composition or abundance. Function and the abundance of N cycling communities were mainly unaffected by fertilisation or the use of inhibitors. The observed effect of NI was primarily on the nitrification process. There was a significant reduction in nitrification potential associated with the use of NI, and in the case of the Urea + DCD treatment a reduction in COMAMMOX nitrifier abundance, and an increase in potential N mineralisation and N2O emissions. Finally, there was a significant impact of fertilisation and fertiliser type (i.e. CAN or Urea) on the fungal community structure but no impact on bacterial community structure. These results provide a knowledge base that will inform policy regarding the utilisation of N inhibitors as a mitigation measure for reducing gaseous N losses in grasslands.

The Efficiency of Stabilized Fertilizers in Reducing Ammonia Loss Is Influenced by Liming Method

ABSTRACT Urea is the most used nitrogen (N) fertilizer worldwide, but its rapid hydrolysis on the soil surface results in N loss in the form of ammonia (NH3-N). Enzyme inhibitors have been investigated for their ability to reduce NH3-N volatilization, particularly from no-till and surface-limed soils. This study assessed the efficiency of stabilized fertilizers in reducing NH3-N volatilization under different lime rates and application methods. The experiment followed a 2 × 4 × 3 factorial design, with two liming methods (surface application and incorporation), four base saturation levels (50, 60, 70, and 90%), and three urea (45% N) sources: conventional urea, urea + N-(n-butyl)-Thiophosphoric triamide (NBPT), and urea + Boron (B) + Copper (Cu). NH3-N volatilization losses varied from 9.15 to 20.43 kg ha−1, accounting for 11.4 to 25.5% of the applied N rate. Base saturation did not influence NH3-N volatilization. Liming method, however, had a significant effect. Urea + B + Cu was effective in reducing volatilization loss only in soils ameliorated by lime incorporation (23% reduction compared with conventional urea). Urea + NBPT was effective in surface-limed and incorporated soils (up to 55.5% reduction). The results showed that soil management influences the efficiency of stabilized fertilizers and that urea + NBPT provides the best results.

Degradation of N-(n-butyl) Thiophosphoric Triamide (NBPT) with and without Nitrification Inhibitor in Soils

Recent studies have shown that nitrification inhibitor (NI) impairs the efficacy of urease inhibitor, N-(n-butyl) thiophosphoric triamide (NBPT), in reducing ammonia volatilization and urea hydrolysis rate. A laboratory study was conducted to evaluate the influence of NI (specifically 3,4-dimethyl pyrazole phosphate) on the degradation of NBPT in six soils. Soils were amended with either NBPT (10 mg NBPT kg−1 soil) or NBPT plus NI (DI; 10 mg NBPT + 2.5 mg NI kg−1 soil), incubated at 21 °C, and destructively sampled eight times during a 14-day incubation period. The degradation of NBPT in soil was quantified by measuring NBPT concentration with high-performance liquid chromatography-mass spectrometry, and the degradation rate constant was modeled with an exponential decay function. The study showed that the persistence of NBPT in soil was not influenced by the presence of NI, as the NBPT degradation rate constant across soils was 0.5 d−1 with either NBPT or DI. In contrast, the degradation rate constant was significantly dependent on soils, with values ranging from 0.4 to 1.7 d−1. Soil pH was the most important variable affecting the persistence of NBPT in soils. The half-life of NBPT was 0.4 d in acidic soil and 1.3 to 2.1 d in neutral to alkaline soils. The faster degradation of NBPT in acidic soils may explain its reduced efficacy in such soils.

Potential of chemical stabilizers to prolong urease inhibition in the soil–plant system#

AbstractBackgroundUrea is the most common nitrogen fertilizer applied to agricultural lands, and it is often treated with urease inhibitors to prevent loss of ammonia during urea hydrolysis. However, urease inhibitors like N‐(n‐butyl) thiophosphoric triamide (NBPT) are susceptible to degradation in soil.AimsThis study tested dimethyl sulfoxide, ethylene glycol and glycerol as stabilizers that could extend the inhibition effect of NBPT in a soil–plant system that received liquid urea fertilizer.MethodsWe undertook a pot experiment in which two soil types (brown and black soils) were amended with liquid urea plus NBPT, with and without chemical stabilizers, then planted with bok choy. The urease activity, urea and mineral N concentration in soil and nitrogen uptake in bok choy were monitored for the next 30 days.ResultsFive days after adding fertilizer, urease activity was 27%–51% lower in brown soil amended with the urea‐NBPT solutions and 32%–75% less when black soil received urea‐NBPT solution than in the control soil that received urea solution. Nearly 100% of the urea was hydrolyzed in control soil receiving urea solution after 5 days, but only 21%–41% of urea was hydrolyzed in soil amended with urea‐NBPT solution after 5 days. Stabilizers did not improve the stability of NBPT, nor did they affect the nitrogen uptake by bok choy, which was similar in the urea‐amended control soil (124 mg N pot–1) and the urea‐NBPT‐treated soil (117 mg N pot–1) during the growth period.ConclusionsChemical stabilizers did not prolong the NBPT inhibition of urease activity, probably because the stabilizer compounds are vulnerable to degradation in well‐watered and planted soils.

Experimental Study of Enzyme-Induced Carbonate Precipitation for High Temperature Applications by Controlling Enzyme Activity

Biomineralization is a popular reinforcement technology, but which is rarely studied at high temperatures. Some potential application targets are high-temperature environments. So it's essential to study the feasibility of biomineralization at high temperatures. In this article, plant urease was selected as a cost-effective enzyme for enzyme-induced carbonate precipitation (EICP) at high temperatures. Urease activity and urease enzyme-induced carbonate precipitation were studied as a function of temperature, urease concentration, and N-(n-butyl)-thiophosphoric triamide (NBPT) addition. The effects of reaction time, number of perfusions, urease concentration, temperature, and NBPT addition on the curing efficiency of sand columns were studied by unconfined compressive strength tests and by determining the resulting concentration of CaCO3. The results demonstrated that the urease could maintain a stable activity at temperatures below 65 °C. At temperatures higher than 65 °C, urease was gradually inactivated with increasing temperature, which would influence the yield of precipitation. However, increasing the urease concentration and the number of infusions could ensure the sand solidified with adequate CaCO3. In addition, NBPT was proposed as a new way to control urease activity, which resulted in a high UCS of the sand columns formed at high temperatures. This paper bears out that sand solidification can be achieved at high temperatures using EICP and lays the foundation for future application of EICP at high temperatures.

Interaction and inhibition mechanism of urease in vitro and soil system by a natural benzylisothiocyanate isolated from Moringa oleifera

Urease catalyzes urea hydrolysis in NH3 and CO2 in the soil, leading to N-urea losses by volatilization (30–70%); thus, urease inhibitor addition is an alternative that reduces these losses. In this sense, biophysical studies are important to evaluate potential urease inhibitors and biotechnological applications since currently, the N-(n-butyl)thiophosphoric triamide (NBPT) is the only commercial urease inhibitor for agriculture purposes. Thus, this work focused on evaluating the mechanism of urease inhibition by 4-(4′-O-acetyl-α-L-rhamnosyloxy)benzylisothiocyanate (MFC) isolated from Moringa oleifera L. (Moringaceae). The experiment consisted of spectroscopic studies of enzyme kinetics and activity (urease 12 mU and MFC 0–800 µM); assays to evaluate conformational changes in the enzyme using ultraviolet–visible molecular absorption and molecular fluorescence (5 µM urease and MFC 0–200 µM); the evaluation of thiols and amino/guanidine groups using 5,5′-dithiobis(2-nitrobenzoic acid) (50 µM) and fluorescamine (100 µM). Inhibition of soil ureases using Ferralsol soil samples was performed with MFC compared with thiourea, hydroxyurea, and NBPT (0.5 mM for all). The results of enzymatic studies indicated that MFC is a mixed inhibitor with concentration necessary to produce 50% inhibition (IC50) of 487 μM. From the spectrofluorimetric titration were obtained Ksv (1.30 ×103 M−1) and Kb (1.80 ×102 M−1), which reflect the magnitude of fluorescence suppression and the interaction between urease and MFC, while the n value 0.77 indicates that the stoichiometry of the complex is 1:1. Besides, the interaction process MFC-urease changes protein structure, especially tryptophan (Trp) residues' microenvironment, highlighting MFC action as a mixed inhibitor since the Trp495 and Trp648 residues are far away from the urease catalytic site. The monitoring of the residues containing thiol and amino/guanidine groups indicated covalent interaction of isothiocyanate with these groups forming dithiocarbamates and thiourea (urease inhibitor group) was confirmed as majority products by mass spectrometry. Finally, MFC was applied to the soil samples, and the residual activity of soil ureases was determined, with inhibition of 49.4% (soil A) and 32.0% (soil B), noting that soil inhibition is like NBPT (54.4%, soil A) and can be considered a potential compound for biotechnology application.

Controlled nitrogen transformation in chemo-amended urea improves nitrogen use efficiency and productivity of wheat grown on alkaline calcareous soil.

Low wheat production is linked to soil degradation, low organic matter, temperature variation, and nutrient depletion in soils of semiarid regions. Nitrogen is mostly applied as urea to meet crop requirements; however, excessive N application may pollute the environment and contaminate groundwater. The current studies explored possible ways for decreasing N losses (NH3 volatilization and NO3 leaching) and improving N availability for wheat production in alkaline soil. The ZnO was coated on urea (1% Zn coating) to get zinc-coated urea (ZnU), and both urea and ZnU were incubated in laboratory at recommended rate (RR), i.e., 150kgNha-1 and 80% (N of RR), after further coating with inhibitors [N-(n-butyl) thiophosphoric triamide (NBPT) at 1% of urea and 4-amino-1,2,4-triazole (ATC) at 2% of urea], thus creating six treatments. The results showed higher NH3-N loss at day 4 and thereafter a decreasing trend reaching to minimum at day 14. The cumulative NH3-N volatilization from urea alone was found higher (28.99%), except ATC treatments producing statistically similar losses due to restriction in nitrification process. In greenhouse, the treatments were tested in wheat cultivars (Faisalabad 2008 and Lasani) for crop growth, nutrient (N, P, K, and Zn) uptake, and yield parameters, where 80% of RR treatment, i.e., NBPT + ZnU80, was found at par with full RR as commercial products, especially comparable to ZnU (at RR) that produced the highest chlorophyll (53.65unit value), net leaf photosynthetic rate (19.64μmol CO2 m-2s-1), plant biomass (208.13g/pot), grain yield (63.65g/pot), and nutrient (NPK and Zn) accumulation in grain of Fsd-2008 cultivar. In field trial, NBPT + ZnU80 also outperformed and produced the highest physiological efficiency (PE), agronomic efficiency (AE), and nitrogen recovery efficiency (REN); the treatment also found statistically similar with ZnU (at RR) that produced the maximum plant height (95.4cm), plant biomass (11.58 t/ha), grain yield (4.69 t/ha), and 1000-grain weight (42.55g). The relative NO3 leaching was found lower in 80% N treatments, yet leaching was not significant from either treatment at the three stages of crop growth. Overall, current studies revealed the effectiveness of NBPT-amended urea (followed by ZnU) with 20% saving of N inputs through higher N availability for plant uptake that could benefit growers as well as conserve environment.

Transient application of foliar urea with N-(n-Butyl) thiophosphoric triamide on N metabolism of pineapple under controlled condition

Traditional fertilization and the loss of Nitrogen (N) is a common phenomenon in agriculture. Application of urea with urease inhibitor is an alteration measure of urea hydrolysis and N metabolism. Hence, the objective of this study was to determine the short-term foliar application effect of N-(n‑butyl) thiophosphoric triamide (NBPT) on N metabolism, physiological and biochemical changes in the pineapple plant. At 4 month after planting (MAP), 1% urea (Urea) and 1% urea with NBPT (NLU) were applied. Data on urease enzyme activity, internal urea content, inorganic N [ammonium (NH4+) and nitrate (NO3−)], amino acids, total soluble protein, NBPT content, lipid peroxidase (MDA) activity, and electrolyte leakage were recorded for 10 days after treatment (DAT). The results indicated that the NBPT was taken up by the plant, thereby a clear inhibition of the urease activity was observed in pineapple leaf. A higher amount of urea content and a lower amount of NH4+ content in the leaf were the evidence of hydrolysis inhibition by NBPT. Consequently, the contents of amino acid and protein were diminished upon NBPT treatment which demonstrated a change in N metabolism. In addition, amino acid composition demonstrated that amide forms of amino acids were the major components of the decreased amino acid pool. In conclusion, lower MDA activity and electrolyte leakage were also observed under NBPT treated plants indicate that NBPT could release abiotic stress to some extent by protecting the cell wall from damage.