Ammonia Volatilization Losses Research Articles

Negligible ammonia volatilization loss with one-time root-zone targeted application of common nitrogen, phosphorus, and potassium fertilizers in transplanted rice cultivation

The minimization of nitrogen (N) loss and enhancement of efficient N use are of great importance in agricultural crop production. Here we propose a method of one-time root-zone targeted fertilization (ORZTF), to reduce ammonia volatilization (AV) loss and increase N use efficiency. ORZTF is updated from one-time root-zone fertilization (ORZF), in which common N fertilizer is one-time applied in crop root-zone, and phosphate (P) and potassium (K) are surface broadcasted. In ORZTF, common N, P and K are together placed at certain sites in the root-zone. Three rice field trials with the methods of conventional surface broadcasting (CSB), ORZF, and ORZTF, and a soil incubation experiment with CSB and ORZTF, were conducted. In 2018, the treatments comprised CSB with no N (N0), with the local N rate (CSB, 195 kg N hm−2 and 150 kg N hm−2 for two sites, respectively), with higher N (HCSB, 225 kg N hm−2 and 195 kg N hm−2, respectively), ORZF (195 kg N hm−2 and 150 kg N hm−2, respectively), and ORZTF (195 kg N hm−2 and 150 kg N hm−2, respectively). In 2019, the treatments were: N0, CSB, ORZF, ORZTF with urea (ORZTF-U), with ammonium chloride (ORZTF-Cl), and with ammonium sulfate (ORZTF-S) at 180 kg N hm−2. In the incubation experiment, there’re three treatments: N0, CSB, and ORZTF. The rates of P and K were the same in all experiments. Compared with CSB, ORZTF and ORZF significantly increased the yield, N uptake, N recovery efficiency, and N partial factor productivity of rice with the same N input. After 4.5 months of incubation, 78.5–92.7% of fertilizer N was reserved in the soils with ORZTF, about two-fold that with CSB. In all field and incubation experiments, AV loss was negligible when N was one-time root-zone applied alone or together with PK, close to that in N0 treatment. Compared with ORZF, ORZTF seemed to be a more promising method in rice fertilization, having the similar effect on N uptake increase and N loss reduction, but more convenience. Although the benefits of targeting fertilization were not significantly observed in the current work, with the idea of ‘fertilizing the roots but not the soil’, the method of ORZTF with common N, P and K fertilizers should be beneficial for cleaner and more efficient agricultural crop production in China.

Unexpected high suppression of ammonia volatilization loss by plastic film mulching in Korean maize cropping system

Plastic film mulching (PFM) as an agronomic practice was rapidly expanded to improve crop yield and quality, mainly due to improving soil water and temperature condition. PFM has been known to increase greenhouse gas (GHG) emissions, but its influence on ammonia (NH3) volatilization loss was not properly studied. To determine the impact of PFM on NH3 emission loss, PFM and no-mulching were designed as the main treatment. In addition, chemical (NPK) and organic fertilization plots as the sub-treatment were placed under the same mulching condition. In the NPK, the recommendation level (N-P2O5-K2O=186–35–74 kg ha-1) of chemical fertilizers was only applied for maize cultivation. In the organic fertilization, the mixture of barley and hairy vetch was cultivated during the fallow season and its whole biomass as green manure was incorporated for maize cultivation. PFM considerably improved average soil water and temperature regimes during cropping season by 0.02–0.05 m3 m-3 and 0.8–1.4 ℃ over no-mulching, respectively. These improved soil properties enhanced maize grain yield by around 95–270 and 80–300% in NPK and organic fertilization plots over no-mulching, respectively. The emission loss of NH3 gas which is highly water-soluble was 70–215% higher in NPK than organic fertilization under the same mulching. However, PFM significantly decreased seasonal NH3 emission loss by approximately 40–45% over no-mulching, probably due to physical trapping in water drops under the plastic film. To verify the suppression mechanism of NH3 emission loss by PFM, the emission rates of nitrous oxide (N2O) which is a water-insoluble gas were simultaneously monitored using the closed chamber method. Different from NH3 emission loss, PFM slightly increased N2O emission without a statistical difference, regardless of fertilization background. In conclusion, PFM could be a very useful cropping practice to decrease NH3 emission loss, as well as improve soil properties and crop productivity.

Distinct enhanced efficiency urea fertilizers differentially influence ammonia volatilization losses and maize yield

Distinct enhanced efficiency urea fertilizers differentially influence ammonia volatilization losses and maize yield

Analysis of Ammonia Volatilization Loss from a Paddy Soil with Empirical and Mechanistic Models

AbstractAmmonia volatilization from agricultural land has a negative impact on the atmospheric, aqueous, and land environments. However, this process is still not fully understood. In this study, a 2‐year field experiment is conducted in the Taihu Lake region of China to monitor ammonia volatilization from a paddy soil. The ammonia volatilization losses are in the range of 43.4 to 53.6 kg N ha−1 in the year 2013 and 25.9 to 35.4 kg N ha−1 in the year 2014, which account for 19.7% to 19.9% and 11.8% to 13.1% of the applied nitrogen with two different N treatments (N1: 220 kg N ha−1, N2: 270 kg N ha−1). The ammonia volatilization loss is highest during the basal fertilizer application, followed by the tillering and the ear‐differentiation stages. Then, two empirical models and one mechanistic model are used to simulate the ammonia volatilization process. These models are calibrated and validated with field experimental data. The results show that none of the three models accurately predict the ammonia volatilized from the rice field (R2 < 0.40), however, among the three models evaluated, the mechanistic model is more effective in simulating the ammonia volatilization process (R2 = 0.38).

Duromide increase NBPT efficiency in reducing ammonia volatilization loss from urea

ABSTRACT Novel fertilizer stabilization technologies are needed to decrease ammonia (NH3-N) losses and increase nitrogen use efficiency. Duromide + NBPT is a new technology that combines two molecules, Duromide and NBPT, whose propose is to increase the efficiency of the urease inhibitor NBPT in reducing NH3-N loss from urea. Preliminary results showed that Duromide + NBPT can be a more effective product than just NBPT, particularly under low soil pH and high-temperature conditions. This study aimed to compare the effects [...]

No significant influence of biochar and manure application on nitrogen fate and sequestration by tomato and garlic crops: A field experiment in California, USA

AbstractOrganic soil amendments can improve soil health but their role in improving N management has not been well quantified. The objectives of this research were to evaluate the influence of biochar and manure compost application on crop yield, N uptake, changes in soil and environmental losses and to use the information to assess the N requirement and project fertilization needs. A field experiment was conducted in California, USA, with processing tomato (Lycopersicon esculentum Mill.) grown first, followed by garlic (Allium sativum). The soil was a sandy loam with a pH of 7.2 and CEC of 9.1 cmol(+) kg−1. Treatments included two biochar products, derived from almond shell or softwood feedstocks, applied at 20 or 40 tonnes (t) ha−1, dairy manure compost at 20 t ha−1, combinations of the manure and the biochar (each at 20 t ha−1), and a control. Although biochar and manure applications improved the surface soil organic C and total N content, no significant effects on crop yield, biomass and N uptake, as well as ammonia volatilization and leaching loss, were observed. The amount of N sequestered by plants ranged from 3.2 to 3.8 and 9.9 to 10.0 kg N Mg−1 to produce fresh tomato fruits and garlic bulbs, respectively. However, about half of the N for tomato and 93% for garlic plants were removed from soil by harvesting. The N sequestered per unit biomass (or yield) production appears a stable parameter, which can be used to reliably project fertilization needs that target high NUE and minimal loss to the environment.

Influence of Nano-Zinc Oxide Coated Urea Fertilizer on Ammonia Volatilization Loss and Inorganic Nitrogen Content in Loamy Sand Soil

A laboratory incubation experiment in a closed dynamic air flow system was conducted for 30 days to estimate the volatilization loss of NH3-N from 0, 1, 2 and 3% Nano-ZnO coated urea treated soil. The volatilized NH3-N from the soil chambers was collected and titrated every 48 hours. Another incubation experiment was carried out to study the effect of coating urea with Nano-ZnO on the inorganic nitrogen (NH4-N and NO3-N) content in the treated soils at 2, 4, 8, 14 and 21 days of incubation period. The two experiments were arranged in a completely randomized design with three replications. The results of the first experiment indicated that coating urea fertilizer with Nano-ZnO reduced the total loss of NH3-N from 22.82 % of applied N in the soil treated with uncoated urea (0 % coating) to 13.03% for the highest coating level (3%) with a reduction in NH3-N loss by 42.90%.The results of second incubation experiment showed that the average of NH4-N content increased from 86.52 mg Kg-1 for 0% Nano-Zn coated urea to 131.04 mg Kg-1 in the soil treated with 3% Nano-Zn coated urea, and the ratio of extractable NO3-N average to the extractable NH4-N average was 1: 1.06, 1: 1.17, 1: 1.50 and 1: 1.75 in the soil treated with 0, 1, 2 and 3% Nano-Zn coated urea, respectively. Also, the average of total inorganic N content increased from 168.19 mg Kg-1 in the soil treated with uncoated urea (0% coating) to 205.70 mg Kg-1 in soil treated with highest coating level (3%).Therefore, using the Nano-Zn coated urea fertilizer improves nitrogen use efficiency and reduce ammonia loss from urea fertilizer applied to loamy sand soil.

Enhanced efficiency nitrogen formulations on stockpiled tall fescue production

AbstractLate summer application of nitrogen (N) fertilizer on stockpiled tall fescue [Schedonorus arundinaceus (Schreb.)] can improve forage yields. Using enhanced efficiency N fertilizers may be of benefit by reducing ammonia volatilization losses and promoting forage growth later in the growing season. This study evaluated the effect of different enhanced efficiency N formulations (Agrotain‐treated urea, SuperU, and Environmentally Smart Nitrogen) and untreated urea on the yield and nutritive value of stockpiled ‘KY‐31’ tall fescue over two stockpiling periods (2015–2016 and 2016–2017). Nitrogen was applied at four rates (0, 45, 90, and 134 kg N ha−1) in one application in late August prior to the beginning of the stockpiling period in Lexington, KY. During the 2015–2016 stockpiling period, forage yields increased with increasing N rates; forage yields ranged from 2,913 kg dry matter (DM) ha−1 when no N was applied up to 4,132 kg DM ha−1 when 134 kg N ha−1 was applied. Although forage yield was lower during the 2016–2017 stockpiling period, yield increased 75% even with the lowest N rate. Forage nutritive value was improved with increasing N rate. There were no differences in forage yield or nutritive value among enhanced efficiency N sources and standard urea. In summary, N applied in August improved stockpiled forage yield and nutritive value, regardless of N source.

Ammonia volatilization losses from urea coated with copper, boron, and selenium

Urea coated with copper and boron may be a vehicle for selenium fertilization in grazing systems to improve both forage and animal productivity, and consequently, the nutritional quality of milk and meat. Urea is the most often used form of N fertilizer in Brazil; however, it can experience high losses by volatilization, primarily in pastures with high amounts of senescent biomass. The goal of this study was to evaluate losses by ammonia volatilization from urea coated with Cu, B, and Se. The fertilizer was applied to the soil surface under forage straw residues in cylindric glass chambers under controlled laboratory conditions. The treatments were urea (UR), urea coated with boric acid and copper sulfate (UBC), urea coated with boric acid, copper sulfate, and selenium (UBCS), and ammonium sulfate (AS). Measurements were recorded at regular intervals after fertilizer application for 27 days. High losses occurred from ammonia volatilization of amidic-N sources in the initial days after fertilizer application. The total loss of N by ammonia volatilization according to fertilizer treatment was UR > UBC = UBCS > AS. Urea lost by ammonia volatilization accounted for up to 50% of the N applied, although losses from coated urea treatments UBC and UBCS were 11.45% lower than that of urea. The Cu and B in the coated urea reduced losses by ammonia volatilization and the inclusion of Se had no effect. It is suggested that Se may be added to the Cu and B coating of urea to reduce ammonia volatilization.

Fertilizer source and placement influence ammonia volatilization losses from water‐seeded rice systems

AbstractAmmonia volatilization, a primary N loss pathway from rice (Oryza sativa L.) production systems, leads to a reduction in N use efficiency and environmental problems. Ammonia volatilization has not been studied in water‐seeded rice systems or where aqueous NH3 is the primary fertilizer N source. Our objective was to quantify NH3 volatilization from preplant aqueous NH3 and compare it with drilled or broadcast urea. In addition, NH3 volatilization from a topdress N application applied midseason was quantified. This was accomplished with 10 field experiments representing a range of soil types. Preplant N treatments were a zero‐N control, injected aqueous NH3, broadcast urea, and drilled urea all applied at the farmer application rate to a dry soil. For the topdress experiment, the treatments were a zero‐N control and urea or (NH4)2SO4 applied at 34 kg N ha−1. Ammonia volatilization was measured up to 3 and 1 wk after the preplant and topdress N was applied, respectively, using a semi‐open static chamber. Losses due to NH3 volatilization from preplant broadcast urea were significantly higher than from the other other treatments but accounted for <2% of applied N. Losses from aqueous NH3 and banded urea were lower but were significantly greater than from the control. The losses occurred in the first week after flooding. When N was topdressed, 1.5 and 2.6% of applied N were lost via volatilization from urea and (NH4)2SO4, respectively.

Combined application of organic and inorganic fertilizers mitigates ammonia and nitrous oxide emissions in a maize field

This long-term study used a lysimeter platform to monitor the NH3 and N2O emissions of summer maize resulting from various fertilization treatments in the Huanghuaihai area, with the goal to assess the efficiency of fertilization measures aimed at reducing NH3 and N2O losses during the production of summer maize; the results provide a theoretical basis for synergistically improving maize yield and fertilizer utilization efficiency. A 2-year field trial was conducted. The trial included a no-N-fertilizer treatment as a control to study the following three fertilizer treatments: the exclusive application of urea, the exclusive application of cattle manure, and the combined application of organic and inorganic fertilizers. The results show that during the two maize growth seasons included in the trial, the average N2O losses associated with exclusively applying urea, exclusively applying cattle manure, and the combined application of organic and inorganic fertilizers were 273%, 542%, and 376% higher than those associated with the control treatment, respectively. During the same period, the average accumulative ammonia volatilization losses were 311%, 542% and 376% higher than those for the control treatment, respectively. The average nitrogen accumulation resulting from the combined application of organic and inorganic fertilizers was 82% higher than that for the control treatment, 12% higher than that for the exclusive application of cattle manure, and 6% higher than that for the exclusive application of urea. The average grain yield for the combined application of organic and inorganic fertilizers, the exclusive application of urea and the exclusive application of cattle manure were 76%, 68% and 61% higher than that for the control treatment, respectively. Overall, the combined application of organic and inorganic fertilizers showed a lower ammonia volatilization loss than the exclusive application of urea, which resulted in a higher ammonium nitrogen and nitrate nitrogen content in the soil, an increased nitrogen uptake, an increased dry matter accumulation of maize, and a high grain yield and nitrogen recovery efficiency.

Characteristics of soil nitrogen cycle and mechanisms underlying the increase in rice yield with partial substitution of mineral fertilizers with organic manure in a paddy ecosystem: A review

Partial substitution of mineral fertilizers with organic manure is a key strategy for stable and increase crop yield accompanying with zero growth of mineral fertilizers. Based on recent stu-dies, we reviewed the effects of partial substitution of mineral fertilizers with organic manure on rice yield, nitrogen utilization efficiency, soil nitrogen fractions, and microbial nitrogen fixation, ammonification, nitrification, and denitrification in rice paddy ecosystems. We further compared the cha-racteristics of soil nitrogen cycle of mineral fertilizers alone and partial substitution of mineral fertili-zers with organic manure. The partial substitution altered key processes of nitrogen cycling, including enhancement of ammonification, mediation of nitrification and denitrification, reduction of ammonia volatilization and nitrogen loss, improved the status of nitrogen supplements (enriching the supplement of low-molecular-weight organic nitrogen, adjusting the distribution of inorganic nitrogen components, increasing the amount of microbial biomass nitrogen, and decreasing the loss of total nitrogen), improved soil nitrogen supply (increasing supply of small molecule organic nitrogen, coordinating inorganic nitrogen components and proportions, and increasing soil microbial biomass nitrogen and total nitrogen fixation), which promoted nitrogen uptake and regulated nitrogen allocation in rice plant to realize stability and enhancement of rice yield.

Optimum rates of surface-applied coal char decreased soil ammonia volatilization loss.

Fertilizer N losses from agricultural systems have economic and environmental implications. Soil amendment with high C materials, such as coal char, may mitigate N losses. Char, a coal combustion residue, obtained from a sugar factory in Scottsbluff, NE, contained 29% C by weight. A 30-d laboratory study was conducted to evaluate the effects of char addition on N losses via nitrous oxide (N2 O) emission, ammonia (NH3 ) volatilization, and nitrate (NO3 -N) leaching from fertilized loam and sandy loam soils. Char was applied at five different rates (0, 6.7, 10.1, 13.4, and 26.8 Mg C ha-1 ; char measured in C equivalent) to soils fertilized with urea ammonium nitrate (UAN) at 200kg N ha-1 . In addition, there were two negative-UAN control treatments: no char (no UAN) and char at 26.8 Mg C ha-1 (no UAN). Treatment applied at 6.7 and 10.1 Mg C ha-1 in fertilized sandy loam reduced NH3 volatilization by 26-37% and at 6.7, 10.1, and 13.4 Mg C ha-1 in fertilized loam soils by 24% compared with no char application. Nitrous oxide emissions and NO3 -N leaching losses were greater in fertilized compared with unfertilized soil, but there was no effect of char amendment on these losses. Because NO3 -N leaching loss was greater in sandy loam than in loam, soil residual N was twofold higher in loam than in sandy loam. This study suggests that adding coal char at optimal rates may reduce agricultural reactive N to the atmosphere by decreasing NH3 volatilization from fertilized soils.

Comparing ammonia volatilization between conventional and slow-release nitrogen fertilizers in paddy fields in the Taihu Lake region.

Pollution arising from ammonia volatilization in paddy fields could be reduced by using slow-release nitrogen fertilizers. In recent years, slow-release nitrogen fertilizers have been commonly used to replace conventional nitrogen fertilizers in the Taihu Lake region to reduce ammonia volatilization and improve nitrogen-use efficiency. To compare ammonia volatilization losses and examine the effects of different factors (N rates, types, field water NH4+, pH, and rainfall) between conventional nitrogen fertilizer and slow-release nitrogen fertilizer, paddy field experiments were conducted using conventional urea and sulfur-coated urea (SCU) fertilizers. The results indicated that ammonia volatilization flux positively increased with N application rate following an exponent function and depended on field water NH4+ concentration and pH. The ammonia volatilization under SCU treatment was 37.95-70.48kg/hm2, accounting for 40.66-52.86% of the fertilizer application rate. Compared with the same N input, the ammonia volatilization loss rate was 11.53-25.33% lower under the SCU treatment. Besides, SCU produced an unfavorable environment for ammonia volatilization, with a 1.15-2.61% decrease in pH and a 40.83-43.58% decrease in field water NH4+ concentration.

Nitrogen Release Characteristics of a Bag Controlled Release Fertilizer

Slow release fertilizers are designed to enhance crop yield and minimizing the loss of nitrogen (N) to environment. However, N release in leaching and loss in ammonia emission from bag controlled release fertilizers have not been previously evaluated under the standardized conditions in soil. Accordingly, a laboratory study was conducted to evaluate the characteristics of N release from a bag controlled fertilizer with 1, 3, 5 and 7 rows of hole (B-1, B-3, B-5, B-7) and a kraft bag without hole (B-W). The results showed that the amount of N leaching of B-1, B-3, B-5, B-7 and B-W were significantly lower than urea fertilizer without bag (U). The maximum N release from the fertilizers followed the order: U (83.16%) > B-7 (54.61%) > B-5 (54.02%) > B-W (51.51%) > B-3 (48.87%) > B-1 (38.60%) during the experimentation. Compared with U treatment, ammonia volatilization losses were significantly decreased by B-1, B-3, B-5, B-7 and B-W treatments. Based on N release and loss, a suitable bag with holes should be considered in practice when using the bag controlled fertilizer to meet an environment good objective. The evaluation method merits further study combined with field experiment.

Ammonia Volatilization Losses during Irrigation of Liquid Animal Manure

Ammonia loss resulting from land application of liquid animal manure varies depending on the composition of the manure and the method used to apply manure to cropland. High levels of ammonia volatilization result in an economic loss to the farmer based on the value of the nitrogen and have also been shown to be a source of air pollution. Using irrigation as a method of applying liquid manure to cropland has generally been accepted as a method that increases the volatilization of ammonia. However, only three studies available in the literature measured the amount of ammonia lost during the irrigation process. Only one of the three studies concluded that ammonia loss during irrigation was significant. A pooled statistical and uncertainty analysis of the 55 available observations was performed to determine if ammonia loss occurred during irrigation of animal manure. Data on the total solids content of the manure were also included as an indicator of evaporation losses. Volatilization losses during irrigation were not found to be statistically significant, and evaporation losses were small, 2.4%, and agreed with previous studies on irrigation performance. Furthermore, the range of ammonia loss reported in previous studies was determined to be within the errors associated with the measurement of total ammoniacal nitrogen concentrations and the calculation of per cent differences.

Effect of Two Soil Synergists on Ammonia Volatilization in Paddy Fields

Nitrification inhibitor and biochar are commonly used as soil synergists. Among them, nitrification inhibitor can increase crop yields and N use efficiency, while biochar is a relatively new way of using biomass resources and has certain adsorption characteristics. In order to reduce nitrogen loss and environmental pollution caused by ammonia volatilization in paddy fields, a pot experiment with chemical fertilizer application (CN) as a control was conducted to study the effects of biochar (B), nitrapyrin (CP), and compound application (BCP) on pH, NH4+-N concentration dynamics in the flood water, rice yields, and ammonia volatilization from paddy fields. The results showed that the application of these two synergists had no significant effect on rice yields, and the nitrification inhibitors had a tendency to increase rice yields. The two synergists significantly increased ammonia volatilization from paddy fields, accounting for 25%-35% of the total N rate. Ammonia volatilization during periods of fertilizer application accounted for 86%-91% of the total loss, representing the main period of ammonia volatilization. Compared with the CN treatment, the CP treatment increased NH4+-N concentrations in flood water and the loss of ammonia via volatilization, which was increased by 59.18% and mainly occurred during a week after the basal fertilization(138%) and spike fertilization (48%), and non-fertilization stage (78%). Biochar had a promoting effect on ammonia volatilization with typically phased characteristics. The initial increasing effect of biochar on ammonia volatilization was higher than during the later stages, when NH4+-N concentrations and the pH of flood water showed the same trend. In addition, the coupling of nitrification inhibitor and biochar significantly increased the total loss of ammonia via volatilization loss due to the promotion effect of CP and B. The problem of increased ammonia volatilization loss caused by the application of nitrification inhibitors requires further research.

Effect of controlled drainage on nitrogen losses from controlled irrigation paddy fields through subsurface drainage and ammonia volatilization after fertilization

The effect of controlled drainage (CD) on nitrogen (N) losses from controlled irrigation (CI) paddy fields through subsurface drainage and ammonia volatilization (AV) was investigated by managing water table control levels (WTC) with a lysimeter equipped with an automatic water table control system. Three drainage treatments were implemented, namely, controlled water table depths 1–3. The increases of the WTC resulted in a high proportion of groundwater levels below the WTC, which reduced the subsurface outflow from CI paddy fields by 30.5% during the first week after fertilization. Total N concentrations in the 0–10 cm soil solution and subsurface drain water were higher as the WTC increased. The increase of the WTC during the first week after fertilization could effectively decrease the N losses from CI paddy fields by 9.5%, and the first weekly N losses through subsurface drainage and AV after fertilization were reduced by 17.2% and 9.3%, respectively. The large reductions in subsurface outflow decreased the first weekly N losses through subsurface drainage after fertilization. The retention time of shallow water in CI paddy fields was extended with the increases in WTC, which may reduce the first weekly AV losses after fertilization. Results show that the combination of CI and CD may be an effective water management method for mitigating N losses through subsurface drainage and AV after fertilization from paddy fields.

Ammonia Volatilization Loss and Corn Nitrogen Nutrition and Productivity with Efficiency Enhanced UAN and Urea under No-tillage

New urease and nitrification inhibitors and polymer coatings were introduced in recent years, but their effects on N loss and plant N nutrition were scarcely examined in agronomic no-tillage production systems. A field experiment of urea treated with efficiency enhancers was conducted on no-tillage corn (Zea mays L.) in Tennessee, the USA during 2013–2015. A field experiment on urea and ammonium nitrate (UAN) treated with efficiency enhancers was carried out on no-tillage corn in Tennessee in 2014 and 2015. Urea treated with N-(n-butyl) thiophosphoric triamide (NBPT) at concentrations of 20% (NBPT1), 26.7% (NBPT2), or 30% (NBPT3) and polymer coated urea (PCU) were effective but maleic-itaconic copolymer treated urea was ineffective in reducing ammonia volatilization loss and improving N nutrition, grain yield, and N agronomic use efficiency of corn compared with untreated urea. Specifically, NBPT1, NBPT2, or NBPT3 treated urea and PCU reduced the total ammonia volatilization loss by 29.1–78.8%, 35.4–81.9%, 77.3–87.4%, and 59.1–83.3% during the 20 days after N applications, but increased grain yield by 15.6–31.4%, 12.9–34.8%, 18.7–19.9%, and 14.6–41.1%, respectively. The inhibitory effect of NBPT on ammonia volatilization did not improve with NBPT concentration increased from 20% to 30%. UAN treated with NBPT3 or a combination of urease and nitrification inhibitors resulted in 16.5–16.6% higher corn yield than untreated UAN only when they were surface applied. In conclusion, when urea-containing fertilizers are surface applied without any incorporation into the soil under no-tillage, their use efficiencies and performances on corn can be enhanced with an effective urease inhibitor in areas and years with noticeable urea N losses.

Ammonia volatilization and nitrogen runoff losses from moso bamboo forests after different fertilization practices

Moso bamboo (Phyllostachys edulis (Carrière) J. Houz.) is a major giant bamboo species. Unreasonable fertilization and nitrogen (N) loss is a serious problem. A field experiment was conducted to determine the effects of application methods (furrow and hole) and depths (0–20 and 20–40 cm) on ammonia (NH3) volatilization and N runoff losses from June to December, 2015. Ammonia volatilization was detected as a single peak curve after fertilization. Three weeks later, fluxes of all fertilization treatments were similar to those of the control and remained stable. After the experiment, the cumulative NH3 volatilization was 17.2–21.4 kg·ha−1. Approximately 90% of NH3 volatilization occurred within the first two weeks. The NH4+-N loss was higher than the NO3−-N loss, and the total runoff losses were relatively low. For the same application method, with the increase of application depth, the NH3 volatilization and N runoff losses reduced; for the same application depth, the NH3 volatilization and N runoff losses after furrow application were lower than those after hole application. Therefore, the deep and furrow application methods were effective in reducing N loss through NH3 volatilization and runoff. In the present study, furrow application at a 20–40 cm depth has been appropriate for field practice.