Ammonia Volatilization Research Articles

Trace metal uptake in forage systems receiving long‐term applications of alum‐treated or untreated poultry litter

AbstractTreating poultry litter with alum (Al2[SO4]3·14H2O) is a commonly used best management strategy for reducing ammonia (NH3) volatilization and phosphorus (P) runoff and leaching. However, little is known about how this amendment affects trace metal availability and uptake by forages, as well as potential issues with phytotoxicity, toxicity to grazing animals, and overall yield. The objective of this study was to determine longitudinal effects of alum‐treated poultry litter, untreated litter, ammonium nitrate, and an unfertilized control on trace metal (As, Cu, Se, and Zn) and S concentrations and uptake by tall fescue (Festuca arundinacea Schreb.), yield, as well as availability in soil over 20 years. Greater (p < 0.05) Mehlich‐3 extractable soil As and subsequent forage As uptake occurred with alum beyond the 6.72 Mg ha−1 rate; however, forage As concentrations were not affected by alum. Forage yields were greater with alum‐treated and untreated litters than with ammonium nitrate applied at the same N rate. Treating litter with alum generally did not improve tall fescue yields, except at the lowest litter rate (2.24 Mg ha−1). Alum treatment of poultry litter has been shown to be a cost‐effective best management practice that reduces ammonia volatilization, which improves air quality and poultry production, while reducing P and heavy metal runoff and ultimately improving water quality. Given that trace metal and S concentrations in forages were all in the normal ranges, treating poultry litter with alum does not pose issues with respect to metal phytotoxicity and/or toxicity to grazing animals.

Nitrogen migration and transformation in a saline-alkali paddy ecosystem with application of different nitrogen fertilizers.

With the increasing transformation of saline-alkali land into paddy, the nitrogen (N) loss in saline-alkali paddy fields becomes an urgent agricultural-environmental problem. However, N migration and transformation following the application of different N fertilizers in saline-alkali paddy fields remains unclear. In this study, four types of N fertilizers were tested to explore the N migration and transformation among water-soil-gas-plant media in saline-alkali paddy ecosystems. Based on the structural equation models, N fertilizer types can change the effects of electrical conductivity (EC), pH, and ammonia-N (NH4+-N) of surface water and/or soil on ammonia (NH3) volatilization and nitrous oxide (N2O) emission. Compared with urea (U), the application of urea with urease-nitrification inhibitors (UI) can reduce the potential risk of NH4+-N and nitrate-N (NO3--N) loss via runoff, and significantly (p < 0.05) reduce the N2O emission. However, the expected effectiveness of UI on NH3 volatilization control and total N (TN) uptake capacity of rice was not achieved. For organic-inorganic compound fertilizer (OCF) and carbon-based slow-release fertilizer (CSF), the average TN concentrations in surface water at panicle initiation fertilizer (PIF) stage were reduced by 45.97% and 38.63%, respectively, and the TN contents in aboveground crops were increased by 15.62% and 23.91%. The cumulative N2O emissions by the end of the entire rice-growing season were also decreased by 103.62% and 36.69%, respectively. Overall, both OCF and CSF are beneficial for controlling N2O emission and the potential risks of N loss via runoff caused by surface water discharge, and improving the TN uptake capacity of rice in saline-alkali paddy fields.

Soil mineral nitrogen content and grain yield with enhanced efficiency fertilizers in maize

AbstractUrea is the most common N fertilizer worldwide, but N from urea breakdown can be easily lost through ammonia (NH3) volatilization, ammonium (NH4+) nitrification, nitrate (NO3−) denitrification or NO3−–leaching processes. Enhanced efficiency fertilizers (EEFs) are formulated to minimize N losses and maximize plant N uptake and crop yields. The capacity of urea EEFs (urea with urease inhibitor, nitrification inhibitor, both urease and nitrification inhibitors, and polymer‐coated) to maintain N in the soil profile throughout the growing season was determined by the analysis of [NH4+–N] and [NO3−–N] in three top‐soil depth increments at three dates in three seasons of no‐till maize (Zea mays L.). Surface‐applied EEFs, untreated urea, and injected urea ammonium nitrate (UAN) were compared at an application rate of 168 kg N ha−1. Within and across years, soil [NO3−–N] and [NH4+–N] typically decreased with depth and time since urea application. Among the EEFs, only a polymer‐coated urea produced greater [NO3−–N] and [NH4+–N] at several sampling dates and depths, and greater grain yields than untreated urea across the 3 yr. Nonetheless, the polymer‐coated urea resulted in significantly greater fertilizer use efficiency (FUE) than untreated urea in only 1 of 3 yr. Several EEFs increased grain yields compared to untreated urea each year, but FUE generally was similar to that with untreated urea. Environmental conditions influenced the effectiveness of EEFs in improving soil mineral N availability and increasing grain yield.

Mitigating Ammonia Volatilization without Compromising Yield and Quality of Rice through the Application of Controlled-Release, Phosphorus-Blended Fertilizers

Ammonia (NH3) volatilization from paddy fields is a major issue which leads to poor fertilizer use efficiency and is considered a severe threat to the atmosphere. The previous research studies gave importance to the use of nitrogen fertilizers to mitigate NH3 volatilization, while very little emphasis was given to the role of other fertilizers, such as phosphorus (P), for the alleviation of NH3 volatilization in rice fields. Considering P importance herein, we conducted two consecutive field experiments using an innovative, controlled-release, phosphorus-blended fertilizer (CRPBF, with levels CRP0, CRP1, and CRP2). We compared CP0 (in which no fertilizer was applied), CP1 (112.5 kg P ha−1 P of locally recommended fertilizers), and CP2: (P and K blended fertilizers) to determine the best possible way to reduce NH3 volatilization without affecting the yield and quality of rice. The results of the study suggested that the yield of rice increased significantly with the application of CRP1 (11.11 t ha−1) and CRP2 (11.99 t ha−1). The addition of CRP1 and CRP2 to the rice field also enhanced yield-related components, i.e., panicle weight, total spikelets per unit area, spikelets per panicle, and above-ground biomass. CRP0 showed a lower yield and related components when compared to CP2. The addition of CRP1 and CRP2 demonstrated lower protein contents when compared to other treatments. The CRPBF application improved starch content and taste scores, and reduced the chalkiness of the rice grain during both years. The results showed a decreasing trend in NH3 volatilization from CRPBF amendments by improving the nitrogen use efficiency traits when compared to other treatments: CRP2, CRP1, and CRP0 reduced NH3 volatilization by 45%, 35%, and 15%, respectively. The results of this study indicate that, due to the episodic nature of NH3 volatilization, CRPBFs with 50% P and 100% P can markedly reduce NH3 volatilization from paddy fields without compromising the yield and quality of the crop, and could be a promising alternative to the ordinary commercial fertilizers used in rice fields.

Effects of warming and fertilization on paddy N2O emissions and ammonia volatilization

Several studies have proved the influence of warming to N2O emissions and NH3 volatilization in paddies. However, it is not clear whether the performance is affected by fertilization. Here, we performed a field trial to evaluate the impacts of warming and fertilization on N2O emissions and NH3 volatilization from paddies. A free air temperature increase system was used for the experimental warming treatment (ET), while the control treatment used ambient temperature (AC). Both ET and AC treatments were combined with nitrogen (N) fertilizer (CF) or without fertilizer input (CK). The results showed insignificant interaction effects of warming and fertilization on seasonal cumulative N2O emissions and NH3 volatilization. Compared with AC, seasonal cumulative N2O emissions and ammonia volatilization in the ET treatment increased by 118.44% and 38.41%, respectively. Moreover, fertilization surprisingly stimulated seasonal cumulative N2O emissions and ammonia volatilization; values were 15.91 and 2.35 times higher than those in the CK treatment. These results imply that fertilization could intensify the increasing effect of warming on N2O emissions and ammonia volatilization. The variable importance for the projection (VIP) analysis revealed that soil N transformation (the rates of N mineralization, nitrification, and denitrification) was the key to affecting reactive N loss rather than soil fertility. Additionally, the ammonia volatilization rate increased with ambient temperature and NH4+-N solution concentration in the microsystem. Importantly, there was a "surge" inflection point of the ammonia volatilization rate under both high ambient temperature (30 °C) and NH4+-N concentration (15 mg/L) conditions. Our findings indicate that warming did promote N2O emissions and ammonia volatilization in paddies by accelerating soil N transformation, which might be aggravated by fertilization. Furthermore, the "surge" effect of high ambient temperature and NH4+-N concentration on ammonia volatilization deserves further attention.

Low-Cost Greywater Treatment Using Polyculture Microalgae-Microalgal Growth, Organics, and Nutrient Removal Subject to pH and Temperature Variations During the Treatment.

Organics and nutrient removal studies are rarely done using polyculture microalgae, and that too in outdoor conditions, as they are often not deemed effective for wastewater treatment purposes. This study examined the organics and nutrient removal efficiency of polyculture microalgae cultivated in greywater. The reactor was operated in outdoor conditions. Hence, it was subjected to natural pH and temperature variations. A growth rate of 0.05gL-1day-1 was observed for temperatures up to 37°C, beyond which the growth rate declined by 0.07g L-1day-1. During the treatment, the pH of the system was observed to be between 7.4 and 8.4. However, the growth rate would again pick up (0.05gL-1day-1) when the pH and temperature moved towards the optimum range, indicating that the polycultures adapt very quickly to their environment. The maximum biomass concentration reached 0.82 gL-1. The highest removal efficiency of organic carbon, ammonia, and phosphate was 80.7, 61.9, and 58.4%, respectively. Nitrate and nitrite concentrations remained ≤ 1.3 mgL-1 and ≤ 2mgL-1, respectively, indicating the absence of nitrification/denitrification and ammonia volatilization. The mass balance of microalgae indicated that the primary removal mechanism of nitrogen and phosphorus removal was assimilation by the microalgae. The study proved polyculture microalgae to be as effective as some monoculture species in wastewater treatment, which require costlier controlled growth conditions. The high organics and nutrient removal by polycultures in outdoor conditions could pave the way to reducing wastewater treatment costs.

Simultaneous recovery of nutrients and water from human urine by a novel thermally activated peroxydisulfate and membrane distillation integrated system

Membrane distillation (MD) has been applied to urine recovery with growing interest and demand for resource recovery from waste. However, MD application to urine is limited by obstacles, including the inability to recover nutrients and water simultaneously, low separation efficiency due to ammonia permeation, and membrane fouling. Herein, a novel system integrating thermally activated peroxydisulfate with MD (TAP-MD) was developed to overcome the above obstacles. The synergy effects were found between TAP pretreatment and MD process. With TAP pretreatment, membrane fouling was alleviated by organics degradation and mineral precipitation reduction, resulting in significant improvements in MD performance. Water flux of pretreated urine decreased from 25 L/m2/h to 15 L/m2/h after 80 % of water recovery, but that of unpretreated urine decreased to near zero after 38 % of water recovery. Meanwhile, MD process revealed further enhancement in urine stability by activating residual peroxydisulfate, reducing nutrient losses due to ammonia volatilization during storage and utilization of concentrated fertilizer. As a result, nearly 92.95 % of N-urea, 97.35 % of P, and 99.77 % of K was recovered as concentrated liquid fertilizer, meanwhile, 80 % of water was recovered as high-quality reclaimed water. The energy efficiency was improved by reusing waste heat from pretreatment. The TAP-MD system achieved a 45.63 % increase in thermal efficiency and a 38.25 % reduction in specific energy consumption compared to no pretreatment. This study developed an energy-efficient and high-performance separation treatment for complete resource recovery from urine.

Value-Added Fertilizers Enhanced Growth, Yield and Nutrient Use Efficiency through Reduced Ammonia Volatilization Losses under Maize–Rice Cropping Cultivation

Plant nutrition is an essential element for crop production and enormous amounts of fertilizers are used in agricultural systems. However, these sources emit toxic gasses and compounds in the environment that not only deteriorate soil quality but also cause a reduction in the use efficiency of applied nutrients. Therefore, the value addition of these fertilizer sources by coating micronutrients, microbes, polymers or other organic and inorganic compounds have been advocated recently. The present study aimed to evaluate the effectiveness of value-added fertilizer sources for growth and yield improvement of Zea mays (Pioneer-30T60) and Oryza sativa (Super Basmati-515) with a reduction in ammonia volatilization and an improvement in nutrient recovery by crop grains. Different phosphorus (P), potassium (K) and nitrogen (N) fertilizer sources (Di-ammonium phosphate (DAP), polymer coated DAP, zarkhez plus NPK, urea, polymer-coated urea and zabardast urea) were used in different combinations keeping one control for N. The results revealed that maximum growth, yield and nutrient recovery was shown by polymer-coated urea and DAP followed by zarkhez plus NPK and zabardast urea. Moreover, a minimum ammonia emission was recorded by polymer-coated fertilizers, but other value-added fertilizers were found inefficient in reducing ammonia emission, though these sources improved all growth and yield attributes. Nutrient recovery efficiency was patterned as; polymer coated fertilizers &gt; zarkhez plus NPK + zabardast urea &gt; zarkhez plus NPK + urea &gt; DAP + zabardast urea &gt; DAP + urea &gt; DAP. Thus, the use of polymer-coated fertilizers was beneficial for both the reduction in ammonia volatilization and for improving nutrient use efficiency with maximum crop benefits.

Arbuscular Mycorrhizal Fungi Shift Soil Bacterial Community Composition and Reduce Soil Ammonia Volatilization and Nitrous Oxide Emissions.

Arbuscular mycorrhizal fungi (AMF) establish mutualistic relationships with the majority of terrestrial plants, increasing plant uptake of soil nitrogen (N) in exchange for photosynthates. And may influence soil ammonia (NH3) volatilization and nitrous oxide (N2O) emissions directly by improving plant N uptake, and/or indirectly by modifying soil bacterial community composition for the soil C availability increasing. However, the effects of AMF on soil NH3 volatilization and N2O emissions and their underlying mechanisms remain unclear. We carried out two independent experiments using contrasting methods, one with a compartmental box device (in 2016) and the other with growth pot experiment (in 2020) to examine functional relationships between AMF and soil NH3 volatilization and N2O emissions under varying N input. The presence of AMF significantly reduced soil NH3 volatilization and N2O emissions while enhancing plant biomass and plant N acquisition, and reducing soil NH4+ and NO3-, even with high N input. The presence of AMF also significantly reduced the relative abundance within the bacterial orders Sphingomonadales and Rhizobiales. Sphingomonadales correlated significantly and positively with soil NH3 volatilization in 2016 and N2O emissions, whereas Rhizobiales correlated positively with soil N2O emissions. High N input significantly increased soil NH3 volatilization and N2O emissions with increasing relative abundance of Sphingomonadales and Rhizobiales. These findings demonstrate the contribution of AMF in regulating NH3 and N2O emission by improving plant N uptake and altering soil bacterial communities. They also suggest that altering the rhizosphere microbiome might offer additional potential for restoration of N-enriched agroecosystems.

Effects of tanniferous sainfoin and Acacia mearnsii extract on urinary N excretion and ammonia volatilization from the slurry of dairy cows

This study examined whether the effects of the tanniferous extract of Acacia mearnsii on N partitioning in dairy cows and ammonia (NH3) volatilization from their excreta are additive to that of the tanniferous legume sainfoin (Onobrychis viciifolia) and remain consistent when supplemented to different silage types with varying crude protein (CP) content. In a 6 × 6 Latin Square arrangement, six multiparous Holstein cows (milk yield: 36.6 ± 3.9 kg/d; 70 ± 13 d in milk) were assigned randomly to six treatments. The experiment included a 14-d adaptation and a 7-d data collection period, where intake, milk yield, and composition were recorded daily and excreta were collected. Cows had ad libitum access to one of six total mixed rations containing (dry matter [DM] basis) 750 g/kg DM silage. The silages were rich in either sainfoin (180 g/kg CP of DM), ryegrass (118 g/kg CP) or clover (220 g/kg CP). Each silage was supplemented with 20 g/kg DM of Acacia mearnsii extract or straw meal. The effects on N partitioning, ruminal volatile fatty acids (VFA) and microbiota, and NH3 volatilization from slurry reconstituted from fresh urine and feces were determined. The sainfoin-based diet reduced the apparent digestibility of organic matter, acid detergent fiber, and N compared with the ryegrass- and clover-based diets (P < 0.001). Acacia reduced the DM intake (P < 0.05) and apparent digestibility of organic matter and N across all silage types (P < 0.01). The digestibility of neutral detergent fiber was reduced with sainfoin, and ryegrass with Acacia (Silage × Acacia interaction P < 0.05). Acacia reduced the ruminal acetate proportion (P < 0.05) but did not affect ruminal propionate and n-butyrate or the microbiota composition. With ryegrass, the rumen fluid had lower acetate (P < 0.001) and greater n-butyrate proportions (P < 0.01) compared to sainfoin and clover, lower propionate proportions as compared with sainfoin (P < 0.05), and the lowest blood urea N concentration (P < 0.001). Acacia reduced energy-corrected milk yield (P < 0.05). Milk protein content was reduced with the sainfoin diet (P < 0.05). Sainfoin (compared to clover) and Acacia supplementation shifted the N excretion from urine to feces and decreased urinary urea N excretion and NH3 volatilization from the slurry (P < 0.05). The effects of the two tannin sources were widely additive in mitigating urinary urea N and NH3 volatilization. The results illustrate that combinatory N-abatement measures based on different CT sources are efficient, but supplementing Acacia resulted in decreasing dry matter intake and milk production, while sainfoin supplementation resulted in lower organic matter digestibility.

Diet Composition and Using Probiotics or Symbiotics Can Modify the Urinary and Faecal Nitrogen Ratio of Broiler Chicken's Excreta and Also the Dynamics of In Vitro Ammonia Emission.

The objective of this research was to determine whether diet composition, or adding probiotic or symbiotic feed additives to broiler diets can modify the N composition of the excreta and the dynamics of ammonia volatilization from the manure. A total of 574 one-day-old Ross 308 broiler chickens were fed four different diets. The treatments included a corn and soybean meal-based control diets (C), wheat-based and wheat bran containing diets (W), a multi-strain probiotic treatment (Broilact®; Br), and a symbiotic additive containing Bacillus subtilis, inulin, and Saccharomices cerevisiae (Sy). Feeding the wheat-based diet significantly improved the weight gain and FCR of chickens. Treatment W also significantly increased the dry matter content of the excreta compared with the probiotic and symbiotic treatments. Both Br and Sy tended to decrease the amount of excreted uric acid, which is the main substrate of ammonia. Treatment Sy reduced the urinary N ratio of the excreta in comparison with treatment W. The symbiotic additive resulted in significantly higher ammonia emission in the first two hours. On the other hand, the dynamics of the emission was slow at the beginning and increased steeply after 15 h when the wheat-based diets were fed. Based on our results, the wheat-based diets, containing soluble arabinoxylans, and the symbiotic treatments of broiler diets have an impact on the urinary and faecal nitrogen composition of the excreta, and also on the dynamics of ammonia release from the manure.

Regulation of denitrification/ammonia volatilization by periphyton in paddy fields and its promise in rice yield promotion.

Nitrogen (N) is the most limiting nutrient in rice production. N loss via denitrification and ammonia (NH3 ) volatilization decreases N utilization efficiency. The effect of periphyton (a widespread soil surface microbial aggregate in paddy soil) on N-cycling processes and rice growth in paddy soils remain unclear. The purpose of this study was to reveal the interactions of periphyton with the overlying water and sediment in paddy soils on denitrification/NH3 emissions and rice yield by combining pot experiments and path analysis modeling. The sediment exerted significant direct and positive effects on denitrification. The periphyton both directly and indirectly enhanced denitrification, mainly by regulating the ammonium (NH4 + )-N content in the sediment. The total contribution of periphyton to denitrification was stronger than that of the overlying water but smaller than that of the sediment. The pH in the overlying water and the NH4 + -N content in the sediment had a strong positive effect on NH3 volatilization. Although the periphyton biomass and chlorophylla directly prohibited NH3 emissions, this was counterbalanced by the indirect stimulation effects of the periphyton due to its positive alteration of the pH. Moreover, periphyton facilitated rice yield by 10.2% by releasing N. Although the periphyton may have driven N loss by regulating the NH4 + -N content in the sediment and the pH in the overlying water, our study also found that the periphyton was considered a temporary N sink and provided a sustained release of N for rice, thus increasing the rice yield. © 2022 Society of Chemical Industry.

Predicting nitrogen use efficiency, nitrogen loss and dry matter intake of individual dairy cows in late lactation by including mid-infrared spectra of milk samples

BackgroundNitrate leaching to groundwater and surface water and ammonia volatilization from dairy farms have negative impacts on the environment. Meanwhile, the increasing demand for dairy products will result in more pollution if N losses are not controlled. Therefore, a more efficient, and environmentally friendly production system is needed, in which nitrogen use efficiency (NUE) of dairy cows plays a key role. To genetically improve NUE, extensively recorded and cost-effective proxies are essential, which can be obtained by including mid-infrared (MIR) spectra of milk in prediction models for NUE. This study aimed to develop and validate the best prediction model of NUE, nitrogen loss (NL) and dry matter intake (DMI) for individual dairy cows in China.ResultsA total of 86 lactating Chinese Holstein cows were used in this study. After data editing, 704 records were obtained for calibration and validation. Six prediction models with three different machine learning algorithms and three kinds of pre-processed MIR spectra were developed for each trait. Results showed that the coefficient of determination (R2) of the best model in within-herd validation was 0.66 for NUE, 0.58 for NL and 0.63 for DMI. For external validation, reasonable prediction results were only observed for NUE, with R2 ranging from 0.58 to 0.63, while the R2 of the other two traits was below 0.50. The infrared waves from 973.54 to 988.46 cm−1 and daily milk yield were the most important variables for prediction.ConclusionThe results showed that individual NUE can be predicted with a moderate accuracy in both within-herd and external validations. The model of NUE could be used for the datasets that are similar to the calibration dataset. The prediction models for NL and 3-day moving average of DMI (DMI_a) generated lower accuracies in within-herd validation. Results also indicated that information of MIR spectra variables increased the predictive ability of models. Additionally, pre-processed MIR spectra do not result in higher accuracy than original MIR spectra in the external validation. These models will be applied to large-scale data to further investigate the genetic architecture of N efficiency and further reduce the adverse impacts on the environment after more data is collected.

Effect of Deep Fertilization with Slow/Controlled Release Fertilizer on N Fate in Clayey Soil Wheat Field

Clayey soil seriously affects water-holding capacity and nutrient movement. Adopting appropriate agronomic measures to optimize the distribution of soil inorganic nitrogen (SIN) and reduce the nitrogen (N) loss in this soil is the key to agricultural sustainable development. To clarify the effect of deep fertilization of slow/controlled release fertilizer with sowing on N loss in a clayey soil wheat field, two types of fertilizers, conventional fertilizer (CN) and slow/controlled release fertilizer (RCU), were selected in this study. Here, we evaluated the effects of these two fertilizer types on wheat yield, seasonal N runoff loss, ammonia volatilization, and N2O emissions in wheat fields in two typical fertilization modes (manual surface sowing and spreading (B) and belowground fertilization of slow/controlled release urea with mechanized strip sowing (D)). The temporal and spatial distribution characteristics of SIN in topsoil were also analyzed. The results showed that under the same fertilizer type, the wheat yield of D treatment was significantly higher than that of B treatment, whereas the yield of RCU was notably higher than that of CN under the same fertilization mode. D-RCU achieved the highest yield of 6.97 t·hm-2. The seasonal N losses from runoff and ammonia volatilization were higher than that from N2O emissions, and the responses of different N loss pathways to fertilizer types and fertilization methods were diverse. Fertilizer type and runoff occurrence time were the main influencing factors of N runoff loss, and N runoff loss of the RCU treatment was higher in the non-fertilization period. Unfortunately, affected by annual rainfall pattern, the seasonal N runoff loss of the RCU treatment (20.35 kg·hm-2) was significantly higher than that of the CN treatment (10.49 kg·hm-2). The late growth period was the main phase of ammonia volatilization, and the later period was jointly affected by fertilization modes and fertilizer types. The B-CN treatment induced the highest seasonal ammonia volatilization (18.15 kg·hm-2), which was significantly higher than that of the other treatments (7.31-8.38 kg·hm-2). Additionally, the D-RCU treatment (2.41 kg·hm-2) tended to reduce the N2O emissions in comparison to that in the B-CN treatment (4.02 kg·hm-2). The results also indicated that the horizontal movement of SIN was higher than the vertical movement. Deep fertilization of RCU was conducive to optimizing the spatial and temporal distribution of SIN, which was the main reason for the increase in wheat yield and the control of N loss from wheat fields. These results suggest that RCU is a suitable alternative fertilizer for increasing yield and reducing N loss in clayey soil wheat fields; D-RCU can increase the wheat yield and reduce ammonia volatilization and N2O emissions in wheat fields by optimizing the spatial and temporal distribution of SIN, and its increasing effect on N runoff loss in the non-fertilization period deserves attention.

Activating soil nitrification by co-application of peanut straw biochar and organic fertilizer in a rare earth mining soil

The intensive mining activities to extract rare earth elements from ion-adsorption rare earth deposits have introduced massive amounts of ammonium into the tailing soils in southern China. Compared to the ubiquitous soil nitrification in cropland, forest, and grassland soils, however, there is no feasible strategy to alleviate the ammonium contamination in tailing soil. Herein, the feasibility to remove ammonium by adding ammonium adsorbents (e.g., biochar, activated carbon, and zeolite), alkaline materials, and organic fertilizer to the rare earth mining soil was explored. The amendment of rice straw biochar, activated carbon, or zeolite in combination with CaCO3 and organic fertilizer showed no significant effect on ammonium removal due to their limited capacity to elevate soil pH. However, the co-application of peanut straw biochar (PSBC), CaCO3, and organic fertilizer activated both the ammonia volatilization and soil nitrification processes. Specifically, the three components functioned as follows: organic fertilizer supplied active ammonia-oxidizing bacteria (AOB); PSBC stimulated AOB proliferation by elevating soil pH above 7.75; CaCO3 ameliorated soil acidity and reduced the lag time for activating soil nitrification. The soil ammonium removal and nitrate accumulation rates were positively correlated to the acid neutralization capacity of PSBC prepared at 400 °C–800 °C. The qPCR and microbial community analysis results indicated that Nitrosomonas europaea was the dominant AOB that was responsible for enhanced soil nitrification. Our findings pave the way for developing cost-effective strategies to remediate ammonium contamination in rare earth mining soils.

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.

Controlled synthesis of twinning β-form anhydrous guanine nanoplatelets in aqueous solution

Controlled synthesis of twinning β-phase anhydrous guanine nanoplatelets is realized for the first time in an aqueous solution via ammonia volatilization.

Ammonia volatilisation losses from urea applied to acidic cropping soils is regulated by pH buffering capacity

Context Ammonia (NH3) volatilisation can be a significant nitrogen (N) loss pathway in the grains industry following the surface broadcast application of urea. However, the extent of urea volatilisation from acidic soils and the soil properties that regulate this N loss pathway have not been investigated widely. Aims We conducted a laboratory incubation experiment to measure NH3 volatilisation loss potential following the broadcast application of urea prills (1–2 mm diameter; 50 kg N ha−1) onto moistened acidic and neutral cropping soils, sampled from four long-term cropping research sites. Methods The selected soils varied in pH, clay content, organic carbon, pH buffering capacity (pHBC) and cation exchange capacity. Volatilised NH3 was captured in a phosphoric acid trap after 7, 14 and 21 days and then measured using colorimetric analysis. We compared the measured NH3 losses with predicted NH3 losses derived from an existing empirical NH3 volatilisation prediction model. Key results Of the applied urea-N, 0.9–25% was volatilised. Cumulative NH3 losses were strongly related (R2 = 0.77) with soil pHBC derived from a pedotransfer function. The existing NH3 loss model generally had poor predictive capacity (RMSE = 34%). Conclusions Using clay content as a surrogate variable for pHBC in the predictive model for sandy kaolinitic soils where it is largely a function of organic carbon content can cause poor estimates of NH3 volatilisation loss potential. Implications Grain production on sandy, acidic soils with low pHBC could lead to substantial NH3 volatilisation losses if urea is broadcast.

Effect of Dietary Zeolite Supplementation on Production, Egg Quality, Ammonia Volatilization, Organ Morphometry and Blood Parameters in Brown Laying Hens

Effect of Dietary Zeolite Supplementation on Production, Egg Quality, Ammonia Volatilization, Organ Morphometry and Blood Parameters in Brown Laying Hens

Improving spring maize yield while mitigating nitrogen losses under film mulching system by right fertilization and planting placement

Efficient agronomic management strategies, such as “4 R” fertilization techniques combined with rational agronomic practices, are crucial options to overcome the challenge of increasing yields while mitigating environmental hazards. A three-year (2019–2021) field trial was carried out to screen for the right fertilization and planting placement that is suitable for labor-saving and mechanical cultivation practices. Fertilization placement [nitrogen (N) fertilizer was deep applied under the film-mulched band (FM) and in the un-mulched zone (FuM)] and planting placement [seeds were sowed in the film-mulched band (PM) and un-mulched zone (PuM)] were assigned as the main plots and split plots, separately, in a split-plot design. So, there were four treatments (FM-PM, FM-PuM, FuM-PM, and FuM-PuM). The yield, carbon and N accumulation and translocation, root traits and their spatial distribution with soil mineral N, soil N loss, etc., were examined. Results showed that the grain yield of FM and PuM was significantly higher by 10.7 % and 8.8 % than that of FuM and PM, respectively. Root traits and dry matter and N accumulation in maize at the silking stage in FM were higher than those in FuM due to the synergistic root and mineral N spatial distribution in soil profiles. The PuM had higher post-anthesis dry matter and N accumulation than PM, which was attributed to the more root distribution in the un-mulched zone and deep soil (40–100 cm), higher leaf area index and chlorophyll relative content at the milk stage. Compared with FuM, FM cut down the ammonia volatilization loss by 17.6 % and prevented nitrate leaching. The PuM cut down the ammonia volatilization loss by 41.2 % compared with PM. Although there was no significant difference in the yield of FM-PuM, FM-PM and FuM-PuM, lower ammonia loss and smaller deep nitrate leaching in the rooting zone were observed under FM-PuM treatment. The band and deep applied N fertilizer under the film-mulched zone combined with planting in the un-mulched zone (FM-PuM) could be recommended as an effective agronomic practice for rainfed spring maize production with banded film mulching. • The N placement under film-mulched band cut down NH 3 loss and nitrate leaching. • Seeding at un-mulched zone increased post-anthesis dry matter and N accumulation. • The N and planting placement manipulated root and soil mineral N distribution. • Right N and planting placement enhanced maize yield and lowed N loss.