Sources Urea Research Articles

Effects of nitrogen dosage and urea source on morphological composition and forage accumulation in massai grass

The effects of nitrogen (N) dose and urea source on forage mass (FM), percentage of dry matter of leaf blades (LBDMP), stem (SDMP), and dead material (DMDMP), and the forage accumulation rate (FAR) of Panicum maximum ‘Massai’ (massai grass) were evaluated. We set up an experiment with a completely randomized block design in a factorial arrangement (3×2) + 1, consisting of three doses (100, 200, and 400 kg ha–1 year–1), two urea sources (common and coated with Policote®), and a control treatment, in five consecutive climatic seasons, including the summers of 2011/2012 (summer I), autumn, winter, and spring of 2012, and the summers of 2012/2013 (summer II). We found an interaction effect between N dose, urea source, and season (p < 0.05). LBDMP linearly increased during dry periods (autumn and winter) and SDMP in autumn and DMDMP in winter linearly decreased when coated urea were used. FAR showed a linear increase with the use of both urea sources, except for common urea in autumn, and the increases in the winter were owing to a greater contribution of leaf blades to FM. The use of coated urea for N fertilization linearly increases FAR in all seasons of the year and improves the morphological composition of the forage of massai grass, mainly in dry seasons.

Enhanced heterogeneous activation of peroxydisulfate by S, N co-doped graphene via controlling S, N functionalization for the catalytic decolorization of dyes in water

3D porous sulfur and nitrogen co-doped graphene aerogel has been fabricated by a facile one-pot process. Both experimental and theoretical studies have demonstrated that sulfur and nitrogen co-doping could synergistically enhance the catalytic performance for activating peroxydisulfate (PDS) compared to the original and N doped graphene aerogels. The ratio of sulfur/nitrogen in the aerogel can be controlled by regulating the additions of thiourea and urea sources, and the aerogel with the S/N ratio of about 1:2.5 shows a better catalytic effect due to more significant changes in the electrostatic potential and the surface charge distribution, as revealed by the theoretical simulations. The radical quenching tests indicated that both SO4·- and ·OH radicals could be formed in the SN-rGO aerogel + PDS system and contribute most to RhB degradation.

The response of Stevia (Stevia rebaudiana Bertoni) to nitrogen supply under greenhouse condition

ABSTRACTStevia (Stevia rebaudiana Bertoni) is a perennial plant producing some natural sweeteners. Stevia is considered as a new crop in some countries. This study was conducted to find the stevia response to nitrogen fertilizer supply. Different levels of nitrogen (0, 30, 60, 90, 120, and 150 kg/ha from urea source) were used in a greenhouse condition and then the stevia growth and metabolites were assessed under different availability of nitrogen. Results showed that the optimum growth of stevia was obtained by 60 kg/ha nitrogen and more nitrogen supply did not enhance the stevia growth. It was observed that the total steviol glycosides (SVglys) content of Stevia was significantly increased by nitrogen fertilizer application just up to 30 kg/ha, while it decreased by more rates of nitrogen fertilizer. Our result clearly showed that SVglys yield reached to maximum value by application of 60 kg/ha of nitrogen fertilizer. Since the variation of SVglys content and shoot growth of the stevia were compromised by 60 kg/ha nitrogen, it can be concluded that 60 kg/ha of nitrogen fertilizer could be considered as an optimum rate of nitrogen for stevia and could also be recommended for greenhouse conditions.

Nitrogen fertilization in super-early cycle common bean using new sources of urea

The efficiency of new fertilizers as a nitrogen source in super-early cycle common bean cultivars still needs to be better known. The objective was to quantify the effect of new sources and time of application of nitrogen on yield and yield components of a super-early cycle bean cultivar. The experiment was conducted in the city of Rio Verde, state of Goias, Brazil, using the experimental design of randomized blocks, in a 3x3+1 factorial scheme, with four replications. The first factor was constituted by nitrogen (N) sources: traditional urea, zeolite-associated urea, and urea with urease inhibitor, using the dose of 80 kg ha -1 N. The second factor was application stages: V2, V3, and V4, that is, when 50% of the plants had the first pair of unifoliolate leaves, the first trifoliolate leaf, and the third trifoliolate leaf fully expanded, respectively. Moreover, an additional treatment was used, without N application (control). The cultivar used was BRS FC104, of super-early cycle, from 60 to 65 days. The following were measured: relative chlorophyll index (RCI), plant height, first pod insertion height, number of pods per plant, number of grains per pod, mass of 100 grains and yield. There was no significant difference between sources and application stages regarding the number of pods per plant, number of grains per pod, plant height and first pod insertion height. The highest yields were obtained with the use of zeolite-associated urea, and the best application stage was V4. The use of urea with urease inhibitor did not provide an increase in grain yield compared to the control treatment.

Agricultural answers and chemical composition of Massai grass under different nitrogen doses and urea sources

Under the hypothesis that modifying nitrogen sources and doses could increase nitrogen fertilization efficiency and productivity and improve forage quality, this study aimed to evaluate the morphological composition, structural characteristics and chemical composition of Panicum maximum cv. Massai forage cultivated under different urea sources (common and coated with Policote®) and nitrogen doses (200, 400 and 600 kg ha-1 year-1) during the autumn, winter and spring of 2014 and the summer and autumn of 2015. The experiment was carried out in Seropédica, RJ, under a randomized complete block design in a factorial arrangement (3x2) + 1 with four replications. High nitrogen rates promoted higher percentages of leaf blade dry mass and lower percentages of dead material dry mass in the forage mass and provided higher tiller population density and forage accumulation rate of Massai grass during the studied seasons. The use of coated urea promoted higher levels of crude protein in the forage than did the use of common urea in all seasons. The intensification of nitrogen fertilization reduced the nitrogen use efficiency but benefitted the structural characteristics, forage accumulation and chemical composition of Massai grass forage. The use of coated urea promoted greater of nitrogen use efficiency during all seasons of the year.

Nitrogen source contribution in sugarcane-inoculated plants with diazotrophic bacterias under urea-N fertigation management

Although Brazilian sugarcane crops use lower nitrogen rates when compared to other producing countries, the biological nitrogen fixation (BFN) could be performed aiming to reduce costs, since almost all nitrogen fertilization used in Brazil is imported. BFN can occur in sugarcane; however, its role in non-leguminous plants is controversial. Therefore, this study aimed to assess the nitrogen source contribution (using N isotope 15N technique) along a growing period in sugarcane plants under different management (diazotrophic bacteria inoculation and N fertigation rates). The natural abundance of nitrogen isotope (15N) abundance in + 1 leaves of fourth ratoon cultivar SP 80-3280 was used to indicate the comparative importance of N sources, including BFN for sugarcane nutrition. The treatments were irrigated with two levels of nitrogen fertilizer 50 and 100 kg ha−1 (urea source), including a control without fertilizer, with (I) and without (NI) inoculation of nitrogen-fixing bacterias. The bacteria cocktail used consisted of five strains: Gluconacetobacter diazotrophicus, Herbaspirillum seropedicae, H. rubrisubalbicans, Burkholderia tropica and Azospirillum amazonense. Although the nitrogen content in + 1 leaves, the above ground dry matter, cane yield and stalk sugar content expanded by increasing nitrogen fertilizer rates, no significant interactions between nitrogen-fixing bacteria inoculation and nitrogen fertilizer rates were observed. In the treatment without N fertilizer application, no differences in δ15N‰ (per thousand) values between sugarcane-inoculated and sugarcane-non-inoculated sugarcane leaves was found. The temporal variation of δ15N‰ in sugarcane + 1 leaves indicated that nitrogen content and δ15N‰ values decreased during the phenological development stages and that the main sources of nitrogen for sugarcane were from synthetic fertilizer and mineralization of nitrogen from soil organic matter.

The influence of foliar "feeding" of urea on yield and its components of Iranian hybrid rice Oryza sativa L. ‘Bahar 1’

Because of waterlogged conditions in rice cultivation, much of the surface-broadcasted urea dissolves in paddy water and is unreachable to the rice crop for this reason. A field experiment was conducted to estimate the influence of urea fertilisation on yield and yield components of hybrid rice ‘Bahar 1’. Three doses (N0, N10, N20 kg N ha-1) of nitrogen from urea sources were foliar-sprayed once at active tillering and booting stages. Grain yield, the number of panicles per unit area, and the number of grains per panicle in the tillering stage of rice were significantly (p < 0.01) increased in a linear fashion when N rates increased from 0 to 20 kg ha-1. The rate of panicle fertility was negatively/positively influenced with increasing N rates in the tillering and booting stages, respectively, indicating the creation of more number of non/partial productive tillers per hill in the vegetative stage than in the reproductive stage. In line with panicle fertility (%), the grain yield was also significantly affected by N treatments with urea fertilisation in the booting stage. Maximum grain yield was obtained with the application of 20 kg N ha-1 at both the tillering and booting stages. Foliar spraying of urea at tillering (20 kg N ha-1) and booting (10 kg N ha-1) stages had a pronounced effect on achieving higher yields as compared to other combinations. The study suggests that foliar application of urea for hybrid rice cultivation might have a potential role in improving nitrogen use efficiency.

The Influence of Nitrogen Doping Concentration on the Strain and Band Gap Energy of N-Doped Zinc Oxide Prepared Using Spray Coating Technique

N-ZnO thin layer is widely used in application of wastewater photo catalyst. N-ZnO thin films have been successfully deposited on glass substrate using spray coating technique at 450 °C with varying concentrations of N from Urea source. XRD test results showed that the N-ZnO has a polycrystalline structure with diffraction field (100), (002), (101) and (110). The presence of nitrogen atoms in the lattice of ZnO causes a shift in diffraction angle between 0.08o - 0.18o. N-ZnO thin layer showed the occurrence of tensile strain. Surface morphology of N-ZnO is shaped like mine (like root). All samples have band gap energies lower than that of ZnO and the smallest is sample N6 with Eg = 3.249 eV. The presence of nitrogen atom increases surface roughness and decreases band gap energy.

Nitrogen losses, use efficiency, and productivity of early rice under controlled-release urea

Ammonia (NH3) volatilization and nitrogen (N) surface runoff from rice (Oryza sativa L.) paddies contribute to air and water pollution in China and everywhere else. The purposes of this study were to assess N losses through NH3 volatilization and surface runoff and to determine the grain yield and N use efficiency (NUE) of early rice in double rice cropping system in southern China. We implemented six treatments viz., control with 0kgNha−1 (CK), basal application and split application (1/2 at transplanting, 1/4 at tillering, and 1/4 at panicle stages) of urea (U), and basal applications of three controlled-release urea (CRU) sources (polyurethane-coated urea [CRU-1], degradable polymer-coated urea [CRU-2], and water-based polymer-coated urea [CRU-3]) all applied at 165kgNha−1. Results showed that CRU-1 and CRU-2 significantly reduced NH3 volatilization (23 to 62%) and N surface runoff losses (8 to 58%) compared with U. Precipitation and ammonium-nitrogen (NH4-N) concentration in surface water from rice paddy were predominant factors defining N losses through NH3 volatilization and surface runoff. Application of CRU reduced NH4-N concentration and pH of surface water and N losses through surface runoff. The CRU produced similar (−3 to 4%) or higher (5–16%) rice grain yields and increased NUE (3 to 34%) and N uptake (3–55%) compared with U. Polymer-coated urea can reduce environmental risks of N losses through volatilization and surface runoff while maintaining rice yield and N uptake, it also enhances NUE compared with urea in double rice cropping system in southern China.

تاثیر سطوح آبیاری، تراکم بوته و نیتروژن بر عملکرد و اجزای عملکرد منداب (Eruca sativa Mill.)

تاثیر سطوح آبیاری، تراکم بوته و نیتروژن بر عملکرد و اجزای عملکرد منداب (Eruca sativa Mill.)

Vapour-phase hydrothermal synthesis of Ni2P nanocrystallines on carbon fiber cloth for high-efficiency H2 production and simultaneous urea decomposition

Ni2P nanocrystallines grown on carbon fiber cloth (Ni2P/CFC) was successfully achieved by a facile vapour-phase hydrothermal method. The as-prepared Ni2P/CFC, as an electrocatalyst, exhibited superior electrocatalytic activities toward urea oxidation reaction (UOR) with a potential of 1.42V (vs. RHE) delivering a current density of 10mAcm−2 and hydrogen evolution reaction (HER) with overpotentials of 90 and 155mV at current densities of 10 and 100mAcm−2 in alkaline media. On this basis, a Ni2P/CFC constructed two-electrode system for high-efficiency H2 production and simultaneous urea decomposition was therefore established using commercial urea as reaction source. Besides, such two-electrode system as proof of concept study was also evaluated using human urine as urea source for highly efficient H2 generation with a rate of 0.35μMmin−1 at an applied potential of 1.48V, delivering a current density of 10mAcm−2.

English

The aim of this study was to evaluate the performance of sources and application rates of topdressed nitrogen (N) on second-crop corn following soybean in an improved fertility Latossolo in the region of Campos das Vertentes, MG. Brazil. A randomized block experimental design was used in a 4 x 5 +1 factorial arrangement, with four replications. The treatments consisted of the combination of four N sources via forms of urea: conventional urea (common urea), urea coated with 16% elemental sulfur (Urea+S), urea treated with base compound urease inhibitor with a 0.4% boron and 0.15% copper (Ureia+B+Cu), urea treated with 1.060 mg kg-1 of the urease inhibitor N-(n-butyl) thiophosphoric triamide (Urea+NBPT), and five application rates of N through urea: 30, 45, 60, 90, and 120 kg ha-1, plus an additional treatment without N supplied in topdressing. The N concentrations in the leaves and grain, the exported N, the mineral N in the soil (nitrate and ammonium), grain yield, and profitability were evaluated. The N sources increased the N concentrations in the leaves, in the grain, and the exported N. However, the grain yield and the N concentration in the soil did not vary in accordance with the sources of urea. Increasing application rates of N increase N concentration in the leaves and in the grain, exported N, grain yield, and the mineral N concentration in the soil up to a depth of 10 cm. Application of N in topdressing is not economically beneficial considering the final yield of the second-crop corn following soybean in a soil with improved fertility. Key words: Zea mays L, Urea, Nitrogen, No-tillage system, N rates.

Influence of polymer-coated slow-release urea on total tract apparent digestibility, ruminal fermentation and performance of Nellore steers.

ObjectiveTwo experiments were performed to evaluate the effects of coated slow-release urea on nutrient digestion, ruminal fermentation, nitrogen utilization, blood glucose and urea concentration (Exp 1), and average daily gain (ADG; Exp 2) of steers.MethodsExp 1: Eight ruminally fistulated steers [503±28.5 kg body weight (BW)] were distributed into a d 4×4 Latin square design and assigned to treatments: control (CON), feed grade urea (U2), polymer-coated slow-release urea A (SRA2), and polymer-coated slow-release urea B (SRB2). Dietary urea sources were set at 20 g/kg DM. Exp 2: 84 steers (350.5±26.5 kg initial BW) were distributed to treatments: CON, FGU at 10 or 20 g/kg diet DM (U1 and U2, respectively), coated SRA2 at 10 or 20 g/kg diet DM (SRA1 and SRA2, respectively), and coated SRB at 10 or 20 g/kg diet DM (SRB1 and SRB2, respectively).ResultsExp 1: Urea treatments (U2+SRA2+SRB2) decreased (7.4%, p = 0.03) the DM intake and increased (11.4%, p<0.01) crude protein digestibility. Coated slow-release urea (SRA2+SRB2) showed similar nutrient digestibility compwared to feed grade urea (FGU). However, steers fed SRB2 had higher (p = 0.02) DM digestibility compared to those fed SRA2. Urea sources did not affect ruminal fermentation when compared to CON. Although, coated slow-release urea showed lower (p = 0.01) concentration of NH3-N (−10.4%) and acetate to propionate ratio than U2. Coated slow-release urea showed lower (p = 0.02) urinary N and blood urea concentration compared to FGU. Exp 2: Urea sources decreased (p = 0.01) the ADG in relation to CON. Animals fed urea sources at 10 g/kg DM showed higher (12.33%, p = 0.01) ADG compared to those fed urea at 20 g/kg DM.ConclusionFeeding urea decreased the nutrient intake without largely affected the nutrient digestibility. In addition, polymer-coated slow-release urea sources decreased ruminal ammonia concentration and increased ruminal propionate production. Urea at 20 g/kg DM, regardless of source, decreased ADG compared both to CON and diets with urea at 10 g/kg DM.

English

The Bell peppers is a tropical culture and it is in the 10 most consumed vegetables of the world. The mineral nutrition is essential to the productivity and better quality of the gather fruits. In bell pepper cultivation, high portions of nitrogen are essential to a good performance of fruits. The foliar fertilizing is a complement to the ground fertilizing. The amino acids are a good source of nitrogen, once these are quickly incorporated to the plants metabolism. Therefore, this work aimed to estimate the sources and portions of N to the foliar application in Bell pepper cultivar. The Randomized blocks design was utilized in a factorial scheme 2 × 4, with four repetitions. The first factor corresponded in two sources of N: urea and amino acids. The second factor corresponded to the number of repetitions by foliar: 0, 1, 3, 5 and 7 applications during the culture cycle. The first foliar application occurred ten days after the transplant, and the subsequent in breaks of fifteen days after the first application. In the test there was not application. The baselines evaluated: Cross length of fruits, fruits diameters, number of total fruits and productivity in kg ha-1. The results were submitted to variation and regression analysis. The application of amino acids by foliar in plants of Bell pepper, increased the diameter and the length of fruits. High sources of urea also provided morphological changes in fruits however lower amino acids utilization. Key words: Capsicum annuum L., nitrogen fertilizing, fruit quality.

Effects of polymer coated slow-release urea on ruminal fermentation and nutrient total tract digestion of beef steers

The objective of this study was to evaluate the effects of polymer coated slow-release urea (SRU) in high-forage diets of beef steers on nutrient intake and digestibility, ruminal fermentation, microbial protein synthesis, and energy balance. Eight 24-mo-old rumen-fistulated castrated Nellore steers (average body weight = 418.0±40.0 kg) were used in a replicated 4 × 4 Latin square design. Animals were randomly distributed to receive one of the following diets: no urea inclusion; 1.0% inclusion of feed grade urea in the diet (dry matter [DM] basis); 1.0% inclusion of slow-release urea 1 in the diet (DM basis); and 1.0% inclusion of slow-release urea 2 in the diet (DM basis). Slow-release urea 2 had a similar composition to that of slow-release urea 1 and differed in that it contained 2.95% sulfur. A high-forage diet was provided (75% of total DM) and corn silage was used as the forage source. Diets with urea had increased crude protein (CP) intake, and CP and total digestible nutrients total tract digestion. Urea sources increased ruminal concentrations of ammonia nitrogen and acetate, and decreased butyrate concentrations. The polymer coated urea did not alter ruminal fermentation when compared with feed grade urea. Diets did not affect the energy balance of steers. Feed grade urea presented greater microbial protein synthesis than polymer coated slow-release urea. The partial replacement of soybean meal by 1% slow-release urea in a diet with 75% forage does not improve ruminal fermentation and microbial protein synthesis, and shows similar results as feeding feed grade urea to beef steers.

Effect of slow-release urea inclusion in diets containing modified corn distillers grains on total tract digestibility and ruminal fermentation in feedlot cattle.

Ruminal degradable intake protein (DIP) deficit may result when cattle are fed diets containing a greater inclusion of processed corn grain and small to moderate inclusion of corn distillers grains (DG). This deficit may arise from greater proportions of rapidly fermentable carbohydrates and RUP in corn grain. Urea-derived N is 100% DIP; however, rates of degradation of carbohydrates and conventional urea (CU) may not match. Therefore, beneficial effects may result from the use of slow-release urea (SRU) sources over CU when added to DIP-deficient diets. An experiment was conducted to evaluate the effect of increasing DIP concentration through inclusion of 1 of 2 SRU sources or CU in DG-containing feedlot diets on ruminal fermentation and total tract digestibility. In addition, an in situ experiment was conducted to characterize N disappearance of urea sources from polyester bags. Four ruminally cannulated steers (initial BW = 588 ± 8 kg) were arranged in a 4 × 4 Latin square design and assigned randomly to 1 of 4 dietary treatments containing 0% (CON) or 0.6% urea in the form of CU (UREA) or SRU as Optigen II (polymer-encapsulated urea; OPTI) or NitroShure (lipid-encapsulated urea; NITRO), and 30% corn earlage, 20% modified corn DG with solubles, 7.8% corn silage, 4.3% dry supplement, and dry-rolled corn (DM basis). Dietary DIP was estimated at 6.6% and 8.3% for CON and urea-containing dietary treatments, respectively. Steers were fed ad libitum once daily. Differences in purine derivatives-to-creatinine (PDC) index between treatments were used as indicators of differences in microbial CP synthesis. Intake of OM, digestibility of OM, NDF, CP, and starch, ruminal pH, total VFA ruminal concentration, and PDC index were not affected by treatment ( ≥ 0.21). Concentration of ammonia-N noticeably peaked at 4 h after feed delivery for cattle fed UREA (treatment × time, = 0.06) and measured at least 5.5 mg/dL for any treatment and at any hour after feed delivery. During the first 12 h after incubation, N disappearance was greater for CU and NitroShure than Optigen II (urea source × time, < 0.01). Supplementing DIP through inclusion of CU or SRU did not affect feed intake, digestibility, or most of the ruminal fermentation parameters evaluated, which may relate to the lack of need of urea supplementation in the present experiment. More research is warranted to evaluate the use of SRU in DIP-deficient diets.

Performance of beef cows and calves fed different sources of rumen-degradable protein when grazing stockpiled limpograss pastures.

Two experiments evaluated the effects of different sources of RDP on forage characteristics, animal performance, and ruminal and blood parameters of beef cattle grazing stockpiled limpograss (Hemarthria altissima) from January to May 2011 and 2012. In Exp. 1, 24 mature lactating beef cows and their respective calves were allocated to 8 stockpiled limpograss pastures (3 pairs/pasture). Treatments were 2 different sources of RDP, urea or cottonseed (Gossypium spp.) meal (CSM), distributed in a completely randomized design with 4 replicates. Feather meal and corn (Zea mays) meal were added to the urea treatments to balance RUP and energy. Treatments were mixed in sugarcane (Saccharum officinarum) molasses, which resulted in 3 kg DM/cow per day of supplement. There were no differences (P > 0.10) in herbage mass (HM; 3,200 ± 400 kg DM/ha), herbage allowance (HA; 1.9 ± 0.2 kg DM/kg of BW), CP (5.2 ± 0.2%), and in vitro digestible organic matter (IVDOM; 47 ± 0.5%) concentrations. There was a decrease (P < 0.10) in HM (from 4,100 to 2,600 kg/ha), IVDOM (from 46 to 39.9%), and HA (from 2.5 to 1.4 kg DM/kg BW) from January to March. Cow ADG (0.23 ± 0.08 kg/d), BCS (4.6 ± 0.2), milk yield (7.0 ± 0.4 kg/d), and plasma urea nitrogen (PUN; 16.1 ± 0.8 mg/dL) and calf ADG (0.71 ± 0.05 kg/d) were similar (P > 0.10) among treatments. Sixteen cow-calf pairs were moved to 8 drylot pens after Exp. 1, maintained on the same treatment, and evaluated for forage and total DMI. There was no difference in forage (P = 0.16; 2.1 ± 0.1% BW) and total DMI (P = 0.12; 2.5 ± 0.1% BW) between treatments. In Exp. 2, 2 rumen-cannulated steers were used in a 2 × 2 Latin square design, replicated in 2011 and 2012, to test the effects of the same treatments on rumen fluid and blood parameters. There was no difference (P > 0.10) in ruminal NH3-N (12.9 ± 0.3 mg/dL), pH (6.5 ± 0.1), propionic acid (25 ± 2.2 mol/100 mol), acetic acid (69.2 ± 2.9 mol/100 mol), and butyric acid (4.5 ± 0.5 mol/100 mol) as well as branched-chain VFA (1.3 ± 2.2 mol/100 mol) concentrations in the rumen. In addition, there was no difference (P = 0.91) in PUN (7.9 ± 0.3 mg/dL) concentration between treatments. Therefore, urea can be as effective as CSM as the main source of RDP in the molasses-based supplement offered to mature lactating beef cows grazing stockpiled limpograss pastures.

Effect of protein level and urea in concentrate mixture on feed intake and rumen fermentation in swamp buffaloes fed rice straw-based diet.

Four rumen-fistulated Thai native swamp buffaloes were randomly assigned according to a 2 × 2 factorial arrangement in a 4 × 4 Latin square design to assess the effect of protein (CP) level and urea (U) source in concentrate diet on feed utilization and rumen ecology. The treatments were as follows: concentrate containing CP at 120g/kg (soybean meal, SBM) (T1), 160g/kg (SBM) (T2), 120g/kg (U) (T3), and 160g/kg (U) (T4), respectively. All buffaloes were fed concentrate at 10g/kg of body weight, and rice straw was offered ad libitum. Feed intake and digestibilities of CP, neutral detergent fiber, and acid detergent fiber increased (P < 0.05) in treatments with higher level of CP especially with U source (P < 0.05). In contrast, CP level and source in concentrate did not affect on ruminal pH and temperature (P > 0.05), while concentration of ruminal ammonia (N), blood urea (U), volatile fatty acids profile, microorganism populations, and variable bacterial growth increased in buffaloes consumed concentrate containing CP at 160g/kg (T2 and T4; P < 0.05). Fecal and urinary N excretions decreased in buffaloes consumed concentrate containing higher CP level especially with U source while purine derivatives increased which resulted in a higher N balance as compared to lower CP level and SBM source treatments (P < 0.05). In summary, higher CP level in concentrate improved feed intake, nutrient digestibility, purine derivatives, and rumen ecology, and U had shown better result than SBM. Concentrate mixtures containing 16g/kg CP with U 40g/kg could improved nutrients utilization with no adverse effects for swamp buffaloes fed on rice straw.

Urea-SCR Temperature Investigation for NOx Control of Diesel Engine

SCR (selective catalytic reduction) system is continuously being analyzed by many researchers worldwide on various concerns due to the stringent nitrogen oxides (NOx) emissions legislation for heavy-duty diesel engines. Urea-SCR includes AdBlue as urea source, which subsequently decomposes to NH3 (ammonia) being the reducing agent. Reaction temperature is a key factor for the performance of urea-SCR system, as urea decomposition rate is sensitive to a specific temperature range. This particular study was directed to investigate the temperature of the SCR system in diesel engine with the objective to confirm that whether the appropriate temperature is attained for occurrence of urea based catalytic reduction or otherwise and how the system performs on the prescribed temperature range. Diesel engine fitted with urea-SCR exhaust system has been operated on European standard cycle for emission testing to monitor the temperature and corresponding nitrogen oxides (NOx) values on specified points. Moreover, mathematical expressions for approximation of reaction temperature are also proposed which are derived by applying energy conservation principal and gas laws. Results of the investigation have shown that during the whole testing cycle system temperature has remained in the range where urea-SCR can take place with best optimum rate and the system performance on account of NOx reduction was exemplary as excellent NOx conversion rate is achieved. It has also been confirmed that selective catalytic reduction (SCR) is the best suitable technology for automotive engine-out NOx control.

English

Lettuce demands high levels of nitrogen, which appears in the soil in forms that present a complex dynamic, making it difficult to apply nitrogen-based fertilizers. One way to improve the efficiency of nitrogen absorption is to use controlled-release nitrogen fertilizers, which aim to maintain nitrogen in forms that are less susceptible to loss. The objective of this study was to evaluate the effect of two sources of N (urea and coated urea – slow-release N) in two management systems (fertilizer only at planting and fertilizer at planting and as a dressing) in the cultivation of American lettuce, cultivar Gloriosa, in an Entisols (Quartzipsamments), in the county of Campo Grande, Mato Grosso do Sul state (MS), Brazil. The experimental design used was randomized blocks in a 2 x 2 factorial scheme (2 sources of N and 2 systems for application of N) and eight repetitions. The use of protected (coated) urea on the American lettuce crop did not lead to increased productivity in comparison with urea applied only at planting. On the other hand, the use of urea at planting and as a dressing presented higher productivity than the coated urea source.