Recovery Fraction Research Articles

Anaortic off-pump bilateral internal mammary grafting in severe left ventricular dysfunction – Case report

A 64 years old male diabetic patient with ejection fraction of 16% and renal dysfunction underwent off-pump CABG using both in situ internal mammary artery grafts. Left internal mammary artery was used to bypass left anterior descending artery and right internal mammary artery was used as composite graft. Patient had uneventful recovery and left ventricular ejection fraction improved to 34% within 8 months after surgery. In presence of left ventricular dysfunction, both internal thoracic artery grafting should be preferred for better patency rate and flow reserve. This is the first ever case report of anaortic off-pump bilateral internal thoracic artery grafting in a patient with left ventricular ejection fraction less than 20%.

Mobile lipid bilayers on gold surfaces through structure-induced lipid vesicle rupture.

Forming fluid supported lipid bilayers (SLBs) on a gold surface can enable various lipid-membrane-associated biomolecular interactions to be investigated by several surface sensing techniques, such as surface plasmon resonance and scanning tunneling microscopy. However, forming fluid SLBs on a gold surface through lipid vesicle deposition continues to pose a challenge. In this study, we constructed nanograting structures on a gold surface to induce lipid vesicle rupture for forming a mobile layer of SLBs. Observations based on fluorescence recovery after photobleaching showed that SLBs on the prepared grating supports had some fluidity, while SLBs on the planar support had no fluidity. The anisotropic fluorescence intensity recovery shape changes observed in the SLBs on the grating support suggested that a second layer of SLBs partially formed on top of the first layer in contact with the gold surface and extended along the grating structure. Comparisons of the relative amounts of second bilayer and the fluorescence recovery fractions on supports with various grating edge densities suggested that the second layer formed at the edge regions and that the coverage ratio was directly proportional to the grating edge density. All of these results showed that the grating edges could serve as vesicle-rupture-inducing sites for the formation of a mobile second SLB on a gold surface. The formation of the second layer of SLBs at the edge regions but not in the flat regions enabled us to determine the second layer locations and provided us with an opportunity to pattern mobile lipid bilayers on gold surfaces by controlling the edge locations.

Nitrogen uptake and nitrogen fertilizer recovery in old and modern wheat genotypes grown in the presence or absence of interspecific competition.

Choosing genotypes with a high capacity for taking up nitrogen (N) from the soil and the ability to efficiently compete with weeds for this nutrient is essential to increasing the sustainability of cropping systems that are less dependent on auxiliary inputs. This research aimed to verify whether differences exist in N uptake and N fertilizer recovery capacity among wheat genotypes and, if so, whether these differences are related to a different competitive ability against weeds of wheat genotypes. To this end, 12 genotypes, varying widely in morphological traits and year of release, were grown in the presence or absence of interspecific competition (using Avena sativa L. as a surrogate weed). Isotopic tracer 15N was used to measure the fertilizer N uptake efficiencies of the wheat genotypes and weed. A field experiment, a split-plot design with four replications, was conducted during two consecutive growing seasons in a typical Mediterranean environment. In the absence of interspecific competition, few differences in either total N uptake (range: 98–112 kg N ha−1) or the 15N fertilizer recovery fraction (range: 30.0–36.7%) were observed among the wheat genotypes. The presence of competition, compared to competitor-free conditions, resulted in reductions in grain yield (49%), total N uptake (29%), and an 15N fertilizer recovery fraction (32%) that were on average markedly higher in modern varieties than in old ones. Both biomass and grain reductions were strongly related to the biomass of the competitor (correlation coefficients > 0.95), which ranged from 135 to 573 g m−2. Variations in both grain and biomass yield due to interspecific competition were significantly correlated with percentage of soil cover and leaf area at tillering, plant height at heading, and total N uptake, thus highlighting that the ability to take up N from the soil played a certain role in determining the different competitive abilities against weed of the genotypes.

Total phenolic content and antioxidant properties of hard low-fat cheese fortified with catechin as affected by in vitro gastrointestinal digestion

The total phenolic content (TPC) and antioxidant activity (AA) of a low-fat hard cheese fortified with different concentrations of catechin was examined over 90 days of ripening after in vitro digestion of cheese samples. TPC and AA increased in cheese after manufacturing and over the ripening period at 8 °C. Prior to analysis, the cheese samples were subjected to a two-stage in vitro digestion with gastric and intestinal phases to simulate human digestive conditions. The AA, measured as both ferric reducing antioxidant power and oxygen radical absorbance capacity, showed a high degree of correlation (R2 > 0.89) with the TPC results. The in vitro recovery fraction of catechin after 90 days of ripening was 0.607, 0.628 and 0.752 for the cheeses fortified with catechin at 125, 250 and 500 mg kg−1, respectively. This study shows the feasibility of incorporating phenolic antioxidants into a protein-rich food, such as cheese, and maintaining antioxidant activity after digestion.

Effects of water on light oil recovery by air injection

We formulate a mathematical model for one dimensional flow with chemical reactions resulting from injection of air into a porous medium initially filled with gas, water and volatile oil. Our goal is to investigate the effect of water and steam on oil recovery, and we do so for a medium pressure air injection process. We show that, when the boiling point of the volatile oil is below or slightly above the boiling point of water, the hot steam region moves upstream of the medium temperature oxidation (MTO) wave (where oil vaporization and combustion occur), while the volatile oil and steam condense at the same location; it leads to considerable improvement of oil recovery by the MTO wave. Remarkably, the recovery curves (recovery fraction vs. time) depend weakly on the initial water and light oil saturations. If the volatile oil boiling point is much higher than the boiling point of water, the steam region moves downstream of the MTO wave. In this case the water effect on recovery is weaker and becomes negative for high water saturations. Numerical calculations suggest the existence of an oil boiling point at which a bifurcation occurs that separates solutions with the steam region upstream or downstream of the combustion zone.

Analysis of refuse-derived fuel from the municipal solid waste reject fraction and its compliance with quality standards

The final disposal of the Municipal Solid Waste is still a problem in many countries. The lack of space, the generation of leachate, and the emission of greenhouse gases as well as the requirements of the new legislation on waste dissuade the administrations involved from using the landfill option as a possible means of final disposal of MSW. The terms of the European Legislation on waste management and energy encourage member states to develop waste recovery techniques before sending it to a landfill. Therefore, member states have introduced source separation and mechanical-biological treatment to separate biodegradable recovery fractions (organic, paper-cardboard, plastic packaging, and glass) from the reject fraction, which is afterwards disposed of in landfills. One of the main aims of this study is to analyse the energy recovery properties of the reject fraction from a biological-mechanical treatment plant in Spain. For this purpose, this work presents a physical and chemical characterization of waste reject fraction from a real mechanical-biological treatment plant as well as the metal and halogen content. Additionally, the quality standards of the refused derived fuel processed at the laboratory and the atmospheric emissions of this type of fuel have been determined.

Switchgrass (Panicum virgatum L.) nutrients use efficiency and uptake characteristics, and biomass yield for solid biofuel production under Mediterranean conditions

Switchgrass produces high amounts of biomass that can be used for solid biofuel production. In this study, the dry biomass yield vs. N–P–K nutrient uptake relations as well as the N-mineralization and the N-fertilization recovery fraction for switchgrass (cv. Alamo) were determined under field conditions for three N-fertilization (0, 80 and 160 kg ha−1) and for two irrigation (0 and 250 mm) levels, in two soils in central Greece with rather different moisture status over the period 2009–2012. It was found that dry biomass yield on the aquic soil may reach 27–30 t ha−1 using supplemental irrigation, and remain at high levels (19–24 t ha−1) without irrigation. In the xeric soil, however, lower biomass yields of 14–15 t ha−1 may be produced with supplemental irrigation. The average N-concentration varies between 0.23% in stems and 1.10% in leaves, showing the very low needs in N. P-content varies between 0.16% in leaves and 0.03% in stems, whereas K-content fluctuates between 0.67% and 0.78%. Linear biomass yield-nutrient uptake relationships were found with high R2, pointing to nutrient use efficiencies of 240 and 160 kg kg−1, for N and K respectively. The base N-uptake ranged 70–84 kg ha−1 in the aquic to 60 kg ha−1 or less in the xeric soil. N-recovery fraction was about 30% in the aquic soil and lower in the xeric. Therefore, switchgrass is very promising for biomass production and its introduction in land use systems (especially in aquic soils of similar environments) should be seriously taken into consideration.

Methodology development and simulations for estimating greenhouse gas emission reductions from improved forest management with reduced impact logging

A method was developed to estimate greenhouse gas (GHG) emission reductions, using a set of calculations to quantify the changes in biomass carbon when conventional logging (CL) is replaced by improved forest management (IFM) with reduced impact logging (RIL). A case study of 30,000 ha net harvestable area of tropical rainforest in Paragominas, Pará, Brazil, was employed, where 25 m3 ha−1 was harvested over 30 years. To simulate changes from CL to RIL, the residual stand damage factor was reduced from 1.94 to 1.5 Mg C damaged per Mg C extracted, losses in harvested wood volumes were reduced from 16 to 5% while the lumber recovery fraction was increased from 0.47 to 0.55, the area for landing, roads and skid trails was decreased from 20% to 10%, and regrowth rate increased from 0.5 to 2.5 Mg of dry matter ha−1 yr−1. The simulations attained emissions reductions in the order of 3,175,212 Mg CO2-e, which equates to 28.8 Mg C ha−1 or 0.96 Mg C ha−1 yr−1, an approximate 82% reduction from CL baseline emissions. The increase in regrowth rate in RIL areas provided the largest affect on emission reductions (51%). The simulated results were comparable with both field and model studies, and demonstrate that RIL can achieve carbon credit revenue of USD 105,840 per year, or approximately USD 3,175,212 after 30 years, based on a 2014 carbon price of USD 1.00 per Voluntary Carbon Unit (VCU).

Optimising nitrogen in order to improve the efficiency, eco-physiology, yield and quality on one cultivar of durum wheat

A 3-year field experiment was carried out in southern Italy to evaluate the effect of different combinations of nitrogen (N) fertilizer rates (0, 55, 90, 135 kg ha–1), time of application (sowing, tillering, stem elongation) and number of nitrogen applications on durum wheat (Triticum turgidum L., var. durum). A total of eight different combinations - in terms of quantity and time of application - were arranged in a randomized complete block design with four replications. Soil plant analysis development was analysed along with leaf area index, grain and straw yield, plant height, plant lodging, thousand-kernel weight, non-vitreous kernels, shrunken and discarded kernels, hectolitre weight, grain protein content, and sodium dodecylsulfate sedimentation. Nitrogen contents of soil, grain and straw were measured in order to assess nitrogen efficiency. The results showed the positive effect of increased nitrogen dosages of 90 and 135 kg ha–1. The optimization of nitrogen administration increased by splitting the nitrogen into three application times, as shown by the eco-physiological, productive and qualitative parameters, and the nitrogen efficiency parameters measured (N application efficiency and N recovery fraction).

Recycling of Dry-Batch Digestate as Amendment: Soil C and N Dynamics and Ryegrass Nitrogen Utilization Efficiency

In this work a residue of dry-batch anaerobic digestion (DB) from the organic fraction of municipal solid waste, its composted homologous (CDB), and a municipal solid waste compost (MSWC) were characterized for their main physico-chemical traits and biological stability [oxygen uptake rate (OUR)]. These were then compared in soil incubations at 200 mg N kg−1, to assess carbon (C) and nitrogen (N) mineralization. The products’ nitrogen apparent recovery fraction (ARF) was assessed in a pot trial on Italian ryegrass. DB showed the highest OUR, followed by CDB and the more stable MSWC: 161.7; 20.7 and 5.7 mmol O2 kg−1 VS h−1, partially in agreement with the potentially mineralizable C pools in soil: 58.4; 16.6 and 19.5 % and their kinetics (k, 0.1906; 0.1405 and 0.1377 day−1). Composting greatly reduced the total carbon dioxide (CO2) emissions from 7,950 to 3,449 mg kg−1 in DB and CDB, even higher than MSWC (1,936 mg kg−1). After intense N-immobilization in soil (−22.3 %), DB finally reduced the gap (−6.9 %), also having a positive ARF (5.0 %), while CDB had greater N-immobilization (−12.9 %) and a negative ARF (−3.4 %). MSWC showed 3.8 % N-mineralization, and an intermediate ARF (2.7 %). The management of DB for plant nutrition therefore seems difficult since DB can furnish nitrogen not easily synchronizable with plant growth due to its release pattern characterized by initial immobilization. Composting increased stability but amplified N-immobilization due to the high C:N ratio of the bulking agent. A prolonged and more balanced composting process can reduce this restriction, aligning CDB with MSWC.

Technical and economic assessment of trash recovery in the sugarcane bioenergy production system

Mechanized sugarcane (Saccharum spp.) harvest without burning has been increasingly adopted in Brazil, increasing trash availability on the field. This study aims at showing the importance of using an integrated framework tool to assess technical and economic impacts of integral harvesting and baling trash recovery strategies and different recovery rates as well as its implications in the sugarcane production, transport and processing stages. Trash recovery using baling system presents higher costs per unit of mass of recovered trash in comparison to system in which trash is harvested and transported with sugarcane stalks (integral harvesting system). However, the integrated agricultural and industrial assessment showed that recovering trash using baling system presents better economic results (higher internal rate of return and lower ethanol production cost) than the integral harvesting system for trash recovery rates higher than 30 %. Varying trash recovery fraction, stalks productivity and mean transport distance for both integral harvesting and baling systems, sensitivity analyses showed that higher trash recovery fractions associated with higher stalks yields and long transport distances favors baling system, mainly due to the reduction of bulk load density for integral harvesting system under those conditions.

Biosorption of Tungsten by Escherichia coli for an Environmentally Friendly Recycling System

In this study, tungsten (W) recovery via biosorption using Escherichia coli was assessed to establish an environmentally friendly recycling system for W. The recovery fraction of soluble WVI was highly dependent on the solution pH, and E. coli cells exhibited the highest WVI uptake capacity for an initial pH of 1.08–2.56. Fourier transform infrared analysis revealed that carboxyl and phosphate functional groups on the surface of the bacteria play a crucial role in adsorption of WVI. Equilibrium and kinetic modeling of WVI biosorption showed that the equilibrium adsorption data fit the Langmuir isotherm model better than the Freundlich model. Kinetic studies revealed that WVI adsorption followed a pseudo-second-order rate model. WVI was recovered by desorption and heating, and adjustment of the pH enabled 95.8% WVI desorption from the E. coli cells. Heating at 1000 °C for 2 h under atmospheric conditions produced concentrates with relatively high concentrations of WVI (97.1% WO3).

The effectiveness of N-fertilization and microbial preparation on spring wheat

The efficiency of the application of microbial preparations enhancing soil properties as well as the diversified fertilization of spring wheat nitrogen was evaluated in the field experiment. Factors of the experiment referred to the levels of nitrogen fertilization: 0, 40, 80, 120 and 160 kg/ha as well as the application of microbial preparations, namely, Proplantan (disaccharide, and polysaccharide, lactic acid, carotene, riboflavin, thiamine, amylase, sea salt, minerals), Effective microorganisms (milk bacteria, photosynthetic bacteria, yeast, actinomycetes, moulds) and UG<sub>max</sub> microorganisms (lactic acid bacteria, photosynthetic bacteria, nitrogen-fixing bacteria, actinomycetes, macro- and microelements). The quantity of N<sub>min</sub> in the soil layer of 0–0.9 m ranged in respective years from 72.8 to 98.5 kg/ha before the spring wheat seeding and from 58.6.8 to 68.2 kg/ha after the crop was harvested, whereas the amount of N mineralization ranged from 18.9 to 53.3 kg/ha. Grain yields of wheat developed at a high level from 3.26 to 8.31 t/ha. To create the biomass, spring wheat plants absorbed nitrogen ranging from 78 kg N/ha in objects not fertilized to 184 kg N/ha in objects fertilized with the dose of 160 kg N/ha, and the share of nitrogen accumulated in the seeds amounted on average to 82% of the total uptake of that element. The highest N use efficiency, N physiological efficiency, N agronomic efficiency and N apparent recovery fraction were detected in objects fertilized with the dose of 40 kg N/ha. Each increase in the level of nitrogen fertilization affected lowering of the values of evaluated fertilization efficiency ratios.

BIOMASS PRODUCTION AND N-USE OF FIBRE SORGHUM UNDER DIFFERENT COVER CROPPING MANAGEMENT, NITROGEN INFLUXES AND SOIL TYPES IN CENTRAL GREECE

SUMMARYField experiments were carried out over a period of three years to evaluate the effect of cover cropping faba bean with fibre sorghum, compared to mono-crop cultivation, on yield (dry matter), nitrogen utilization efficiency (NUE) and N fertilizer recovery fraction of sorghum. Experimental sites were located in central Greece on a fertile, clayey to loamy textured soil, and on a sandy soil of moderate fertility. A factorial combination of four nitrogen application rates (0, 50, 100, 150 kg ha−1) and three legume treatments (incorporated into the topsoil or harvested before the sowing of sorghum and mono-cropping) were tested in a split plot design in three blocks. The results showed importance of legume cover crops for both soil types as sorghum total dry biomass yield for clayey soil fluctuated from 23 to 27 t ha−1for control plots, from 25.2 to 30.9 t ha−1when faba bean was harvested and from 26.3 to 32.5 t ha−1when incorporated, and for sandy soil the yield fluctuated from 18.1 to 22.1 t ha−1for control plots, from 22 to 27 t ha−1when faba bean was harvested and from 23.1 to 28.1 t ha−1when incorporated. The NUE was estimated at 62 kg kg−1and 60 kg kg−1for clayey and sandy soils respectively. The N recovery fraction was doubled after incorporating faba bean as green manure, reaching large amounts for both soil types.

Maize Biomass Production, N-Use Efficiency and Potential Bioethanol Yield, Under Different Cover Cropping Managements, Nitrogen Influxes and Soil Types, in Mediterranean Climate

To evaluate the effect of cover cropping faba bean with maize, compared to maize monocrop cultivation, on yield (dry matter), nitrogen utilization efficiency (NUE) and N fertilizer recovery fraction of maize, field experiments were carried out over a period of three years. Experimental sites were located in central Greece, on a fertile, clayey soil and on a sandy soil of moderate fertility, A factorial combination of four nitrogen dressings (0, 80, 160, 240 kg ha-1) and three legume treatments (incorporated into the topsoil or harvested before the sowing of maize and mono-cropping) were tested in a split plot design in three blocks. Results showed a substantial importance of the legume cover crop for both soil types, for all studied factors. Maize total dry biomass yield fluctuated from 13.4 to 20.3 Mg ha-1 for the control plots, from 15.1 to 21.6 Mg ha-1 when faba bean was harvested and from 15.3 to 22.4 Mg ha-1 when incorporated, for clayey soil and from 12.4 to 16.9 Mg ha-1 for the control plots, from 14.9 to 19.4 Mg ha-1 when faba bean was harvested and from 14.5 to 19.6 Mg ha-1 when incorporated, for sandy soil. The NUE was estimated at 56 kg kg-1 and 55 kg kg-1 for clayey and sandy soil, respectively. The N recovery fraction was enhanced by 10-15% after faba bean cover cropping, for both soil types. Such systems should be seriously considered in future land use planning, with respect to the sustainable cultivation of maize.

A sensitivity analysis of the WFCAM Transit Survey for short-period giant planets around M dwarfs

The WFCAM Transit Survey (WTS) is a near-infrared transit survey running on the United Kingdom Infrared Telescope (UKIRT), designed to discover planets around M dwarfs. The WTS acts as a poor-seeing backup programme for the telescope, and represents the first dedicated wide-field near-infrared transit survey. In this paper we describe the observing strategy of the WTS and the processing of the data to generate lightcurves. We describe the basic properties of our photometric data, and measure our sensitivity based on 950 observations. We show that the photometry reaches a precision of ~4mmag for the brightest unsaturated stars in lightcurves spanning almost 3 years. Optical (SDSS griz) and near-infrared (UKIRT ZYJHK) photometry is used to classify the target sample of 4600 M dwarfs with J magnitudes in the range 11-17. Most have spectral-types in the range M0-M2. We conduct Monte Carlo transit injection and detection simulations for short period (<10 day) Jupiter- and Neptune-sized planets to characterize the sensitivity of the survey. We investigate the recovery rate as a function of period and magnitude for 4 hypothetical star-planet cases: M0-2+Jupiter, M2-4+Jupiter, M0-2+Neptune, M2-4+Neptune. We find that the WTS lightcurves are very sensitive to the presence of Jupiter-sized short-period transiting planets around M dwarfs. Hot Neptunes produce a much weaker signal and suffer a correspondingly smaller recovery fraction. Neptunes can only be reliably recovered with the correct period around the rather small sample (~100) of the latest M dwarfs (M4-M9) in the WTS. The non-detection of a hot-Jupiter around an M dwarf by the WFCAM Transit Survey allows us to place an upper limit of 1.7-2.0 per cent (at 95 per cent confidence) on the planet occurrence rate.

Thermo-sensitive polyelectrolytes as draw solutions in forward osmosis process

A series of polyelectrolytes were evaluated as draw solutions for the forward osmosis (FO) process. Such polyelectrolytes were synthesized by copolymerization of N-isopropylacrylamide with different amounts of sodium acrylate. These polyelectrolytes were thermo-sensitive and water soluble. Hot ultrafiltration (HUF) operated at 45°C and 2bar was used as a low-energy method to recover the water from the polyelectrolyte draw solutions. The results showed that 4%PNIPAM-SA solution worked best among nine polyelectrolytes in the forward osmosis process and HUF process, and its FO water flux was 0.347LMH while the feed solution was pure water and its water recovery fraction was 65.2%.

Production of phenols from lignin-derived slurry liquid using iron oxide catalyst

A two-step process consisting of depolymerization and catalytic cracking without hydrogen addition was carried out to produce phenols from lignin. In the first step, lignin was depolymerized using a silica-alumina catalyst in a water/1-butanol solution at 623K for 2h. After the reaction, lignin-derived slurry liquid was obtained in 67C-mol% yield. From the model studies, it was considered that lignin was mainly depolymerized via hydrolysis of aryl ether bonds between lignin units. For the second step, the catalytic reaction of the 1-butanol phase of the slurry liquid was carried out over an iron oxide catalyst using a high pressure fixed-bed flow reactor at 673K. The catalytic reaction under high pressure steam conditions was effective for the suppression of the formation of solid products. In addition, the recovery fraction of phenols increased as the FH2O/F value (the flow rate ratio of steam to the slurry liquid) increased, resulting in 17% of phenols at FH2O/F=5 for 2–4h. From the model studies and our previous results, catechol and methoxyphenol in the slurry liquid were considered to be converted into phenols, cresols and other alkyl phenols over the iron oxide catalyst.

Evaluation of cover-cropping managements on productivity and N-utilization efficiency of kenaf (Hibiscus cannabinus L.), under different nitrogen fertilization rates and soil types

Biomass productivity, nitrogen recovery fraction and nitrogen utilization efficiency (NUE) of kenaf (Hibiscus cannabinus L.) cultivar Tainung 2 were tested, under three Lens culinaries treatments (incorporated, harvested before the sowing of the energy crop and mono-cropping) and four nitrogen dressings (0, 50, 100 and 150kgha−1), in two field experiments carried out on a fertile, clayey to loamy soil, and on a sandy soil of moderate fertility, in central Greece, over the period 2007–2009. The obtained results showed a positive response in L. culinaries cover cropping on kenaf total yield, on both experimental sites. Total dry biomass fluctuated from 16.07 to 21.46tha−1 for incorporated plots and from 13.63 to 16.55tha−1 for control treatments (relied only on applications of N-fertilization) for sandy soil, and from 14.98 to 19.28tha−1 in case of legume incorporation and from 12.34 to 16.69tha−1 for control plots, for clayey soil, respectively. The evaluated NUE was 76kgkg−1, for sandy soil, and 72kgkg−1, for clay soil. The recovery fraction escalated from 41% in control plots to 70% in plots with previous L. culinaries cultivation for sandy soil, while for clayey soil an increase of 20% was recorded, indicating a prominent effect of legume cover-cropping management.

Optimizing fertilizer nitrogen use efficiency by intensively managed spring wheat in humid regions: Effect of split application

Velasco, J. L., Rozas, H. S., Echeverría, H. E. and Barbieri, P. A. 2012. Optimizing fertilizer nitrogen use efficiency by intensively managed spring wheat in humid regions: Effect of split application. Can. J. Plant Sci. 92: 847–856. Efficient N fertilizer management is critical for the economical production of wheat and the long-term protection of the environment. Six experiments were conducted at three locations in the south-east of the province of Buenos Aires (SE), Argentina, during a 4-yr period, on Typic Argiudoll and Petrocalcic Paleudoll. The study was designed to evaluate the effects of splitting nitrogen (N) fertilizer on N use efficiency (NUE) in wheat (Triticum aestivum L.). Rates of 0 to 150 kg N ha−1were used, applied at tillering (Z24) or split between Z24 and flag leaf (Z39). The experimental design was a randomized complete block with three replications. Grain yield ranged from 3522 to 8185 kg ha−1, according to N availability and application time. In the experiments without water stress (three out of six), average grain yield (across experiments) was 6669 and 6989 kg ha−1for full and split fertilization, respectively. In four out of six experiments, average N in above-ground biomass (NAB), N recovery fraction (NRF), and grain protein content (GPC) for split N application were greater than for full N at Z24 (NAB, 176 and 157 kg N ha−1; NRF, 66 and 51%; GPC, 100 and 92 g kg−1, for split and full N application, respectively). In years without water stress, splitting N between Z24 and Z39 is an appropriate strategy to improve NRF, reducing N losses, and minimizing the environmental impact of fertilization.