Synergizing structure and function: Cinnamoyl hydroxamic acids as potent urease inhibitors.

The current investigation encompasses the structural planning, synthesis, and evaluation of the urease inhibitory activity of a series of molecular hybrids of hydroxamic acids and Michael acceptors, delineated from the structure of cinnamic acids. The synthesized compounds exhibited potent urease inhibitory effects, with IC50 values ranging from 3.8 to 12.8 µM. Kinetic experiments unveiled that the majority of the synthesized hybrids display characteristics of mixed inhibitors. Generally, derivatives containing electron-withdrawing groups on the aromatic ring demonstrate heightened activity, indicating that the increased electrophilicity of the beta carbon in the Michael Acceptor moiety positively influences the antiureolytic properties of this compounds class. Biophysical and theoretical investigations further corroborated the findings obtained from kinetic assays. These studies suggest that the hydroxamic acid core interacts with the urease active site, while the Michael acceptor moiety binds to one or more allosteric sites adjacent to the active site.

Ammonia volatization from conventional and stabilized fertilizers, agronomic aspects and microbiological attributes in a Brazilian coffee crop system.

We aimed to quantify the N losses through volatilization of the main conventional and stabilized N fertilizers applied in coffee plantations. Additionally, we also assessed microbiological attributes of the soil (microbial biomass carbon (MBC); microbial biomass nitrogen (MBN); microbial basal respiration (MBR); metabolic quotient (qCO2); urease, ß-glucosidase, acid phosphatase, and arylsulfatase activities) and agronomic aspects of the crop (N content in the leaves and beans, yield, and N exportation by the beans). Treatments consisted of the combination of three fertilizers (ammonium nitrate - AN, conventional urea - U, and urea with N- (n-butyl) thiophosphoric triamide (NBPT) - UNBPT, and five doses of N (0, 150, 275, 400, and 525 kg ha-1 year-1 of N), with four replicates, totalling 60 experimental plots. In the two crop seasons evaluated, daily and cumulative losses of N-NH3 from the split fertilizer applications were influenced by the N fertilizer technologies. The application of U resulted in losses of 22.0% and 22.8% for the doses of 150 and 400 kg ha-1 year-1 of N. This means that 66 and 182 kg ha-1 of N-NH3 were lost, respectively, at the end of six fertilizations with U. UNBPT reduced urease activity and N-NH3 losses compared to conventional urea, avoiding the volatilization of 15.9 and 24.3 kg ha-1 of N. As for AN, N-NH3 losses did not exceed 1% of the applied dose, regardless of the weather conditions during the fertilization. Urease activity was higher on days of maximum NH3 volatilization. There was an effect of the N sources (NS), soil sampling time (ST), and their interaction (NS × ST) on the MBN and arylsulfatase activity. The N sources also influenced the MBC and the qCO2. A substantial amount of N was removed from the system by the beans and husks of the harvested fruits. Our study showed that N fertilizer technologies are interesting options to reduce N-NH3 losses by volatilization, increase N retention in the soil, and improve microbiological attributes and the sustainability of coffee production systems.

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.(AU)

Schiff bases and their metal complexes as urease inhibitors - A brief review.

Schiff bases, an aldehyde- or ketone-like compounds in which the carbonyl group is replaced by an imine or azomethine, are some of the most widely used organic compounds. Indeed, they are widely used for industrial purposes and also exhibit a broad range of biological activities, including anti-urease activity. Ureases, enzymes that catalyze urea hydrolysis, have received considerable attention for their impact on living organisms' health, since the persistence of urease activity in human and animal cells can be the cause of some diseases and pathogen infections. This short review compiles examples of the most antiurease Schiff bases (0.23 µM < IC50 < 37.00 µM) and their metal complexes (0.03 µM < IC50 < 100 µM). Emphasis is given to ureases of Helicobacter pylori and Canavalia ensiformis, although the active site of this class of hydrolases is conserved among living organisms.

Volatilização da amônia da ureia estabilizada com NBPT na adubação em cobertura da Urochloa ruziziensis / Ammonia volatilization from stabilized urea with NBPT of the topdressing fertilization in Urochloa ruziziensis

A ureia é o principal adubo nitrogenado utilizado em pastagens. Nesse fertilizante, uma das principais perdas de nitrogênio (N) está relacionada com a volatilização da amônia. O uso de produtos que proporcionam redução das perdas de N da ureia pode contribuir para aumentar a eficiência de uso desse nutriente em pastagens. Assim, objetivou-se determinar o efeito de fontes e doses de N aplicado parcelado em cobertura na Urochloa ruziziensis, nas perdas de N pela volatilização de amônia (N-NH3). O experimento foi conduzido em Santo Antônio de Goiás, GO, em Latossolo Vermelho Distrófico. Utilizou o delineamento experimental de blocos ao acaso, com quatro repetições em arranjo fatorial 2 x 5 x 5. Os tratamentos foram compostos pelas fontes de N: ureia comum e ureia com inibidor de urease, doses de N: 0, 50, 100, 200 e 300 kg ha-1 (parceladas em 5 aplicações) e cinco períodos de crescimento da forrageira: 14/11 a 13/12 (1º período), 14/12 a 12/01 (2º período), 13/01 a 11/02 (3º período), 24/03 a 22/04 (4º período), e 10/07 a 08/08 (5º período). O uso de ureia com inibidor de urease proporcionou reduções nas perdas de amônia por volatilização em relação à ureia comum. O aumento das doses de N proporcionou aumento da volatilização de N-NH3. Ocorreram maiores perdas de N pela volatilização da amônia nos períodos mais secos do ano.(AU)

Urea is the major nitrogen fertilizer used in pastures. In this fertilizer, one of the main nitrogen (N) losses is related to ammonia volatilization. The use of products that provide reduced losses of N from urea can help to increase the use efficiency of this nutrient in pastures. This study aimed to determine the effect of nitrogen sources and doses split applied at topdressing in Urochloa ruziziensis in the N losses by ammonia N-NH3 volatilization. The experiment was conducted in Santo Antônio de Goiás, GO, in a in a Brazilian Oxisol. It was used the randomized blocks experimental design, with four replications, in a factorial arrangement 2 x 5 x 5. Treatments were composed by N sources: common urea and urea with urease inhibitor, N rates: 0, 50, 100, 200 and 300 kg ha-1 (split in 5 applications) and five forage growth period: 11/14 to 12/13 (1º period), 12/14 to 01/12 (2º period), 01/13 to 02/11 (3º period), 03/24 to 04/22 (4º period) and 07/10 to 08/08 (5º period). The use of urea with urease inhibitor provided reductions in ammonia loss by volatilization in comparison to the common urea. Increasing N rates led to increased NNH3 volatilization. In drier periods of the year it was found greater losses of N by ammonia volatilization.(AU)

Volatilização da amônia da ureia estabilizada com NBPT na adubação em cobertura da Urochloa ruziziensis / Ammonia volatilization from stabilized urea with NBPT of the topdressing fertilization in Urochloa ruziziensis

A ureia é o principal adubo nitrogenado utilizado em pastagens. Nesse fertilizante, uma das principais perdas de nitrogênio (N) está relacionada com a volatilização da amônia. O uso de produtos que proporcionam redução das perdas de N da ureia pode contribuir para aumentar a eficiência de uso desse nutriente em pastagens. Assim, objetivou-se determinar o efeito de fontes e doses de N aplicado parcelado em cobertura na Urochloa ruziziensis, nas perdas de N pela volatilização de amônia (N-NH3). O experimento foi conduzido em Santo Antônio de Goiás, GO, em Latossolo Vermelho Distrófico. Utilizou o delineamento experimental de blocos ao acaso, com quatro repetições em arranjo fatorial 2 x 5 x 5. Os tratamentos foram compostos pelas fontes de N: ureia comum e ureia com inibidor de urease, doses de N: 0, 50, 100, 200 e 300 kg ha-1 (parceladas em 5 aplicações) e cinco períodos de crescimento da forrageira: 14/11 a 13/12 (1º período), 14/12 a 12/01 (2º período), 13/01 a 11/02 (3º período), 24/03 a 22/04 (4º período), e 10/07 a 08/08 (5º período). O uso de ureia com inibidor de urease proporcionou reduções nas perdas de amônia por volatilização em relação à ureia comum. O aumento das doses de N proporcionou aumento da volatilização de N-NH3. Ocorreram maiores perdas de N pela volatilização da amônia nos períodos mais secos do ano.

Urea is the major nitrogen fertilizer used in pastures. In this fertilizer, one of the main nitrogen (N) losses is related to ammonia volatilization. The use of products that provide reduced losses of N from urea can help to increase the use efficiency of this nutrient in pastures. This study aimed to determine the effect of nitrogen sources and doses split applied at topdressing in Urochloa ruziziensis in the N losses by ammonia N-NH3 volatilization. The experiment was conducted in Santo Antônio de Goiás, GO, in a in a Brazilian Oxisol. It was used the randomized blocks experimental design, with four replications, in a factorial arrangement 2 x 5 x 5. Treatments were composed by N sources: common urea and urea with urease inhibitor, N rates: 0, 50, 100, 200 and 300 kg ha-1 (split in 5 applications) and five forage growth period: 11/14 to 12/13 (1º period), 12/14 to 01/12 (2º period), 01/13 to 02/11 (3º period), 03/24 to 04/22 (4º period) and 07/10 to 08/08 (5º period). The use of urea with urease inhibitor provided reductions in ammonia loss by volatilization in comparison to the common urea. Increasing N rates led to increased NNH3 volatilization. In drier periods of the year it was found greater losses of N by ammonia volatilization.

Chemical soil attributes after wheat cropping under nitrogen fertilization and inoculation with Azospirillum brasilense / Atributos químicos do solo após cultivo de trigo sob adubação nitrogenada e inoculação com Azospirillum brasilense

Azospirillum brasilense plays an important role in biological nitrogen fixation (BNF) in grasses. However, further studies are needed to define how much mineral N can be applied while simultaneously maintaining BNF contribution and maximizing crop yield and to determine the impact of these practices on soil fertility. Thus, we aimed to investigate the effect of inoculation with A. brasilense, in conjunction with varying N doses and sources in a Cerrado soil, on soil chemical attributes after two years of irrigated wheat production. The experiment was initiated in Selvíria MS under no-tillage production in an Oxisol in 2014 and 2015. The experimental design was a randomized block design with four replications, and treatments were arranged in a 2 x 5 x 2 factorial arrangement as follows: two N sources (urea and Super N urea with inhibitor of the enzyme urease NBPT (N (n-butyl thiophosphoric triamide))), five N rates (0, 50, 100, 150 and 200 kg ha-1), and with or without seed inoculation with A. brasilense. The increase in N rates did not influence the chemical soil attributes. Super N acidified the soil more compared to urea. A. brasilense inoculation reduced the effect of soil acidification in intensive irrigated wheat cultivation; however, the base extraction was higher, resulting in a lower soil CEC after cultivation with inoculation. Therefore, the cultivation of wheat inoculated with A. brasilense was not harmful to soil fertility because it did not reduce the base saturation and organic matter contents of, P, K, Ca, Mg, and S.(AU)

O Azospirillum brasilense destaca-se no processo de fixação biológica de nitrogênio (FBN) em gramíneas. Contudo, mais estudos necessitam ser conduzidos para definir quanto se pode aplicar de N mineral considerando-se a eficiência da FBN para alcançar altas produtividades sem alterar a fixação, bem como sobre o impacto dessas práticas na fertilidade do solo. Sendo assim, objetivou-se avaliar o efeito da inoculação de trigo com A. brasilense, associada a doses e fontes de N, em solo de Cerrado, avaliando-se os atributos químicos do solo após dois cultivos de trigo irrigado. O experimento foi desenvolvido em Selvíria MS, em sistema plantio direto, em Latossolo Vermelho distrófico, em 2014 e 2015. O delineamento experimental foi o de blocos ao acaso, com quatro repetições, dispostos em um esquema fatorial 2 x 5 x 2, sendo: duas fontes de N (ureia e Super N ureia com inibidor da enzima urease NBPT (N(-n-butil tiofosfórico triamida)); cinco doses de N em cobertura (0, 50, 100, 150 e 200 kg ha-1); com e sem inoculação das sementes com A. brasilense. O incremento das doses de N não influenciou os atributos químicos do solo. O Super N pode acidificar mais o solo comparativamente à ureia. A inoculação com A. brasilense pode reduzir o efeito da acidificação do solo em cultivos intensivos de trigo irrigado, contudo a extração de bases foi maior, refletindo em menor CTC do solo após cultivo com inoculação. Portanto, o cultivo de trigo inoculado com A. brasilense não é prejudicial à fertilidade do solo, pois não reduz a saturação por bases e os teores de matéria orgânica, P, K, Ca, Mg e S.(AU)

Chemical soil attributes after wheat cropping under nitrogen fertilization and inoculation with Azospirillum brasilense / Atributos químicos do solo após cultivo de trigo sob adubação nitrogenada e inoculação com Azospirillum brasilense

Azospirillum brasilense plays an important role in biological nitrogen fixation (BNF) in grasses. However, further studies are needed to define how much mineral N can be applied while simultaneously maintaining BNF contribution and maximizing crop yield and to determine the impact of these practices on soil fertility. Thus, we aimed to investigate the effect of inoculation with A. brasilense, in conjunction with varying N doses and sources in a Cerrado soil, on soil chemical attributes after two years of irrigated wheat production. The experiment was initiated in Selvíria – MS under no-tillage production in an Oxisol in 2014 and 2015. The experimental design was a randomized block design with four replications, and treatments were arranged in a 2 x 5 x 2 factorial arrangement as follows: two N sources (urea and Super N – urea with inhibitor of the enzyme urease NBPT (N – (n-butyl thiophosphoric triamide))), five N rates (0, 50, 100, 150 and 200 kg ha-1), and with or without seed inoculation with A. brasilense. The increase in N rates did not influence the chemical soil attributes. Super N acidified the soil more compared to urea. A. brasilense inoculation reduced the effect of soil acidification in intensive irrigated wheat cultivation; however, the base extraction was higher, resulting in a lower soil CEC after cultivation with inoculation. Therefore, the cultivation of wheat inoculated with A. brasilense was not harmful to soil fertility because it did not reduce the base saturation and organic matter contents of, P, K, Ca, Mg, and S.

O Azospirillum brasilense destaca-se no processo de fixação biológica de nitrogênio (FBN) em gramíneas. Contudo, mais estudos necessitam ser conduzidos para definir quanto se pode aplicar de N mineral considerando-se a eficiência da FBN para alcançar altas produtividades sem alterar a fixação, bem como sobre o impacto dessas práticas na fertilidade do solo. Sendo assim, objetivou-se avaliar o efeito da inoculação de trigo com A. brasilense, associada a doses e fontes de N, em solo de Cerrado, avaliando-se os atributos químicos do solo após dois cultivos de trigo irrigado. O experimento foi desenvolvido em Selvíria – MS, em sistema plantio direto, em Latossolo Vermelho distrófico, em 2014 e 2015. O delineamento experimental foi o de blocos ao acaso, com quatro repetições, dispostos em um esquema fatorial 2 x 5 x 2, sendo: duas fontes de N (ureia e Super N – ureia com inibidor da enzima urease NBPT (N(-n-butil tiofosfórico triamida)); cinco doses de N em cobertura (0, 50, 100, 150 e 200 kg ha-1); com e sem inoculação das sementes com A. brasilense. O incremento das doses de N não influenciou os atributos químicos do solo. O Super N pode acidificar mais o solo comparativamente à ureia. A inoculação com A. brasilense pode reduzir o efeito da acidificação do solo em cultivos intensivos de trigo irrigado, contudo a extração de bases foi maior, refletindo em menor CTC do solo após cultivo com inoculação. Portanto, o cultivo de trigo inoculado com A. brasilense não é prejudicial à fertilidade do solo, pois não reduz a saturação por bases e os teores de matéria orgânica, P, K, Ca, Mg e S.

Fertilizers with coated urea in upland rice production and nitrogen apparent recovery / Doses de fertilizantes com ureia revestida na produção de arroz de terras altas e recuperação aparente de nitrogênio

Urea is the most used N fertilizer for upland rice, however, a great percentage of N loss can occur with the use of this fertilizer. The use of products that provide reduction of N loss for urea fertilizers can contribute to increase N use efficiency. The objective of this study was to determine the effect of N rates applied in the form of coated urea in the content and accumulation of N in dry biomass, apparent recovery of nitrogen and grain yield of upland rice. The experimental design was a randomized complete blocks arranged in a 4 x 3 + 1 factorial scheme. The treatments consisted of four sources of N fertilizer [1. Common urea; 2. Polymer-coated urea for slow release of N (PCU); 3. urea with the urease inhibitor N-(n-Butyl) thiophosphoric triamide (NBPT); and 4. urea coated with copper sulfate and boric acid as urease inhibitors (UCCB)], with three fertilization rates (30, 60 and 90 kg ha-1 of N). In addition, we included a control treatment without N application. Coated urea did not provide increases in rice grain yield in relation to common urea. The increasing amount of N resulted in significant increases in rice grain yield (from 3217 to 5548 kg ha-1, 2010/11, and from 3392 to 4560 kg ha-1, 2011/12). The apparent nitrogen recovery rate decreased with the increase in N applied doses.

A ureia é o fertilizante nitrogenado mais utilizado para o arroz de terras altas, no entanto, esse fertilizante tem grande percentual de perda de N. O uso de produtos que proporcionam redução da perda de N em fertilizantes com ureia pode contribuir para aumentar a eficiência de uso do nitrogênio. O objetivo deste estudo foi determinar o efeito de doses de N aplicadas na forma de ureia encapsulada no teor e acúmulo de N na biomassa seca, recuperação aparente de nitrogênio e produtividade de grãos de arroz de terras altas. O delineamento experimental foi em blocos ao acaso no esquema fatorial 4 x 3 + 1. Os tratamentos consistiram de quatro fontes de N fertilizante [1. ureia tradicional; 2. Polímero de ureia revestida para liberação lenta de N (PCU); 3. ureia com o inibidor de urease N- (n-butil) triamida tiofosfórico (NBPT); e 4. ureia revestida com sulfato de cobre e ácido bórico como inibidores de urease (UCCB)], com três doses de fertilizante (30, 60 e 90 kg ha-1 de N). Além disso, incluímos uma testemunha sem aplicação de N. Ureia revestida não forneceu aumentos no rendimento de grãos de arroz em relação à ureia comum. O aumento da quantidade de N resultou em aumentos significativos no rendimento de grãos de arroz (de 3217 para 5548 kg ha-1, 2010/11, e de 3392 para 4560 kg ha-1, 2011/12). A taxa de recuperação aparente de nitrogênio diminuiu com o aumento das doses aplicadas de N.

Resposta do feijoeiro de outono-inverno a fontes e doses de nitrogênio em cobertura / Response of dry beans to source and rate of n application topdressing

O estudo teve o objetivo de avaliar o efeito de fontes e doses de nitrogênio (N), em cobertura, na nutrição, desenvolvimento e produtividade do feijoeiro irrigado, cultivado no outono-inverno, no Cerrado. O experimento foi conduzido na Embrapa Arroz e Feijão, em um Latossolo Vermelho distrófico, de textura argilosa. Utilizou-se o delineamento de blocos ao acaso, com três fontes nitrogenadas, uréia, uréia + NBPT e N liberação gradual, e quatro doses de N em cobertura 0; 50; 100 e 150 kg ha-1, combinados em esquema fatorial 3 x 4, com quatro repetições. Foram avaliados a massa de matéria seca da parte aérea (MSPA), índice de área foliar, teor de N total nas folhas, N acumulado na parte aérea, índice relativo de clorofila, estande final, componentes de produção e rendimento de grãos do feijoeiro. A utilização de uréia na dose de 150 kg ha-1 de N resultou em um maior índice relativo de clorofila nas folhas do feijoeiro. A produtividade máxima estimada, de 2.876 kg ha-1, foi obtida com a dose de 133,6 kg ha-1 de N. O teor de N total nas folhas, o acúmulo de N na parte aérea, a MSPA, o índice de área foliar e o índice relativo de clorofila no feijoeiro correlacionaram-se positivamente com a produtividade. As fontes N de liberação gradual, assim como a uréia com inibidor de urease não proporcionaram aumentos no rendimento de grãos, em comparação com a uréia comum.

The study aimed to evaluate the effect of sources and rates of nitrogen (N) topdressing, nutrition, development and productivity of common beans crop irrigated, grown in the autumn-winter, in the Cerrado. The experiment was conducted at Embrapa Arroz e Feijão, in Santo Antônio de Goiás, Goiás State, using a dystrophic Dark Red Latosol, of clay texture. We used a randomized block design, with three sources of nitrogen fertilizer, urea, urea + NBPT and gradual release N fertilizer, and four rates of nitrogen in 0; 50; 100 and 150 kg ha-1, combined in a regimen 3 x 4 factorial, with four replications. We evaluated the dry mass weight (MSPA), leaf area index, leaf N content, N accumulated uptake, relative chlorophyll index, final stand, yield components and grain yield of common beans. The use of urea at 150 kg ha-1 of N resulted in a greater relative chlorophyll content in leaves of common beans. The estimated maximum yield of 2.876 kg ha-1 was obtained with a dose of 133,6 kg N ha-1. The leaf N content, the accumulation of N in the shoot, the dry mass weight, leaf area index and relative chlorophyll content in common beans correlated positively with their productivity. The gradual release N fertilizer and urea with urease inhibitor does not provide increases in common beans yield.

Ammonia volatilization losses, dry biomass yield and levels of foliar nitrogen on marandu palisade grass after surface-applied urea with urease inhibitor / Perdas por volatilização da amônia, produção de biomassa seca e teores de n foliar de capim marandu após a aplicação superficial de uréia com inibidor

Urea is the N source most widely used in pastures in Brazil. A significant amount of N is lost to the atmosphere by ammonia and nitrous oxide emissions and leached surface or ground water as nitrate contributing to environmental degradation such as the global warming or eutrophication. The loss of nitrogen by ammonia volatilization is a major factor for low efficiency of urea applied in soil surface. An alternative to reducing these losses is the use of urease inhibitors. The aim of this study was to investigate the effects of treating urea with urease inhibitor (NBPT N-(n-butyl) thiophosphoric acid triamide) on the dry biomass yield in pasture of Urochloa (syn. Brachiaria) brizantha Marandu to minimize NH3 volatilization. The study was performed at the Instituto de Zootecnia (IZ) at Nova Odessa, SP, Brazil, in a typic acrudox soil composed of sand (49.5%), clay (20.9%) and loam (29.6%). A randomized experimental design with three treatments and four replications was used. The treatments were: i) No N; ii) Urea; iii) Urea treated with urease inhibitor NBPT. The rate of N was 50 kg/ha applied to the surface of the soil. Measurements of NH3 volatilized were done by semiopen PVC chambers. Controls chambers were added to allow NH3 volatilized from unfertilised soil or contained in the air that swept over the soil surface. We evaluated the yield and plant height, SPAD value and N

O artigo não apresenta resumo em português.

Ammonia volatilization losses, dry biomass yield and levels of foliar nitrogen on marandu palisade grass after surface-applied urea with urease inhibitor / Perdas por volatilização da amônia, produção de biomassa seca e teores de n foliar de capim marandu após a aplicação superficial de uréia com inibidor

Urea is the N source most widely used in pastures in Brazil. A significant amount of N is lost to the atmosphere by ammonia and nitrous oxide emissions and leached surface or ground water as nitrate contributing to environmental degradation such as the global warming or eutrophication. The loss of nitrogen by ammonia volatilization is a major factor for low efficiency of urea applied in soil surface. An alternative to reducing these losses is the use of urease inhibitors. The aim of this study was to investigate the effects of treating urea with urease inhibitor (NBPT N-(n-butyl) thiophosphoric acid triamide) on the dry biomass yield in pasture of Urochloa (syn. Brachiaria) brizantha Marandu to minimize NH3 volatilization. The study was performed at the Instituto de Zootecnia (IZ) at Nova Odessa, SP, Brazil, in a typic acrudox soil composed of sand (49.5%), clay (20.9%) and loam (29.6%). A randomized experimental design with three treatments and four replications was used. The treatments were: i) No N; ii) Urea; iii) Urea treated with urease inhibitor NBPT. The rate of N was 50 kg/ha applied to the surface of the soil. Measurements of NH3 volatilized were done by semiopen PVC chambers. Controls chambers were added to allow NH3 volatilized from unfertilised soil or contained in the air that swept over the soil surface. We evaluated the yield and plant height, SPAD value and N

O artigo não apresenta resumo em português.

Morphophysiological characteristcs and nutrition of aries grass (Panicum maximum, jacq.) with nitrogen fertilization / Características morfofisiológicas e nutrição de capim Áries (Panicum maximum, jacq.) mediante a adubação nitrogenada

Low availability of nitrogen (N) is a factor that limits forage production. Pastures are mostly formed of grasses, which need large N amounts to sustain high yields. Additionally, the availability of this nutrient affects the persistence and quality of the forage produced. However, when applying fertilizers containing nitrogen up to 50% can be lost, making their use costly for farmers. N is a highly volatile gas, and urea, widely used in agriculture, contains 46% N. When urea comes in contact with moisture in the soil, hydrolysis occurs due to the precipitation of the enzyme urease, accelerating the transformation of urea into ammonia, which can be lost by volatilization. One of the techniques to increase the efficiency of using urea is application of nitrogen fertilizers along with urease inhibitors, to retard the breakdown of urea so that it becomes incorporated in the soil slowly. One of the inhibitors used is N-(n-butyl) phosphate triamide (NBPT). This study aimed to assess the effect of nitrogen sources and doses on some productive characteristics of Áries grass (Panicum maximum, Jacq) to find ways to improve the effectiveness of nitrogen application. The tests were performed at Centro Nutrição Animal e Pastagens Instituto de Zootecnia in Nova Odessa, São Paulo, from March to August 2012. The experimental design was randomized blocks, with five replications in 2 x 3 fact

O artigo não apresenta resumo em português.

Morphophysiological characteristcs and nutrition of aries grass (Panicum maximum, jacq.) with nitrogen fertilization / Características morfofisiológicas e nutrição de capim Áries (Panicum maximum, jacq.) mediante a adubação nitrogenada

Low availability of nitrogen (N) is a factor that limits forage production. Pastures are mostly formed of grasses, which need large N amounts to sustain high yields. Additionally, the availability of this nutrient affects the persistence and quality of the forage produced. However, when applying fertilizers containing nitrogen up to 50% can be lost, making their use costly for farmers. N is a highly volatile gas, and urea, widely used in agriculture, contains 46% N. When urea comes in contact with moisture in the soil, hydrolysis occurs due to the precipitation of the enzyme urease, accelerating the transformation of urea into ammonia, which can be lost by volatilization. One of the techniques to increase the efficiency of using urea is application of nitrogen fertilizers along with urease inhibitors, to retard the breakdown of urea so that it becomes incorporated in the soil slowly. One of the inhibitors used is N-(n-butyl) phosphate triamide (NBPT). This study aimed to assess the effect of nitrogen sources and doses on some productive characteristics of Áries grass (Panicum maximum, Jacq) to find ways to improve the effectiveness of nitrogen application. The tests were performed at Centro Nutrição Animal e Pastagens Instituto de Zootecnia in Nova Odessa, São Paulo, from March to August 2012. The experimental design was randomized blocks, with five replications in 2 x 3 fact

O artigo não apresenta resumo em português.

Forms of urea and nitrogen levels in top dressing in the agronomic performance of wheat genotypes / Formas de ureia e doses de nitrogênio em cobertura no desempenho agronômico de genótipos de trigo

The objective of this study was to evaluate the effect of nitrogen fertilization in top dressing from various forms of urea in wheat genotypes on no-till system. Wheat genotypes developed by EMBRAPA (cultivars BRS 208 and BRS Pardela and line IWT 04008) were evaluated in three independents experiments in Ponta Grossa, State of Paraná, Brazil in 2008. Three forms of urea were evaluated (conventional urea, urea with urease inhibitor and protected urea) with four levels of N (0, 40, 80 and 120 kg ha-1) applied in top dressing in early tillering. Randomized block design, in a 3 x 4 factorial experiment, with four replications were used. The increase in the levels of nitrogen in any form of urea used, increase the dry mass of the flag leaf, the number of spikes m-2 and yield, but reduces hectoliter mass. The form of urea applied in top dressing does not influence the agronomic characteristics of the evaluated genotypes. Cultivars BRS 208 and BRS Pardela were more productive and had higher N content grain than line IWT 04008.

O objetivo do trabalho foi avaliar o efeito de doses de adubação nitrogenada em cobertura, provenientes de diferentes formas de ureia, em genótipos de trigo, no sistema de semeadura direta. Os genótipos de trigo desenvolvidos pela EMBRAPA (cultivares BRS 208 e BRS Pardela e linhagem IWT 04008) foram avaliados em três experimentos independentes em Ponta Grossa-PR na safra de 2008. O delineamento experimental foi o de blocos casualizados em esquema fatorial 3 x 4, com quatro repetições. Avaliou-se três formas de ureia (ureia convencional, ureia com inibidor de urease e ureia protegida) com quatro doses de N (0, 40, 80 e 120 kg ha-1) aplicadas em cobertura no início do perfilhamento. O incremento das doses de N em cobertura, independentemente da forma de ureia utilizada, favorece a massa seca da folha bandeira, o número de espigas m-2 e a produtividade, porém reduz o peso do hectolitro. A forma de ureia aplicada em cobertura não interfere nas características agronômicas dos genótipos avaliados. Os cultivares BRS 208 e BRS Pardela foram os mais produtivos e apresentaram grãos com maior teor de N que a linhagem IWT 04008.

Forms of urea and nitrogen levels in top dressing in the agronomic performance of wheat genotypes / Formas de ureia e doses de nitrogênio em cobertura no desempenho agronômico de genótipos de trigo

The objective of this study was to evaluate the effect of nitrogen fertilization in top dressing from various forms of urea in wheat genotypes on no-till system. Wheat genotypes developed by EMBRAPA (cultivars BRS 208 and BRS Pardela and line IWT 04008) were evaluated in three independents experiments in Ponta Grossa, State of Paraná, Brazil in 2008. Three forms of urea were evaluated (conventional urea, urea with urease inhibitor and protected urea) with four levels of N (0, 40, 80 and 120 kg ha-1) applied in top dressing in early tillering. Randomized block design, in a 3 x 4 factorial experiment, with four replications were used. The increase in the levels of nitrogen in any form of urea used, increase the dry mass of the flag leaf, the number of spikes m-2 and yield, but reduces hectoliter mass. The form of urea applied in top dressing does not influence the agronomic characteristics of the evaluated genotypes. Cultivars BRS 208 and BRS Pardela were more productive and had higher N content grain than line IWT 04008.

O objetivo do trabalho foi avaliar o efeito de doses de adubação nitrogenada em cobertura, provenientes de diferentes formas de ureia, em genótipos de trigo, no sistema de semeadura direta. Os genótipos de trigo desenvolvidos pela EMBRAPA (cultivares BRS 208 e BRS Pardela e linhagem IWT 04008) foram avaliados em três experimentos independentes em Ponta Grossa-PR na safra de 2008. O delineamento experimental foi o de blocos casualizados em esquema fatorial 3 x 4, com quatro repetições. Avaliou-se três formas de ureia (ureia convencional, ureia com inibidor de urease e ureia protegida) com quatro doses de N (0, 40, 80 e 120 kg ha-1) aplicadas em cobertura no início do perfilhamento. O incremento das doses de N em cobertura, independentemente da forma de ureia utilizada, favorece a massa seca da folha bandeira, o número de espigas m-2 e a produtividade, porém reduz o peso do hectolitro. A forma de ureia aplicada em cobertura não interfere nas características agronômicas dos genótipos avaliados. Os cultivares BRS 208 e BRS Pardela foram os mais produtivos e apresentaram grãos com maior teor de N que a linhagem IWT 04008.

Fontes alternativas à ureia no fornecimento de nitrogênio para o arroz irrigado / Alternative sources of supply in the urea nitrogen for rice production

A ureia é a principal fonte de N usada na agricultura, mas apresenta grandes perdas em arroz irrigado por alagamento. O objetivo deste trabalho foi avaliar a eficiência de fontes de N alternativas à ureia para utilização pelo arroz irrigado aplicadas em diferentes estádios de desenvolvimento da planta através da quantificação da volatilização de N-NH3 e de parâmetros agronômicos. O experimento foi realizado em campo nos anos agrícolas 2007/08 e 2008/09. O delineamento experimental foi de blocos ao acaso com quatro repetições. Os tratamentos foram compostos de diferentes fontes de N aplicados na semeadura, no perfilhamento e no estádio de diferenciação floral: testemunha sem aplicação de N, ureia, ureia+inibidor de urease, duas fontes de N líquido (N-28 e N- 30), sulfato de amônio e ureia + enxofre. Nas duas safras, a volatilização de N-NH3 na semeadura foi praticamente insignificante, enquanto no estádio V4 a fonte que menos volatilizou foi o sulfato de amônio. A resposta em produtividade variou entre os anos, provavelmente em função da disponibilidade de N no solo e aspectos climáticos. Quando vantajoso economicamente, o uso do inibidor de urease e o sulfato de amônio proporcionam produtividades semelhantes à fonte ureia.

Urea is the main source of N used in agriculture, but has large losses in irrigated rice. The objective of this study was to evaluate the efficiency of N sources alternative to urea for use by rice applied at different stages of plant development through the quantification of N-NH3 and agronomic parameters. The experiment was conducted in the field in the agricultural years 2007/08 and 2008/09. The experimental design was randomized blocks with four replications. The treatments consisted of different N sources applied at seeding, tillering and at the stage of floral differentiation: control without N, urea, urea + urease inhibitor, two sources of liquid N (N-28 and N-30) ammonium sulfate and urea + sulfur. In both seasons, the volatilization of N-NH3 at seeding was almost negligible, whereas in the V4 stage, the source that was less volatilized was the ammonium sulfate. Yield response varied among years, probably due to the availability of N in the soil and climatic aspects. When economically advantageous, the use of urease inhibitor and ammonium sulfate provide yields similar to urea supply.

Productivity and efficiency of nitrogen fertilization in maize under different levels of urea and NBPT-treated urea / Produtividade e eficiência da adubação nitrogenada em milho sob doses de uréia comum e com NBPT

The management of nitrogen fertilization is complex due to the various transformations of the nitrogen that occur in the soil-plant-atmosphere system, reducing the efficiency of the fertilization, productivity and the profit margin of the maize production areas. This study aimed to evaluate the effect of different levels of common urea and urea treat with NBPT [N-(n-butyl) thiophosphoric triamide] on the productivity and efficiency of the nitrogen fertilization in maize, correlated with simple economic analysis. The design of the field experiment was in randomized complete blocks with six repetitions, in a 2 x 4 factorial outline, made up of by two sources of nitrogen (urea and NBPT-treated urea) and four levels of nitrogen as top dressing (60, 120, 180 and 240 kg ha-1). The sources and applied nitrogen levels influenced the productivity and the leaf and grain nitrogen contents, while the production components (size and diameter of the ear, and percentage of straw and cob) were not altered. The agronomic efficiency of the nitrogen fertilization decreased with the increase of the applied nitrogen levels. The highest gross profit margin in the maize culture is obtained with 180 kg ha-1 of nitrogen supplied in the NBPT-treated urea.

O manejo da adubação nitrogenada é complexo em razão das diversas transformações do nitrogênio que ocorrem no sistema solo-planta-atmosfera, diminuindo a eficiência da adubação, produtividade e a margem de lucro das áreas de produção de milho. Neste trabalho, objetivou-se avaliar o efeito de diferentes doses de uréia comum e com NBPT [N-(n-butyl) thiophosphoric triamide] na produtividade e eficiência da adubação nitrogenada na cultura do milho, correlacionado com análise econômica simples. O delineamento experimental foi em blocos completos casualizados com seis repetições, em esquema fatorial 2 x 4, constituídos por duas fontes de N (uréia comum e uréia tratada com NBPT) e quatro doses de nitrogênio em cobertura (60, 120, 180 e 240 kg ha-1). As fontes e doses de nitrogênio influenciaram na produtividade e nos teores de N da folha e dos grãos, enquanto que os componentes de produção (tamanho e diâmetro da espiga e porcentagem de palha e sabugo) não foram alterados. A eficiência agronômica da adubação nitrogenada diminuiu com o aumento das doses de N aplicadas em cobertura. A maior margem bruta de ganho da cultura do milho é obtida com aplicação de uréia tratada com NBPT, na dosagem de 180 kg ha-1.