Conversion of ammonium to nitrate and abundance of ammonium-oxidizing-microorganism in Tropical soils with nitrification inhibitor

The use of nitrification inhibitors (NIs; dicyandiamide - DCD) is an alternative to reduce oxidation of ammonium (NH4+-N) to nitrate (NO3–-N) in the soil, reducing NO3–-N losses from fertilization practices. Based on the hypothesis that DCD reduces conversion of NH4+-N to NO3–-N in tropical soils and inhibits ammonia oxidizing microorganisms (AOM) abundance, soils from the Piracicaba region, São Paulo, with different textures (sand, loam and clay) were incubated with ammonium sulphate (AS) and DCD. Contents of NH4+-N, NO3–-N, soil pH, and AOM abundance were quantified periodically. Ammonium sulphate increased AOM abundance in all soils, but AS+DCD presented AOM abundances similar to the control. During 90 days of incubation, the effectiveness of DCD in reducing NO3–-N production was 1.8, 86.4, and 145.6 mg kg–1, while the effectiveness of DCD in reducing AOM abundance was 1.2, 3.0 and 2.3 × 10–3 g soil–1 for sandy, loamy, and clayey soils, respectively. DCD effectiveness was greater in loamy and clayey soils due to the naturally low nitrification in sandy soils. Application of AS treated with DCD showed potential not only to reduce NO3–-N production in loamy and clayey soils, but also to decrease the soil nitrification rate. Overall, DCD was effective in reducing AOM abundance and conversion of NH4+-N to NO3–-N in loamy and clay soils evaluated here. The increase in clay content directly influences DCD effectiveness in reducing conversion of NH4+-N to NO3–-N.

Conversion of ammonium to nitrate and abundance of ammonium-oxidizing-microorganism in Tropical soils with nitrification inhibitor

The use of nitrification inhibitors (NIs; dicyandiamide - DCD) is an alternative to reduce oxidation of ammonium (NH4+-N) to nitrate (NO3–-N) in the soil, reducing NO3–-N losses from fertilization practices. Based on the hypothesis that DCD reduces conversion of NH4+-N to NO3–-N in tropical soils and inhibits ammonia oxidizing microorganisms (AOM) abundance, soils from the Piracicaba region, São Paulo, with different textures (sand, loam and clay) were incubated with ammonium sulphate (AS) and DCD. Contents of NH4+-N, NO3–-N, soil pH, and AOM abundance were quantified periodically. Ammonium sulphate increased AOM abundance in all soils, but AS+DCD presented AOM abundances similar to the control. During 90 days of incubation, the effectiveness of DCD in reducing NO3–-N production was 1.8, 86.4, and 145.6 mg kg–1, while the effectiveness of DCD in reducing AOM abundance was 1.2, 3.0 and 2.3 × 10–3 g soil–1 for sandy, loamy, and clayey soils, respectively. DCD effectiveness was greater in loamy and clayey soils due to the naturally low nitrification in sandy soils. Application of AS treated with DCD showed potential not only to reduce NO3–-N production in loamy and clayey soils, but also to decrease the soil nitrification rate. Overall, DCD was effective in reducing AOM abundance and conversion of NH4+-N to NO3–-N in loamy and clay soils evaluated here. The increase in clay content directly influences DCD effectiveness in reducing conversion of NH4+-N to NO3–-N.(AU)

Influence of fertilization with swine manure and mineral fertilizer added by nitrification inhibitor on corn yield and nutrition / Influência da adubação com dejeto suíno e adubo mineral adicionada de inibidor de nitrificação sobre a produtividade e a nutrição do milho

Swine production in Santa Catarina is remarkable because of both the large number of animals as well as the high volume of swine slurry (DLS) generated. The DLS has fertilizer value, but its excessive or improper use can pollute surface and groundwater as well as contribute to the emission of greenhouse gases. An experiment was carried out in the Santa Catarina plateau to evaluate the incorporation into the soil and the addition of nitrification inhibitor as ways to increase the efficiency of DLS and mineral fertilizer (NPK) as sources of nitrogen (N) and other nutrients for corn. The treatments were the DLS and NPK fertilizers, the presence and absence of dicyandiamide (DCD), a control and the surface (Sup) or incorporated (Inc) applications and were arranged in a randomized block design with split plots and four replicates. The incorporation of fertilizer increased the N content in leaves, shoot dry matter and grain yields and the accumulation of N and K in the dry matter and P in corn grain. The DCD in general did not affect grain yield, except in superficial application of the DLS where their presence increased the yield compared to its absence. The DLS and mineral NPK fertilizers have similar efficiency that increases with incorporation into the soil compared to the surface application.

A suinocultura se destaca entre as atividades econômicas de Santa Catarina, tanto pelo número de animais criados, quanto pelo grande volume de dejeto líquido de suíno (DLS) que gera. O DLS possui valor fertilizante, porém seu uso excessivo ou inadequado pode poluir as águas superficiais e subterrâneas além de contribuir na emissão de gases do efeito estufa. Para avaliar a incorporação no solo e a adição de inibidor de nitrificação, como formas de aumentar a eficiência do DLS e de fertilizante mineral (NPK) como fontes de nitrogênio (N) e de outros nutrientes à cultura do milho, um experimento foi conduzido na região do Planalto de Santa Catarina. Os tratamentos compreenderam os fertilizantes DLS e NPK, a presença e ausência da dicianodiamida (DCD), testemunha e as formas de aplicação superficial (Sup) e incorporada (Inc) e foram organizados no delineamento blocos casualizados, com parcelas subdivididas e quatro repetições. A incorporação dos fertilizantes aumentou o teor de N nas folhas, os rendimentos de fitomassa da parte aérea e de grãos e o acúmulo de N e K na fitomassa e de P nos grãos de milho. A DCD em geral não afetou o rendimento de grãos, exceto na aplicação superficial do DLS onde a sua presença aumentou o rendimento comparado à sua ausência. Os fertilizantes DLS e NPK mineral possuem eficiência semelhante que aumenta com a incorporação no solo comparada à aplicação em superfície.

Influence of fertilization with swine manure and mineral fertilizer added by nitrification inhibitor on corn yield and nutrition / Influência da adubação com dejeto suíno e adubo mineral adicionada de inibidor de nitrificação sobre a produtividade e a nutrição do milho

Swine production in Santa Catarina is remarkable because of both the large number of animals as well as the high volume of swine slurry (DLS) generated. The DLS has fertilizer value, but its excessive or improper use can pollute surface and groundwater as well as contribute to the emission of greenhouse gases. An experiment was carried out in the Santa Catarina plateau to evaluate the incorporation into the soil and the addition of nitrification inhibitor as ways to increase the efficiency of DLS and mineral fertilizer (NPK) as sources of nitrogen (N) and other nutrients for corn. The treatments were the DLS and NPK fertilizers, the presence and absence of dicyandiamide (DCD), a control and the surface (Sup) or incorporated (Inc) applications and were arranged in a randomized block design with split plots and four replicates. The incorporation of fertilizer increased the N content in leaves, shoot dry matter and grain yields and the accumulation of N and K in the dry matter and P in corn grain. The DCD in general did not affect grain yield, except in superficial application of the DLS where their presence increased the yield compared to its absence. The DLS and mineral NPK fertilizers have similar efficiency that increases with incorporation into the soil compared to the surface application.(AU)

A suinocultura se destaca entre as atividades econômicas de Santa Catarina, tanto pelo número de animais criados, quanto pelo grande volume de dejeto líquido de suíno (DLS) que gera. O DLS possui valor fertilizante, porém seu uso excessivo ou inadequado pode poluir as águas superficiais e subterrâneas além de contribuir na emissão de gases do efeito estufa. Para avaliar a incorporação no solo e a adição de inibidor de nitrificação, como formas de aumentar a eficiência do DLS e de fertilizante mineral (NPK) como fontes de nitrogênio (N) e de outros nutrientes à cultura do milho, um experimento foi conduzido na região do Planalto de Santa Catarina. Os tratamentos compreenderam os fertilizantes DLS e NPK, a presença e ausência da dicianodiamida (DCD), testemunha e as formas de aplicação superficial (Sup) e incorporada (Inc) e foram organizados no delineamento blocos casualizados, com parcelas subdivididas e quatro repetições. A incorporação dos fertilizantes aumentou o teor de N nas folhas, os rendimentos de fitomassa da parte aérea e de grãos e o acúmulo de N e K na fitomassa e de P nos grãos de milho. A DCD em geral não afetou o rendimento de grãos, exceto na aplicação superficial do DLS onde a sua presença aumentou o rendimento comparado à sua ausência. Os fertilizantes DLS e NPK mineral possuem eficiência semelhante que aumenta com a incorporação no solo comparada à aplicação em superfície.(AU)

Root extracts of Bracchiaria humidicola andSaccharum spontaneum to increase N use by sugarcane

Retaining the mineral N in the form of NH4+ in the soil for a lengthy period is desirable for reducing losses. Furthermore, there is evidence that sugarcane prefers NH4+-N in place of NO3-N. This study aimed firstly, to evaluate the potential of root extracts of Bracchiaria humidicola andSaccharum spontaneum, in contrast with the DCD (Dicyandiamide) inhibitor, to increase absorption of N by plants fertilized with ammonium sulfate, and secondly, to quantify the emission of N2O fluxes with the use of this inhibitor. The experiment was developed in a glasshouse in an entirely randomized design where four treatments were applied: AS) ammonium sulfate (control); AS+DCD) ammonium sulfate associated with dicyandiamide; AS+BCH) ammonium sulfate associated with root extracts ofBrachiaria humidicola; and AS+SCS) ammonium sulfate associated with root extracts of Saccharum spontaneum. Differences were observed in biomass production in plants 45 and 60 days after fertilization (DAF) and 15 and 60 days in biomass accumulation of roots. The application of AS associated with DCD synthetic inhibitor kept NO3-N values low throughout the evaluation period, while in other treatments the concentration increased right up to the second evaluation 15 DAF. Sugarcane plants did not benefit from the increased presence of ammoniacal N promoted by DCD. The use of DCD reduced the average flux of N2O during the evaluation period compared to plants receiving AS treatments only, which was not observed when root extracts of B. humidicola and S. spontaneum were used.

Root extracts of Bracchiaria humidicola andSaccharum spontaneum to increase N use by sugarcane

Retaining the mineral N in the form of NH4+ in the soil for a lengthy period is desirable for reducing losses. Furthermore, there is evidence that sugarcane prefers NH4+-N in place of NO3-N. This study aimed firstly, to evaluate the potential of root extracts of Bracchiaria humidicola andSaccharum spontaneum, in contrast with the DCD (Dicyandiamide) inhibitor, to increase absorption of N by plants fertilized with ammonium sulfate, and secondly, to quantify the emission of N2O fluxes with the use of this inhibitor. The experiment was developed in a glasshouse in an entirely randomized design where four treatments were applied: AS) ammonium sulfate (control); AS+DCD) ammonium sulfate associated with dicyandiamide; AS+BCH) ammonium sulfate associated with root extracts ofBrachiaria humidicola; and AS+SCS) ammonium sulfate associated with root extracts of Saccharum spontaneum. Differences were observed in biomass production in plants 45 and 60 days after fertilization (DAF) and 15 and 60 days in biomass accumulation of roots. The application of AS associated with DCD synthetic inhibitor kept NO3-N values low throughout the evaluation period, while in other treatments the concentration increased right up to the second evaluation 15 DAF. Sugarcane plants did not benefit from the increased presence of ammoniacal N promoted by DCD. The use of DCD reduced the average flux of N2O during the evaluation period compared to plants receiving AS treatments only, which was not observed when root extracts of B. humidicola and S. spontaneum were used.(AU)

Dicyandiamide as nitrification inhibitor of pig slurry ammonium nitrogen in soil / Dicianodiamida como inibidor da nitrificação do nitrogênio amoniacal de dejetos líquidos de suínos no solo

Inhibition of nitrification of ammoniacal nitrogen pig slurry after its application to the soil can mitigate nitrogen (N) losses by nitrate (NO3 -) denitrification and leaching, with economical and environmental benefits. However, the use of this strategy is incipient in Brazil and, therefore, requires further assessment. The aim of this study was to evaluate the efficiency of dicyandiamide (DCD) nitrification inhibitor in slowing the nitrification of ammoniacal N applied to the soil with pig slurry (PS). For this, incubation was performed in laboratory, where nitrification was assessed by NO3 - accumulation in the soil. Rates of 2.8, 5.7 and 11.3kg DCD ha-1 were compared, being applied to the soil during PS addition. Nitrification was inhibited by DCD, and inhibition magnitude and duration depended on DCD applied rate. At a dose of 11.3kg ha-1 DCD, nitrification was completely inhibited in the first 12 days. During the first month after PS application, each 2.8kg of DCD increase applied per hectare promoted NO3 --N reduction in the soil of 13.3kg ha-1, allowing longer ammoniacal N maintenance in the soil.(AU)

A inibição da nitrificação do nitrogênio amoniacal dos dejetos de suínos, após sua aplicação no solo, poderá mitigar as perdas de nitrogênio (N) por desnitrificação e lixiviação de nitrato (NO3 -), com benefícios econômicos e ambientais. Todavia, o uso dessa estratégia é incipiente no Brasil e, por isso, necessita ser avaliada. O objetivo deste trabalho foi verificar a eficiência do inibidor de nitrificação dicianodiamida (DCD) em retardar a nitrificação do N amoniacal aplicado ao solo com dejetos líquidos de suínos (DLS). Para isso, foi realizada uma incubação no laboratório, quando a nitrificação foi avaliada através do acúmulo de NO3 - no solo. Foram comparadas as doses de 2,8, 5,7 e 11,3kg de DCD ha-1, aplicadas ao solo no momento da adição dos DLS. A nitrificação foi inibida pela DCD, sendo que a magnitude e a duração da inibição foram dependentes da dose de DCD aplicada. Na dose de 11,3kg de DCD ha-1, a nitrificação foi completamente inibida nos primeiros 12 dias. Durante o primeiro mês após a aplicação dos dejetos, cada incremento de 2,8kg de DCD aplicado por hectare promoveu uma redução no aparecimento de N-NO3 - no solo de 13,3kg ha-1, o que permite a manutenção de N amoniacal por mais tempo no solo.(AU)

Manejo da adubação nitrogenada na atividade da nitrato redutase e acúmulo de biomassa por plantas do arroz de terras altas / Source and doses of nitrogen fertilizers as affecting nitrate reductase activity and biomass accumulation by upland rice plants

O uso de alternativas que proporcionem aumento da atividade da enzima nitrato redutase (NR) no início do desenvolvimento das plantas pode viabilizar a introdução do arroz de terras altas no sistema plantio direto (SPD). O objetivo foi determinar a interferência de épocas e fontes de nitrogênio na atividade da enzima nitrato redutase e no acúmulo de biomassa por plantas de arroz de terras altas em SPD. O experimento foi realizado na Fazenda Experimental Lageado, Botucatu (SP), em área cultivada há seis anos no SPD. As parcelas foram constituídas por seis espécies de plantas de cobertura do solo (Urochloa brizantha, U. decumbens, U. humidicola, U. ruziziensis, Pennisetum americanum e Crotalaria spectabilis) e as subparcelas por sete formas de manejo da adubação nitrogenada aplicados aos 0 e 30 dias após a emergência do arroz, respectivamente [(1- controle, sem N, 2- nitrato de cálcio (40+40 kg ha-1 ), 3-nitrato de cálcio (0+80 kg ha-1 ), 4-sulfato de amônio, (40+40 kg ha-1 ), 5- sulfato de amônio (0+80 kg ha-1 ), 6- sulfato de amônio + dicianodiamida (40+40 kg ha-1 ) e 7-sulfato de amônio + dicianodiamida (0+ 80 kg ha-1 )]. As plantas de cobertura C. spectabilis e a U. ruziziensis proporcionaram as maiores atividades da enzima nitrato redutase nas plantas de arroz, enquanto que milheto e U. humidicola as menores. A atividade da enzima nitrato redutase nas plantas de arroz foi maior com aplicação de todo o nitrogênio aos 30 dias após a emergência do arroz, independentemente da fonte. O fornecimento de nitrogênio na forma amoniacal com inibidor de nitrificação proporcionou maior acúmulo de biomassa por plantas de arroz. As formas de manejo de nitrogênio que proporcionaram os maiores acúmulos de biomassa foram as parceladas. O milheto foi a planta de cobertura que proporcionou o maior acúmulo de biomassa pelas plantas de arroz.

The use of alternatives that promote increase in the activity of the nitrate reductase (NR) enzyme in the beginning of plant development could allow the introduction of upland rice in the no-tillage (NT). This paper aimed to evaluate the interference of cover crops and rates of N in the nitrate reductase activity and biomass accumulation by rice plants on NT. The experiment was conducted in Botucatu (SP), in an area under NT for six years. Plots consisted of six species of cover crops (Urochloa brizantha, U. decumbens, U. humidicola, U. ruziziensis, Pennisetum americanum and Crotalaria spectabilis), and the split plots seven forms of nitrogen fertilizer management at 0 and 30 days after rice emergence, respectively [(1- control, no N, 2- calcium nitrate (40+40 kg ha-1 ), 3- calcium nitrate (0+80 kg ha-1 ), 4- ammonium sulfate (40+40 kg ha-1 ), 5- ammonium sulfate (0+80 kg ha-1 ), 6- ammonium sulfate + dicyandiamide (40+40 kg ha-1 ) e 7- ammonium sulfate + dicyandiamide (0+ 80 kg ha-1 )]. C. spectabilis and U. ruziziensis provided the highest nitrate redutase enzyme activity in rice and P. americanum and U. humidicola the lowest. The nitrate redutase enzyme activity in rice plants was higher when all the nitrogen was applied at 30 days after emergence. The supply of nitrogen as ammonium with nitrification inhibitor showed higher biomass accumulation on rice plants. The forms of nitrogen fertilization showed the highest biomass accumulation were the splitting. The millet was showed the highest biomass accumulation on rice.

Manejo da adubação nitrogenada na atividade da nitrato redutase e acúmulo de biomassa por plantas do arroz de terras altas / Source and doses of nitrogen fertilizers as affecting nitrate reductase activity and biomass accumulation by upland rice plants

O uso de alternativas que proporcionem aumento da atividade da enzima nitrato redutase (NR) no início do desenvolvimento das plantas pode viabilizar a introdução do arroz de terras altas no sistema plantio direto (SPD). O objetivo foi determinar a interferência de épocas e fontes de nitrogênio na atividade da enzima nitrato redutase e no acúmulo de biomassa por plantas de arroz de terras altas em SPD. O experimento foi realizado na Fazenda Experimental Lageado, Botucatu (SP), em área cultivada há seis anos no SPD. As parcelas foram constituídas por seis espécies de plantas de cobertura do solo (Urochloa brizantha, U. decumbens, U. humidicola, U. ruziziensis, Pennisetum americanum e Crotalaria spectabilis) e as subparcelas por sete formas de manejo da adubação nitrogenada aplicados aos 0 e 30 dias após a emergência do arroz, respectivamente [(1- controle, sem N, 2- nitrato de cálcio (40+40 kg ha-1 ), 3-nitrato de cálcio (0+80 kg ha-1 ), 4-sulfato de amônio, (40+40 kg ha-1 ), 5- sulfato de amônio (0+80 kg ha-1 ), 6- sulfato de amônio + dicianodiamida (40+40 kg ha-1 ) e 7-sulfato de amônio + dicianodiamida (0+ 80 kg ha-1 )]. As plantas de cobertura C. spectabilis e a U. ruziziensis proporcionaram as maiores atividades da enzima nitrato redutase nas plantas de arroz, enquanto que milheto e U. humidicola as menores. A atividade da enzima nitrato redutase nas plantas de arroz foi maior com aplicação de todo o nitrogênio aos 30 dias após a emergência do arroz, independentemente da fonte. O fornecimento de nitrogênio na forma amoniacal com inibidor de nitrificação proporcionou maior acúmulo de biomassa por plantas de arroz. As formas de manejo de nitrogênio que proporcionaram os maiores acúmulos de biomassa foram as parceladas. O milheto foi a planta de cobertura que proporcionou o maior acúmulo de biomassa pelas plantas de arroz.(AU)

The use of alternatives that promote increase in the activity of the nitrate reductase (NR) enzyme in the beginning of plant development could allow the introduction of upland rice in the no-tillage (NT). This paper aimed to evaluate the interference of cover crops and rates of N in the nitrate reductase activity and biomass accumulation by rice plants on NT. The experiment was conducted in Botucatu (SP), in an area under NT for six years. Plots consisted of six species of cover crops (Urochloa brizantha, U. decumbens, U. humidicola, U. ruziziensis, Pennisetum americanum and Crotalaria spectabilis), and the split plots seven forms of nitrogen fertilizer management at 0 and 30 days after rice emergence, respectively [(1- control, no N, 2- calcium nitrate (40+40 kg ha-1 ), 3- calcium nitrate (0+80 kg ha-1 ), 4- ammonium sulfate (40+40 kg ha-1 ), 5- ammonium sulfate (0+80 kg ha-1 ), 6- ammonium sulfate + dicyandiamide (40+40 kg ha-1 ) e 7- ammonium sulfate + dicyandiamide (0+ 80 kg ha-1 )]. C. spectabilis and U. ruziziensis provided the highest nitrate redutase enzyme activity in rice and P. americanum and U. humidicola the lowest. The nitrate redutase enzyme activity in rice plants was higher when all the nitrogen was applied at 30 days after emergence. The supply of nitrogen as ammonium with nitrification inhibitor showed higher biomass accumulation on rice plants. The forms of nitrogen fertilization showed the highest biomass accumulation were the splitting. The millet was showed the highest biomass accumulation on rice.(AU)

Redução na velocidade da nitrificação no solo após aplicação de cama de aviário com dicianodiamida

The fast nitrification of ammoniacal nitrogen (N) of organic and mineral sources in soil can result in losses of nitrate (NO3-) to the environment. One strategy to reduce these losses involves the use of nitrification inhibitors. The objective of this study was to evaluate, in laboratory conditions, the efficiency of Agrotain® Plus (AP), which contains dicyandiamide (DCD), as a nitrification inhibitor of ammoniacal nitrogen from poultry manure (PM) in soil. Were evaluated five treatments, one with PM incorporated into the soil, three with PM incorporated into the soil with AP at the doses of 3.5, 7.0 e 14.0kg ha-1 and one treatment without PM and AP. Nitrification was monitored by measuring changes in soil mineral N (NH4+ and NO3-) periodically over 69 days. The highest rate of nitrification occurred in the treatment in which PM was incorporated into the soil without AP. The doses of 3.5 and 7.0kg ha-1 of AP inhibited partially the nitrification of ammoniacal nitrogen of PM in the initial phase of incubation, losing the ability to inhibit this process in the period between 12 and 27 days. The treatment with the higher dose of AP (14kg ha-1) was on in which the DCD exerted more inhibitory effect on nitrification, preserving most NH4+ and delaying the onset of NO3- in soil. The results of this study indicate that the DCD, contained in the Agrotain® Plus, reduces the nitrification rate of ammoniacal nitrogen from PM in soil, that may contribute to reduce NO3- losses to the environment.

A rápida nitrificação do nitrogênio (N) amoniacal de fontes orgânicas e minerais no solo pode resultar em perdas de nitrato (NO3-) para o ambiente. Uma estratégia para a redução dessas perdas envolve o uso de inibidores de nitrificação. O objetivo do presente trabalho foi o de avaliar, em condições de laboratório, a eficiência da dicianodiamida (DCD), presente no produto Agrotain® Plus (AP), em inibir a nitrificação do N amoniacal de cama de aviário (CA) no solo. Foram avaliados cinco tratamentos, sendo um com CA incorporada ao solo, três com CA incorporada ao solo com AP, nas doses de 3,5, 7,0 e 14,0kg ha-1, além de um tratamento somente com solo. A nitrificação foi monitorada através da determinação periódica dos teores de NH4+ e NO3 no solo durante 69 dias. A maior taxa de nitrificação ocorreu no tratamento em que a CA foi incorporada ao solo sem AP. As doses de 3,5 e 7,0kg de AP ha-1 inibiram parcialmente a nitrificação do N amoniacal da CA na fase inicial da incubação, perdendo a eficiência em inibir esse processo no período entre 12 e 27 dias. O tratamento com a maior dose de AP (14kg ha-1) foi aquele em que a DCD exerceu maior efeito inibitório da nitrificação, preservando maior quantidade de NH4+ e retardando o aparecimento de NO3- no solo. Os resultados deste trabalho indicam que a DCD, contida no Agrotain® Plus, reduz a taxa de nitrificação do N amoniacal da CA no solo, o que poderá contribuir à redução das perdas de NO3- para o ambiente.

Redução na velocidade da nitrificação no solo após aplicação de cama de aviário com dicianodiamida

The fast nitrification of ammoniacal nitrogen (N) of organic and mineral sources in soil can result in losses of nitrate (NO3-) to the environment. One strategy to reduce these losses involves the use of nitrification inhibitors. The objective of this study was to evaluate, in laboratory conditions, the efficiency of Agrotain® Plus (AP), which contains dicyandiamide (DCD), as a nitrification inhibitor of ammoniacal nitrogen from poultry manure (PM) in soil. Were evaluated five treatments, one with PM incorporated into the soil, three with PM incorporated into the soil with AP at the doses of 3.5, 7.0 e 14.0kg ha-1 and one treatment without PM and AP. Nitrification was monitored by measuring changes in soil mineral N (NH4+ and NO3-) periodically over 69 days. The highest rate of nitrification occurred in the treatment in which PM was incorporated into the soil without AP. The doses of 3.5 and 7.0kg ha-1 of AP inhibited partially the nitrification of ammoniacal nitrogen of PM in the initial phase of incubation, losing the ability to inhibit this process in the period between 12 and 27 days. The treatment with the higher dose of AP (14kg ha-1) was on in which the DCD exerted more inhibitory effect on nitrification, preserving most NH4+ and delaying the onset of NO3- in soil. The results of this study indicate that the DCD, contained in the Agrotain® Plus, reduces the nitrification rate of ammoniacal nitrogen from PM in soil, that may contribute to reduce NO3- losses to the environment.

A rápida nitrificação do nitrogênio (N) amoniacal de fontes orgânicas e minerais no solo pode resultar em perdas de nitrato (NO3-) para o ambiente. Uma estratégia para a redução dessas perdas envolve o uso de inibidores de nitrificação. O objetivo do presente trabalho foi o de avaliar, em condições de laboratório, a eficiência da dicianodiamida (DCD), presente no produto Agrotain® Plus (AP), em inibir a nitrificação do N amoniacal de cama de aviário (CA) no solo. Foram avaliados cinco tratamentos, sendo um com CA incorporada ao solo, três com CA incorporada ao solo com AP, nas doses de 3,5, 7,0 e 14,0kg ha-1, além de um tratamento somente com solo. A nitrificação foi monitorada através da determinação periódica dos teores de NH4+ e NO3 no solo durante 69 dias. A maior taxa de nitrificação ocorreu no tratamento em que a CA foi incorporada ao solo sem AP. As doses de 3,5 e 7,0kg de AP ha-1 inibiram parcialmente a nitrificação do N amoniacal da CA na fase inicial da incubação, perdendo a eficiência em inibir esse processo no período entre 12 e 27 dias. O tratamento com a maior dose de AP (14kg ha-1) foi aquele em que a DCD exerceu maior efeito inibitório da nitrificação, preservando maior quantidade de NH4+ e retardando o aparecimento de NO3- no solo. Os resultados deste trabalho indicam que a DCD, contida no Agrotain® Plus, reduz a taxa de nitrificação do N amoniacal da CA no solo, o que poderá contribuir à redução das perdas de NO3- para o ambiente.

Redução na velocidade da nitrificação no solo após aplicação de cama de aviário com dicianodiamida

The fast nitrification of ammoniacal nitrogen (N) of organic and mineral sources in soil can result in losses of nitrate (NO3-) to the environment. One strategy to reduce these losses involves the use of nitrification inhibitors. The objective of this study was to evaluate, in laboratory conditions, the efficiency of Agrotain® Plus (AP), which contains dicyandiamide (DCD), as a nitrification inhibitor of ammoniacal nitrogen from poultry manure (PM) in soil. Were evaluated five treatments, one with PM incorporated into the soil, three with PM incorporated into the soil with AP at the doses of 3.5, 7.0 e 14.0kg ha-1 and one treatment without PM and AP. Nitrification was monitored by measuring changes in soil mineral N (NH4+ and NO3-) periodically over 69 days. The highest rate of nitrification occurred in the treatment in which PM was incorporated into the soil without AP. The doses of 3.5 and 7.0kg ha-1 of AP inhibited partially the nitrification of ammoniacal nitrogen of PM in the initial phase of incubation, losing the ability to inhibit this process in the period between 12 and 27 days. The treatment with the higher dose of AP (14kg ha-1) was on in which the DCD exerted more inhibitory effect on nitrification, preserving most NH4+ and delaying the onset of NO3- in soil. The results of this study indicate that the DCD, contained in the Agrotain® Plus, reduces the nitrification rate of ammoniacal nitrogen from PM in soil, that may contribute to reduce NO3- losses to the environment.

A rápida nitrificação do nitrogênio (N) amoniacal de fontes orgânicas e minerais no solo pode resultar em perdas de nitrato (NO3-) para o ambiente. Uma estratégia para a redução dessas perdas envolve o uso de inibidores de nitrificação. O objetivo do presente trabalho foi o de avaliar, em condições de laboratório, a eficiência da dicianodiamida (DCD), presente no produto Agrotain® Plus (AP), em inibir a nitrificação do N amoniacal de cama de aviário (CA) no solo. Foram avaliados cinco tratamentos, sendo um com CA incorporada ao solo, três com CA incorporada ao solo com AP, nas doses de 3,5, 7,0 e 14,0kg ha-1, além de um tratamento somente com solo. A nitrificação foi monitorada através da determinação periódica dos teores de NH4+ e NO3 no solo durante 69 dias. A maior taxa de nitrificação ocorreu no tratamento em que a CA foi incorporada ao solo sem AP. As doses de 3,5 e 7,0kg de AP ha-1 inibiram parcialmente a nitrificação do N amoniacal da CA na fase inicial da incubação, perdendo a eficiência em inibir esse processo no período entre 12 e 27 dias. O tratamento com a maior dose de AP (14kg ha-1) foi aquele em que a DCD exerceu maior efeito inibitório da nitrificação, preservando maior quantidade de NH4+ e retardando o aparecimento de NO3- no solo. Os resultados deste trabalho indicam que a DCD, contida no Agrotain® Plus, reduz a taxa de nitrificação do N amoniacal da CA no solo, o que poderá contribuir à redução das perdas de NO3- para o ambiente.