Agronomic performance of rice to the use of urease inhibitor in two cropping systems

Abstract

-The use of urea coated with urease inhibitor may become a useful tool for increasing the efficiency of nitrogen top-dressing in rice crop, thereby reducing nutrient losses through volatilization of NH 3 (ammonia). Thus, the aim of this study was to evaluate the volatilization of NH 3 and the response of rice to the use of urea coated with urease inhibitor in two cropping systems, no-tillage and conventional. For this purpose, field experiments were developed in the agricultural years 2007/2008 and 2008/2009, in UFSM in Santa Maria-RS. The design was randomized blocks in bifactorial scheme (2x5) with two sources, urea and urea + NBPT and five intervals of water intake (0; 3; 6; 9; 12 days) after application of nitrogen sources. The results of two seasons show that the urease inhibitor present in urea slows and decrease the conversion of N to NH 3 , reducing the losses by volatilization, compared to urea without inhibitor. Among the systems, the losses are magnified in the no-tillage cropping system. The behavior of the response variable in relation to productivity is variable in two cropping systems used in this study and the stress caused to the rice plant by the late start of the irrigation is more damaging than the losses caused by the volatilization of NH 3 .Key words: Rice cultivation. Urease inhibitor. Use straw in agriculture.RESUMO -A utilização de uréia recoberta com inibidor de urease pode tornar-se uma ferramenta útil para aumentar a eficiência da adubação nitrogenada em cobertura na cultura do arroz irrigado, diminuindo assim perdas do nutriente por volatilização de NH 3 (amônia). Com isso, o objetivo desse trabalho foi avaliar a volatilização de NH 3 e a resposta do arroz irrigado ao uso de uréia recoberta com inibidor de urease em dois sistemas de cultivo, direto e convencional. Para tanto, conduziram-se experimentos em campo, nos anos agrícolas 2007/2008 e 2008/2009, na UFSM em Santa Maria-RS. O delineamento utilizado foi o delineamento experimental blocos completos casualizados em esquema bifatorial (2x5), com duas fontes, uréia e uréia+NBPT e cinco intervalos de início da irrigação (0; 3; 6; 9; 12 dias) após a aplicação das fontes de N. Os resultados das duas safras demonstram que o inibidor de urease presente na uréia retarda e diminui a conversão de N para NH 3 , reduzindo as perdas por volatilização, comparativamente à uréia sem inibidor. Entre os sistemas, as perdas são potencializadas no sistema plantio direto. O comportamento da variável resposta em relação à produtividade é variável nos dois sistemas de cultivo utilizados e o estresse causado na planta de arroz pelo atraso no início da irrigação é mais prejudicial do que as perdas causadas pela volatilização de NH 3 .

Yield and Nitrogen Recovery of Wheat Plants Subjected to Urea Application With or Without a Urease Inhibitor in the Absence of Irrigation

“…For wheat, Espindula et al (2013) reported yield gains with the use of NBPT in the same location as this study; therefore, the absence of significant effects in this experiment may be related to the cropping conditions as suggested by Marchesan et al (2013). The high humidity, low temperature and low incidence of winds ( Figure 1) were unfavorable for the losses by volatilization; thus, the wheat plants had a suitable N supply for development.…”

“…The thousand-grain mass was determined as the mean of eight replications of 100 grains with extrapolation to 1,000 grains. The hectoliter mass was determined using a precision balance based on the grains collected from the plants within the useful plot area, and the grain yield at 13% moisture was determined based on the grains collected from the plants within the useful plot area and converted to kg ha (Grant and Bailey, 1999) and rice (Oryza sativa L.) (Marchesan et al, 2013) and for the grain yield, dry matter production, and N content in the dry matter and the grains of wheat plants subjected to urea or urea+NBPT in two types of soil (Gioacchini et al, 2002).…”

“…Among these inhibitors, NBPT [N-(n-butyl)thiophosphoric triamide] stands out as a promising agent for the reduction of NH 3 volatilization (Malhi et al, 2001;Gioacchini et al, 2002;Cantarella et al, 2008;Giovannini et al, 2009;Marchesan et al, 2013;Espindula et al, 2013).…”

The molecular processes of urea hydrolysis in relation to ammonia emissions from agriculture

“…In general, it is difficult to estimate to what extent crop yield is influenced by the use of urease inhibitors due to the many different factors that determine the overall ammonia emissions and N-retention, but a recent meta-analysis found that the average cumulative ammonia loss was reduced by 52% (from 31.0% of applied N to 14.8%) and that the grain yield increased on average by 5.3% when synthetic urea fertilizer was amended with NBPT (Silva et al 2017). Marchesan et al noted that NBPT generally slowed the hydrolysis of urea to ammonia when applied to the rice crop compared to the urea fertilizer without NBPT, but the effectiveness was highly influenced by climate, type of soil, and moisture (Marchesan et al 2013). Application of Agrotain to pure urea fertilizer or cattle urine yielded reductions in the ammonia emissions of 47 and 22%, respectively (Singh et al 2013).…”

Fertilizantes nitrogenados de eficiência aumentada e ureia na cultura do milho

“…Segundo Cantarella et al (2008) o NBPT inibe a hidrólise da ureia pelo período de três a quatorze dias, dependendo das condições de umidade e temperatura do solo. Diversos autores já constaram redução de perdas por volatilização quando se utilizou ureia tratada com NBPT em países de clima tropical (Pereira et al, 2009;Scivittaro et al, 2010;Marchesan et al, 2013) e temperado (Watson et al, 2008;Sanz-Cobena et al, 2011).…”