Emissão de óxido nitroso em sistemas intensificados de produção a pasto com adubação nitrogenada
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Data
2022-08-19
Autores
Gomes, Laís Mayumi
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Universidade Estadual Paulista (Unesp)
Resumo
O Painel Intragovernamental de Mudanças Climáticas (IPCC) estipula, para os cálculos de inventários de emissão de gases do efeito estufa brasileiros, dados default de emissão de óxido nitroso (N2O), sem distinguir fezes e urina. Os fatores de emissão default, de acordo com o guia do IPCC (2019), são de 2 % de N excretado, emitido na forma de N2O [quantidade de nitrogênio nas excretas (fezes + urina)] e 1 % de perdas como N2O para fertilizantes nitrogenados. A fim de elucidar esse problema, tivemos por objetivo avaliar o fator de emissão de N2O, na combinação, fezes ou urina com doses de nitrato de amônio. Foi conduzido um experimento, por dois anos consecutivos, nas condições de clima tropical, em Jaboticabal - SP. A fim de avaliar/calcular a emissão de óxido nitroso e o fator de emissão, foram constituídos oito tratamentos, sendo: 1) Fezes (F), 2) Fezes + 75 kg de N ha-1 ano-1 (F+75N), 3) Fezes + 150 kg de N ha-1 ano-1 (F+150N), 4) Urina (U), 5) Urina + 75 kg de N ha-1 ano-1(U+75N), 6) Urina + 150 kg de N ha-1 ano-1 (U+150N), 7) 75 kg de N ha-1 ano-1 (75N) e 8) Basal. Foi utilizado delineamento em Blocos Casualizados (duplo bloqueio = ano e declividade do terreno), com cinco repetições. O fator de emissão de N2O foi maior (P < 0,05) na Urina (0,60 %), intermediário nas Fezes (0,22 %) e menor a dose de 75 kg de nitrato ha-1 ano-1 (0,17 %) e tem efeito linear aditivo (P < 0,05) na combinação de fezes ou urina, com nitrato de amônio. Assim os fatores de emissão de óxido nitroso, nas condições de clima tropical, são menores que os reportados pelo IPCC.
The Intragovernmental Panel on Climate Change (IPCC) stipulates, for the calculation of Brazilian greenhouse gas emission inventories, default nitrous oxide (N2O) emission data, without distinguishing feces and urine. The default emission factors, according to the IPCC guide (2019), are 2 % of excreted N emitted in the form of N2O [amount of nitrogen in the excreta (feces + urine)] and 1 % of losses as N2O for fertilizers nitrogenous. In order to elucidate this problem, we aimed to evaluate the N2O emission factor in the combination of feces or urine with doses of ammonium nitrate. An experiment was carried out, for two consecutive years, under tropical climate conditions, in Jaboticabal - SP. In order to evaluate/calculate the nitrous oxide emission and the emission factor, eight treatments were constituted, being: 1) Feces (F), 2) Feces + 75 kg of N ha-1 year-1 (F+75N) , 3) Feces + 150 kg of N ha-1 year-1 (F+150N), 4) Urine (U), 5) Urine + 75 kg of N ha-1 year-1 (U+75N), 6) Urine + 150 kg of N ha-1 year-1 (U+150N), 7) 75 kg of N ha-1 year-1 (75N) and 8) Basal. A randomized block design was used (double blockage = year and terrain slope), with five replications. The N2O emission factor was highest (P < 0,05) in Urine (0,60 %), intermediate in Feces (0,22 %) and lowest in 75 kg of nitrate ha-1 year-1 (0,17 %) and has an additive linear effect (P < 0,05) in the combination of feces or urine with ammonium nitrate. Thus, nitrous oxide emission factors, under tropical climate conditions, are lower than those reported by the IPCC.
The Intragovernmental Panel on Climate Change (IPCC) stipulates, for the calculation of Brazilian greenhouse gas emission inventories, default nitrous oxide (N2O) emission data, without distinguishing feces and urine. The default emission factors, according to the IPCC guide (2019), are 2 % of excreted N emitted in the form of N2O [amount of nitrogen in the excreta (feces + urine)] and 1 % of losses as N2O for fertilizers nitrogenous. In order to elucidate this problem, we aimed to evaluate the N2O emission factor in the combination of feces or urine with doses of ammonium nitrate. An experiment was carried out, for two consecutive years, under tropical climate conditions, in Jaboticabal - SP. In order to evaluate/calculate the nitrous oxide emission and the emission factor, eight treatments were constituted, being: 1) Feces (F), 2) Feces + 75 kg of N ha-1 year-1 (F+75N) , 3) Feces + 150 kg of N ha-1 year-1 (F+150N), 4) Urine (U), 5) Urine + 75 kg of N ha-1 year-1 (U+75N), 6) Urine + 150 kg of N ha-1 year-1 (U+150N), 7) 75 kg of N ha-1 year-1 (75N) and 8) Basal. A randomized block design was used (double blockage = year and terrain slope), with five replications. The N2O emission factor was highest (P < 0,05) in Urine (0,60 %), intermediate in Feces (0,22 %) and lowest in 75 kg of nitrate ha-1 year-1 (0,17 %) and has an additive linear effect (P < 0,05) in the combination of feces or urine with ammonium nitrate. Thus, nitrous oxide emission factors, under tropical climate conditions, are lower than those reported by the IPCC.
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Palavras-chave
Solos, Adubação, Pastagem, Oxido nitroso