Dynamics of ammonia volatilization from NBPT-treated urea in tropical acid soils

Autor(es)

Johnny Rodrigues Soares ^[1] ; Heitor Cantarella ^[2]

Afiliação do(s) autor(es)

^[1] Instituto Agronômico. Centro de Solos e Recursos Ambientais - Brasil

^[2] Instituto Agronômico. Centro de Solos e Recursos Ambientais - Brasil

• Tipo de documento: Artigo Científico
• Fonte: Scientia Agricola; v. 80, 2023-04-07.

Resumo

ABSTRACT 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)

• Processo FAPESP: 18/20793-9 - Inibidores de nitrificação e urease como estratégias de mitigação das Emissões de N2O e volatilização de NH3 em áreas de cultivo de cana-de-açúcar com adição de resíduos orgânicos
• Beneficiário: Heitor Cantarella
• Modalidade de apoio: Auxílio à Pesquisa - Programa BIOEN - Regular