Fontes e doses de adubação nitrogenada na atividade microbiana e fertilidade do solo cultivado com Brachiaria brizantha
Carregando...
Data
2011-06-01
Autores
Delbem, Flavia Cristina [UNESP]
Scabora, Márcia Helena [UNESP]
Soares Filho, Cecílio Viega [UNESP]
Heinrichs, Reges [UNESP]
Crociolli, Carlos Alberto [UNESP]
Cassiolato, Ana Maria Rodrigues [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Editora da Universidade Estadual de Maringá (EDUEM)
Resumo
As pastagens geralmente perdem seu potencial produtivo e vigor de rebrota nos primeiros anos, frequentemente associada à falta de adubação nitrogenada. O objetivo deste foi verificar o efeito de fontes e doses de adubação nitrogenada na atividade microbiana (carbono da biomassa microbiana e carbono do CO2 liberado) e na fertilidade do solo cultivado com Brachiaria brizantha cv. Xaraés. O delineamento experimental foi em blocos casualizados, em arranjo fatorial 3 x 4, envolvendo três fontes de nitrogênio (uréia, sulfato de amônio e Ajifer-L40) e quatro doses de nitrogênio (0, 100, 200 e 400 kg ha-1), nas profundidades 0 - 0,10 e 0,10 - 0,20 m, com três repetições. O aumento nas doses de nitrogênio, na camada 0,0 a 0,10 m de profundidade, reduziu os valores de pH, MO, K+, Ca2+, Mg2+, SB e V%. O Ajifer e a uréia elevaram os valores de Ca2+ na camada 0,10 - 0,20 m, e as doses de 100 e 200 kg ha-1 aumentaram os valores de Mg2+ e SB. em doses elevadas o sulfato de amônio acidificou o solo. A perda de carbono pela elevada atividade microbiana pode estar relacionado ao estresse metabólico devido à acidificação do solo. A aplicação de 100 kg ha-1 de nitrogênio acarretou as menores perdas de carbono pela atividade microbiana.
Pastures usually lose their yield potential and re-growth energy in a few years, most often due to the lack of nitrogen fertilization. The objective of this study was to verify the effect of sources and levels of nitrogen (N) fertilization, under microbial activity (carbon of microbial biomass and carbon released as CO2) and fertility of soil cropped with Brachiaria brizantha cv. Xaraés. The experimental design was randomized, organized under a 3 x 4 factorial scheme, with three nitrogen sources (urea, ammonium sulfate and Ajifer-L40) and four nitrogen levels (0, 100, 200 and 400 kg ha-1), analyzed on two depths (0 - 0,10 e 0,10-0,20 m), with 3 replications. The higher levels of N doses, the 0 - 0.10 m depths, reduced the values of pH, MO, K+, Ca2+, Mg2+, SB and V%. Ajifer and urea resulted in higher values of Ca2+, in the depths of 0.10 - 0.20 m, and the values of Mg2+ and SB exhibited high values with the doses of 100 and 200 kg ha-1 levels of N. The higher levels of ammonium sulfate resulted in soil acidification. Soil carbon loss, due to the high microbial activity, could be the result of metabolic stress caused by soil acidification. The application of 100 kg ha-1 of nitrogen was the best fertilizing level, considering the smaller loss of soil carbon by microbial activity.
Pastures usually lose their yield potential and re-growth energy in a few years, most often due to the lack of nitrogen fertilization. The objective of this study was to verify the effect of sources and levels of nitrogen (N) fertilization, under microbial activity (carbon of microbial biomass and carbon released as CO2) and fertility of soil cropped with Brachiaria brizantha cv. Xaraés. The experimental design was randomized, organized under a 3 x 4 factorial scheme, with three nitrogen sources (urea, ammonium sulfate and Ajifer-L40) and four nitrogen levels (0, 100, 200 and 400 kg ha-1), analyzed on two depths (0 - 0,10 e 0,10-0,20 m), with 3 replications. The higher levels of N doses, the 0 - 0.10 m depths, reduced the values of pH, MO, K+, Ca2+, Mg2+, SB and V%. Ajifer and urea resulted in higher values of Ca2+, in the depths of 0.10 - 0.20 m, and the values of Mg2+ and SB exhibited high values with the doses of 100 and 200 kg ha-1 levels of N. The higher levels of ammonium sulfate resulted in soil acidification. Soil carbon loss, due to the high microbial activity, could be the result of metabolic stress caused by soil acidification. The application of 100 kg ha-1 of nitrogen was the best fertilizing level, considering the smaller loss of soil carbon by microbial activity.
Descrição
Palavras-chave
Ajifer, biomassa microbiana, mineralização do C, sulfato de amônio, ureia, Ajifer, microbial biomass, C mineralization, ammonium sulfate, urea
Como citar
Acta Scientiarum. Agronomy. Editora da Universidade Estadual de Maringá (UEM) - EDUEM, v. 33, n. 2, p. 361-367, 2011.