Article

Efecto de rastrojos en el nitrógeno de biomasa microbiana en un agroecosistema arrocero inundado

Agronomía Mesoamericana 01/2006; DOI: 10.15517/am.v17i2.5157
Source: DOAJ

ABSTRACT Del año 2002 al 2004 se investigó en un agroecosistema arrocero inundado a fin de evaluar cambios en la actividad de la biomasa microbiana y su contenido de nitrógeno ¿N¿, durante cuatro ciclos consecutivos del cultivo. Se comparó la tendencia del contenido de nitrógeno de la biomasa microbiana ¿NBM¿ en los sistemas siembra directa sobre rastrojos ¿SDR¿ y labranza mecanizada convencional ¿LMC¿. Durante el tercer ciclo de arroz se evaluó el efecto de los rastrojos de mucuna ¿Mucuna deeringiana (Bort.) Merr¿; se comparó la materia orgánica del suelo ¿MOS¿ y el NBM. Adicionalmente, durante el cuarto ciclo de arroz del estudio, fueron contrastados cambios en la actividad de la biomasa microbiana en tres diferentes etapas de crecimiento del cultivo. En los primeros 5 cm del perfil del suelo la cantidad de NBM siempre fue mayor en SDR. En esta capa del suelo, la combinación de rastrojos de arroz acumulados durante tres ciclos con rastrojos de mucuna del ciclo previo, permitió una mayor estratificación de la MOS. Se observó un incremento de la MOS de 2,3 a 4,1%, mientras que el NBM fue casi cuatro veces mayor. La respiración de los microorganismos del suelo y la mineralización del N fue afectada principalmente por la presencia continua de una lámina de agua sobre el suelo. Se concluyó que la SDR es un sistema capaz de complementar la fertilización química e incrementar los rendimientos del arroz mediante la gradual liberación de N y otros nutrimentos derivados de la descomposición de los rastrojos

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