Data/hora: 22/06/2024 06:57:43

Biblioteca(s): | Embrapa Florestas.
Data corrente: | 22/09/2008
Data da última atualização: | 22/09/2008
Autoria: | GOEDE, R. de; POSTMA-BLAAUW, M.; BLOEM, J.; FABER, J.; BRUSSAARD, L.
Título: | Nitrogen cycling and soil biodiversity after (de-) intensification of agroecosystem management.
Ano de publicação: | 2008
Fonte/Imprenta: | In: INTERNATIONAL COLLOQUIUM ON SOIL ZOOLOGY, 15; INTERNATIONAL COLLOQUIUM ON APTERYGOTA, 12., 2008, Curitiba. Biodiversity, conservation and sustainabele management of soil animal: abstracts. Colombo: Embrapa Florestas. Editors: George Gardner Brown; Klaus Dieter Sautter; Renato Marques; Amarildo Pasini. 1 CD-ROM.
Idioma: | Inglês

Conteúdo:

Understanding functional biodiversity with respect to the regulation of nitrogen mineralization
and retention is a key factor to support more sustainable production and prevent environmental
complications. We studied the relationship between a range of soil biota functional group
abundances and diversities and nitrogen mineralization and retention in agroecosystems after
(de-)intensification. This included conversion of grassland to arable land and vice versa, reduced
cropping diversity and reduced levels of mineral fertilization. Contributions of different soil biota
groups were compared with respect to potential N mineralization (i.e. short-term mineralization
of soil organic matter as quantifiable in laboratory incubations) and with respect to net N
mineralization under field conditions.
Agricultural intensification generally resulted in decreased N mineralization and increased NO3-
leaching in the second year after conversion. Vice versa, agricultural de-intensification resulted
in increased N mineralization and decreased NO3- leaching. Increased N mineralization was
related to both functional group abundances and functional diversity of soil biota. The relationships
with taxonomic diversity were inconsistent. Key trophic groups associated with N mineralization
were endogeic earthworms (A. caliginosa) and trophic groups in the bacterial energy channel,
whereas N mineralization was negatively related to fungal biomass and nematode fungivores.
In the short-term and under disturbed conditions, N mineralization can be explained by a high
presence of opportunistic nematodes, whereas under field conditions N mineralization increased
with a higher diversity of nematode life-strategy groups. Taxonomic diversity of nematodes did
not contribute to N mineralization, but indications were found for a correlation between bacterial
genetic diverisity and N mineralization.
Whether mineralized NO3- is incorporated into the crop or leached out below the rooting zone
depends on the cropping system. Mineral N applied as synthetic fertilizer confers a higher risk
of leaching during the cropping season than mineralized N, but year-round NO3- leaching was
not dependent on the source of mineral N. We conclude that both trophic group abundances
and life-strategy diversity of soil biota significantly determine mineral N availability in extensively
managed systems, and may at least in part compensate for reduced mineral N inputs from
fertilizers. Such increased N mineralization may confer a low risk of NO3- leaching during the
cropping season, as well as in systems with a high and continuous crop production.

Categoria do assunto: | --
Registro original: | Embrapa Florestas (CNPF)
Exemplares: | CNPF - (43653-1) - UPE - PL - -- - CD0305 -  -  - DIS