Data/hora: 02/06/2024 09:07:23

Biblioteca(s): | Embrapa Florestas.
Data corrente: | 06/10/2008
Data da última atualização: | 06/10/2008
Autoria: | SHON, N. L.; YEATES, G. W.; MACKAY, A. D.; HEDLEY, M. J.; MINOR, M. A.
Título: | Towards an invertebrate-based index of soil health for pastoral soils in New Zealand.
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:

Sustainable agriculture requires that key soil functions be maintained. Intensifying pastoral
agriculture in New Zealand is putting increasing pressure on soil invertebrates, threatening the
key soil functions which they regulate (e.g., decomposition, nutrient cycling, maintenance of
pore structure). This project is exploring the feasibility of developing an index of soil health
applicable to a range of New Zealand pastoral soils. The index is based on trophic groups, lifehistory
characteristics and morphological features of earthworms, mesofauna and nematodes
in the topsoil. The impact of management practices on soil has been assessed using various
invertebrate characteristics. Faunal density, diversity, and activity are affected by the
management, but are too variable in time and space for practical use. A useful soil biological
indicator should vary little through time and space, be adapted to local conditions and practices,
and give some insight into changes in soil functioning. For example, agriculture alters soil food
resources and influences trophic groups, with intensive systems often becoming dominated by
bacteria-feeders over fungi-feeders (as seen in the Nematode Channel Ratio). As disturbance
frequency increases, the soil community shifts towards short-lived, opportunistic species. These
changes are demonstrated and captured by the Maturity Index for nematodes and gamasid
mites. Increased liveweight of livestock compacts the soil, decreasing habitable pore space.
This in turn influences morphological features (ie. size) of soil invertebrates. The Italian QBS
index attempts to capture this change in the habitatable pore space. To date this index has not
been examined for its potential use in New Zealand farming systems. To test the usefulness of
existing indices under New Zealand conditions and to explore the feasibility of developing an
index that included each of the elements that influence the soil community, field-sized replicated
plots at six major long-term experimental sheep and dairy grazed pasture sites throughout New
Zealand were used. The plots are located on two major soil groups (Sedimentary and Volcanic)
and at each site plots differ in grazing intensity. Additionally, three ungrazed field sites provide
?controls?. We test the hypothesis that on more intensive livestock (dairy) systems, which are
characterized by faster nutrient cycling and higher nutrient loss, the decomposer / detritus subset
of organisms will be dominated by small, short lived, bacterial-feeding invertebrates. Preliminary
results from two sites ? a low and medium intensity sheep-grazed pasture (8 and 16 sheep/ha)
on a sedimentary soil, and a nil to very high intensity dairy pasture (treatments included fallow,
cut and carry, 3 , 4, and 5 cows/ha) on a volcanic soil ? were idiosyncratic. Intensification led
trophic groups to be dominated by bacterial-feeding nematodes at the sheep-grazed site, but
not at the dairy site. As expected, slow-reproducing Oribatida (and the proportion of sexually
reproducing Oribatida) decreased with management intensification at both sites. In contrast,
larger ?persister? nematodes were more abundant under 5 cows/ha on the volcanic soil. The
index aims to complement chemical measures of soil fertility, and to give farmers a greater
understanding of the implications of management practices on soil biological processes. This
is an important step towards ensuring sustainable agricultural practices.

Categoria do assunto: | --
Registro original: | Embrapa Florestas (CNPF)
Exemplares: | CNPF - (43813-1) - UPE - PL - -- - CD0305 -  -  - DIS