Data/hora: 25/06/2024 13:04:45

Biblioteca(s): | Embrapa Florestas.
Data corrente: | 02/10/2008
Data da última atualização: | 02/10/2008
Autoria: | GIMÉNEZ, R. A.; JULIAN, P.; FUCHS, J.; KESTEN, E. M.
Título: | Land use intensity: effect on earthworms population and litterbag decomposition.
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:

Agricultural intensification involves methods of soil tillage and broad-spectrum pesticide use.
The intensity of soil tillage strongly influences the crop residues distribution and decomposition,
and induces changes in decomposer communities. Additionally, can directly disrupt the earthworm
populations. Pesticides has both targeted and non-targeted effects on the composition and
diversity of soil organisms. In this paper we compare the earthworms population and litterbag
decomposition in two situations of land use in grasslands of Pedro Luro (south of Buenos Aires
Province, Argentina), where the annual precipitation and temperature are 433 mm and 14°C in
typical molisols. In the higher intensity use (HI) the landscape was levelled with laser technology
and plowing (with soil layers mix), and 15 years of vegetable production (onion, carrots and
garlic) were made, but in the last 2 years a Lucerne pasture were planted for soil recovery. The
crop management of vegetables in HI involves 6-9 sprays year-1 with carbendazim (100 cm3
a.i. 100 L-1 of water). While the system with lower intensity use (LI) corresponds to grasslands
for livestock feeding, as the HI soils before the last 17 years.
Four plots for each system were evaluated. The earthworms were expelled using formalin (0.2%)
and then hand sorted on the surface; we separated juvenile and mature earthworms, and the
last ones were identified to the species level. Density and the total biomass (24h gut empty)
were measured. A biomass index (BI) as Biomass/Max. Biomass, was calculated. To assess
the organic matter breakdown we used the litterbag method with 0.2 and 3.4mm mesh bags
filled with 30g of dry Medicago sativa buried 10cm deep. At 0, 6, 12, 18 and 24 months the
mass loss was determinate. 80 bags were used (2 mesh x 2 intensity of land use x 5 dates x 4
repetitions).
Earthworm density was 26.16; 8.01 and 35.17 ind.m-2 (adult, juvenile, total) in HI. In LI were
statistically higher: 146.02, 27.86 and 173.89. The total B was 10.73 and 58.03 g m-2 on HI and
LI respectively (conf. level 95%, ANOVA p < 0.05). We found Aporrectodea trapezoides, A.
Turgida (Lumbricidae) and Metaphire californica (Megascolicidae) in both systems. The
Spearman rank correlation analysis (n = 8, p < 0.05) showed strong correlations between BI and
Carbendazim Applications (rs = 0.845), Plowings (rs = 0.842), and lack of correlation for Years
of Agriculture (rs = 0.512). The mass loss on litterbags was higher in LI than HI at 12, 18 and 24
months (p < 0.05). The effect of the mesh size was significant always in LI, and at 24 months in
HI plots, while the 0.2 mesh report a very slow decomposition rate. Our report of the effect of
agricultural intensification on earthworm biomass and density and the negative impact on the
breakdown of organic matter in long term field conditions, agrees with the predictions of Burrows
and Edwards (2002) using a microcosm model for carbendazim applications.

Categoria do assunto: | --
Registro original: | Embrapa Florestas (CNPF)
Exemplares: | CNPF - (43784-1) - UPE - PL - -- - CD0305 -  -  - DIS