TABLE CONTENTS

Nematode Indicators of Soil Quality in Forest to Pasture Conversion
Lloyd, D.A. (1), L.M. Condron (2), G. Edwards (1) & N.L. Bell (2)
(1) Agriculture and Life Sciences, PO Box 84, Lincoln University, Lincoln 7647, New Zealand;
(2) AgResearch Limited, Ruakura Research Centre, Private Bag 3123, Hamilton, New Zealand.
In New Zealand present and projected decline in the price of primary forest products has lead
to conversion from forest to pastoral farming in many areas. Several decades of forest cover
coupled with intrusive harvest operations, and mulching of residue wood material have
produced a remnant soil that is acidic, contains toxic levels of exchangeable aluminum and
low available nitrogen, very high C:N ratio and, is devoid of earthworms and structural
integrity.
An experiment was established in April 2005 to determine the best regime of lime and
nitrogen to be used for successful conversion. However, concerns grew of the short and longterm
biological impact of such interventions to the conversion process. Use of worm counts
as an evaluation of biological soil quality was precluded by the absence of earthworms.
Nematode assessments became an attractive surrogate since several researchers provided
conclusive evidence of the association of specific nematode groups and community structures
with particular soil conditions and habitats. We hypothesized that an assessment of the
nematode community would discriminate soil management practices (application of lime and
nitrogen fertilizer) in a recently converted experimental pasture block.
The results indicate that lime (10 tons/ha) and nitrogen fertilizer (200 kg N/ha) did not
influence nematode abundance or community structure at the conversion site after 2 years. A
total of 22 nematode families were identified and placed into six feeding groups. Faunal
assessment of the food-web condition also showed similarities between all treatments in the
converted site. However, the converted land (whether treated or untreated) was very different
from two reference sites (long-term pasture and a 60-year forest stand) located within a 500
m radius of converted site. This suggests that land use rather than lime or nitrogen fertilizer
influenced the nematode community and probably other soil biological properties.
5 th International Congress of Nematology, 2008 90