Populations of nematode genera in soils under pasture

Abstract

Mean totals for nematode populations found in 12 samples of 0–10 cm soil from grazed pastures, taken monthly, are 1 500 000 per m² for Rotoiti loamy sand, 1 030 000 per m²for Kokotau silt loam, 4 750 000 per m² for Kaitoke silt loam, 960 000 per m² for Judgeford silt loam, and 790 000 per m² for Pomare silt loam. These totals are positively correlated with annual herbage production at the sites. Population levels of the 40 taxa distinguished (most of them genera) were poorly correlated with seasonal variation in the environmental factors measured; the factors operating are unknown because of inadequate knowledge of nematode biology. Genera contributing at least 4% to total numbers at two or more sites are Cephalenchus, Helicotylenchus, Pratylenchus, Paratylenchus, Cephalobus, Heterocephalobus, Anaplectus, Chronogaster, Pungentus, and Aporcelaimus. Mean and maximum population levels are given for each genus and site; this information is useful in estimating any damage these nematodes may cause and in determining their role in cycling nutrients in the soil.

Keywords:

• nematodes
• grass nematodes
• soil nematodes
• populations
• soil sampling
• Rotoiti loamy sand
• Kokotau silt loam
• Kaitoke silt loam
• Judgeford silt loam
• Pomare silt loam
• pastures

Additional information

Notes on contributors

G.W. Yeates

Most identifications were to genus level, a few to only family level.‘Genus‘ is used for convenience to allude to all the taxa listed in Table 2 under ordinal headings.