Farm Table says:
What is the problem?
The effects of production practices on the relative abundance of springtails (Collembola) in irrigated cotton fields were studied over 2 yr to examine effects of farm management on these decomposer organisms.
What did the research involve?
This study was conducted in cotton fields in northern New South Wales. Pitfall trapping and soil core extraction were undertaken in both pseudoreplicated plots within whole fields on cotton farms and on experimental replicate plots of Envirofeast cotton and Lucerne. The relative abundance of surface-active springtails in cotton rows and densities of soil species from the rhizosphere were calculated. Twenty-three species of Collembola were collected from 5 fields, 19 in pitfall traps, and 11 in soil cores. Five species, Setogaster sp., Proisotoma minuta, Entomobrya unostrigata, Entomobrya multifasciata grp, and Lepidobrya sp. were numerically dominant on the ground at 86–96% of individuals and Mesaphorura sp., Folsomides parvulus, and Hematoma thermophila grp dominant in the soil.
What were the key findings?
Native grassland samples contained 15 species of which a probable 10 were native and 8 were not found in cotton. Nineteen species of the 24 species identified from cotton were predominantly fungal feeders. Highest catches of Collembola occurred after flowering and soil Collembola increased with depth and during cotton growth on unsprayed plots but decreased on sprayed plots. Surface soil moistures affected daily catch rates with decomposing residues, crop stage, predator abundance, and season as secondary factors. Insecticide (endosulfan, pyrethroid, carbamate, and organophosphate) and predator effects were either negligible or unclear depending on the factor involved. Springtails appear to be predominately food-limited during times of adequate soil moisture in cotton fields.
There was considerable variability between sites. This is surprising given that the four sites are located relatively closely together (three within 100 km of each other). Despite this, data shows that the dominant surface active species were different at each locality and that species richness per site was generally low in cotton fields and highest in the native grassland.