Influence of cropping on the population of a native earthworm and consequent effects on hydraulic properties of vertisols

Abstract

Population density of Heteroporodrilus mediterreus, a large native earthworm found on the Mitchell grassland (Astrebla lappacea) on the Vertisol plains near Walgett, New South Wales, was investigated at two sites (brown and grey clays). Maximum earthworm activity at the soil surface layer was observed during winter (July/August) corresponding to more favourable soil moisture conditions. The highest earthworm population density (7.5 m-2) and biomass (0.89 t ha-1) were detected at the brown clay site under natural pasture. Populations were much lower (by two thirds in the brown clay) and the proportion of immature worms was much higher in the cropped soils than in the pasture soils. Current wheat cropping practices involving long fallowing and excessive cultivation during the period when earthworms are active at the surface are the possible causes of the reduction in population. Disc permeameter measurements compared with infiltration through single earthworm holes showed that the earthworm channels contributed significantly to the movement of water into the subsoil. Their persistence under wet conditions, even after closure of shrinkage cracks, suggests they are also important in maintaining subsoil aeration. Significant reductions in sorptivity and infiltration rate were observed in the cropped soils.

Diagnosis and Remediation of Nutrient Constraints in Citrus

“…Improvement in soil properties, especially available N, permeability, structure in form of water stable aggregates due to stabilization of soil particles by polysaccharide gums produced by bacteria present in earthworms' intestine, and hydraulic properties (Friend and Chan 1995) due to creation of permanent burrows of earthworms, are well documented. Considerable increase in available K extracted from the worm casts due to partial conversion of nonexchangeable K into exchangeable form is another useful role of earthworms in soil K transformation (Rao et al 1997).…”

Temporal change in soil macropores measured using tension infiltrometer under different land uses and slope positions in subtropical China

“…Live plants or crop residues covering on soil surface properly enhance water infiltration rates by lowering the impact of rainfall (Mukhtar et al 1985;Radke and Berry 1993). Rooting processes which may vary with type of crop are also considered to have an impact on macropore formation (Friend and Chan 1995;Holden 2005). In tilled soils, pores are formed primarily by the tillage tool.…”

Occurrence of Tylosin-Resistant Enterococci in Swine Manure and Tile Drainage Systems under No-Till Management

“…Both soils of the two plots are classified as a loam, however, the Kenyon soil in plot 25 (spring simulation) usually occurs on convex ridge crests or side slopes which may result in low moisture while the Floyd soil in plot 20 (fall simulation) are often found in the lower sides of slopes (USDA and NRCS, 1995). Application of slurry manure will contribute to the increase of earthworm population and thus increase macropore density in soil (Friend and Chan, 1995). …”