@article{fdi:010037841,
  title = {{W}hat happens to earthworm casts in the soil ? {A} field study of carbon and nitrogen dynamics in {N}eotropical savannahs},
  author = {{M}ariani, {L}ucero and {J}imenez, {J}. {J}. and {A}sakawa, {N}. and {T}homas, {R}. {J}. and {D}ecaens, {T}hibaud},
  editor = {},
  language = {{ENG}},
  abstract = {{I}n the {O}xisols of the eastern plains of {C}olombia, the large native anecic earthworm {M}artiodrilus sp. is an abundant ecosystem engineer producing long-lasting casts and burrows. {C}asts deposited in the soil by this species have been estimated at several tonnes per hectare per year. {T}he physical and chemical processes occurring in these casts have never been studied. {I}n this study, we compared the dynamics of water content ({WC}), total {C} ({C}-tot), and available {N} ({N}-avail) contents, and the distribution in size of aggregates in ageing below-ground casts of this species and in the bulk soil. {I}n a native herbaceous savannah and a sown grass/legume pasture ({B}rachiaria humidicola, {A}rachis pintoi, {D}esmodium ovalifolium and {S}tylosanthes capitata), fresh surface casts were experimentally injected into artificial burrows of 1 cm {O} and 10 cm depth and sampled at different dates during a total period of 120 days. {T}he injection procedure used resulted in a 34% decrease in {WC} of the casts from the sown pasture and reduced the mean mass diameter ({MMD}) of the aggregates of casts from the savannah by 19%. {O}ther properties were not significantly affected by the procedure. {F}or injected casts in both grasslands, {MMD} and {C}-tot were stable during cast ageing while {WC} and {N}-avail were initially at levels several times higher than the bulk soil and decreased to similar bulk soil values with ageing. {T}he {C}-tot was twice and one third higher in casts compared with the bulk soil in the pasture and the savannah, respectively. {O}verall means for cast {MMD} (8.3 and 7.4 mm) were twice as high as those in the bulk soil (3.8 mm) in the savannah and the pasture, respectively. {H}owever, {MMD} was not significantly different between the casts and the bulk soil in two occasions in the pasture. {A}vailable nitrogen ({N}-avail) in injected casts was initially greater than bulk soil levels, reaching maximum levels just after injection (116 and 93 mg kg(-1)) and remained significantly greater during 1-2 weeks, in the savannah and the pasture, respectively. {I}n conclusion, the tonnes of casts deposited in the soil profile by {M}artiodrilus sp. each year are likely to contribute greatly to plant nutrition and to the regulation of the soil structure. {F}or each anecic earthworm species, the ecological impact of its below-ground casts is likely to be as important as its surface casts.},
  keywords = {earthworms ; field experiment ; casts ; nutrient dynamics ; carbon ; nitrogen dynamics ; tropical savannahs ; ecosystem engineers ; redundancy analysis},
  booktitle = {},
  journal = {{S}oil {B}iology and {B}iochemistry},
  volume = {39},
  numero = {3},
  pages = {757--767},
  ISSN = {0038-0717},
  year = {2007},
  DOI = {10.1016/j.soilbio.2006.09.023},
  URL = {https://www.documentation.ird.fr/hor/fdi:010037841},
}