@article{fdi:010041423,
  title = {{M}ass proportion of microaggregates and bulk density in a {B}razilian clayey oxisol},
  author = {{V}olland {T}uduri, {N}. and {B}ruand, {A}. and {B}rossard, {M}ichel and {B}albino, {L}. {C}. and de {O}liveira, {M}. {I}. {L}. and {M}artins, {T}. {D}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he physical properties of {B}razilian {O}xisols are closely related to the development of their microstructure, which typically consists of stable microaggregates > 1 mm. {T}here is no model available to predict changes in microstructure in {O}xisols. {T}he objective of this work was to relate the proportion of microaggregates to the bulk density ({D}-b) in the soil studied. {F}ive sites of a typic {H}aplustox under native vegetation (two sites) and pasture (three sites) were sampled. {S}oil bulk density, sand, silt, and clay content and aggregate-size distribution were measured from the surface to 1.6 m deep in increments of 0.1 in. {T}hin sections were prepared from undisturbed samples collected in duplicate from 0- to 0.1-, 0.3- to 0.4-, 0.8- to 0.9-, and 1.5- to 1.6-m depths, and backscattered electron scanning images ({BESI}) were generated. {C}lay content ranged from 672 to 798 g kg(-1) and bulk density between 0.87 and 1.18 g cm(-3) among the 80 samples studied. {B}ulk density was poorly correlated with clay content ({R}-2 = 0.358) and at any depth was not significantly smaller under native vegetation than under pasture. {V}isual assessment of {BESI} revealed that soil material corresponded to either microaggregates (< 0.1 mm) in loose arrangement or to much larger aggregates. {Q}uantification of {BESI} from the deepest sampling depth of all soils showed that 96.2 and 95.7% of microaggregates were < 0.8 mm with 73.2 and 95.7% between 0.1 and 0.5 mm under native vegetation and pasture, respectively. {T}he mass proportion of microaggregates can be estimated using the < 0.84-mm soil material that is obtained by dry sieving ({P}hi < 0.84). {F}inally, our results showed that {P}hi < 0.84 varied with {D}-b. {L}inear regression coefficients were calculated for the relationship between {P}hi < 0.84 and the reciprocal of bulk density (1/{D}-b) [{P}hi < 0.84 = 1.97 (1/{D}-b) - 1.52, {R}-2 = 0.82], assuming no interaction between microaggregates and macroaggregates, the porosity of these two structural types was estimated as 0.71 and 0.51, respectively.},
  keywords = {},
  booktitle = {},
  journal = {{S}oil {S}cience {S}ociety of {A}merica {J}ournal},
  volume = {69},
  numero = {5},
  pages = {1559--1564},
  ISSN = {0361-5995},
  year = {2005},
  DOI = {10.2136/sssaj2003.0344},
  URL = {https://www.documentation.ird.fr/hor/fdi:010041423},
}