02489naa a2200301 a 450000100080000000500110000800800410001910000270006024501120008726000090019950001420020852014460035065000250179665000170182165000160183865000180185465000200187265000240189265000240191665000250194065300220196565300230198765300310201065300250204170000170206670000120208377300920209520576092017-05-24       2016    bl uuuu     u00u1 u    #d1 aSEBEN JUNIOR, G. de F.  aSoil aggregation according to the dynamics of carbon and nitrogen in soil under different cropping systems.  c2016  aTítulo em português: Agregação do solo de acordo com a dinâmica de carbono e nitrogênio em solo sob diferentes sistemas de cultivo.  aThe objective of this work was to evaluate total soil carbon and nitrogen, as well as their contents in particulate and mineral-associated C fractions; to determine C stock and sequestration rates in the soil; and to verify the effect of C and N contents on soil aggregation, using different crop rotations and crop sequences under no-tillage. The study was carried out for nine years in a clayey Oxisol. The treatments consisted of different cropping systems formed by the combination of three summer crops (cropped until March) ? corn (Zea mays) monocropping, soybean (Glycine max) monocropping, and soybean/corn rotation ? and seven second crops (crop successions). Soil samples were taken at the 0.00?0.10-m layer for physical fractionation of C and N, and to determine soil aggregation by the wet method. Soybean monocropping increased C and N in particulate C fraction, while the crop systems with corn monocropping x pigeon pea (Cajanus cajan), corn monocropping x sun hemp (Crotalaria juncea), and soybean monocropping x corn as a crop succession increased total C in the soil. Greater rates of soil C sequestration were observed with soybean/corn rotation and with soybean monocropping, as well as with sun hemp as a second crop. The increase in total N increases soil C stock. Soil aggregation was most affected at particulate C fraction. Increases in soil N promote C addition to particulate fraction and enhance soil aggregation.  aCarbon sequestration  aCarbon sinks  aCover crops  aCrop rotation  aSoil aggregates  aSoil organic matter  aPlanta de cobertura  aRotação de cultura  aAgregados do solo  aEstoque de carbono  aMatéria orgânica do solo  aSequestro de carbono1 aCORÁ, J. E.1 aLAL, R.  tPesquisa Agropecuária Brasileira, Brasília, DFgv. 51, n. 9, p. 1652-1659, set. 2016.