03529naa a2200673 a 450000100080000000500110000800800410001902400370006010000140009724501240011126000090023552016890024465000160193365000180194965000190196765000290198665000120201565000180202765000150204565000200206065000150208065000210209565000190211665000180213565000200215365000180217365000150219165000210220665000250222765000110225265000150226365000190227865000190229765000250231665000090234165000170235065000220236765300160238965300100240565300180241565300220243365300250245565300260248065300450250665300140255165300140256565300210257965300190260065300220261965300260264165300160266770000140268370000200269770000220271770000190273970000210275870000120277977300640279115804462011-12-12       2009    bl uuuu     u00u1 u    #d7 a10.1016/j.still.2009.10.0012DOI1 aGOMES, J.  aSoil nitrous oxide emissions in long-term cover crops-based rotations under subtropical climate.h[electronic resource]  c2009  aIt has been shown that cover crops can enhance soil nitrous oxide (N2O) emissions, but the magnitude of increase depends on the quantity and quality of the crop residues. Therefore, this study aimed to evaluate the effect of long-term (19 and 21 years) no-till maize crop rotations including grass [black oat (Avena strigosa Schreb)] and legume cover crops [vetch (Vigna sativa L.), cowpea (Vigna unguiculata L. Walp), pigeon pea (Cajanus cajan L. Millsp.) and lablab (Dolichos lablab)] on annual soil N2O emissions in a subtropical Acrisol in Southern Brazil. Greater soil N2O emissions were observed in the first 45 days after the cover crop residue management in all crop rotations, varying from -20.2 ± 1.9 to 163.9 ± 24.3 ug N m-2 h-1. Legume-based crop rotations had the largest cumulative emissions in this period, which were directly related to the quantity of N (r2 = 0.60, p = 0.13) and inversely related to the lignin:N ratio (r2 = 0.89, p = 0.01) of the cover crop residues. After this period, the mean fluxes were smaller and were closely related to the total soil N stocks (r2 = 0.96, p = 0.002). The annual soil N2O emission represented 0.39-0.75% of the total N added by the legume cover crops. Management-controlled soil variables such as mineral N (NO3- and NH4+) and dissolved organic C influenced more the N2O fluxes than environmental-related variables as water-filled pore space and air and soil temperature. Consequently, the synchronization between N mineralization and N uptake by plants seems to be the main challenge to reduce N2O emissions while maintaining the environmental and agronomic services provided by legume cover crops in agricultural systems.  aCover crops  aCrop rotation  aForage grasses  aGreenhouse gas emissions  aLegumes  aNitrous oxide  aNo-tillage  aSoil management  aSubtropics  aAveia forrageira  aAvena strigosa  aCajanus cajan  aDolichos lablab  aEfeito Estufa  aErvilhaça  aFeijão de corda  aGramínea forrageira  aGuandu  aLeguminosa  aManejo do solo  aPlantio direto  aRotação de cultura  aSolo  aVicia sativa  aVigna unguiculata  aAveia preta  aCaupi  aCero labranza  aClima subtropical  aCultivo de cobertura  aCultivos de cobertura  aEmisiones de gases de efecto invernadero  aLabe-labe  aLegumbres  aManejo del suelo  aÓxido nitroso  aPastos forrajeros  aRotación de cultivos  aSubtrópico1 aBAYER, C.1 aCOSTA, F. de S.1 aPICCOLO, M. de C.1 aZANATTA, J. A.1 aVIEIRA, F. C. B.1 aSIX, J.  tSoil & Tillage Researchgv. 106, n. 1, p. 36-44, Dec. 2009.