02844naa a2200289 a 450000100080000000500110000800800410001902400360006010000190009624501650011526000090028050002200028952016820050965000220219165000240221365000160223765000110225365300260226465300210229065300260231165300190233770000170235670000140237370000160238770000130240377301380241610617752021-08-10       2021    bl uuuu     u00u1 u    #d7 adoi.org/10.1002/saj2.202042DOI1 aBAETHGEN, W.E.  aEcosystem dynamics of crop-pasture rotations in a fifty-year field experiment in Southern South AmericabCentury model and field results.h[electronic resource]  c2021  aArticle History: Accepted manuscript online: 26 November 2020;  Manuscript accepted: 18 November 2020;  Manuscript revised: 02 November 2020 ; Manuscript received: 12 February 2020;  Published online: 24 March 2021.  aAbstract: The Century model was used to simulate soil carbon (C) and nitrogen (N) cycling, and crop production dynamics in an ongoing field experiment in Uruguay (started in 1963). The model was calibrated using observed data from three treatments (crop or crop?pasture rotations) and validated with a fourth treatment. The model correctly predicted the impact of different treatments on microbial biomass, N mineralization, soil respiration, and crop yields. The model and observed data show that soil respiration, N mineralization, soil C, and crop yields increase with increasing plant derived C inputs caused by increasing the frequency of pastures in the rotations. This is one of the first papers which show the strong positive correlation of observed soil C with plant C soil inputs to field?observed microbial biomass, soil respiration, and N mineralization. The results also showed that reducing tillage and transitioning to a no?till system increased soil C and reduced soil erosion. The main path of soil C losses was heterotrophic microbial respiration which accounted for 66% of the total C lost in a continuous crop rotation and no fertilizers, 71% in a continuous crop rotation with fertilizers, and 86% in a crop?pasture rotation with fertilizers. Model results from a degraded cropping system showed that adding grass/clover pastures greatly increased plant production and soil C, while reducing the frequency of grass/clover pastures in high?fertility cropping systems from 50% of the time to 25% reduces crop yields and soil C. Including cover crops substantially increases crop production and maintains soil C in high fertility and degraded cropping systems  aCICLO DEL CARBONO  aCICLO DEL NITROGENO  aECOSISTEMAS  aSUELOS  aCROP PASTURE ROTATION  aCROPPING SYSTEMS  aGRASS-CLOVER PASTURES  aHIGH FERTILITY1 aPARTON, W.P-1 aRUBIO, V.1 aKELLY, R.H.1 aLUTZ, S.  tSoil Science Society of America Journal, Volume 85, Issue 2, Pages 423-437, March/April 2021. DOI: https://doi.org/10.1002/saj2.20204