02073naa a2200349 a 450000100080000000500110000800800410001910000140006024501460007426000090022050000200022952011380024965000150138765000090140265000140141165000260142565000090145165000120146065000230147265000120149565000100150765000140151765000120153165000100154365300130155365300310156665300120159765300230160970000200163270000170165277300540166915445601999-01-15       1983    bl ---       0--  u    #d1 aCOUTO, W.  aEffect of excess water in an oxisol on ammonium, nitrate, iron and manganese availability and nutrient uptake of two tropical forage species.  c1983  aC. Sanzonowicz.  aA glasshouse experiment was condcted to determine how reduction conditions would affect plant nutrient availability and uptake in red-yellow latosol (Acrustox). Soil analysis showed that the most important change were a marked increase in extractable and in inhibition of nitrification. The grass andropogon (Andropongon gayanus Kunth var. bisquamulatus (Hoechst) Hack) and the legume stylo (Stylosanthes capitata (Vog) responded differently to reducing conditions. Andropogon showed low P, Ca, Mg Fe and Mn content in the shoots but an intense coating of oxidized iron was observed on the surface roots. Stylo plant, on the other hand, showed no iron deposition on the root surfaces a high iron content in the shoots. No decreased P, Ca or Mg content was observed in this case. Is was concluded tha in water saturated soil, reduction took place and plant performance was affected no only by restricted root development but by preventing P, Ca and Mg uptake in Andropogon and increasing Fe uptake stylo plants. It is suggested that restricted P, Ca and Mg uptake by Andropogen would be the result of iron deposition on root surfaces.  aFerralsols  airon  amanganese  aStylosanthes capitata  azinc  aAmônia  aAndropogon Gayanus  aCerrado  aFerro  aManganês  aNitrato  aZinco  aAmmonium  aLatossolo vermelho-amarelo  aNitrate  aRed-yellow latosol1 aSANZONOWICS, C.1 aLEITE, G. G.  tPlant and Soil, The Haguegv.73, p.159-166, 1983.