Abstract: An indoor pot experiment was carried out to study systematically the effects of nutrient and water regimes on soil eco environment by measuring and comparing changes in soil physical and chemical properties,such as soil pH,redox potential(Eh),organic matter,transformation of Fe and Mn,soil bulk density and soil porosity.Results indicated that under continuous flooding(CLW),organic manure,especially barnyard manure,decreased soil Eh and aggravated soil reduction process,which resulted in increase in amorphous Fe 2O 3.In addition,its effect on improving soil physical environment was also weakened significantly.Under the alternation of dry and wet conditions(ADW),combined application of chemical fertilizers and organic manure not only increased soil organic matter content but also markedly improved soil oxidation reduction conditions and physical properties.

Key words: paddy soil, nutrient and water regimes, soil eco environment