Dissimiiatory Fe(Ⅲ) reduction is an important process in the geochemicai cycle of iron in anoxic environment.As the main products of dissimiiatory iron reduction,the Fe(Ⅱ) species accumulation could indicate the reduction ability.The effects of different green manures on Fe(Ⅲ) reduction in paddy soil were explored based on a 31-year rice-rice-winter green manure cropping experiment.Four treatments were involved,i.e.,rice-rice-milk vetch(RRV),rice-rice-rape(RRP),rice-rice-ryegrass(RRG) and rice-rice-winter fallow(RRF).Soils were sampled at flowering stage of milk vetch and rape(S1),before transplantation(S2),at tillering(S3),jointing(S4),and mature(S5) stages of the early rice,and after the harvest of the late rice(S6).The contents of TFe_(HCI)(HCI-extractable total Fe),Fe(Ⅱ)_(HCI)(HCI-extractable Fe(ll) species) and Fe(Ⅲ)_(HCI)(HCIextractable Fe(Ⅲ) species) were measured.The correlations among those Fe species with selected soil environmental factors and the dynamic characteristics of Fe(Ⅱ)_(HCI) accumulation were investigated.The results showed that TFe_(HCI) in RRF was significantly higher than those in the green manure treatments at most of the sampling stages.Fe(Ⅱ)_(HCI) increased rapidly after the incorporation of green manures in all treatments and kept rising with the growth of early rice.Fe(Ⅱ)_(HCI) in RRG was quite different from those in other treatments,i.e.,it reached the highest at the S2 stage,then increased slowly and became the lowest one atthe S4 and S5 stages.Fe(Ⅲ)_(HCI) showed oppositely,and Fe(Ⅱ)_(HCI)/Fe(Ⅲ)_(HCI) performed similarly to Fe(Ⅱ)_(HCI).The maximum accumulation potential of Fe(Ⅱ)_(HCI) was significantly higher in RRF,while the highest maximum reaction rate of Fe(Ⅱ)_(HCI) accumulation appeared in RRG.Significant correlations were found between the indexes of Fe(Ⅱ)_(HCI)accumulation and soil pH,oxidation-reduction potential(Eh) and total organic acids,respectively.In together,we found that long-term application of green manures decreased the TFe_(HCI) in red paddy soils,but promoted the ability of Fe(Ⅲ)reduction,especially the ryegrass;Fe(Ⅱ)_(HCI) increased along with the growth of rice and was affected by soil conditions and environmental factors,especially the water and redox ability. Dissimiiatory Fe (III) reduction is an important process in the geochemicai cycle of iron in anoxic environment. As the main products of dissimiiatory iron reduction, the Fe (II) species accumulation could indicate the reduction ability. The effects of different green manures on Fe (Ⅲ) reduction in paddy soil were explored based on a 31-year rice-rice-winter green manure cropping experiment. Four treatments were involved, ie, rice-rice-milk vetch (RRV) , rice-rice-ryegrass (RRG) and rice-rice-winter fallow (RRF) .Soils were sampled at flowering stage of milk vetch and rape (S1), before transplantation (S2), at tillering (S3), jointing (S5) stages of the early rice, and after the harvest of the late rice (S6). Contents of TFI HCI (extractable total Fe), Fe (II) HCI (HCI) -extractable Fe (ll) species) and Fe (III) _ (HCI) (HCIextractable Fe (III) species) were measured.The correlations among those Fe species with selected soil environmental factors and the dynamic charact eristics of Fe (II) _ (HCI) accumulation were investigated. The results showed that TFe_ (HCI) in RRF was significantly higher than those in green manure treatments at most of the sampling stages. rapidly after the incorporation of green manures in all treatments and kept rising with the growth of early rice. Fe (II) _ (HCI) in RRG was quite different from those in other treatments, ie, it reached the highest at the S2 stage, (HCI) / Fe (Ⅲ) _ (HCI) performed similarly to Fe (Ⅱ) The maximum accumulation potential of Fe (Ⅱ) _ (HCI) was significantly higher in RRF, while the highest maximum reaction rate of Fe (Ⅱ) _ (HCI) accumulation was found in the indexes of Fe (Ⅱ) _ (HCI) accumulation and soil pH, oxidation-reduction potential (Eh) and total organic acids, respectively.In together, we found that long-term appli cation of green manures decreased the TFe_ (HCI) in red paddy soils, but promoted the ability of Fe (Ⅲ) reduction, especially the ryegrass; Fe (Ⅱ) _ (HCI) increased along with the growth of rice and was affected by soil conditions and environmental factors Especially the water and redox ability.