Abstract: Soil samples were collected from Yama Mountain area in Urumqi,and Tessier sequential extraction procedure was used to extract different chemical forms of soil Fe and Mn.Pot experiments were conducted to investigate the relationships of soil Fe and Mn forms with soil physical-chemical proprieties,and their availability to plants.The results showed that soil Fe was dominated by residual form,which accounted for 92.3% of soil total Fe.The proportion of other Fe forms was less than 8%.Soil Mn was dominated by Fe and Mn oxidesbound and residual forms,and their contents were 49% and 41.6% of total Mn,respectively.The proportion of other Mn forms was less than 10%.Irrigation with secondary effluent increased the availability of Fe and Mn,but irrigation with untreated wastewater was not profitable to Fe and Mn supply.The deficiency of soil Fe and Mn could be improved by adding Fe and Mn salts.Correlation analysis showed that there was certain relativity between soil physicalchemical proprieties and soil Fe and Mn forms.Soil pH,CaCO₃,organic matter,and exchangeable cations had significant effects on the availability of Fe and Mn.Stepwise regression analysis showed that Fe-Mn oxides-bound Fe was most available to plant Fe nutrition,whereas organic matterbound Mn contributed to the largest share in plant Mn availability.

Key words: Organic rice field, Pests, Enemies, Population dynamics