Abstract: The soil nutrient status, microbial communities and fruit quality of Newhall navel oranges planted for 8 and 13 years respectively in orchards of Luran ecological farm and Xinyuan fruit industry in Shanghang County in Fujian Province were determined and analyzed in 2010. The results showed that, the available K content in soils increased significantly with the planting time of orange trees in the two tested orchards, but the contents of total N, NO3N, total P, available P and organic matter changed in different patterns from each other as the planting time increased, the contents of exchangeable Ca, exchangeable Mg and effective S were not significantly different between the two orchards. All the soil nutrient contents, except pH value, were in an acceptable range for orange growing. The total microbe biomass of PLFAS and the specific PLFA, such as i16∶0,14∶0,20∶0,15∶0,a15∶0,10 Me 16∶0,10Me18∶0 etc in different treatments, except for 8 planting years time in the tested orchardsⅠ, were significantly higher than that in the control with pure chemicalfertilizers. The Simpon, Shannon and Mclntosh index in the tested orchardsⅡ were significantly higher than the control.The contents of total sugar, reducing sugar and total soluble solids (TSS) significantly increased as the age of tree became longer, but the changing patterns for the contents of vitamin C (Vc), total acid (TA), sugaracid ratio and TSS/TA were different from each other, and there was no significant difference in individual fruit weight, edible rate, fruit shape index observed between the two orchards.

Key words: planting years, navel orange, soil, phospholipid fatty acids (PLFAs), microbial community, soil nutrient status