Status of soil fertility in citrus orchards of Chongqing Sanxia Reservoir Area

Knowing soil nutrient fertility status is a basis to formulate a suitable fertilization strategy.Top soil(0-30 cm)samples collected from 459 citrus orchards in Chongqing Sanxia Reservoir Area were tested and classified in present study.The results showed that the soil pH of 78.7% orchards was suitable for citrus growth,soil organic matter of 60.3% orchards were low,and the deficiency rate of available macro-nutrients N and P was 72.4% and 41.7%,respectively,while soil available K were high in some orchards.The deficiency rate of available B,Zn,Fe and Mn was 86.3%,37.9%,27.0% and 20.3%,respectively.The results also indicated that amounts of citrus soils which have excessive available Fe,Mn and Cu accounted for 52.5%,36.4% and 26.4% of total citrus orchards.Therefore,it was suggested that more B,Zn,lime or other alkaline fertilizer and less Cu fungicide should be used in the tested citrus orchards.