Status of soil fertility in citrus orchards of Chongqing Sanxia Reservoir Area Effect of Rotation of Leguminous Plants on Soil Available Nutrients and Physical and Chemical Properties in Continuous Cropping Potato Field A STUDY ON LONGTERM SOIL FERTILITY MONITORING FINDINGS IN NEWLY ESTABLISHED HIGHYIELD TIMBER PLANTATIONS OF MAIN SPECIES Study on parameters of balanced fertilization for winter wheat in cinnamon soil in Northern China Study of classification of the soil nutrient status of citrus orchard in Hubei Province