EFFECTS OF ORGANIC FERTILIZER DOSAGE AND SOD CULTURE ON SOIL REACTION, ORGANIC MATTER AND AVAILABLE NUTRIENTS CONTENT OF A 'TANKAN' (CITRUS TANKAN) ORCHARD

The experiment was conducted at Ear-mei to study the effects of organic fertilizer dosage and sod culture on soil reaction, organic matter and available nutrients content of a ‘Tankan’ (Citrus tankan) orchard. Split plot design with three replicates was used in this experiment. The main factors of the treatment included total, half, a quarter and zero amount of organic fertilizer. The sub factors included sod culture and weed control. The ability of sustainable management of ‘Tankan’ will be approached from this experiment. The sod culture plots had significantly higher soil organic matter, available P, K, Ca and Mg contents than the weed control plots. Results from experiments over five years showed that the soil pH and available Ca content increased and available P and Mg contents decreased in sod culture plots. Organic fertilizer dosage also significantly influenced soil pH. The soil pH values were maintained from 6 to 6.5 in high organic fertilizer dosage plots. The soil pH values dropped under 5.0 in chemical fertilizer plots. Most soils in Taiwan orchards have excess P, K, Mg contents, therefore, heavy dose of organic matter and sod culture are recommended.