Growth and Yield Performance of Maize (Zea mays L.) under Different Phosphorus Levels in Reddish Brown Earth Soil (Rhodustalfs) in Sri Lanka

Maize (Zea mays L.) is the second most important cereal crop after rice produced in Sri Lanka. The government of Sri Lanka has taken several steps to expand maize production in the country. A larger proportion of maize cultivation of the country is confined to the dry zone where Reddish Brown Earth (RBE) is the major great soil group in uplands. Reddish Brown Earth soils show high P adsorption capacity, hence availability of P to plant uptake is low. As such this study aimed to investigate growth and yield performance of maize under different P levels in RBE soils. The study was conducted as a pot experiment under greenhouse condition. Six different P levels [0, 20, 40, 80, 160 and 320 mg/kg of soil] were compared using two factor factorial in complete randomized design with seven replicates. Plant height, leaf area content, biomass content and yield parameters showed significant difference among tested treatments. Most of the tested parameters showed increasing trend with added P up to 80 mg/kg but negative relationship exhibited afterward. Treatment no. 4 (80 mg/kg of soil) recorded highest yield of 6.6 mt/ha. The study concludes that 80 mg P/kg soil is the most suitable phosphorus level for cultivating maize in RBE soil. However further field studies are needed to confirm the findings.