Effects of controlled-release fertilizer on growth and ectomycorrhizal colonization of pot-grown seedlings of the dipterocarp Dryobalanops lanceolata in a tropical nursery

Abstract The effects of the application of controlled-release fertilizer on the growth and ectomycorrhizal colonization of pot-grown seedlings of the dipterocarp species Dryobalanops lanceolata were studied in a nursery in Sarawak, Malaysia, to produce a sufficient number of healthy dipterocarp seedlings to reforest degraded tropical lands. Samples of a forest soil were mixed with an equal volume of river sand following a typical practice in the Niah Forest Research Station nursery. About 1.4 kg of the soil mixture was placed in plastic bags. Either a 700-day (80% elution of the ingredients at 20°C) controlled-release fertilizer (CRF, N: P : K = 12: 14: 12) or a chemical fertilizer (CF, N: P : K = 15 : 15 : 15) was applied at the rate of 2,5, and 10 g per pot. After 16 months of cultivation, mycorrhizal colonization and photosynthetic activity of the seedlings were evaluated, and the nutrient concentration and dry mass were analyzed. Application of ten grams of CRF resulted in the enhancement of the bioma...