Microbial Biofertilizers and Soil Amendments Enhanced Tree Growth and Survival in a Barren Mined-out Area in Marinduque, Philippines

A bioremediation protocol was developed for rehabilitating mine tailing areas using microbial biofertilizers and soil amendments. The effects on the growth and survival of tree species in a three-decade barren mined-out area in Barangay Capayang, Mogpog, Marinduque, Philippines were also determined. Three concurrent field experiments were established in June 2016 using Pterocarpus indicus, Acacia mangium and Eucalyptus urophylla. Treatments for this study were uninoculated seedlings and seedlings inoculated with mycorrhiza (MYKORICH® for P. indicus) or Surigao isolate (for A. mangium and E. urophylla) with and without nitrogen-fixing bacteria. Aseptically germinated seedlings were inoculated when they were transplanted from seed boxes into individual polybags. After six months, the seedlings were planted in the mined-out area following Randomized Complete Block Design. The excavated soil were mixed with 1 kg vermicompost and 500 g lime before backfilling the 30 cm3 planting hole. After one month, 10 g NPK fertilizer and 5 g urea were applied on each seedling. Microbial-inoculated seedlings showed better growth performance with higher plant dry weight and microbial population compared to the uninoculated plants after 27 months. Hence, P. indicus, A. mangium, and E. urophylla inoculated with arbuscular mycorrhizal fungi and applied with lime, vermicompost, and basal inorganic fertilizer could be effective as reforestation species in barren mined-out areas.