One of the efforts to increase the production of oil palm flower bunches in ultisols is applying biofertilizers and inorganic fertilizers. Biofertilizers can reduce the use and adverse effects of inorganic fertilizers. Arbuscular Mycorrhizal Fungi (AMF) is one of the biofertilizers that can help plants absorb nutrients and increase plant resistance to various environmental stresses. This study aimed to examine the role of AMF (as biofertilizer) and inorganic fertilizers in increasing the production of oil palm flower bunches in Ultisol. This experiment is a factorial experiment using a Randomized Block Design. The first factor is the application of biofertilizers, which consists of two levels without biofertilizers (AMF) and with biofertilizers (AMF). The second factor is the dose of inorganic fertilizer, composed of 5 levels, no inorganic fertilizer, 25, 50, 75, and 100% recommended doses of inorganic fertilizer. The variables observed were the number of sheaths, the percentage of broken sheaths, the number of male flower bunches, the number of female flower bunches, the percentage of male and female flower bunches, sex ratio per plant, and AMF colonization. The results showed that AMF biofertilizer saved 25% of inorganic fertilizers and increased 29.33% of female flowers production. The highest production of oil palm flower bunches was obtained from the application of AMF biofertilizer and 75% of inorganic fertilizers (1.5 kg Urea, 1.1 kg SP-36, 1.2 kg MOP, 0.7 kg Kisserite per plant). Oil palm with AMF had a higher average sex ratio than plants without AMF biofertilizers. The average sex ratio in oil palm plants applying AMF biofertilizer and inorganic fertilizers ranged from 0.42 to 0.73.

Soybean is planted in some types of land agroecology, but production centers are mostly on peat and tides. This research was conducted at the soybean center in Rantau Rasau District with agroecology peat and tideland. The trial was arranged in a Randomized Block Design (RBD) with ten treatments and four times repeatitions. It consisted of several doses of organic material decanter cake (DC) and the percentage of the recommended amount of mineral fertilizer (RDF). RDF was selected based on Indonesia Food Crop Agriculture Service. Decanter cake from palm oil mill waste was used as a source of organic material. Experimental parameters are plant height, leaf number, grain yield, 100 grain weight, and the number of pods, seeds per pod, and plant. The result indicated the combination of mineral fertilizer and organic material DC had significant differences in increasing plant height and number of leaves. Different types of RDF and DC combinations showed substantial effects on the soybean yield and yield components. The combination of RDF 25% and decanter cake at any dose positively impacted soybean height, leaf number, and grain yield component. The highest dry seed yield of 2.48 tons per hectare was achieved by a combination of 25% RDF and 20 ton ha-1 decanter cake. Soybean yield in this study was higher than Anjasmoro’s description of 2.03–2.25 tons ha-1