The potential for using peatlands in South Kalimantan is very large. One of the efforts that can be done to increase production yields from the use of peatlands is to use biological fertilizers. This biofertilizer is very suitable to be applied to peat soil which is generally rich in organic matter but has a slow process of breaking down organic matter, with the provision of biofertilizer it can help the process of decompose organic matter in the peat soil and of course it can improve the quality of the peat soil for the better. . This study aims to determine the effect of giving biological fertilizers on the production of lettuce planted on peat soil and to determine the best type of biofertilizer for the application of the fertilizer. The method used was a one-factor completely randomized design (CRD) with five treatments: P0, P1, P2, P3 and P4 i.e without, EM-4, Agrobost, Bioboost and Bio-extrim biological fertilizer respectively. The stages carried out in this study were the preparation of materials and tools for biological fertilizers, preparation of planting media, sowing of lettuce seeds, making of biological fertilizers and application to planting media, planting of lettuce seeds into polybags, maintenance, observation and harvesting. The results showed that the application of biofertilizers affected the number of leaves, leaf area index, plant weight, plant and root weight, but had no significant effect on root length. P3 treatment was the best treatment with an average number of leaves 26.5, leaf area 97.9 cm², crown and root weight 142.3 g, plant weight 132.5 g, while for P1 was the best treatment to increase root length by the average length is 11.6 cm.