Conventionally, banana crop nutrition involves the use of chemicals. Organic banana production uses inputs from natural products and reduces the use of nonrenewable resources, in order to minimize the impact on soil, water, air and organisms in the environment. An experiment was conducted on an organic banana plantation (Musa AAA cv Williams) at EARTH University, Costa Rica, to evaluate the effect of natural sources of N and K on variables of production. The experimental design was a randomized block with eight treatments and four repetitions. Each experimental plot consisted of 22 plants and along each block leguminous species Erythrina berteroana and Cratylia argentea were planted and cyclically pruned. This material was placed on the soil as a source of organic matter and nutrients. Additional N was supplied with applications of organic amendments, EM-compost and Abimgra, and additional K with K₂SO₄ and Kmag. The N doses ranged from 164 kg/ha to 206 kg/ha per year, and K₂O between 499 kg/ha and 1188 kg/ha per year. At the time of inflorescence crop, the growth variables of plant height, pseudostem circumference, height of sucker, and number of leaves, were evaluated. The number of leaves, bunch weight, number of hands, and caliper of the fruit at harvest time also were evaluated. According to statistical analysis none of the variables showed significant differences (p>0.05).