Utilization of Titonia and soybean crop residues (soy straw) as compost, is an alternative fertilizer to increase soil fertility of Ultisols. This study aims to determine the effect of the compost mixture of Titonia lime soybean straw and artificial fertilizers in increasing soil fertility and soybean crop production. The research was conducted in the Limau Manis field experiment and laboratory analysis was carried out at the P3IN Laboratory, Andalas University, Padang. The study used a randomized design (RBD) which consisted of 10 treatments with 3 repetitions of testing. The results showed that the application of lime, compost and fertilizer had an effect on changes in the chemical properties of Ultisols, namely the soil pH value, soil N, P and K content. The provision of artificial fertilizers as much as 50% of the need for soybean plants, has a higher impact than artificial fertilizers, namely 25% on increasing soil fertility and the growth and production of soybean plants. The highest weight of soybean dry seed production was obtained at 1.85 tonnes/ha in the treatment of 500 kg/ha dolomite lime mixture + 5 tonnes of titonia/ha compost mixture with 5 tonnes/ha of soybean straw + NK fertilizer by 50% of soybean plant needs (treatment G ).

Keywords: Titonia, Soybean straw, Dolomite lime, Fertilizers, Soybean and Ultisol