Application of bio and NPK fertilizer to improve yield soybean and acid sulfate soil properties in Indonesia

In Indonesia, soybean (Glycine max (L.) Merr.) is the second most important staple food with low production compared to the demand. This problem can be overcome by using marginal land such as acid sulfate soil of tidal swampland, however, the optimal application of fertilizer in such soil is minimal. Therefore, this study aims to examine the application of fertilizer in acid sulfate soil in South Kalimantan, Indonesia. It was conducted using a split-plot design with three replicates and the main plot was biofertilizer, which consisted of no-biofertilizer (P1); biofertilizer consortium of decomposer fungi, P-solubilizing bacteria, N-fixing bacteria (P2), and biofertilizer consortium of N-fixing bacteria symbiotic and nonsymbiotic, P-solubilizing bacteria and phytohormone-producing bacteria (P3). Meanwhile, the subplot was NPK fertilizer dosage, consisting of no-fertilizer (A1), dose of 150% (A2), dose of 100% (A3), and dose of 50% (A4) of the recommendation. The results showed that the biofertilizer and NPK fertilization dose did not show an interaction with soil pH and Al3+. The highest N and K nutrient uptake was in P2 at 50% NPK fertilizer dosage, while P in P3 at 150% NPK fertilization dose. The highest soybean yields were obtained in the application of biofertilizer P3 with 150% NPK, i.e., 1.6 t ha-1, followed by the 1.5 t ha-1 in the application of P2 + 50% NPK. This showed that the use of P2 biofertilizer can reduce NPK fertilizer application to 50% in soybean plants in acid soil tidal lands. Furthermore, the application of biofertilizers can increase soybean productivity in acid sulfate soil in Indonesia.