Effectiveness of plant growth promoting microrganisms as biofertilizer for soybeans under oil palm plantations on tidal land

Abstract

A research to study the effectiveness of biofertilizers on nodulation, growth and productivity of soybean was carried out at two locations on type D tidal lands in South Kalimantan, using a randomized block design with four replications. The treatments tested were N-fixing bacteria Rhizobium japonicum, P solubilizing bacteria (PSB) Pseudomonas sp and mycorrhiza biofertilizers, combined with inorganic nitrogen (N) and phosphorus (P) fertilizers in the form of Urea and SP36 with low (25:25), moderate (50:50) and high (100:100) kg/ha doses. At the first location, the highest seed yield (2.04 t ha) was obtained in the rhizobium + PSB treatment combined with moderate dose of Urea and SP36 (50:50). This yield was 34% increase compared to seed yield at the same fertilizer rate without any biofertilizer. The same response was also obtained in second location where the soil was more acidic. The highest seed yield (1.9 t/ha) was obtained in the rhizobium + PSB treatment with a moderate dose of N and P fertilizer (50:50). This treatment resulted in 70% yield increase compared to that obtained by the treatment of the same fertilizer rate without bio fertilizer. In treatment of rhizobium + PSB + mycorrhiza, the seeds yield obtained were not different from the rhizobium + PSB treatment. This yield increase was supported by increasing the number and weight of root nodules, leaf chlorophyll index, weight of 100 seeds, and the number of filled pods per plant. This shows that the tested biofertilizers was effective on tidal land, and was able to increase soybean productivity.