Development and Formulation of Beneficial Rhizobacteria Consortia to Improve Soil Health and Agricultural Practice Sustainability in Indonesia

Abstract

Since the green revolution, the inorganic fertilizers and other agrochemical products have been used intensively to boost the agricultural productivity. Thus, these practices increased the food production significantly but, at the same time, caused the severe degradation of soil health. Currently, about 70% of paddy soils and 90% of the dry land ecosystem have been exhausted and severely degraded as indicated mainly by the low organic content (<1.5%). These chemical inputs also slowly change the nutrient supplying capacity, making the soils even more infertile. Nutrient deficiency has become a major limiting factor in food production. Beneficial microorganisms in the rhizosphere and soil mediate nutrient cycle, enhance nutrient mobilization, and facilitate the uptake, leading to increased root growth, biomass, and yield of plants. Based on the condition, we conducted field experiments to investigate the effect of beneficial rhizobacteria consortia to improve soil health, fertilizer use efficiency, and crop productivity in various Indonesian soil ecosystems. The consortia of beneficial rhizobacteria were formulated with organic-based carriers. Consortia of Bradyrhizobium japonicum, Pseudomonas sp., and Bacillus sp., given at the rate of 200–400 g ha⁻¹ on soybean; Azotobacter sp., Azospirillum sp., Pseudomonas sp., Bacillus sp., and Acinetobacter sp., at 400–600 g ha⁻¹ on rice; and Azotobacter sp., Azospirillum sp., Pseudomonas sp., Bacillus sp., Streptomyces sp., and Trichoderma sp., at 800–1200 g ha⁻¹ on corn, were evaluated. Our results showed that soybean inoculants could increase the soybean grain yield and reduce the inorganic N fertilizers by 50–75%; rice inoculants increased the grain yield and reduced the inorganic N and P by 25%, and corn inoculants increased the corn grain yield and reduced the inorganic N and P fertilizers by 25%. The combination of rhizobacterial inoculant and 2–5 t straw compost (ameliorant) increased the soil organic carbon and rice productivity and reduced inorganic NPK fertilizer by 25–50%. Beneficial rhizobacteria consortia composition with organic-based carriers has a great commercial potential to improve soil health, crop productivity, and sustainability of agricultural practices.