Organic soil amendments using vermicomposts under inoculation of N₂-fixing bacteria for sustainable rice production

Abstract

Organic and biological fertilizers are considered as a very important source of plant nutrients. A field experiment was conducted during 2017−2018 in paddy soil to investigate the effect of vermicomposting of cattle manure mixture with Azolla and rice straw on soil microbial activity, nutrient uptake, and grain yield under inoculation of N2-fixing bacteria. Experimental factors consisted of organic amendments at six levels (vermicomposts prepared from manure (VM); manure + rice straw (VRM); manure + Azolla mixture (VAM); manure + rice straw + Azolla mixture (VRAM); raw manure without vermicomposting (M), and a control) and N2-fixing bacteria at three levels (Azotobacter chroococcum, Azospirillum brasilence, and non−inoculation). The results showed that, vermicompost treatments compared to control and raw manure significantly increased the number and biomass−C of soil microorganisms, urease activity, number of tillers hill−1, phosphorus (P) and potassium (K) uptake, and grain and protein yield. Inoculation of plants with N2-fixing bacteria, especially Azotobacter increased the efficiency of organic amendments, so that the maximum urease activity, soil microbial activity, P and N uptake, and grain yield (4,667 (2017) and 5,081 (2018) kg/h) were observed in vermicompost treatments containing Azolla (VAM and VRAM) under inoculation with Azotobacter. The results of the study suggested that, using an organic source along with inoculation with appropriate N2-fixing bacteria for vermicompost has a great effect on enzyme activity, soil biology, nutrient uptake and grain yield has a synergistic interaction on agronomic traits under flooded conditions. Therefore, this nutrient method can be used as one of the nutrient management strategies in the sustainable rice production.

Azolla Compost as an Approach for Enhancing Growth, Productivity and Nutrient Uptake of Oryza sativa L.

“…Overall, the addition of organic fertilizers results in improved acquisition of NPK nutrients; in contrast, using synthetic fertilizers (as a full recommended dose) is a corollary to achieving NPK status in both plants and their cultivated soil. Moreover, the addition of organic fertilizers can substantially decrease the amounts of synthetic fertilizer required [49,59,60].…”

Combined Effect of Prickly Pear Waste Biochar and Azolla on Soil Fertility, Growth, and Yield of Roselle (Hibiscus sabdariffa L.) Plants

“…−1 ); AZ 0%, AZ 3%, and AZ 6%, Azolla at rates of (0, 3, and 6%). Means denoted by the same letter indicate no significant difference according to Duncan's tests at p < 0.05 However, the conjunction use of BC and AZ resulted in a significant increase in yield and quality via improvement soil properties, increasing soil organic matter which leads to soil carbon-rich that enhances soil microorganisms and nutrient availability resulting higher plant yield and its quality (Eissa 2019;Ghadimi et al 2021;Kabiri et al 2021). Also, combined application of biochar and Azolla improved the growth features of rosemary plants in calcareous soils of arid and semiarid regions (Sadegh Kasmaei et al 2019).…”

Effects of Vermicompost on Soil and Plant Health and Promoting Sustainable Agriculture

“…It also possesses antimicrobial substances and defense systems that protect worms from the infective effects of microorganisms [29]. Using VC in nutrient management offers cost savings and mitigates environmental issues associated with raw manure, providing a safer and more stable soil amendment [23].…”

“…To enhance the nutrient content of VC, the addition of nitrogen-rich Azolla pinnata, cattle dung, and inoculation with nitrogen-fixing bacteria has been suggested. This combination, known as VAM (VC, Azolla, manure), has demonstrated high-quality VC suitable for agricultural applications and has shown the highest biological yield [23]. Earthworms play a vital role in increasing nitrogen content through various mechanisms, including introducing nitrogen-rich mucus, decaying worm tissues, and promoting microbial-mediated nitrogen mineralization.…”