Effect of rock phosphate and plant growth-promoting rhizobacteria on physical and chemical properties change of corn residues during composting

Abstract

This study aims to study the effect of adding rock phosphate and plant growth-promoting rhizobacteria (PGPR), in the physical and chemical properties of the corn residues compost during aerobic decomposition. Four composting heaps were included in this study as it follows, 1) traditional method composting heap (T1), 2) heap was supplied with rock phosphate (T2), 3) heap was supplied with rock phosphate + Bacillus megatherum culture (T3), and 4) heap was supplied with rock phosphate+(Bacillus.megatherum, Azospirillum lipoferum, Azotobacter chroococcum) mixed cultures (T4). All compost treatments showed an increase in temperature right after composting started. The heap treated with three bacterial inoculums (T4) reached the highest peak values of 62.2°C on day 12 compared to other treatments. At the end of the composting period T1 recorded the lowest value of bulk density (533 kg/m 3 ) compared to other treatments. The pH value declined to stabilize with the end result at 100 days being 6.9, 7.4, 7.1 and 7.0 for composting treatment T1, T2, T3 and T4, respectively. The initial C/N ratio was 61:1 for all composting treatments, and the final values of total C/N ratio after the 100 days were 15:1, 14:1, 12:1 and 10:1 for composting treatments T1, T2, T3 and T4 respectively. Compost supplied with rock phosphate and three bacterial inoculums (T4) reached has more N, P and K content compared to other composting treatments T1, T2, T3. These results indicated that adding rock phosphate and (PGPR) to corn residues during composting improve nutritional value of the resulting compost.

Composting of Rice Straw–Based Materials using Aerobic Bioactivator Isolated from Rice Straw, Mahogany Bark and Cassava Peels

“…Important factors that can accelerate the composting process and improve compost quality are the quality of the main organic material and compost additives, the selected microbial biostarter or bioactivator, and the technology used during the composting process (Tognetti et al, 2005;Sánchez et al, 2017). Exploration and examination of microbial consortia as compost bioactivator have been reported in many previous studies, such as evaluation of the traditional bioactivator (MOL) with commercial bioactivator EM4 using Takakura Method (Wikurendra et al, 2022), the effect of exogenous cellulosedegrading bacteria as bioactivator in the co-composting of corn straw and cattle manure (Wang et al, 2022), the addition effect of rock phosphate and plant growth-promoting rhizobacteria in the composting of corn residue (Rasslan et al, 2021), and effect of lignocellulolytic microorganisms isolated from the peel of cassava, dried rice straw and sawdust for the composting of rice straw (Cahyani et al, 2021). Various studies on compost bioactivators have been carried out, but information on the effect of microbial consortia of aerobic bioactivators isolated from several sources, such as the thermophilic stage of composting, lignocellulosic residue, and added as a set with natural bio supplement in the composting, is still limited.…”