The Effect of The Application of Soil Biostructures Created Using Biochar and Seaweed Extract on Upland Rice Growth

Abstract

Abstract Earthworms play an important role in mixing soil particles with biochar grains, as well as creating biostructures, and the application of seaweed extract to soil affects the microbes within, as well as plant growth. This study, therefore, aims to investigate the effect of mixing soil, teak leaf biochar, as well as seaweed extract on the arbuscularmycorrhizal fungal (AMF) spores within the biostructures formed, and analyze the effect of applying these biostructures to planting media soil on the growth and yield of local upland rice. Before the experiment, extract stock from Sargassum sp. was diluted with water into five separate concentration levels, 0%, 20%, 40%, 60%, and 80%. Subsequently, 20 individual earthworms were released on the soil surface previously mixed with biochar and seaweed extract in a reactor. The planting media used in this study was soil from the cogongrass area with grain sizes below 4 mm, and about 10% (w/w) of the biostructures formed were added to the media in a polybag, then the mixture was transplanted with upland rice seedlings of local variety Sorawolia.According to the results, the treatment containing had the highest total AMF spores. Furthermore, the addition of biostructures significantly affected plant height, leaf number as well as area, and the number of tillers at 42, 42 to 70, and 70 days after application, respectively. Meanwhile, the highest plant dry weight and panicle length were obtained from the treatments containing 80% and 60% extract stock, respectively. However, there was no significant difference in the spikelet number and percentage of filled spikelets between the biostructures. Therefore, the application of both teak leaf biochar and extract of Sargassum sp. was concluded to be able to improve the performance of earthworms (Pheretima sp.) in creating soil biostructures containing AMF spores, for local upland rice development in conditions of poor soil fertility. However, future studies are required to investigate this application’s potential as a source of inoculum for AMF spores or other beneficial microbes, for application at the smallholder farm level.