The correlations and spatial characteristics of microbiome and silage quality by reusing of citrus waste in a family-scale bunker silo

Untreated agricultural waste results in significant environmental pollution and reduces economic efficiency in The Three Gorges Reservoir Region. Ensiling is a method used to improve biowaste-to-resource systems and enhance the efficiency of resource recycling. Nutrient-rich citrus waste are suitable raw material for ensiling in China, but unsuitable for large-scale ensiling. In this study, citrus waste and other agricultural by-products were used to ensile as livestock feed in a family-scale silo. Spatial variation in microbiome composition and silage quality was analyzed in the bunker silo. From the top to the bottom of the silo, the crude protein, crude fiber, and pectin contents all increased, while the loss rate of dry matter decreased, indicating that the silage quality was better in the lower section of the silo. Spatial variation in temperature, pH, and moisture significantly influenced silage quality by influencing the composition of the microbiome. Undesirable Enterobacteriaceae and Trichocomaceae were replaced by Lactobacillus, Saccharomycetaceae, Sphingobium, and Pediococcus during ensiling. Proteolysis was mainly due to the decomposition of crude protein and further hydrolysis of soluble protein by Sphingobium, Brevundimonas, and fungi. Crude fiber and pectin were primarily degraded by unclassified_o_Saccharomycetales and norank_o_Eurotiales. The pH of the silage decreased from the top to the bottom of the silo as well from the outside to the center, which is attributed to the presence of Lactobacillus and Pediococcus. More homofermentative lactic acid bacteria should be added to raw materials that are positioned higher in the bunker silo to improve silage quality. The reuse of agricultural waste as silage in Changshou Agricultural Park of the Three Gorges Reservoir Region could result in increase in annual profits of $8,282.50 USD; however, the waste handling expenses totaled $8,416.00 USD. The application of this BTR method will reduce the shortage of fermented feed and result in significant economic benefits. (C) 2019 Elsevier Ltd. All rights reserved.