High-Energy-Density Organic Amendments Enhance Soil Health

Abstract

Soil microbial biomass (SMB) and soil microbial communities (SMCs) are the key factors in soil health and agricultural sustainability. We hypothesized that low bioavailable carbon (C) and energy were the key limiting factors influencing soil microbial growth and developed a new fertilization system to address this: the simultaneous application of mineral fertilizers and high-energy-density organic amendments (HED-OAs). A microcosm soil incubation experiment and a Brassica rapa subsp. chinensis pot culture experiment were used to test the effects of this new system. Compared to mineral fertilizer application alone, the simultaneous input of fertilizers and vegetable oil (SIFVO) achieved a bacterial abundance, fungal abundance, and fungal:bacterial ratio that were two orders of magnitude higher, significantly higher organic C and nitrogen (N) content, significantly lower N loss, and nearly net-zero N2O emissions. We proposed an energy and nutrient threshold theory to explain the observed bacterial and fungal growth characteristics, challenging the previously established C:N ratio determination theory. Furthermore, SIFVO led to microbial community improvements (an increased fungal:bacterial ratio, enriched rhizosphere bacteria and fungi, and reduced N-transformation bacteria) that were beneficial for agricultural sustainability. A low vegetable oil rate (5 g/kg) significantly promoted Brassica rapa subsp. chinensis growth and decreased the shoot N content by 35%, while a high rate caused severe N deficiency and significantly inhibited growth of the crop, confirming the exceptionally high microbial abundance and indicating severe microbe–crop competition for nutrients in the soil.

Anaerobic Storage Completely Removes Suspected Fungal Pathogens but Increases Antibiotic Resistance Gene Levels in Swine Wastewater High in Sulfonamides

“…The decrease in bacterial and fungal abundances can be mainly attributed to the loss of nutrients (e.g., C and N) and the long period of exposure to inhibitory sulfonamides in the SWW under anaerobic conditions. In particular, the fungi could be more sensitive to nutrient loss because fungi have higher nutrient requirements than bacteria [ 23 ]. Additionally, fungi could be more seriously inhibited than bacteria by the sulfonamides in the SWW under anaerobic conditions.…”

“…The 16S rRNA gene of bacteria (in the V3–V4 region) was amplified using the primer pairs 515F and 806R, and 528F and 706R [ 3 ]. The rRNA gene of fungi was amplified using the ITS1-F, ITS2-2043R, and ITS5-1737F primers [ 23 ]. Sequencing of bacteria and fungi was performed using the Illumina HiSeq 2500 platform (BGI Co., Ltd., Shenzhen, China).…”

“…Sequencing of bacteria and fungi was performed using the Illumina HiSeq 2500 platform (BGI Co., Ltd., Shenzhen, China). Sequence analyses were conducted according to the methods of Wang et al [ 3 ] and Shi et al (2022) [ 23 ].…”

Manure enriched with nitrogen derived from high-protein food waste in a large dining facility

“…Bacterial and fungal DNA sequencing was performed using an Illumina HiSeq 2500 platform (BGI Co. Ltd., Shenzhen, China). Sequence analyses were conducted according to the methods described by Shi et al (2022) [ 24 ].…”