Biomass ash as soil fertilizers: Supercharging biomass accumulation by shifting auxin distribution

Growing quantities of biomass ashes (phyto-ashs) are currently produced worldwide due to the increasing biomass consumption in energy applications. Utilization of phyto-ash in agriculture is environmentally friendly solution. However, mechanisms involving the coordination of carbon metabolism and distribution in plants and soil amendment are not well known. In the present study, tobacco plants were chemically-fertilized with or without 2‰ phyto-ash addition. The control had sole chemical fertilizer; for two phyto-ash treatments, the one (T1) received comparable levels of nitrogen, phophorus, and potassium from phyto-ash and fertilizers as the control and another (T2) had 2‰ of phyto-ash and the same rates of fertilizers as the control. Compared with the control, phyto-ash addition improved the soil pH from 5.94 to about 6.35; T2 treatment enhanced soil available potassium by 30% but no difference of other elements was recorded among three treatments. Importantly, bacterial (but not fungal) communities were significantly enriched by phyto-ash addition, with the rank of richness as: T2 > T1 > control. Consistent with amelioration of soil properties, phyto-ash promoted plant growth through enlarged leaf area and photosynthesis and induced outgrowth of lateral roots (LRs). Interestingly, increased auxin content was recorded in 2nd and 3rd leaves and roots under phyto-ash application, also with the rank level as T2 > T1 > control, paralleling with higher transcripts of auxin synthetic genes in the topmost leaf and stronger [3H]IAA activity under phyto-ash addition. Furthermore, exogenous application of analog exogenous auxin (NAA) restored leaf area, photosynthesis and LR outgrowth to the similar level as T2 treatment; conversely, application of auxin transport inhibitor (NPA) under T2 treatment retarded leaf and root development. We demonstrated that phyto-ash addition improved soil properties and thus facilitated carbon balance within plants and biomass accumulation in which shifting auxin distribution plays an important role.

Performance evaluation of moving bed bioreactor for simultaneous nitrification denitrification and phosphorus removal from simulated fertilizer industry wastewater

With increasing demand for agricultural production, chemical fertilizers are now being intensively manufactured and used to provide readily available nutrients in larger quantities, which often leach out and contaminate the groundwater source. At the same time, effluents from fertilizer plants also pollute water bodies, when disposed of without proper treatment. The present study evaluates nitrogen and phosphorus removal efficiencies in a single-stage aerobic moving bed bioreactor (MBBR) from diammonium phosphate (DAP)-spiked wastewater containing no organic carbon. To date, no similar study has been undertaken that treats fertilizer plant effluent or agricultural runoff without the aid of external carbon, where organic carbon is hypothesized to be supplied from endogenous degradation of biomass. Both denitrification and phosphorus removal occurs in the anoxic zones of deeper layers of the biofilm. The present investigation demonstrates the feasibility of the processes with the requirement of a two-stage MBBR for effective simultaneous nitrification, denitrification, and phosphorus removal (SNDPr) together with a polishing technology to bring down the phosphorus concentration within limits. A novel bio-carrier designed for efficient SND was used in the study, with a carrier filling ratio of 35% that supported the formation of deep biofilms creating anoxic zones in the inner surface. Identification of the bacterial species reflects the occurrence of simultaneous nitrification, denitrification, and phosphorous removal (SNDPr) in the reactor. A maximum ammonium nitrogen removal efficiency of 98% was recorded with 95% total nitrogen removal, 69% phosphorus removal, and 85% SND efficiency, indicating the applicability of the process with a tertiary phosphorus removal unit to lower the nutrient concentration of effluents prior to disposal.

Effects of Fermented Seaweed Fertilizer Treatment on Paddy Amino Acid Content and Rhizosphere Microbiome Community

Seaweed has often been reported on for it potential bioresources for fertilizers to improve crop productivity and reduce the use of chemical fertilizers (CF). However, little is known about the nutritional status of the crop grown with the implementation of seaweed fertilizers (SF). In this study, the amino acid content of rice produced by SF implementation was evaluated. Furthermore, the rhizosphere bacterial community was also investigated. The paddy seedlings were divided into five groups, control (C0), chemical fertilizer (CF), seaweed fertilizer (SF), chemical and seaweed fertilizer combination 25:75 (CFSF1), and chemical and fertilizer combination 50:50 (CFSF2). The CFSF2 group shown significantly better growth characteristics compared to other groups. Based on the concentration of macronutrients (N, P, K) in paddy leaf, CFSF2 also shown the best results. This also correlates with the abundant amino acid composition in CFSF2 in almost all tested amino acids, namely, serine, phenylalanine, isoleucine, valine, glycine, tyrosine, proline, threonine, histidine, and arginine. Interestingly, beneficial bacteria Rhizobiales were significantly higher in CFSF2-treated soil (58%) compared to CF (29%). Another important group, Vicinamibacterales, was also significantly higher in CFSF2 (58%) compared to CF (7%). Hence, these potentially contributed to the high rice amino acid content and yield in the CFSF2-treated paddy. However, further field-scale studies are needed to confirm the bioindustrial application of seaweed in agricultural systems.