Production and characterization of sustainable vermimanure derived from poultry litter and rice straw using tiger worm Eisenia fetida

Enhanced vermicomposting of rice straw and pressmud with biogas slurry employing Eisenia fetida: Production, characterization, growth, and toxicological risk assessment

The biogas plant plays a dual role: it directly provides energy and indirectly promotes organic farming through outlet slurry. However, agricultural biomass wastes such as rice straws (RS) and pressmud (PM), which can't be used as fertilizers on their own, were vermicomposted (60 days) with biogas slurry (BS), using earthworm, into four blends: T1(BS, 100%), T2(3:2, BS: RS), T3(3:2, BS: PM), and T4(3:1:1, BS: RS: PM). The characterization, elemental analysis, and toxicological risk assessment of derived vermimanure were carried out using various analytical tools, such as an organic elemental analyzer such as CHNS, FT-IR, FESEM-EDXA, XPS, and ICP-OES. The pH, electrical conductivity, and C/N values were within 7.1-7.8, 3.2-6.0 dSm-1, and 12-15, respectively, for all treatments. The proportions of N (38%), P (70%), K (58%), Mg (67%), Ca (42%), and ash (44%), increased significantly (P < 0.05) over the initial feedstocks. The ecological risks of heavy metals (Zn, Cu, Ni, Pb, Cd, and Cr) in all feedstocks were found to be under WHO-permitted levels. The growth performance of earthworms was also considerably higher (P < 0.05) over the control feedstock group. The analytical methods verified that feedstock T4 (3:1:1, BS: RS: PM) was more porous, containing NH4+, PO43-, K+, and other nutrients. Pellets of all vermimanure groups keep 65-75% of the original volume. As well, when these pellets have been employed for agronomy and dispersed in the field, they will cause less dust than traditional or powdered compost or manure. In comparison to the control group, the synergistic approach of RS, PM, and BS in vermimanure significantly (P < 0.05) enhanced seed germination (83%), vigour index (42.5%), and decreased mean germination time by 27%. Furthermore, pot trials with Abelmoschus esculentus seed indicated that seedlings cultivated with 40% vermimanure of T4 (3:1:1, BS: RS: PM) mixed soil showed high growth in shoot, root, and plant yield.

Rice straw derived cellulose-based hydrogels synthesis and applications as water reservoir system

This study synthesized new cellulose-based hydrogels, namely cellulose and cellulose/poly acrylic acid, using cellulose extracted from rice straw via alkaline and acidic pulping processes. The research demonstrated alkaline treatment with sodium hydroxide to be more effective for cellulose extraction compared to acidic treatment. Hydrogel synthesis used graft polymerization and chemical crosslinking with potassium persulfate as initiator and epichlorohydrin as a crosslinker. Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TG), and scanning electron microscopy (SEM) characterized the prepared hydrogels. Important factors determining hydrogel competence are swelling ratio and water retention rate. The cellulose hydrogel exhibited the highest swelling ratio in tap water (9811%) with 76.25 wt% water retention and in artificial hard water (3121.43%) with 64.58 wt% retention after 4 days outdoors at 298 K. Finally, hydrogels were investigated extensively for agricultural applications. Fenugreek seeds germinated and grew well (67% germination after 7 days) in normal soil mixed with 10% cellulose hydrogel. Biodegradability testing exhibited 6% degradation after 40 days and 10% after 120 days in an open-air lab at room temperature and 60% humidity.

Rationalizing mineral gypsum use through microbially enriched municipal solid waste compost for amelioration and regaining productivity potential of degraded alkali soils

Reclamation of alkali soils to harness their productivity potential is more complex due to the presence of excess sodium ions, poor hydraulic conductivity and infiltration rate, resulting in poor plant growth and crop productivity. Sodic soil reclamation using inorganic ameliorants like mineral gypsum or phosphogypsum is beyond the reach of small and marginal farmers having alkali soils because of their higher market prices and shortage of availability. Conjoint use of inorganic and organic amendments can be a pragmatic solution for improving soil physico-chemical and biological properties and sustaining crop productivity. Municipal solid waste compost (MSWC) available in abundant quantity if enriched with the efficient halophilic microbial consortium and used in conjunction with a reduced dose of gypsum can be a cost-effective approach for sustainable reclamation of alkali soils and harnessing their productivity potential. Hence, a field experiment was conducted on a high alkali soil (pH₂ 9.2 ± 0.10), electrical conductivity (EC) 1.14 ±  0.12 dS m^-1, exchangeable sodium percentage 48 ± 2.50 and organic carbon (0.30%) was conducted during 2018-19 to 2020-21 to study the combined effect inorganic and organic (enriched municipal solid waste compost (EMSWC)) amendments on amelioration of alkali soils and sustaining productivity of rice-wheat cropping system. Application of gypsum @ 25% GR + enriched MSW compost @ 10 t ha^-1 (T₆) showed significant improvement in soil physico-chemical and biological properties over the sole application of organic (T₃ and T₄), inorganic (T₂) and control (T₁). A significant improvement in soil fertility status in terms of available nitrogen and micronutrients as well as CO_3, HCO₃, Cl, Ca and Mg content were recorded with the combined application of organic and inorganic soil amendments (T₅ and T₆) over the sole application of mineral gypsum. Soil microbial biomass carbon (MBC), nitrogen (MBN) and phosphorus (MBP) improved significantly due to the application of EMSWC with gypsum over the application of gypsum only. Grain yield of rice and wheat increased significantly (P < 0.05) owing to the application of a reduced dose of gypsum (25% GR) and EMSWC @ 10 t ha^-1 (T₆) with values of 5.55 and 3.83 t ha^-1, respectively over rest of the treatments. Three years economic analysis of the study revealed that treatments T₆ and T₅ gave the highest positive net return whereas it was lowest in treatment T₁ and negative in treatment T₂. The highest benefit-to-cost ratio (B:C) was obtained in treatments T₆ and T₅ which were significantly higher compared to the rest of the treatments.

Bioconversion of Eichhornia crassipes into vermicompost on a large scale through improving operational aspects of in-vessel biodegradation process: Microbial dynamics

Eichhornia crassipes is a common, abundant aquatic weed biomass found globally. The present study examined optimum biodegradation procedures through batch studies (550 L rotating drum composter) and the resulting best combination on a large scale (5000 L rotary drum composter). The pilot scale rotary drum reactor was commenced with cow manure and then treated for 3 months with 250 kg/day of homogenously mixed E. crassipes and dry leaves. The rotary drum's inlet and outlet temperatures were 60 °C and 39 °C, respectively, suggesting thermophilic conditions with a 7-day waste retention duration. Eisenia fetida was used for vermicomposting the outlet material for 20 days, raising the nitrogen content to 3.2%. Bacterial diversity (16S-rRNA) sequencing revealed that Proteobacteria and Euryarchaeota are the most predominant. After 27 days, the volume dropped by 71%, and the product was stable and soil-safe. Large-scale optimised biodegradation may be a better way to handle aquatic weed biomass.