Hydrolytic Amino Acids Employed as a Novel Organic Nitrogen Source for the Preparation of PGPF-Containing Bio-Organic Fertilizer for Plant Growth Promotion and Characterization of Substance Transformation during BOF Production

Effects of magnesite on nitrogen conversion and bacterial community during pig manure composting

The objective of this research was to elucidate the effect of varying proportions of magnesite (MS) addition - 0% (T1), 2.5% (T2), 5% (T3), 7.5% (T4), and 10% (T5) - on nitrogen transformation and bacterial community dynamics during pig manure composting. In comparison to T1 (control), MS treatments amplified the abundance of Firmicutes, Actinobacteriota, and Halanaerobiaeota, bolstered the metabolic functionality of associated microorganisms, and enhanced the nitrogenous substance metabolic pathway. A complementary effect in core bacillus species played a key role in nitrogen preservation. Compared to T1, 10% MS demonstrated the most substantial influence on composting because Total Kjeldahl Nitrogen increased by 58.31% and NH₃ emission decreased by 41.52%. In conclusion, 10% MS appears to be optimal for pig manure composting, as it can augment microbial abundance and mitigate nitrogen loss. This study offers a more ecologically sound and economically viable method for curtailing nitrogen loss during composting.

Effects of Valine and Urea on Carbon and Nitrogen Accumulation and Lignin Content in Peach Trees

Nitrogen availability and uptake levels can affect nutrient accumulation in plants. In this study, the effects of valine and urea supplementation on the growth of new shoots, lignin content, and carbon and the nitrogen metabolism of 'Ruiguang 39/peach' were investigated. Relative to fertilization with urea, the application of valine inhibited shoot longitudinal growth, reduced the number of secondary shoots in autumn, and increased the degree of shoot lignification. The application of valine also increased the protein level of sucrose synthase (SS) and sucrose phosphate synthase (SPS) in plant leaves, phloem, and xylem, thereby increasing the soluble sugar and starch content. It also resulted in an increase in nitrate reductase (NR), glutamine synthase (GS), and glutamate synthase (GOGAT) protein levels, with an increase in plant contents of ammonium nitrogen, nitrate nitrogen, and soluble proteins. Although urea application increased the protein level of carbon- and nitrogen-metabolizing enzymes, the increase in plant growth reduced the overall nutrient accumulation and lignin content per unit tree mass. In conclusion, the application of valine has a positive effect on increasing the accumulation of carbon and nitrogen nutrients in peach trees and increasing the lignin content.

Fungi That Promote Plant Growth in the Rhizosphere Boost Crop Growth

The fungi species dwelling in the rhizosphere of crop plants, revealing functions that endeavor sustainability of the plants, are commonly referred to as 'plant-growth-promoting fungi' (PGPF). They are biotic inducers that provide benefits and carry out important functions in agricultural sustainability. The problem encountered in the agricultural system nowadays is how to meet population demand based on crop yield and protection without putting the environment and human and animal health at risk based on crop production. PGPF including Trichoderma spp., Gliocladium virens, Penicillium digitatum, Aspergillus flavus, Actinomucor elegans, Podospora bulbillosa, Arbuscular mycorrhizal fungi, etc., have proven their ecofriendly nature to ameliorate the production of crops by improving the growth of the shoots and roots of crop plants, the germination of seeds, the production of chlorophyll for photosynthesis, and the abundant production of crops. PGPF's potential mode of action is as follows: the mineralization of the major and minor elements required to support plants' growth and productivity. In addition, PGPF produce phytohormones, induced resistance, and defense-related enzymes to inhibit or eradicate the invasion of pathogenic microbes, in other words, to help the plants while encountering stress. This review portrays the potential of PGPF as an effective bioagent to facilitate and promote crop production, plant growth, resistance to disease invasion, and various abiotic stresses.

Tannery waste as a renewable source of nitrogen for production of multicomponent fertilizers with biostimulating properties

The studies presented in this work show that solid tannery waste-like shavings can be used as high-protein materials for fertilizer production following the concept of the circular economy. To select appropriate process parameters (mass ratio of shavings meal to the hydrolyzing agent (S:L), hydrolysis medium concentration, temperature) and to ensure the highest possible hydrolysis efficiency, it is useful to apply the well-known response surface methodology (RSM). The analyses revealed that chromium shavings (SCr) were most preferably treated with 10% KOH in a ratio of S:L 1:1 with the process being carried out at 160 °C (6.59% N). The optimal hydrolysis conditions for non-chromium (S) shavings were: S:L ratio 1:2, 10% H₂SO₄, and temperature 160 °C (4.08% N). Chromium concentrations in hydrolysates from S and SCr shavings obtained under optimal conditions were 15.2 mg/kg and 9483 mg/kg, respectively. Hydrolysate samples were analyzed by reversed-phase high-pressure liquid chromatography (RP-HPLC) that revealed that the type of hydrolysis (acidic/alkaline) affects the amino acid profile. Approximately 4.5 times more amino acids were extracted in the KOH environment than during acidic treatment. The hydrolysates contained mainly glycine, alanine, and proline, which are primarily responsible for stimulating plant growth by supporting chlorophyll synthesis, chelating micronutrients, improving pollen fertility, or resistance to low temperatures. The conversion of tannery waste into fertilizer requires the control of contaminant levels, especially chromium, which can oxidize to the carcinogenic form Cr(VI) that is hazardous to humans and the environment.

Coupling thermophilic composting and vermicomposting processes to remove Cr from biogas residues and produce high value-added biofertilizers

Removing pollutants and producing high value-added products are essential steps for sustainable disposal and utilization of biogas residues. Here, a coupled thermophilic composting and vermicomposting process was used to remove Cr from biogas residues, and the composting products were co-fermented with the plant growth-promoting fungus Trichoderma to produce high value-added biofertilizers. The results showed that thermophilic composting for 37 d markedly increased the total content of Cr but decreased the percentage of available Cr fractions. Synchrotron-radiation-based observations further provided direct evidence of the binding sites to support the results from traditional sequential extraction. At a density of 60 g earthworm/kg biogas residues, vermicomposting removed 23-31% of Cr from biogas residues. After vermicomposting, co-fermentation of biogas residues and Trichoderma was optimized, in which Trichoderma spores were 2-5 × 10⁸ cfu/g substrates. Together, coupling thermophilic composting and vermicomposting processes is a promising technique to remove a portion of heavy metals from biogas residues.

Bioprospecting of Rhizosphere-Resident Fungi: Their Role and Importance in Sustainable Agriculture

Rhizosphere-resident fungi that are helpful to plants are generally termed as 'plant growth promoting fungi' (PGPF). These fungi are one of the chief sources of the biotic inducers known to give their host plants numerous advantages, and they play a vital role in sustainable agriculture. Today's biggest challenge is to satisfy the rising demand for crop protection and crop yield without harming the natural ecosystem. Nowadays, PGPF has become an eco-friendly way to improve crop yield by enhancing seed germination, shoot and root growth, chlorophyll production, and fruit yield, etc., either directly or indirectly. The mode of action of these PGPF includes the solubilization and mineralization of the essential micro- and macronutrients needed by plants to regulate the balance for various plant processes. PGPF produce defense-related enzymes, defensive/volatile compounds, and phytohormones that control pathogenic microbes' growth, thereby assisting the plants in facing various biotic and abiotic stresses. Therefore, this review presents a holistic view of PGPF as efficient natural biofertilizers to improve crop plants' growth and resistance.