Soil acidity is a major problem of agriculture in many parts of the world. Soil acidity causes multiple problems such as nutrient deficiency, elemental toxicity and adverse effects on biological characteristics of soil, resulting in decreased crop yields and productivity. Although a number of conventional strategies including liming and use of organic and inorganic fertilizers are suggested for managing soil acidity but cost-effective and sustainable amendments are not available to address this problem. Currently, there is increasing interest in using biochar, a form of biomass derived pyrogenic carbon, for managing acidity while improving soil health and fertility. However, biochar varies in properties due to the use of wide diversity of biomass, variable production conditions and, therefore, its application to different soils can result in positive, neutral and or negative effects requiring an in-depth understanding of biochar-acid soil interactions to achieve the best possible outcomes. Here, we present a comprehensive synthesis of the current literature on soil acidity management using biochar. Synthesis of literature showed that biochars, enriched with minerals (i.e., usually produced at higher temperatures), are the most effective at increasing soil pH, basic cation retention and promoting plant growth and yield. Moreover, the mechanism of soil acidity amelioration with biochar amendments varies biochar types, i.e., high temperature biochars with liming effects and low temperature biochars with proton consumption on their functional groups. We also provide the mechanistic interactions between biochar, plant and soils. Altogether, this comprehensive review will provide guidelines to agricultural practitioners on the selection of suitable biochar for the reclamation of soil acidity.

It is imperative to enhance crop yield to meet the demands of a burgeoning global population while simultaneously safeguarding the environment from adverse impacts, which is one of the dominant challenges confronting humanity in this phase of global climate change. To overcome this problem and reduce dependency on chemical fertilizer, scientists now view the implementation of biostimulant strategies as a cost-effective and environmentally friendly approach to achieving sustainable agriculture. Plant extracts are rich in bioactive phytocompounds, which can enhance plant resistance to disease, pest, and abiotic stresses (e.g., drought, salinity, and extreme temperature), and promote plant growth and productivity. Furthermore, the application of plant extracts through soil drenching can also significantly change the rhizosphere soil microbiome, and indirectly interact with plants, eventually stabilizing plant growth. Currently, the application of plant extracts as a whole is effective, which emphasizes the contribution of complex interactions between multiple compounds, with seaweed extracts being the most widely studied and utilized. Interestingly, plant extracts are compatible with fertilizer and can be applied in conjunction with nutrient inputs to further enhance their effectiveness. Given all this knowledge, exploring the growth and functional effects induced by plant extracts, as well as understanding their interactions and mechanisms in plants, is crucial for developing advantageous approaches with potential value in integrated crop management systems, ultimately contributing to sustainable production.

Co-composting is an effective approach to biowaste management. The co-composting potential of banana pseudostem (BPS) and mushroom media waste (MMW) with chicken manure (CM) has not been explored, let alone their suitable ratios of co-composting being determined. Meanwhile, the imbalance ratios of the feedstocks used in the process severely restrict the physicochemical properties and quality of the finished product. For this reason, six different ratios of BPS, MMW, and CM, viz. 1:1:1, 1:2:1, 1:3:1, 2:1:1, 2:2:1, and 2:3:1, respectively (T₁–T₆), were composted together in aerobic conditions to identify the suitable ratio by evaluating the changes in the physicochemical properties in the composting process. According to the ratio of treatments, the feedstocks were mixed on fresh weight basis. The turning process of co-composting piles was repeated at seven-day intervals to maintain the uniform aeration throughout the composting period. The piles having BPS, MMW, and CM at ratios of 1:2:1, 1:3:1, and 2:3:1, respectively, demonstrated a longer thermophilic phase, indicating more complete decomposition and earlier maturity compared to piles with higher amount of BPS. Of the ratios, BPS:MMW:CM at 1:2:1 ratio (T₂) resulted in the highest total nitrogen (1.53%), lowest C:N ratio (12.4), organic matter loss (54.5%), and increased CEC (41.3 cmol/kg). The highest germination index (129%) was also recorded in the T₂ compost, indicating that it was toxic-free and safe for seed germination. The nutrient-rich compost with high alkaline pH (≥10) can effectively ameliorate soils of an acidic nature, for example, the acidity of Ultisols and Oxisols.

Acid soil is an obstacle to agricultural development and a concern regarding food and environmental security. Therefore, a study was carried out for two consecutive years to see how lime and organic manure (OM) amendments affect yield and nutrient absorption in the Transplanted (T.) Aman–Mustard–Boro cropping pattern in an acidic terrace soil. With nine treatments and three replications, the experiment was set in a randomized complete block design. The treatments were applied to the first crop, T. Aman, with different dosages of lime (dololime at the rate of 1 and 2 t ha⁻¹), OM (cow dung at 5 t ha⁻¹, poultry manure at 3 t ha⁻¹) and lime–OM combination, and their residual effects were studied in the following mustard and boro rice crops. Results demonstrate that the effect of lime and manure was more pronounced in the case of the second and third crops in the first year and of all crops in the pattern in the second year. In the first year, grain and straw yield of T. Aman as well as the overall system productivity were not influenced significantly by the application of lime and manure, but significant increases were obtained in the second year. As an average of both years, the highest grain yield of 5.2 t ha⁻¹ (12% over control) was recorded for T. Aman, 1.7 t ha⁻¹ (41% over control) for mustard and 5.9 t ha⁻¹ (47% over control, 3.9 t ha⁻¹) for boro rice when dololime was applied in combination with poultry manure. In both years, N, P, K and S uptake were significantly increased compared to the control in all the crops due to the combined application of lime and cow dung or poultry manure. Combined application of lime and manure amendment significantly improved nutrient availability and soil quality. Therefore, applying lime in combination with manure can be practiced to uplift crop productivity in acidic terrace soils.

The conversion of chicken feathers, generated annually worldwide on a large scale as a by-product of the poultry industry into value-added products, has economic and environmental benefits. Protein hydrolysate produced from feathers has attracted significant attention in agriculture as a potential plant growth stimulant. Therefore, a study was established with the aim to produce and characterize chicken feather protein hydrolysate (CFPH) and investigate the effects of this product on the early growth of nursery tea plants. Alkaline hydrolysis was used to produce CFPH with the yield of 165 mg amino acids per gram of feathers. Then, the produced CFPH was applied on nursery tea plants as a soil drench at different doses (0.5, 1, 2, 3, and 4 g L⁻¹) in 2-week intervals until the 10th application. Commercially available fish protein hydrolysate (FPH) was included as a treatment to compare the effects with CFPH. The treatments were arranged in a completely randomized block design with three replications. CFPH and FPH significantly improved the shoot and root growth parameters. Plant height (+98%), leaf number (+61%), shoot dry biomass (+128%), root length (+94%), root surface area (+15%), and root dry biomass (+152%) were significantly increased by the application of CFPH (2 g L⁻¹ dose) compared to control. Although the highest CFPH dosage (4 g L⁻¹) showed a reduction in growth parameters, the values obtained were similar or higher than the untreated control plants. The chlorophyll content (a, b, and total) was enhanced by the CFPH dosage of 1 g L⁻¹, whereas the highest photosynthetic rate was recorded in the CFPH 3 g L⁻¹ treatment. The application of protein hydrolysates (PH) did not positively influence stomatal conductance and intercellular CO₂ concentration. Leaf nitrogen, phosphorous, manganese, and copper were positively affected by the CFPH application. The effect of CFPH on growth parameters was more pronounced than FPH. Our findings reveal that CFPH produced by alkaline hydrolysis could be used as a growth booster in raising vigorous tea nursery plants, which are most suitable for field planting and subsequently higher yields.