Responses of aquatic vegetables to biochar amended soil and water environments: a critical review

Lactobacillus reuteri metabolites alleviate apple replant disease (ARD) by driving beneficial bacteria to reshape the core root microbiome

Previous studies have shown that the bacterial fertilizer Lactobacillus reuteri (LBR) significantly alleviates apple replant disease (ARD), but the mechanism behind its effectiveness remains unclear. This study investigated the effects of key LBR metabolites on the rhizosphere microbial community. The biocontrol function of extracellular polysaccharides (EPS) was examined and shown to be further enhanced after optimizing the fermentation conditions. The optimized fermentation conditions were found to generate intermediates involved in various plant metabolic pathways, leading to plant growth promotion, increased abundance of beneficial bacteria like Bacillus and Pseudomonas in the rhizosphere soil, and decreased abundance of pathogenic fungi. Through the isolation and identification of rhizosphere microorganisms, a strain of Pseudomonas monteilii with chemotaxis to EPS was isolated, which had growth promotion ability and effectively improved plant resistance and relieves ARD. To further understand the mechanism underlying the inhibitory effect on soil pathogens of microbial aggregations and development in the rhizosphere driven by beneficial bacteria metabolites. These findings offer valuable technical insights for utilizing biocontrol bacteria metabolites in ARD management.

Biochar amendment affects the fate of phthalic acid esters in the soil-vegetable system

Phthalates, e.g., esters of phthalic acid (PAEs), when used as plasticizers due to weak physical bonding with polymer matrix favoring leaching, are widely noted in the environment. Their confirmed toxicity to plants and animals implies that their fate should be monitored in the environment, especially when considering the interaction between soil and vegetables. Removal of PAEs from the environment or limiting their bioavailability is a key point in reducing their harmful effects. In the present paper, the fate of six PAEs in the biochar-amended soil during the cultivation of two popular vegetables, lettuce, and radish, was estimated. High bioaccumulation in the soil was noted with the biochar obtained from residues from biogas production being up to 15% higher than in the case of the other biochar and up to 10 times higher than in plants due to increased basic character of biochar. This biochar reduced the bioavailability of DEP (diethyl phthalate), DBP (dibutyl phthalate), BBP (butyl benzyl phthalate), and DNOP (di-n-octyl phthalate) in radish roots and DBP in lettuce leaves. However, PAEs significantly increased the fresh mass of radish and slightly increased the mass of lettuce. All six tested PAEs in both plants reached higher concentrations in the leaves (up to two orders of magnitude) than in the roots. Additionally, PAEs were present in two times higher concentrations in the lettuce than in the radish. The biochar aromaticity, porosity, and the presence of organic carbon and inorganics (ash) affect the fate of tested pollutants depending on the tested plant and compound.

Persistent effects of swine manure biochar and biogas slurry application on soil nitrogen content and quality of lotus root

Using swine manure biochar and biogas slurry in agriculture proves to be an effective strategy for soil improvement and fertilization. In this study, a pot trial on the growth of lotus root was conducted to investigate the persistent effects of applying 350°C swine manure biochar (1% and 2%) and biogas slurry (50% and 100%) on soil nitrogen nutrient and lotus root quality. The results showed that compared to chemical fertilizer alone (A0B0), swine manure biochar significantly increased soil nitrogen content after one year of application. The contents of total nitrogen (TN), alkali-hydrolyzed nitrogen (AHN), ammonium nitrogen (NH4 +-N), and nitrate nitrogen (N O 3 -   - N ) increased by 17.96% to 20.73%, 14.05% to 64.71%, 17.76% to 48.68% and 2.22% to 8.47%, respectively, during the rooting period. When swine manure biochar was present, the application of biogas slurry further elevated soil nitrogen content. The co-application of swine manure biochar and biogas slurry significantly increased soil nitrogen content, and the 100% nitrogen replacement with biogas slurry combined with 2% swine manure biochar (A2B2) treatment exhibited the most significant enhancement effect during whole plant growth periods. Soil enzyme activities, including soil protease (NPT), leucine aminopeptidase (LAP), b-glucosidase (β-GC) and dehydrogenase (DHA), showed a tendency to increase and then decrease with the prolongation of lotus root fertility period, reaching the maximum value during the rooting period. Compared to A0B0, the treatment with 2% swine manure biochar had the most significant effect on enzyme activities and increased the lotus root's protein, soluble sugar, and starch contents. Nitrate content decreased with the application of 2% swine manure biochar as the amount of biogas slurry increased. In conclusion, swine manure biochar effectively improved soil nitrogen content, enzyme activity, and lotus root quality. Even after one year of application, 2% swine manure biochar had the best enhancement effect.

Facilitating mitigation of agricultural non-point source pollution and improving soil nutrient conditions: The role of low temperature co-pyrolysis biochar in nitrogen and phosphorus distribution

The current study generated co-pyrolysis biochar by pyrolyzing rice straw and pig manure at 300 °C and subsequently applying it in a field. Co-pyrolysis biochar demonstrated superior efficiency in mitigating agricultural non-point source pollution compared to biochar derived from individual sources. Furthermore, it displayed notable capabilities in retaining and releasing nutrients, resulting in increased soil levels of total nitrogen, total phosphorus, and organic matter during the maturation stage of rice. Moreover, co-pyrolysis biochar influences soil microbial communities, potentially impacting nutrient cycling. During the rice maturation stage, the soil treated with co-pyrolysis biochar exhibited significant increases in available nutrients and rice yield compared to the control (p < 0.05). These findings emphasize the potential of co-pyrolysis biochar for in-situ nutrient retention and enhanced soil nutrient utilization. To summarize, the co-pyrolysis of agricultural waste materials presents a promising approach to waste management, contributing to controlling non-point source pollution, improving soil fertility, and promoting crop production.

In-situ retention of nitrogen, phosphorus in agricultural drainage and soil nutrients by biochar at different temperatures and the effects on soil microbial response

This study conducted a two-year experiment to investigate the impacts of biochar with various temperatures (350 °C, 500 °C, and 650 °C), on the reduction of pollutants in agricultural runoff and the enhancement of soil fertility. The results showed that the biochar significantly reduced the concentrations of total nitrogen and total phosphorus in farmland runoff. Moreover, higher-temperature biochar demonstrated greater efficacy in decreasing pollutants in farmland drainage. Treatment with RB650 resulted in a reduction of the total nitrogen and total phosphorus output load by 29.31-30.67 % and 21.92-25.21 %, respectively, compared to RB350. Furthermore, biochar exhibited substantial enhancements in soil fertility. This was supported by heightened soil organic matter content, increased availability of nutrients, and a noteworthy (P < 0.05) upsurge in pH, organic matter, total nitrogen, and total phosphorus content observed in the second year following the application of biochar. Biochar has the potential to enhance soil enzyme activity and affect microbial community composition, thereby facilitating nutrient cycling. The findings illustrated the regenerative and recyclable characteristics of biochar's adsorption activity throughout crop growth. This process enables sustained improvement in soil nutrient retention capacity and fertility. Thus, it emphasizes the potential of biochar as an in-situ model for nutrient retention and recycling, offering an effective approach to mitigate agricultural non-point source (NPS) pollution and enhance soil fertility.

Mixed pollutants adsorption potential of Eichhornia crassipes biochar on Manihot esculenta processing industry effluents

The starch is one of the most essential food stuff and serves as a raw material for number of food products for the welfare of human. During the production process enormous volume of effluents are being released into the environment. In this regard, this study was performed to evaluate the physicochemical traits of Manihot esculenta processing effluent and possible sustainable approach to treat this issue using Eichhornia crassipes based biochar. The standard physicochemical properties analysis revealed that the most the parameters (EC was recorded as 4143.17 ± 67.12 mhom^-1, TDS: 5825.62 ± 72.14 mg L^-1, TS: 7489.21 ± 165.24 mg L^-1, DO: 2.12 ± 0.21 mg L^-1, BOD 2673.74 ± 153.53 mg L^-1, COD: 6672.66 ± 131.21 mg L^-1, and so on) were beyond the permissible limits and which can facilitate eutrophication. Notably, the DO level was considerably poor and thus can support the eutrophication. The trouble causing E. crassipes biomass was used as raw material for biochar preparation through pyrolysis process. The temperature ranging from 250 to 350 °C with residence time of 20-60 min were found as suitable temperature to provide high yield (56-33%). Furthermore, 10 g L^-1 concentration of biochar showed maximum pollutant adsorption than other concentrations (5 g L^-1 and 15 g L^-1) from 1 L of effluent. The suitable temperature required to remediate the pollutants from the effluent by biochar was found as 45 °C and 35 °C at 10 g L^-1 concentration. These results conclude that at such optimized condition, the E. crassipes effectively adsorbed most of the pollutants from the M. esculenta processing effluent. Furthermore, such pollutants adsorption pattern on biochar was confirmed by SEM analysis.