Soil Supplement Research Articles

Wood-Based Biochar Ratio Used for Partial Peat Replacement in Growing Media for Antirrhinum majus Pot Production

Biochar has been promoted mostly as a soil supplement that improves plant growth/yield and to a lesser extent as a growing medium component. The alarmed situation for peat substitution in growing medium renders biochar as a promising substitute for current research. In this study, biochar derived by wood-based materials was evaluated at different ratios (0, 5, 10, 15, and 20% v/v) for peat partial substitution for Antirrhinum majus pot production. Biochar had increased potassium content and pH, which affected the growing media properties (total pores space and water filled capacity) and decreased nitrogen and phosphorus content in the media. Adding ≥15% biochar increased plant height and decreased flowering, but no effect was observed on plant biomass produced. The presence of biochar increased the total phenols and flavanols content and antioxidant capacity, with greater effects at the higher biochar rates used. This resulted in lipid peroxidation and an increase in hydrogen peroxide content, causing oxidative stress. Potassium and magnesium accumulated more but nitrogen and phosphorus were accumulated less in snapdragon leaves. Biochar at 10% can be considered as a successful candidate to partially substitute peat, and efforts to improve growing media characteristics are required for A. majus pot production.

Effects of Biochar-Amended Composts on Selected Enzyme Activities in Soils

This study examines the effect of biochar as an agricultural soil supplement on soil quality indicators, specifically enzyme activity in Missouri regions. While the benefits of biochar on soil bulk density, soil organic carbon, and infiltration have been established, its effect on soil enzyme activity has remained underexplored in this region. A three-year field investigation was conducted with six treatments (compost, biochar, compost + biochar, biochar + compost tea, fescue, and control) to evaluate the effects on enzymes such as β-glucosidase (BG), acid and alkaline phosphatases (ACP-ALP), arylsulfatase (ARS), dehydrogenases (DG), arylamidase (AMD), cellulase (CLS), and urease (URS). Furthermore, soil pH, organic matter (OM), and cation exchange capacity (CEC) were determined. The results showed that compost and biochar treatments considerably increased soil enzyme activity compared to other treatments, with nitrogen application further increasing enzyme activity. Soil pH, OM, and CEC were all important determinants in determining enzyme activity, with BG demonstrating strong positive associations with ACP and AMD (99.5%). This study shows that compost and biochar amendments significantly improve soil physicochemical and biological properties, thereby enhancing soil health and assisting farmers’ sustainable soil management practices.

A Review on the Applications of Biochar in Agricultural Farms: A Low Carbon Emission Technology

Improving the condition of the soil is essential for successful agriculture since it increases crop output and soil fertility. Applying biochar to the soil can boost crop yields and soil fertility. Biochar is a solid carbon-rich substance made by pyrolyzing biomass, which includes trash, wood, and agricultural crop leftovers under low oxygen conditions. Because biochar has potential uses in waste recycling, soil nutrient retention, and greenhouse gas emission reduction, it is significant for sequestering carbon. Over the last two decades, biochar has received substantial attention in agriculture and the environment. Agriculture soil productivity has long been increased by the application of synthetic fertilizers, some of which leached into the environment and released greenhouse gases (GHG). Improving soil microbiology and water retention, as well as increasing fertilizer efficiency, are some of the basic problems facing agricultural practices. Biochar is becoming more and more popular as a soil supplement to increase crop yields and sequester carbon. Biochar is one of the many conservation agricultural techniques that can be used to improve soil fertility, and crop productivity, and slow down global warming. It is also a readily available and important input for sustainable agriculture. Furthering global food security, biochar may improve soils' ability to produce crops under various biotic and abiotic stress. This review examines the numerous uses of biochar to guarantee the long-term, safe enhancement of soil fertility. An overview of the characteristics, manufacturing process, and applications of biochar in agriculture is given in this review. Researchers, farmers, and academics interested in using biochar might find this review to be a helpful resource.

Impacts of High-Frequency Chicken Manure Biochar Application on N2O and CH4 Emissions from Vegetable Field in Subtropical China

Vegetable production in Subtropical China is distinguished by excessive nitrogen (N) fertilization, frequent irrigation, and multiple crop rotations in a single year. The aforementioned variables are closely related to soil nitrous oxide (N2O) and methane (CH4) emissions. Hence, we conducted a field trial to measure N2O and CH4 emissions using static chamber–gas chromatograph. Four treatments were used: control (CK) with no fertilizer, 100% chemical N fertilization (CN), the conventional 30% chicken manure N plus 70%CN (CMN + CN), and 30% chicken manure biochar N plus 70%CN (CMBN + CN). The annual cumulative N2O emissions reached 12.4, 63.5, 111.8, and 44.1 kg N2O-N ha−1 for the CK, CN, CMN + CN, and CMBN + CN treatments, respectively. Compared to the CN and CMN + CN treatments, the CMBN + CN treatment reduced N2O emissions by 35.9%–65.7%, while it simultaneously increased the total vegetable yield by 16.1% compared to the CN treatment. Seven seasons mean N2O emission factors are 1.3% for CN, 3.8% for CMN + CN, and 0.9% for CMBN + CN. The CH4 emission was negligible, ranging from 0.07 kg CH4-C ha−1 for the CK treatment to 0.8 kg CH4-C ha−1 for the CN treatment. N2O emissions peaked under the conditions of an interior chamber temperature of around 31.9 °C and the water-filled pore space (WFPS) of the soil being approximately 60%. Future climate change will intensify, triggering higher N2O emissions from subtropical vegetable fields. CMB can be one of the best substitutes for direct chicken manure application as a soil supplement because it has a beneficial effect on improving vegetable yield and reducing N2O emissions in Subtropical China.

Effect of integrated soil fertility management on water retention, productivity and physiological parameters of Alfalfa (Medicago sativa) without and under deficit irrigation

The use of subpar agricultural techniques in arid regions is causing depletion of fresh water reservoirs and soil fertility, which has serious implications for the environment and food productivity. Although numerous studies have examined the effects and benefits of biochar as a soil supplement, particularly on soil water holding capacity, plant productivity, and soil fertility, limited information exists on the effects of biochar at different doses with biocompost on the productivity and physiological parameters of alfalfa compared to conventional agricultural practices under water stress in the field. This field study at three repetitions aimed to investigate how biochar made from tomato waste and date seeds pyrolyzed at a temperature around 540 °C affects soil chemical composition, water retention capacity, photosynthesis, protein levels, enzymatic activity, productivity, maturity, and stomatal traits in alfalfa under and without deficit water compared to conventional agricultural practices based on manure and chemical fertilizer. The results showed that biochar significantly increased the water retention capacity, especially when mixed with biocompost. The highest water retention capacity was observed in the 6 % biochar 3 % biocompost and 6 % biochar 6 % biocompost treatments, which exceeded 0.7 g H2O/g dw. The high productivity and maturity were observed with manure at medium doses combined with chemical fertilizers and at high doses of munure alone, but these results were unstable with time and with the irrigation regime. On the other hand, the fluctuation of these data was minimal for the 3 % biochar 0 % biocompost treatment under and without water stress. In addition, the low dose treatment of manure with chemical fertilizers resulted in high levels of proteins, photosynthetic activities, and low enzymatic activities, indicating that this treatment is better adapted to stress conditions. The treatments with biocompost alone yielded low results on all the parameters studied. To conclude, incorporating biochar and biocompost, especially in synergistic combinations, enhances water retention capacity and sustains alfalfa productivity under both stressed and unstressed conditions. These findings suggest a promising alternative to traditional manure and chemical fertilizers, showcasing the potential of biochar-based strategies for resilient and sustainable agricultural practices.

Enhancing iron concentration in bread wheat through Fe-EDTA fortification

Iron (Fe) malnutrition in humans is a global concern which can be revised by improved Fe density in staple crops. A field experiment was performed to evaluate the effect of chelated iron on growth, yield and iron concentration in bread wheat (cv. Moomal) at Tando Jam Pakistan. The treatments included, Control (No Fe-EDTA), Soil supplement of Fe-EDTA (@ 2 kg Fe ha-1), Soil + foliar supplement of Fe-EDTA (@ 2 kg ha-1 and 0.2% Fe at booting, flowering, and milky stage), and Foliar supplement of Fe-EDTA (@ 0.2% Fe at booting, flowering and milky stages). The defined growth and yield traits of wheat were increased with Fe-EDTA applications over control treatment. Among different Fe-EDTA application methods, there was no significant difference for most of the growth and yield parameters (excluding spike length, number of spikelets spike-1, and 1000 grain weight). The amount of Fe in wheat grains was significantly higher in all Fe-EDTA treatments over control, with maximum value (86.54 ± 5.57 mg kg-1) in the treatment where Fe-EDTA was applied in soil + foliar. Similarly, a high Fe build up in surface soil was obtained with treatment of Fe-EDTA in soil + foliar. Overall, with various Fe-EDTA treatments, an increase of 21.2 to 29.1% in grain yield and 1.9 to 4.3 times in Fe concentration of wheat grains was achieved in current study. It is suggested that the Fe should be included in wheat production technology to attain better yield and Fe concentration in grains.

Utilization of palm residues for biochar production using continuous flow pyrolysis unit

Biochar is a carbonaceous solid substance produced by heating biomass without using air. This research aimed to create and evaluate local carbonization pyrolysis using a screw conveyor and filtration equipment. Date palm frond (DPF) biochar was studied and tested at pyrolysis temperatures of 320, 390, and 460 °C, as well as feeding rates of 60, 90, and 120 kg/h. The physicochemical parameters of DPF biochar were evaluated using SEM and FTIR. When the pyrolysis temperature was raised from 320 to 450 °C, and the feed rates were reduced from 120 to 60 kg/h, the biochar yield of DPF and volatiles fell. At 460 °C and 60 kg/h, the maximum ash and fixed carbon content were 11.73 and 77.61 %, respectively. As the feed rate decreased and the temperature increased, the H and O values (1.96 and 2.62 %, respectively) of DPF biochar decreased considerably; the C and N values (83.60 and 0.24 %, respectively) trended inopposite directions. The BET surface area and pore volume increased as a result of the micropore surface area and volume at higher temperatures and lower feeding rates, but water holding capacity increased from 6.04 gwater/10 g at 320 °C to 6.78 gwater/10 g at 390 °C (60 kg/h). The results showed that the heating temperature increased and the feeding rate decreased; phosphorus) P(and magnesium (Mg) increased significantly, whereas the levels of potassium (K) and calcium (Ca) showed a non-significant increase. Furthermore, as the pyrolysis temperature increased, pH and EC increased from 7.90 to 10.96 and 2.91 to 4.25 dSm−1, respectively, while CEC declined; however, there were no significant changes in CEC. DPF biochar demonstrated enhanced macro porosity and surface area at 460 °C and 60 kg/h, making it acceptable for agricultural use as a soil supplement.

Coal fly ash application as an eco-friendly approach for modulating the growth, yield, and biochemical constituents of Withania somnifera L. plants.

The solid waste known as fly ash, which is produced when coal is burned in thermal power plants, is sustainably used in agriculture. It is an excellent soil supplement for plant growth and development since it contains some desired nutrients (macro and micro), as well as being porous. The present study was done to evaluate the effect of different fly ash levels on Withania somnifera. The present study aimed to assess the impact of various fly ash (FA) concentrations on growth, yield, photosynthetic pigments, biochemical parameters, and cell viability of W. somnifera. The results showed that FA enhanced physical and chemical properties of soil like pH, electric conductivity, porosity, water-holding capacity, and nutrients. The low doses of FA-amended soil (15%) significantly increased the shoot length (36%), root length (24.5%), fresh weight of shoots and roots (107.8 and 50.6%), dry weight of shoots and roots (61.9 and 47.1%), number of fruits (70.4%), carotenoid (43%), total chlorophyll (44.3%), relative water content (109.3%), protein content (20.4%), proline content (110.3%), total phenols (116.1%), nitrogen (20.3%), phosphorus (16.9%), and potassium (26.4%). On the other hand, the higher doses, i.e., 25% of fly ash showed a negative effect on all the above parameters and induced oxidative stress by increasing lipid peroxidation (33.1%) and hydrogen peroxide (102.0%) and improving the activities of antioxidant enzymes and osmolytes. Compared to the control plants, the plants growing in soil enriched with 15 and 25% fly ash had larger stomata pores when examined using a scanning electron microscope. In addition, according to a confocal microscopic analysis of the roots of W. somnifera, higher fly ash concentrations caused membrane damage, as evidenced by an increase in the number of stained nuclei. Moreover, several functional groups and peaks of the biomolecules represented in the control and 15% of fly ash were alcohols, phenols, allenes, ketenes, isocynates, and hydrocarbons. Gas chromatography-mass spectrometryanalysis of the methanol extract of W. somnifera leaves cultivated in soil amended with 15% fly ash shows the presence of 47 bioactive compounds. The most abundant compounds in the methanol extract were cis-9-hexadecenal (22.33%), n-hexadecanoic acid (9.68%), cinnamic acid (6.37%), glycidyl oleate (3.88%), nonanoic acid (3.48%), and pyranone (3.57%). The lower concentrations of FA (15%) can be used to enhance plant growth and lower the accumulation of FA that results in environmental pollution.

Rice yield and carbon dioxide emissions in a paddy soil: A comparison of biochar and polystyrene microplastics

AbstractBiochar has been suggested as a soil supplement to improve soil fertility. The world is covered in microplastics (MPs). A pot greenhouse experiment was carried out to examine the effects of polystyrene (PS), sugarcane bagasse biochar (SBB), and their interactions (PS × SBB) on the CO2 emission and rice yield in a rice paddy calcareous soil. The largest CO2 emissions occurred 35–40 days following rice planting, which corresponds to the tillering stages of rice growth. Higher CO2 emissions were detected after SBB treatment. Our findings showed that applying PS increased CO2 emissions in our soil samples. Our research revealed that adding SBB can boosted the negative effects of PS in the soil. The co‐application of SBB and PS increased PS's stimulation of the CO2 emissions. We infer that PS‐SBB interactions have an impact on global warming potential, microbial community activity, and CO2 emissions. Both SBB rates resulted in a significant increase in biomass and rice grain. Our research indicates that PS has a detrimental effect on rice grain output and biomass, but that the addition of SBB can slightly lessen these effects.

Improving Soil Properties by Sand Application in the Saline-Alkali Area of the Middle and Lower Reaches of the Yellow River, China

Excessive soil salinity is a problem that makes soil unusable for agriculture, and most current research focuses on either chemical supplements or water conservation measures. Nevertheless, more information is needed about how sand treatment affects soil quality. In this study, a field experiment assessed the effect of sand application and cropping year on soil properties in an arid and semi-arid saline-sodic agricultural ecosystem. We found that sand application significantly improved the saline–alkali soil’s physical (i.e., pH, EC, TSC, BD), chemical (i.e., OC, AN, AP), and enzyme activity (i.e., Amy, Ure, Alp, Cat) properties, and that soil AN, AP, as well as TSC, were the crucial factors affecting soil properties. Simultaneously, soil properties gradually improved along with increasing cropping years, although these increases gradually became small. Our findings highlight the potential of sand as a soil supplement to enhance soil quality and structure in semi-arid agricultural ecosystems, especially when considering the cost.

Macroalgal-derived alginate/wastepaper hydrogel to alleviate sunflower drought stress

Main conclusionAlginate/wastepaper hydrogel mitigated sunflower drought stress by increasing the water holding capacity of the soil and decreasing phosphate leaching. The hydrogel promoted sunflower growth and decreased stress related biomarkers.There is a growing interest in the development of biodegradable hydrogels for the alleviation of drought stress on plants. A novel hydrogel based on brown algal-derived alginate and wastepaper was developed and tested as a soil supplement for sunflower growth under moderate (75% field capacity (FC)) and extreme (50% FC) water-deficit stress. The hydrogel showed fast swelling in water, which obeyed the pseudo-first order kinetics. Besides, it increased the water holding capacity of the soil and exhibited a good phosphate adsorption (37 mg PO4− g−1 hydrogel after 6 days) in the soil, and more than 67% of the adsorbed phosphate was desorbed after 20 days. Thus, the phosphate leaching from the hydrogel-amended soil in a column experiment was only 2.77 mg after 4 times of over-irrigation, compared to 11.91 mg without the hydrogel. The hydrogel application promoted various root traits such as fresh and dry biomass, area, and length by > 2-, > 1.6-, > 1.35-, and > 1.3-folds under both water regimes in relation to the no-hydrogel treatments at the same conditions. Furthermore, the sunflower shoots exhibited similar proline contents to the well-watered control (100% FC), with > 50% reduction in relation to the drought-stressed plants under the same conditions. Similarly, the malondialdehyde contents were lowered by > 15%. The analysis of the antioxidant enzymes also indicated a marked reduction in the specific activities of catalase and ascorbate peroxidase under both 75 and 50% FC compared to the respective controls. Additionally, the hydrogel promoted the uptake of phosphate by sunflower roots. These results implied that the developed biodegradable hydrogel could be effectively applied as a soil additive to alleviate drought stress on crops.

Positive effects of a formulated microbial consortium on the growth and well-being of okra and tomato crops

The impact of microbial consortium (MC) comprising plant development-promoting organisms (PGPMs), for example, Bacillus sp., Enterobacter sp. (bacteria), Aspergillus sp., Penicillium sp. (fungus), and streptomycin sp. (actinomycetes) which are effective on two vegetable crops (okra and tomato). These strains were collected from five geologically isolated soil samples of agricultural fields around Bhubaneswar, Khurda, India (20.65946°N, 86.75409°E) and were biochemically characterized. The promising isolates were confirmed by 16s rRNA sequence. The MC was applied at five different concentrations, viz., 0.2%, 0.5%, 1.0%, 1.5%, and 2.0% (v/v using MS medium) along with a control were included. The combinations of above mentioned PGPMs strains significantly increased shoot height, plant height, leaf length, and leaf width at three-day intervals, and fresh weight, dry weight, and root length at the end of the study period. The results revealed that the protective effect of MC significantly increased all the parameters. The crop growth parameters were confirmed MC was effective when tested against control crops. The MC was more effective with the soil base than without a soil base. Among different concentrations of MC, 0.5% of MC was more effective for all the test crops as compared to other concentrations. So, 0.5% was optimal for microbial colonization to ensure the provision of soil nutrients, as no discernible change in growth parameters was observed to further increase in concentration. Also, a study on microbial and physicochemical parameters of all the treatments of all the crops was recorded. The lab study is a small-scale investigation to confirm the efficacy and the sustainability of MC in with soil and without soil of Odisha. Overall, the study illustrated a healthy biotic (consortium microbes and natural soil microbes) and abiotic (MS medium and soil supplement) interaction is advantageous for crop development and advancement.

Feasibility of Biochar Derived from Sewage Sludge to Promote Sustainable Agriculture and Mitigate GHG Emissions-A Review.

Sewage sludge (SS) has been connected to a variety of global environmental problems. Assessing the risk of various disposal techniques can be quite useful in recommending appropriate management. The preparation of sewage sludge biochar (SSB) and its impacts on soil characteristics, plant health, nutrient leaching, and greenhouse gas emissions (GHGs) are critically reviewed in this study. Comparing the features of SSB obtained at various pyrolysis temperatures revealed changes in its elemental content. Lower hydrogen/carbon ratios in SSB generated at higher pyrolysis temperatures point to the existence of more aromatic carbon molecules. Additionally, the preparation of SSB has an increased ash content, a lower yield, and a higher surface area as a result of the rise in pyrolysis temperature. The worldwide potential of SS output and CO2-equivalent emissions in 2050 were predicted as factors of global population and common disposal management in order to create a futuristic strategy and cope with the quantity of abundant global SS. According to estimations, the worldwide SS output and associated CO2-eq emissions were around 115 million tons dry solid (Mt DS) and 14,139 teragrams (Tg), respectively, in 2020. This quantity will rise to about 138 Mt DS sewage sludge and 16985 Tg CO2-eq emissions in 2050, a 20% increase. In this regard, developing and populous countries may support economic growth by utilizing low-cost methods for producing biochar and employing it in local agriculture. To completely comprehend the benefits and drawbacks of SSB as a soil supplement, further study on long-term field applications of SSB is required.

A field study on using soybean waste-derived superabsorbent hydrogel to enhance growth of vegetables

Food security is critical and has become a global concern with many of our basic food crops growing in areas with high drought risk. To improve soil water holding capacity, hydrogels are a promising solution. However, the current ones are mostly derived from petroleum products and are environmental unsustainable. In this study, the main objective is to determine if bio-based hydrogel can help in the growth of leafy vegetables while minimizing water use under field conditions. To achieve this, we developed an okara-derived hydrogel (Ok-PAA; OP) from by-products of bean curd and soybean milk production. We incorporated OP into soil and assessed the growth performance of leafy vegetables. We observed that vegetables grown with 0.2% (w/v) OP in soil with a watering frequency of 7 times per week resulted in >60 % and 35 % yield increase for the common Asian leafy vegetables, choy sum (CS) and pak choi (PC), respectively, as compared to without hydrogel supplementation. Both vegetables produced larger leaf areas (20–40 % increment) in the presence of the hydrogel as compared to those without. In addition, with OP amendment, the irrigation water use efficiency improved >60 % and 30 % for CS and PC, respectively. It is estimated that with the use of the hydrogel, a reduction in watering frequency from 21 times to 7 times per week could be achieved, and based on a per hectare estimation, this would result in 196,000 L of water saving per crop cycle. Statistical analysis and modelling further confirmed vegetables grown with 0.2 % (w/v) OP and with a watering frequency of 7 times per week showed the best growth performance and water use efficiency. Such a waste-to-resource approach offers a plant-based soil supplement for crop growers, contributes to waste valorization, and enhances the growth of plants especially under water-limited conditions.

Selection of Smart Manure Composition for Smart Farming Using Artificial Intelligence Technique

A modern worldview has developed in rural methods, devices, and advances. Exactness in agribusiness is required to guarantee site-specific editing of administration, which incorporates soil supplement arrangements that are custom fitted to each crop’s needs. In spite of the fact that preparation is vital for expanding efficiency, it is vital to dissect the possibilities and impediments of soil as a premise for selecting the correct manure sort, amount, and application time to dodge compost utilization instability. Farmers’ dependence on instinct, trial and mistake, mystery, and assessing significantly includes major wasteful aspects such as efficiency misfortunes, asset squandering, and expanded natural defilement due to the complexity of deciding the perfect preparing extend. Agriculturists cannot successfully estimate the impacts of their choices on yield and the environment when utilizing these. This paper illustrates why manure regimes should be adjusted to meet the demands of certain crops and regions, as well as to safeguard the environment by reducing pollution caused by fertilizer and manure waste. A few soil-richness administration strategies, such as the utilization of versatile research facilities or imported gear, have confronted obstacles in terms of fetched, comfort of utilization, and adaption to the neighborhood environment. Other choices, such as sending soil to research facilities for testing, are badly designed, time-consuming, and conflicting. Based on the climate estimate, this thing should be suggested according to the development of an ANN and show the estimates of NPK supplement levels and offer the fitting compost treatment and application timing.

Exploring the Potential of Straw Biochar for Environmentally Friendly Fertilizers

The pyrolysis of wheat straw in order to produce biochar for soil amendment is a potential strategy for producing environmental friendly fertilizers capable of boosting soil fertility, increasing carbon storage, and lowering greenhouse gas emissions. However, straw biochar’s potential to influence these aspects may vary depending on its properties. Our study sought to investigate biochar from wheat straw from three different regions in Bulgaria. A specially designed set up was used for the biochar production. Three pyrolytic temperatures (300, 400, and 500 °C) were applied, resulting in nine biochar samples. The specific characteristics included moisture content, volatile substances content, ash content, fixed carbon content, and joint ash and carbon content, and they were determined for each sample. The chemical content, resulting in 17 chemical elements and compounds, was measured and analysed. The results obtained showed that the produced straw biochar has the potential to be used as a fertilizer and soil supplement.

Foliar use of TiO2-nanoparticles for okra (Abelmoschus esculentus L. Moench) cultivation on sewage sludge-amended soils: biochemical response and heavy metal accumulation.

Considering its richness in organic and inorganic mineral nutrients, the recycling of sewage sludge (SS) is highly considered as a soil supplement in agriculture. However, the fate of hazardous heavy metal accumulation in the crops cultivated in SS amended soils is always a source of concern. Since nanoparticles are widely recognized to reduce heavy metal uptake by crop plants; thus, the present experiment deals with okra (Abelmoschus esculentus L. Moench) cultivation under the combined application of SS and TiO2-nanoparticles (NPs). Triplicated pot experiments were conducted using different doses of SS and TiO2-NPs such as 0g/kg SS (control), 50g/kg SS, 50g/kg SS + TiO2, 100g/kg SS, and 100g/kg SS + TiO2, respectively. The findings of this study indicated that among the doses of treatment combinations investigated, 100g/kg SS + TiO2 showed a significant (p < 0.05) increase in the okra plant yield (287.87 ± 4.06g/plant) and other biochemical parameters such as fruit length (13.97 ± 0.54cm), plant height (75.05 ± 3.18cm), superoxide dismutase (SOD: 110.68 ± 3.11 μ/mg), catalase (CAT: 81.32 ± 3.52 μ/mg), and chlorophyll content (3.12 ± 0.05mg/g fwt.). Also, the maximum contents of six heavy metals in the soil and cultivated okra plant tissues (fruit, stem, and root regions) followed the order of Fe > Mn > Cu > Zn > Cr > Cd using the same treatment. Bioaccumulation and health risk assessment indicated that foliar application of TiO2-NPs significantly reduced the fate of heavy metal accumulation under higher doses of SS application. Therefore, the findings of this study suggested that the combined use of SS and TiO2-NPs may be useful in ameliorating the negative consequences of heavy metal accumulation in cultivated okra crops.

Characteristics and Applications of Biochar in Soil–Plant Systems: A Short Review of Benefits and Potential Drawbacks

The available literary data suggest the general applicability and benefits of different biochar products in various soil–plant–environment systems. Due to its high porosity, biochar might generally improve the physicochemical and biological properties of supplemented soils. Among the direct and indirect effects are (i) improved water-retention capacity, (ii) enhanced soil organic matter content, (iii) pH increase, (iv) better N and P availability, and (v) greater potential uptake of meso- and micronutrients. These are connected to the advantage of an enhanced soil oxygen content. The large porous surface area of biochar might indirectly protect the survival of microorganisms, while the adsorbed organic materials may improve the growth of both bacteria and fungi. On the other hand, N2-fixing Rhizobium bacteria and P-mobilizing mycorrhiza fungi might respond negatively to biochar’s application. In arid circumstances with limited water and nutrient availability, a synergistic positive effect was found in biochar–microbial combined applications. Biochar seems to be a valuable soil supplement if its application is connected with optimized soil–plant–environment conditions. This work aims to give a general review of the potential benefits and drawbacks of biochar application to soil, highlighting its impacts on the soil–plant–microbe system.

Combined effects of vermicompost and vermicompost leachate on the early growth of Meloidogyne incognitastressed Withania somnifera (L.) Dunal.

Roots of Withania somnifera, an important medicinal herb, are prone to the infection of Meloidogyne incognita (a root parasitic nematode). The infection lowers the quality and quantity of plant material and poses a challenge in crop cultivation and obtaining desirable yield. In the present study, in vitro inhibitory activity of vermicompost leachate (Vcom-L) was assessed against % hatch and survival of M. incognita in a 96h assay. Then, Vcom-L was used as soil supplement in combination with vermicompost (Vcom) to evaluate their nematode inhibitory and stress alleviating effect in W. somnifera, in a pot experiment. Root galling intensity and growth performance of nematode-stressed W. somnifera raised from seeds pre-soaked in distilled water (DW), Vcom-L, vermicompost tea (Vcom-T) and different dilutions of Vcom-L were assessed. We observed 79% suppression of egg hatching and 89% juvenile (J2) mortality after 96h compared to control, at 100% concentration of Vcom-L. Significant reduction in gall formation with increase in growth parameters of seedlings was observed after combined application of Vcom (60% or 100%) + Vcom-L and was evident as enhancement in seedling biomass and contents of chlorophyll and protein. However, proline, total phenolics and malondialdehyde (MDA) content declined significantly in these combinations compared to the control (0% Vcom). Activity of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidise (APX), guaiacol peroxidise (GPX) and glutathione reductase (GR) declined with Vcom as well as Vcom + Vcom-L and corresponded with decline in the accumulation of reactive oxygen species in leaves. Further, 1:5 and 1:10 dilutions of Vcom-L in combination with Vcom (60%) proved beneficial in mitigating the nematode-induced stress in W. somnifera. Present results showed the potential of Vcom and Vcom-L in standardised combination as an effective strategy in controlling the pathogenicity of M. incognita in medicinal plants such as W. somnifera.

Complementary allometric model of understory tree biomass in the semi-deciduous rainforest of Cameroon

Forest understorey contains remarkable plant diversity, contributing to the heterogeneous environments for other biotic gatherings and soil supplement aggregations. Nonetheless, the biomass of the understorey vegetation is neglected because of the lack of appropriate allometric equations without which there are uncertainties in biomass estimation. This study was aimed at developing multispecies allometric equations that will be used to estimate the aboveground biomass of different compartments (trunk, crown, and leaves) of understorey trees in the semi-deciduous rainforest of Cameroon. Understorey tree diameter (1.0-10.0 cm), height, and crown diameter were measured on 1023 trees as biomass predictors. The results showed that the fit of the model improves with more predictive variables, four of which were considered in all studied compartments (trunk, crown, and leaves). Existing specific and pantropic allometries based on diameter tend to overestimate the aboveground biomass of understorey trees when compared to the allometry developed in this study. This study highlighted the importance of a specific aboveground biomass allometric equation for understorey trees. Furthermore, the multispecies allometric equation developed for understorey trees complements those recently developed for overstorey trees, thereby contributing to the total aboveground woody biomass estimation in semi-deciduous forest in the Congo Basin.