Search

The aim of this study was to explore the effect of biochar on N2O emissions in soils with different pH levels. Soils with five pH levels (4.0, 5.1, 5.8, 6.6, and 7.2) were incubated in two conditions, with 0% biochar (CK) and 1% biochar (BC), for 23 days. N2O emissions were measured at nine time points, and soil chemical properties, AOA-amoA, AOB-amoA, nirK, nirS, and nosZ, were analyzed. Partial least squares path modelling (PLS-PM) was used to assess the effect of nitrification and denitrification pathways on potential N2O emissions. The results showed that biochar reduced N2O emissions in highly acidic soil (pH 4.0) but increased emissions in soils with pH values ranging from 5.1 to 7.2. In highly acidic soils, decreased N2O emission was associated with increased soil pH (p < 0.05) and decreased dissolved organic carbon content (p < 0.05), leading to higher nosZ gene abundance (p < 0.05). Meanwhile, in acidic to neutral soils, biochar application increased soil pH (6.6–11.7%), dissolved organic nitrogen (5.9–29.5%), dissolved organic carbon (8.6–41.0%), stimulated AOB-amoA, nirK, nirS gene abundance (p < 0.05), and thus increased N2O emissions. The results verified the influence of nitrification and denitrification genes on N2O production in soils with different pH values. In conclusion, biochar had different effects on N2O emissions based on soil pH, highlighting the need to consider pH when using biochar to mitigate N2O emissions in subtropical citrus orchards. [ABSTRACT FROM AUTHOR]

Biochar is widely used to maintain crop yields and the sustainability of agroecosystems due to its characteristics. However, its effect on vegetable yield and quality in southern acidic soils has not been fully elucidated. The effects of two kinds of biochar application rates (3 t ha−1 and 12 t ha−1) on the nutrient availability, nutrient absorption, yield, and fruit quality of sandy acid oxide soil in South China were studied in a 2-year field experiment using two varieties of wax gourd (Tiezhu No. 2 and Dadao). The results showed that optimized fertilization (OPT, nitrogen, phosphorus, and potassium were reduced by 20.0%, 20.6%, and 21.1%, respectively) did not reduce the yield of the different varieties of wax gourd compared to FP (farmer practice). On the basis of the OPT treatment, the application of biochar increased the yield of Tiezhu No. 2 and Dadao wax gourd by 16.0–27.3% and 7.7–13.3%, respectively. The increase in yield was attributed to the improvement in soil organic carbon content which increased by 4.5–19.7%, nutrient effectiveness (NO3−-N and Olsen-P content enhanced by 23.7–27.0% and 15.3–23.4% in Tiezhu No. 2), and nutrient uptake (N, P, K, Ca, and Mg accumulation increased significantly by 21.1%, 46.1%, 36.8%, 25.7%, and 31.9%, respectively) by the plant after the biochar application. Different types of biochar also have some differences in these three aspects. Specifically, under the same dosage, rice biochar has a more significant effect on increasing the yield of winter melon, and has a better effect on the improvement of soil physical and chemical properties, while sawdust biochar has a more significant effect on nutrient absorption. In addition, the commercial quality, namely hardness and glossiness, and the nutritional quality, namely soluble sugar, soluble protein, VC content, and sugar–acid ratio of wax gourd fruits, were significantly improved after the biochar application. In summary, biochar application on acidic soils in South China could achieve a win–win situation in terms of increasing soil nutrient effectiveness to improve vegetable yield and quality while reducing chemical fertilizer. [ABSTRACT FROM AUTHOR]

Biochar as a by-product of the carbonization of biomass has an inherent potential to modify acidic soils due to its alkaline nature. To explore the mechanism and effectiveness of biochar, a case study was conducted on severely acidic soils from six fields under tea cultivation in a subtropical zone, comparing rice husk biochars, in three rates (B5, B10, B15 t ha−1), and CaCO3 as conventional liming practice. The results showed increases in pH of 71.5%, 52.7%, 30.6%, and 29.7% in B15, B10, B5, and CaCO3-treated soils compared to the control. On average, B15 and B10 treatments resulted in the highest organic matter with 12.3% and 9.7%, respectively. B15, B10, B5, and CaCO3 caused increases of 196.6%, 173.4%, 129.7%, and 100.9% in base saturation compared to the control, respectively. Also, after the application of B15, B10, and B5 treatments, the effective cation exchange capacity increased by 191.4%, 112.1%, and 39.5%; however, the application of CaCO3 resulted in a 20.1% decrease. Overall, applying biochar on acidic soils provides adequate negative charges due to its well-extended specific surface area and pore volume, which cause the absorption of additional Al+, resulting in ameliorating soil pH. The application of proper biochar could notably be more effective in improving acidic soils than conventional practices such as the overuse of CaCO3. In this regard, evaluating various biochars in terms of feedstock, pyrolysis conditions, and modification scenarios merits in-depth research in future studies. [ABSTRACT FROM AUTHOR]

The composition of microbial communities and the functioning of ecosystems are greatly influenced by the nutrient inputs. Despite this fact, our knowledge regarding the impact of phosphorus (P) inputs on soil P availability and microbial community structures in subtropical acidic soils remains limited. We hypothesized that diverse P inputs, incubation temperatures, and soil types could significantly alter soil P availability and microbial communities. To address this gap, we conducted a laboratory incubation experiment, investigating the effects of biochar and inorganic P amendments on soil available P, soil pH, acid phosphatase enzymes, and bacterial abundance. We employed two different incubation temperatures (15 °C and 25 °C) using acidic paddy soil and red soil from the subtropical Southern China region. Our results indicate a notable increase in soil pH, reaching 37% and 39% at 15 °C and 40% and 40.6% at 25 °C, respectively, following the application of biochar and inorganic P amendments in paddy soil. In the case of red soil, we observed pH increases of 41% and 43% at 15 °C and 44% and 45% at 25 °C after the application of biochar and inorganic P amendment, respectively. The addition of inorganic P amendment resulted in the highest available P contents in paddy soil, reaching 111.47 mg/kg at 15 °C and 100.17 mg/kg at 25 °C, respectively. However, Proteobacteria decreased after inorganic P addition, which showed that P might not be the only limiting nutrient for various bacterial communities. Bacterial diversity and richness indices were found to be higher after biochar application in both soils. Gemmatimonadetes, Acidobacteria, and Actinobacteria were found to be strongly influenced by incubation temperatures, whereas most of the top abundant bacterial phyla, such as Gemmatimonadetes, Actinobacteria, Chloroflexi, Acidobacteria, Planctomycetes, Firmicutes, Patescibacteria, and Bacteroidetes, were highly dependent on soil type. At the genus level, various important P solubilizing genera (Pseudomonas, Bradyrhizobium, Streptomyces jietaisiensis, Massilia) significantly increased after biochar and inorganic P addition in both soils. The correlation analysis proved that P-solubilizing genera were significantly associated with changes in soil pH, as well as soil available P after biochar and inorganic P addition. Conclusively, in a short-term incubation experiment, inorganic P amendment greatly increased the soil pH and available phosphorus contents compared to biochar and control treatments; however, the microbial community was observed to be strongly associated with biochar application, soil type, and incubation temperature. [ABSTRACT FROM AUTHOR]

Biochar is commonly used to improve acidic soil and reduce nitrogen loss. However, the impact of biochar on soil nitrogen retention, especially at varying pH levels, is not fully understood. Soil samples were obtained from an acidic red soil citrus orchard. The soil pH was adjusted using CaO, with five levels (4.0, 5.1, 5.8, 6.6, and 7.2), and two biochar doses (0% and 1%) were applied. The study used 15N-Tracer and Ntrace to investigate biochar's influence on soil nitrogen retention at different pH levels. The results showed that soil amendment with biochar improved gross mineralization rates (TM) and gross NH4+ immobilization rates (TI), except at pH 4.0 for TI. Biochar enhanced heterotrophic nitrification (ONrec) within pH 4.0–7.4, with a threshold for autotrophic nitrification (ONH4) at pH 6.4. The findings revealed biochar's positive effect on soil nitrogen retention within pH 4.5–6.4. Biochar had a greater impact on TI than TM and inhibited ONH4, potentially enhancing nitrogen retention in this pH range. These results highlight the significance of considering biochar incorporation for improving nitrogen use efficiency and reducing NO3−-N loss in subtropical pomelo orchards. [ABSTRACT FROM AUTHOR]

Given that rice husk biochar has been shown to modulate salinity in salt-affected acid soils, the objective of this study was to investigate the effects of organic amendment of salinized acid soils on P fractions, enzyme activities, and associated rice yield. Four treatments, viz. Rice–Rice–Rice, [RRR]; Fallow–Rice–Rice, [FRR]; Fallow–Rice–Rice + 3 Mg ha−1 of compost [FRR + Comp]; and Fallow–Rice–Rice + 10 Mg ha−1 of biochar [FRR + BC] were established at Ben Tre and Kien Giang sites, Viet Nam, over six consecutive crops. Soil properties at harvest of the sixth crop showed that there were diverse patterns of fractionation between P forms with respect to treatment. Overarchingly, biochar increased labile and moderately labile inorganic P and organic P by 30% to 70%, respectively, whilst compost had a relatively modest effect on these pools. Soil phosphatase activities at crop tillering increased following the FRR + Comp and FRR + BC treatments compared with those in RRR, except for acid phosphatase at Ben Tre. At harvest, there were no significant differences between the enzyme activities among the treatments. Rice yield was positively correlated with the more labile forms of P, soil C, and acid phosphatase activity. In the absence of organic amendments, there was no effect of triple versus double rice crops being grown in one-year cycle. Repeated application of biochar (10 Mg ha−1 × 5 times) showed potential to increase grain yields and total soil C in salt-affected acid soils, via modulation of P transformations to more plant-available forms. [ABSTRACT FROM AUTHOR]

Biochar application has been confirmed as an efficient way to increase the productivity of the agricultural system. However, the potential of biochar combined with reducing fertilization on the yield, and the fertilizer utilization efficiency of the rice (Oryza sativa) farming system on acidic soil remains to be further studied. Field micro-plot experiments with two factors were performed in 2018 and 2019 to evaluate the responses of the rice yield and nutrient utilization to the combined application of biochar (60, 80, and 100 t/ha) and fertilizer reduction (70%, 85%, and standard doses of N-P-K fertilizer). Taoyouxiangzhan and Taiyou 553 were used in the late growing season of 2018 and 2019, respectively. The results showed that compared with the control without adding biochar under standard fertilization, 70% doses of fertilizer application had no negative effects on the yield and the N, P, and K accumulation of rice after biochar application. K accumulation of rice increased with the increase of biochar application. The partial productivity of N, P, and K fertilizers increased as the fertilizer was decreased. The agronomic efficiency of N, P, and K fertilizers significantly increased after the combined applications of biochar and fertilizer. In both years, micro-plots with 70% doses of fertilizer had the highest N and P physiological efficiency, as well as K physiological efficiency in 2019. Compared with the control under standard fertilization, utilization efficiency of N, P, and K fertilizer under different biochar and fertilizer combinations significantly increased by 34.24~75.48%, 27.44~84.84%, and 78.52~166.70%, respectively. To sum up, biochar can partially substitute fertilizer for rice production in acid paddy fields in southern China. When the amount of biochar added is ≥60 t/ha, 70% doses of fertilizer application can still ensure the nutrient absorption of rice, improve the fertilizer utilization efficiency, and ensure the stable yield of rice. [ABSTRACT FROM AUTHOR]

The proportion of acidic purple soils has increased. Consequently, an effective method for amelioration of acidic purple soils is urgently needed. A 40 day incubation experiment using apple tree biochar, fermented sheep manure and chicken manure was conducted to assess the effects of organic materials on the acidity and fertility of acidic purple soil. The results showed that application of organic materials increased soil pH and decreased soil-exchangeable acidity. All of the treatments increased soil-exchangeable and water-soluble base cations after incubation. Specifically, biochar increased soil pH and reduced exchangeable acidity more than the other two fermented manures, because biochar was rich in carbonates and other alkaline substances. The concentration of soil available K was significantly higher under biochar than manure addition, while the opposite was true for soil available P and N, with a higher increase in soil available P in the manure treatments. By evaluating the soil fertility using a fuzzy comprehensive method, it was found that the fermented livestock manure enhanced soil fertility more strongly than biochar. Considering the effectiveness of soil amendments and production cost, applying a large amount of fermented organic fertilizer is an effective approach to the amelioration of acidified purple soil. [ABSTRACT FROM AUTHOR]

When biochars are produced, feedstock is a crucial factor that determines their physicochemical properties. However, the characteristics of tropical crop waste-derived biochar have not been described and limit its availability. In this study, pineapple leaf (PAL), banana stem (BAS), sugarcane bagasse (SCB) and horticultural substrate (HCS), were used to prepare biochar at 300, 500 and 700 °C. Properties of biochars and their applications were analysed. The results indicated that hydrophobicity, nonpolarity and aromaticity of SCB biochar (SCBB) were higher than other biochars due to the loss of H (hydrogen), O (oxygen), and N (nitrogen). The pH of PAL biochar (PALB) and BAS biochar (BASB) ranged from 9.69 to 10.30 higher than that of SCBB and HCS biochar (HCSB) with 7.17–9.77. In PALB and BASB, sylvite was the dominant crystal structure. With temperature rising, C–H stretching, C=C stretching and H–O in alcohol groups decreased, and Si–O stretching in HCSB and SCBB strengthened. Biochars obtained at 500 °C, especially SCBB and HCSB, significantly promoted the growth of maize. The PALB and BASB greatly increased the soil pH/EC to 6.90–7.35 and 0.67–0.95 ms/cm, while those of SCBB and HCSB were 5.97–6.74 and 0.23–0.45 ms/cm. The application of the biochars to the soil increased soil pH, reducing the acidic soil stress in maize growth, especially PAL and BAS biochars prepared at 300 °C. Biochar prepared at lower temperature will greatly reduce energy consumption and increase the utilization efficiency of tropical agricultural waste resources. [ABSTRACT FROM AUTHOR]

Soil acidity is a crop production problem of increasing concern in acid red soil. The potential of biochar as a soil amendment/for soil acid management in agricultural fields is a recently recognized yet underutilized technology. Related evidence is currently limited to short-term indoor experiments with one-time BC applications and no crop cultivation, yet the degree to which soil acidity may be impacted by the biochar aging process on long-time scale remains unclear. To evaluate the effects of successive seasonal applications of rice straw-derived biochar (BC) on acidity and fertility of soil, a five-year outdoor column trial was conducted using wheat-millet rotated acidic upland soils from the south of China. BC was applied to the top 0–15 cm of soil at the rates of 0 (BC0), 2.25 (BCL), and 22.5 (BCM) Mg ha−1 with an identical dose of NPK fertilizers at the beginning of each crop season. Our results showed that the wheat-millet biomass yield gradually decreased over five rotation cycles in BC0 without BC application. In contrast, after five rotations, BCM led to an increase in the total wheat/millet grain yield by 138%, and the straw yield increased by 253% compared to the control. The cumulative above-ground nutrient uptake of P, K, Ca, Na, and Mg in BCM also increased by 139%, 171%, 129%, 182%, and 71%, respectively, compared to that in the control. This positive effect was attributed to the increase in soil pH (3.29 units), cation exchange capacity (5.66 cmol kg−1), soil available P (241%), K (513%), Ca (245%), Mg (265%), exchange base (3.36 cmol kg−1), base saturation percentage (65.7%), and decrease in the exchangeable acidity, especially exchangeable Al3+ content (<0.1 cmol kg−1). Our results demonstrated that rice straw-derived BC application to soil at 22.5 t ha−1 was found to be highly consistent in decreasing soil acidity and reducing soluble and exchangeable Al3+, indicating its higher ameliorating capacity in the south of China in the long run. [ABSTRACT FROM AUTHOR]

The agronomic benefits of biochar (BC) prepared by slow pyrolysis of vine pruning residues, which are produced in large quantities in Romania, were evaluated. Three soil types, i.e., slightly alkaline fluvisol (S1), slightly acidic chernozem (S2), and strongly acidic luvisol (S3), with mean values of pH of 7.99, 6.26, and 5.40, were amended with BC at a volumetric ratio between BC and soil of 20/80. A greenhouse experiment was performed for 109 days to assess the effects of BC amendment on bell pepper growth. The following treatments were applied: foliar fertilizer, BC, BC + foliar fertilizer (using two concentrations of foliar fertilizer solution), and a control. Strongly alkaline BC (pH of 9.89 ± 0.01) had a significant positive effect on the growth performance of bell pepper plants sown in the strongly acidic soil S3. The mean values of height, collar diameter, number of leaves, and root volume of plants grown in BC-amended soil S3 without foliar treatment were significantly higher (13–72% and 14–33%, respectively) than those of plants grown in non-amended soil S3 without and with foliar treatment. This beneficial effect of BC on bell pepper plant growth was due to the changes in the soil properties. BC significantly increased (up to eight times) electrical conductivity, pH, soluble phosphorus, potassium, and ammonium nitrogen concentrations of soil S3, and decreased its bulk density by 51%, resulting in improved water/nutrient uptake and plant growth performance. BC had no favourable effect on the growth parameters of bell pepper plants sown in slightly alkaline soil S1, and slightly acidic soil S2. [ABSTRACT FROM AUTHOR]

The paper aimed at evaluating the effects of biochar (BC) produced by slow pyrolysis of vine pruning residue on soil physicochemical properties and tomato plant growth. A greenhouse experiment was conducted for 66 days, applying different treatments for 3 soil types, i.e., foliar fertilizer, BC (at a volumetric ratio between BC and soil of 20/80), BC + foliar fertilizer, and no treatments. Strongly alkaline BC (pH = 9.89 ± 0.01) had a significant beneficial effect on the growth performance of tomato plants sown in a strongly acidic soil (pH = 5.40 ± 0.02). The mean values of height, number of leaves, and collar diameter of plants grown in BC-amended soil without foliar treatment were up to 50% higher than those of plants grown in soil with the other treatments. This positive effect of BC on plant growth is due to the changes in the soil properties. The addition of BC led to increased values of electrical conductivity, pH, soluble and available nutrient concentration. Moreover, BC reduced soil bulk density by about 50%, resulting in improved plant root development and thus enhanced water and nutrient uptake. Accordingly, BC derived from vine pruning residues can improve soil quality and tomato plant growth, as well as reduce biomass residues. [ABSTRACT FROM AUTHOR]

A serious acidification trend currently affects paddy soil and soil phosphorus (P) availability has declined in rice production. This study investigated the effect of rice-straw biochar on P availability and the adaptability of rice roots in acidified soil. Rice was grown in rhizoboxes, allowing for the precise sampling of rhizosphere and bulk soil for the sequential extraction of P fractions. Biochar may provide a liming effect and strong nutrient adsorption, leading to soil improvement. The results confirmed that biochar application significantly improved plant growth and P accumulation in shoots by 29% and 75%, respectively. However, the application of washed biochar and equivalent lime only increased shoot biomass and P accumulation by 13.4% and 11.2%, and by 42% and 38%, respectively. Compared with the control, applying biochar increased the plant-available P component contents in rhizosphere and bulk soil. Biochar affected the chemical balance among the different P fractions, increased aluminum-bound phosphate (Al-P) pool, calcium-bound phosphate (Ca-P) pool and decreased the occluded phosphate pool in acidic paddy soil. Biochar amendment significantly improved root growth of and increased the citrate exudation from roots under low P supply, accompanied by the enhanced expression of the anion-transporter-related OsFRDL4 gene and the OsPT1 phosphate transporter. The results showed that biochar application in degraded acidic soils could improve rice potential for P acquisition to increase available P component and maintain high citrate exudation. [ABSTRACT FROM AUTHOR]

Humic acids (HAs) regulate soil chemical reactivity and improve many soil functions. The amendment of soil with organic materials increases soil organic matter (SOM) content and promotes the formation of HAs. However, the effect of the type, frequency and duration of amendment, and pedoclimatic conditions on SOM transformation and HA structural changes remains unclear. Herein, four experimental field sites (S1–4) with short-to-long-term organic fertilisation schemes were used to assess the effects of such factors, i.e., S1: loamy sand amended once with farmyard manure (FYM), brown coal waste (BCW), and biochar (BIO) for 0.5 and 1.5 years; S2: silt loam amended once with BIO for 8 years; S3: loamy sand amended every 5 years with FYM for 94 years; and S4: clayey silt amended every 2 years with FYM for 116 years. All HAs were extracted and analysed for structural differences by elemental analysis (EA), attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), solid-state cross polarisation magic angle spinning nuclear magnetic resonance spectroscopy (CP/MAS 13C-NMR), and differential scanning calorimetry (DSC). Results from EA, FTIR, and NMR showed that the long-term samples from S3 (treatments, T9–T10) and S4 (T11–T12) had the greatest aromatic characteristics, which increased with FYM amendment (T10 and T12). These agreed with DSC data, which indicated lower aliphatic contents compared with other samples. Samples from S2 (T7–T8), with receded amendment effects, had less aromatic and greater aliphatic characteristics compared with the short-term samples, S1 (T1–T6). In S1, structural changes were limited, but aromaticity increased with BIO (T3 and T6) compared with corresponding FYM (T1 and T4) and BCW (T2 and T5) amendments due to inherently high aromatic groups in the former. Overall, the results showed that the site (due to differences in pedoclimatic conditions), field age of OM, and amendment frequency were the main factors that influenced HA structure, and hence SOM transformation. Regular, long-term organic amendment increases the aromatic characteristics of HAs, which can improve soil functionality, but short-term structural improvements are achievable only when amending material is rich in aromatic compounds. [ABSTRACT FROM AUTHOR]

Biochar application is considered an effective approach to mitigating nitrous oxide (N2O) emissions from agricultural soils. However, the mechanisms of biochar to mitigate N2O emissions from acidic red soils are still unclear. Therefore, the present study aims to underpin mechanisms associated with rice residue-based biochar in mitigating N2O emissions from acid soils. Soil treated with different rates of biochar control, from 1%, 2%, and 3%, and different soil properties, including soil pH, microbial biomass carbon (MBC), NH4+-N, NO3−-N, genes abundance (nosZ, nirK, AOA, and AOB), and enzymatic activities ((nitrate reductase (NR) and urease (UR)) were studied. The application of 3% biochar increased the soil pH (5.21–6.48), MBC (565–685 mg/kg), NO3−-N contents (24.23–44.5 mg/kg), genes abundance (nosZ, nirK, AOA, and AOB) and UR activity. The highest N2O emission (43.60 μg kg−1) was recorded and compared with the application of 1% (26.3 μg kg−1), 2% (18.33 μg kg−1), and 3% biochar (8.13 μg kg−1). Applying 3% biochar effectively reduced the N2O emission due to increased soil pH, MBC, NO3−-N contents, genes abundance (nosZ, nirK, AOA, and AOB), and weakened NH4+-N and NR activities. Therefore, increasing soil pH, genes abundance, and weakened nitrification following the addition of rice residue-based biochar can effectively reduce the N2O emissions from acidic red soils. [ABSTRACT FROM AUTHOR]

Understanding nitrogen (N) release patterns and kinetics is a key challenge for improving N use efficiency in any agroecosystem. An incubation experiment was done to study the N release pattern and kinetics of contrasting soils amended with compost (CO), poultry manure (PM), rice husk biochar (RHB), poultry manure biochar (PMB) and cowdung (CD) combined with chemical fertilizer (integrated plant nutrient system, IPNS approach) under two moisture regimes, viz. field capacity (FC) and continuous standing water (CSW) at 25 °C for 120 days. Our results revealed that NH4+-N was the dominant under CSW conditions, whereas NO3−-N was dominant under FC conditions. Net mineral N data fitted well to the first order kinetic model. Both N release potential (N0) and rate constant (k) were greater in acidic soil than those of charland soil. The maximum N release varied between 24.90–76.29% of input depending on soil type and moisture status. N mineralization was strongly correlated with urea N application. PM and PMB mineralized in all soil and moisture conditions whereas N immobilization was observed in the case of RHB. N mineralization was strongly correlated with urea N application. Gaseous N losses were different for the organic amendments exhibiting more gaseous N losses in PM, CD and CO based IPNS whereas the lowest gaseous N loss was observed in PMB based IPNS. Biochar based IPNS increased soil pH in all conditions. Thus, the present study suggests that N release depends on soil type, soil moisture and type of organic amendment. However, CO, PM and CD based IPNS can be recommended for both acidic and charland soils in terms of N release as short duration crops will suffer from N deficiency if biochar based IPNS is used in the field. [ABSTRACT FROM AUTHOR]

Blending fertilizer with biochar followed by densification to make it into a tablet can enhance the adsorption of fertilizer on the biochar surface and reduce the nutrient loss during handling. However, the nutrient release and ammonia volatilization from biochar-blended fertilizer with and without densification are not well understood. The objectives of this study were to determine the nutrient release and ammonia volatilization from an acid soil applied with biochar-blended NPK fertilizer with and without densification. The nutrient release of biochar-blended NPK was determined using water incubation for 30 days, whereas daily loss of ammonia was measured using a closed dynamic air flow system for 10 days. The densified biochar-blended NPK caused stronger physical binding of the nutrients within the tablet in addition to stronger chemical bondings between the nutrients with the biochar's functional groups. As a result, nutrient release in the water incubation from the biochar-blended NPK fertilizer tablet was slower. However, blending the biochar with the NPK fertilizer increased soil ammonia volatilization relative to the NPK fertilizer alone. This demonstrates that the biochar-blended fertilizer tablet has the potential to serve as a slow release fertilizer for crop cultivation. [ABSTRACT FROM AUTHOR]

Poultry litter biochar (PLB) is a value-adding soil amendment and an economically sustainable approach that is used to enhance food safety and reduce environmental harm. Poultry litter biochar has promising potential but has been under-examined in regards to carbon (C) sequestration in relation to its type and application rate. The objective of this study was to investigate the effectiveness of PLB in enhancing the C sequestration of acid soils through a short-term incubation experiment. The soil was amended with different materials: PLB (1%, 5%, and 10%) and a control (non-amended). The results indicated that PLB application increased soil C mineralization relative to the control (19–1562%), it significantly increased with an increasing application rate (e.g., increased addition 29, 99, and 172% for 1, 5, and 10% of 400 °C PLB), and the soil C mineralization and applied carbon mineralized (ACM) significantly decreased with temperature (e.g., the cumulative C pool ranges of ACM with 1% PLB, added at pyrolysis temperatures of 200, 300, 400, 500, and 600 °C, were 42.0, 34.4, 19.6, 6.16, and 4.04%, respectively). To assist sustainable soil management and to aid the achievement of multiple sustainable development goals (SDGs), as well as to maximize the benefits of PLB applications and minimize the potential environmental risk, it is suggested that application of PLB, pyrolyzed within 400–600 °C at a rate between 1% to 5%, should be adopted in acidic soils in Taiwan. [ABSTRACT FROM AUTHOR]