The decomposition and efficiency of NPK-enriched biochar addition on Ultisols with soybean

In order to understand the resource utilization of plant biomass, five types of biomass materials were used to produce biochar to treat wastewater containing phosphorus. The phosphorus adsorption capacity of five materials was preliminarily compared through laboratory experiments, and two materials with strong phosphorus adsorption capacity were screened out. The physicochemical characteristics of the selected biochar were analyzed using scanning electron microscopy and a BET specific surface area analyzer, and the effects of different pH values on phosphorus adsorption of the biochar were investigated. Furthermore, the phosphorus adsorption characteristics of the selected biochar were analyzed via isothermal adsorption and adsorption kinetics models. The results showed that among the five biochar materials, only rice straw and corn straw biochar had the ability to adsorb phosphorus. The Langmuir isothermal adsorption curve showed that the adsorption capacity of rice straw biochar for phosphorus in wastewater was stronger than that of corn straw biochar, and the theoretical maximum adsorption capacity was as follows:rice straw biochar (9.78 mg·g-1)>corn straw biochar (0.39 mg·g-1). The specific surface area (148.30 m2·g-1) and total pore volume (0.11 cm3·g-1) of rice straw biochar were much higher than those of corn straw biochar (8.26 m2·g-1 and 0.03 cm3·g-1, respectively), and the contents of Mg, Ca, Fe, and Al were higher in rice straw biochar. The best pH for phosphorus adsorption of rice straw biochar and corn straw biochar was acidic. In different pH ranges (3.0-11.0), the phosphorus adsorption capacity of rice straw and corn straw biochar decreased with the increase in pH. These results indicated that rice straw biochar has strong phosphorus adsorption capacity and has a better application prospect in wastewater treatment.

Removal of Pb(II) ions from aqueous solution by manganese oxide coated rice straw biochar A low-cost and highly effective sorbent

β-cyclodextrin functionalized biochars as novel sorbents for high-performance of Pb2+ removal.

Adsorption kinetics and isotherms of Cd2+ onto different types of biochar are studied in batch experiments. Three types of biochar (rice, wheat and corn straw biochar) and their phosphate or chitosan modified materials were used in this study. Results showed that Langmuir equation can better describe the adsorption isotherms of Cd2+ onto these biochars (r2 > 0.960). Among different types of biochars, rice straw biochar (RB) and its chitosan modified biochar (CRB) had highest adsorption capacity of Cd2+. RB, wheat straw biochar (WB) and their modified biochars were used to remediate Cd-contaminated soil. Soil pH values increased with the increasing of biochar dosage and chitosan modified biochar amended soil had the highest soil pH values. Contents of DTPA extractable Cd in soil decreased with the increase of biochar dosage and incubation time. Among different types of biochars, 5% CRB amended soil at 60 days of incubation had the lowest content of DTPA extractable Cd. This study showed that the application of modified biochars can effectively alleviate soil Cd contamination.

Soil organic carbon content affects the stability of biochar in paddy soil

Two field experiments were raised at Farm of El-Sirw Agriculture Research Station, Dammitta province, Egypt through 2018 and 2019 seasons. The present study was performed to compromise the influence of rice straw biochar and other two soil amendments of rice straw compost and gypsum on rice growth and yield of three contrasting rice varieties,Giza177 (salt sensitive variety), Giza 178 (salt tolerant variety) and Giza179 new (salt tolerant variety) under saline sodic soil. The field experiments were designed in spilt plot design with four replications. The three rice varieties were scattered in the main plot, whereas the amendment treatments; control, gypsum(G), rice straw compost (RS) and rice straw biochar (RSB) were put in the subplots. The tested rice varieties were significantly different in growth parameters, yield attributes and yields in both seasons. Giza 179 as a new salt tolerant variety provided the maximum values of rice growth characteristics and most of yield contributes and yields without significant difference with Giza178 were considering yields. Applying varying soil amendments greatly improved rice growth and yields in addition to yield attributes comparing to the control treatments. Rice straw biochar surpassed significantly other two amendments, particularly in the first season, meanwhile in the second seasonthe three soil amendments were equally in increasing grain yield. Thereby, rice straw biochar could be applied each two years but rice straw compost has to apply in two successive season to get its efficiency. Two field experiments were raised at Farm of El-Sirw Agriculture Research Station, Dammitta province, Egypt through 2018 and 2019 seasons. The present study was performed to compromise the influence of rice straw biochar and other two soil amendments of rice straw compost and gypsum on rice growth and yield of three contrasting rice varieties,Giza177 (salt sensitive variety), Giza 178 (salt tolerant variety) and Giza179 new (salt tolerant variety) under saline sodic soil. The field experiments were designed in spilt plot design with four replications. The three rice varieties were scattered in the main plot, whereas the amendment treatments; control, gypsum(G), rice straw compost (RS) and rice straw biochar (RSB) were put in the subplots. The tested rice varieties were significantly different in growth parameters, yield attributes and yields in both seasons. Giza 179 as a new salt tolerant variety provided the maximum values of rice growth characteristics and most of yield contributes and yields without significant difference with Giza178 were considering yields. Applying varying soil amendments greatly improved rice growth and yields in addition to yield attributes comparing to the control treatments. Rice straw biochar surpassed significantly other two amendments, particularly in the first season, meanwhile in the second seasonthe three soil amendments were equally in increasing grain yield. Thereby, rice straw biochar could be applied each two years but rice straw compost has to apply in two successive season to get its efficiency.

Biochar increases soil fertility by enhancing nutrients retention in amended soil. In addition, biochar increases phosphorus availability in soil by reducing leaching process. The performance of biochar serving as an inoculum carrier depends on physicochemical properties (pH, porosity and, surface area) that impact the establishment of plant growth-promoting bacteria in amended soil. Biochar is largely used as a soil amendment for soil remediation and plants growth. However, little work has been conducted considering biochar suitability when applied as a carrier, which has resulted in inconsistent outcomes. In the present study, six biochar carriers including rice straw biochar (RSB), rice husk biochar (RHB), soybean straw biochar (SSB), peanut shells biochar (PNB), corn cobs biochar (CCB), and wood biochar (WB) were prepared and inoculated with liquid suspension of a phosphate solubilizing bacteria (PSB) identified as Bacillus megaterium KU647234 in a pot experiment. The data revealed that rape (Brassica napus L.) growth and biomass were significantly (P≤ 0.05) improved by up to 304% with amendments of carriers, particularly soybean straw (SSB). P bioaccumulation in roots, stems, and leaves increased significantly (P≤ 0.05) by up to 74%, 111%, and 75% respectively. In addition, RSB, SSB, RHB, PNB, WB, and CCB amendments Plate count assay data revealed that six carriers sustained the Bacillus megateriumabundance to varying degrees. The SSB carrier was identified as the best carrier that sustained higher rape biomass, and P bioaccumulation compared with other carriers

The biochar and microbial inoculant are commonly used amendments in soil improvement, but their effectiveness in protective agriculture is currently unclear. Based on this, this study takes the pepper vegetable greenhouse located in Zhuxi Town, Chongqing as the research object, and selects biochar prepared from corn straw and rice straw, as well as microbial inoculant, as the improvement materials. Five treatments were established, including corn straw biochar alone (CB), rice straw biochar alone (RB), microbial inoculant alone (CKM), combined corn straw biochar and microbial inoculant application (CBM), and combined rice biochar and microbial inoculant application (RBM), conventional fertilization was used as a control. This study explores the changes in soil physicochemical properties of protected vegetable production under different treatments at distinct time points (first, third, and fifth months after returning field) and soil depth (0-10cm and 10-20cm). The results demonstrated that the overall soil bulk density increased With the increase of returning time. There was no significant difference in the soil capillary porosity or mineral-associated organic carbon content (P > 0.05), whereas the other soil properties decreased with increasing return field time. In contrast, the soil bulk density (BD) increased with increasing soil depth. Except the capillary porosity, which exhibited no significant differences at different depths (P > 0.05), all the other soil properties demonstrated downward trends with increasing depth. After 5months of transplantation, the soil carbon pool management index of RBM treatment was higher than that of CBM treatment, with a 4.35% increase. The soil health index was 14.51% lower than that of CBM. However, the differences in soil carbon pool management index and soil health index between the two treatments did not reach a significant level. Overall, the RBM and CBM showed better improvement effects on soil carbon pool management index and soil health status, making them the better ratios for vegetable greenhouse farmland soil improvement in this study.

To compare the dynamic effects of straw and corresponding biochar on soil acidity, nutrients, and exchangeable capacity in red soil, a pot experiment was performed. The treatments included control (CK), rice straw (R1B0), rice straw biochar prepared at 350℃ (R1B1) and 550℃ (R1B2), rape stalk (R2B0), and rape stalk biochar prepared at 350℃ (R2B1) and 550℃ (R2B2). Straw at 1% and corresponding biochar were added to a strongly acidic red soil. The rice was planted as the experimental crop. Soils were collected at the seedling, tillering, filling and mature stages of rice growth, respectively. The changes in soil pH, exchangeable acidity, organic matter, nutrients (NH4+-N and NO3--N), and exchangeable cations in soils were measured. The results showed that soil pH, NH4+-N, and NO3--N concentrations decreased with the growth period of rice, while the organic matter content and cation exchange capacity (CEC) increased. Direct returning of straw and biochar could increase soil pH, organic matter content, and exchangeable cations content, and reduce the total amount of exchangeable acids. In the mature stage of rice, rice straw and rape stalk biochar at 350℃ increased the soil pH by 0.29 and 0.42, respectively, compared to the control treatment. Similarly, biochar decreased the exchangeable acidity and exchangeable Al3+ content significantly compared to the direct returning treatments of straw. The exchangeable acidity and exchangeable Al3+ contents of soils in R1B2 and R2B1 treatments decreased by 54.8% and 58.9%, respectively, compared to the control treatment. The soil organic matter (SOM) content and CEC in biochar treatments were significantly higher than those in direct returning treatments of straw. Overall, the effects of rape stalk biochar on soil properties were slightly stronger than those of rice straw. The correlation analysis showed that soil exchangeable acids had a significantly negative correlation with organic matter (R=-0.912, P<0.01), and CEC (R=-0.866, P<0.05). The CEC in soils was positively related to organic matter (R=0.833, P<0.05). Direct returning of straw and biochar applications can effectively improve soil acidity and increase nutrient contents. The effects of straw biochar on soils were stronger than the direct returning of straw in decreasing soil acidity, and increasing soil organic matter content and exchangeable capacity in acidic soils.

Pyrolysis temperature affects pore characteristics of rice straw and canola stalk biochars and biochar-amended soils

Industrial activities can contribute to the heavy metal accumulation in soils, which could potentially threaten human health, agricultural crop productivity and the environment. This research was conducted to use metal uptake and spectroscopic analysis (X-Ray Diffraction (XRD), Energy Dispersive spectroscopy by X-rays (EDX) and Fourier Transmission Infrared Spectroscopy (FTIR) to evaluate the effect of application of both rice straw biochar and compost with different ratios on heavy metal immobilization in the canola plants grown in the contaminated soil. The results showed that the Cd, Pb, Ni and Zn uptake in the root and shoot of canola plants significantly decreased with the addition of rice straw compost (RC) and biochar (RB) to contaminated soil. The addition of 1% mixture of RC and RB gives the most effective immobilizing metals as 100% and 74.2%, reduction in Cd and Pb accumulation by canola shoots, respectively. The biochar and compost obtained from rice straw showed high carbon content, silica and a high absorption character. The use of spectroscopic analysis observed the precipitation, inner-sphere complex reaction and electrostatic attraction are the dominating mechanism for heavy metal immobilization with organic amendments. Our results indicate that the metal uptake is considered to be the effective tool to assess the efficiency of immobilizing agents on metal phyto-availability.

Soil carbon (C) mineralization was studied in an incubation experiment comprised of two factors having six organic materials and three nitrogen (N) rates. Cow dung (CD), rice straw (RS), wood ash (WA), cow dung biochar (CB), rice straw biochar (RB) and wood biochar (WB) considering 2.5 g C kg−1 soil along with three levels of N, i.e., 0, 0.05 and 0.10 g N kg−1 soil were mixed with 400 g of soil used in each pot. The pots were placed for 0, 30, 60, 90, 120, 150 and 180 days of incubation, and soils were collected after each incubation and analyzed for C and N. Irrespective of treatment factors, C decreased in an irregular fashion until 180 days of incubation. From the initial level of 1.91%, C contents decreased to 1.08, 1.10, 1.06, 1.23, 1.17 and 1.12% in soil mixed with CD, RS, WA, CB, RB and WB, respectively, and to 1.28, 1.11 and 0.99% in 0, 0.05 and 0.10 g N kg−1 soil, respectively, at 180 days of incubation. The mineralization followed the order of WA &gt; CD &gt; RS &gt; WB &gt; RB &gt; CB. Biochars could supply stable C in soil, while N enhances mineralization; optimization of N is therefore essential to ensure soil C accretion.

Aim: Recycling agricultural postharvest waste and re-introducing it again into farmland is one of the tangible ways to address zero waste dream, soil infertility and climate change. Pyrolysis of crop leftovers into biochar remains the most acceptable alternative for proper management of crop waste. The possibility of sustainable biochar production practices and multi-functionality features makes it promising to fufill an increasing demand for soil amendment, agricultural sustainability, environmental protection, cutting-edge materials and mitigation of climate change. Methodology: Same amount (14450 g) in feedstock of rice straw (RS) and soybean straw (SS) undergo slow pyrolysis separately to produce biochar. Physical (percentage yield, moisture, ash, volatile matter, bulk density, pH, electrical conductivity), chemical characterization (Microwave Plasma Atomic Emission Spectroscopy (MP-AES), Scanning Electron Microscope Energy Dispersive X-ray (SEM-EDX), Fourier Transformed Infrared (FTIR) and Thermogravimetric Analysis and Derivative Thermogravimetry (TGA and DTA)) and evaluation of bochar was determined. Results: Rice straw biochar (RSB) recorded a higher char yield of 42.1%. Both lignocellulosic biochars were black and porous with a higher silica (10.6%) content in RSB and higher carbon (82.2%) content in SSB as was revealed by SEM-EDX. Higher ash 27.1%, volatile matter (VM) 31.3% and moisture 29.4% content was seen in RSB compared to SSB because of feedstock composition. Rice straw biochar show higher peaks of macro and micro mineral elements K(14561.21mg/kg), Ca (2401.28 mg/kg), and Na(1735.27 mg/kg) than soybean straw biochar. FTIR was used to identify functional groups that might act as cation adsorbents. As the temperature increased, the TGA and DTG graphs showed mass loss and sample breakdown. Conclusion: Rice and soybean crop wastes were converted into biochar, a nutrient-rich material that maybe utilized to balance acidic soils promoting healthy plant growth and also protecting the environment.

Soil N transformation and microbial community structure as affected by adding biochar to a paddy soil of subtropical China

We analyzed the effects of rice straw biochar (RSBC) and swine manure biochar (SMBC) on N2O emission from paddy soil. The biochars were added to soil at the rates of 1% and 5% (w/w), and N2O emission, soil properties and soil enzyme activities were determined at the elongation, heading and maturation stages of rice growth. The N2O flux started within 2 h of adding the biochar, and decreased significantly thereafter during the three growth stages. The cumulative N2O emission was suppressed by 45.14–73.96% following biochar application, and 5% SMBC resulted in the lowest cumulative emission. In addition, biochar application significantly increased soil pH, soil organic carbon (SOC), NO3− levels and urease activity, and decreased soil NH4+ and nitrate reductase activity. Regression analysis indicated that cumulative N2O emission was correlated positively to NH4+, and negatively to soil pH, SOC and NO3−. SEM further revealed that biochar application weakened the denitrification process, and the NH4+ level had the most significant impact on N2O emission. Taken together, RSBC and SMBC regulated the nitrogen cycle in paddy soil and mitigated N2O emission by increasing soil pH, decreasing nitrate reductase activity and NH4+ content.