Pine Chip Biochar Research Articles

Characterization and Sodium Cations Sorption Capacity of Chemically Modified Biochars Produced from Agricultural and Forestry Wastes.

Excessive amounts of sodium cations (Na+) in water is an important limiting factor to reuse poor quality water in agriculture or industry, and recently, much attention has been paid to developing cost-effective and easily available water desalination technology that is not limited to natural resources. Biochar seems to be a promising solution for reducing high loads of inorganic contaminant from water and soil solution, and due to the high availability of biomass in agriculture and forestry, its production for these purposes may become beneficial. In the present research, wheat straw, sunflower husk, and pine-chip biochars produced at 250, 450 and 550 °C under simple torrefaction/pyrolysis conditions were chemically modified with ethanol or HCl to determine the effect of these activations on Na sorption capacity from aqueous solution. Biochar sorption property measurements, such as specific surface area, cation exchange capacity, content of base cations in exchangeable forms, and structural changes of biochar surface, were performed by FTIR and EPR spectrometry to study the effect of material chemical activation. The sorption capacity of biochars and activated carbons was investigated by performing batch sorption experiments, and adsorption isotherms were tested with Langmuir’s and Freundlich’s models. The results showed that biochar activation had significant effects on the sorption characteristics of Na+, increasing its capacity (even 10-folds) and inducing the mechanism of ion exchange between biochar and saline solution, especially when ethanol activation was applied. The findings of this study show that biochar produced through torrefaction with ethanol activation requires lower energy demand and carbon footprint and, therefore, is a promising method for studying material applications for environmental and industrial purposes.

Nitrogen utilization and environmental losses in organic greenhouse lettuce amended with two distinct biochars

The potential of biochar to prevent nitrogen (N) losses and improve plant performance were studied across various levels of N input for two growing seasons in mesocosms simulating an organic lettuce production system. A silt loam soil was amended with pine chip (PC) and walnut shell (WS) biochar (10tha−1) in combination with five organic N fertilization rates (0, 56, 112, 168, and 225kgNha−1). The N output through harvest, leachate, and N2O emissions were measured to assess N utilization and environmental losses of biochar-amended soils. For both biochars, only at the 100% N fertilization rate was lettuce biomass production improved with significant increases in N use efficiency (NUE); however, only PC biochar decreased N losses via leaching (at 100% N fertilization rate) and seasonal N2O emissions (at 50% N fertilization rate). Thus, due to increases in plant biomass and decreases in N losses, PC biochar significantly decreased the ratio of N lost over N exported in biomass. Findings from this study suggest that both WS and PC biochars can improve organic lettuce production but only at 225kgNha−1. Decreases in N losses via leachate and N2O emissions vary with fertilization level and biochar type.

Organic amendments for risk mitigation of organochlorine pesticide residues in old orchard soils

Performance of compost and biochar amendments for in situ risk mitigation of aged DDT, DDE and dieldrin residues in an old orchard soil was examined. The change in bioavailability of pesticide residues to Lumbricus terrestris L. relative to the unamended control soil was assessed using 4-L soil microcosms with and without plant cover in a 48-day experiment. The use of aged dairy manure compost and biosolids compost was found to be effective, especially in the planted treatments, at lowering the bioavailability factor (BAF) by 18–39%; however, BAF results for DDT in the unplanted soil treatments were unaffected or increased. The pine chip biochar utilized in this experiment was ineffective at lower the BAF of pesticides in the soil. The US EPA Soil Screening Level approach was used with our measured values. Addition of 10% of the aged dairy manure compost reduced the average hazard quotient values to below 1.0 for DDT + DDE and dieldrin. Results indicate this sustainable approach is appropriate to minimize risks to wildlife in areas of marginal organochlorine pesticide contamination. Application of this remediation approach has potential for use internationally in areas where historical pesticide contamination of soils remains a threat to wildlife populations.

Interactive effects of biochar ageing in soils related to feedstock, pyrolysis temperature, and historic charcoal production

Biochar is suggested for soil amelioration and carbon sequestration, based on its assumed role as the key factor for the long-term fertility of Terra preta soils. Several studies have shown that certain biochar properties can undergo changes through ageing processes, especially regarding charge characteristics. However, only a few studies determined the changes of different biochars under the same incubation conditions and in different soils. The objective of this study was to characterize the changes of pine chip (PC)- and corn digestate (CD)-derived biochars pyrolyzed at 400 or 600°C during 100days of laboratory incubation in a historical kiln soil and an adjacent control soil. Separation between soil and biochar was ensured by using mesh bags. Especially, changes in charge characteristics depended on initial biochar properties affected by feedstock and pyrolysis temperature and on soil properties affected by historic charcoal production. While the cation exchange capacity (CEC) markedly increased for both CD biochars during incubation, PC biochars showed no or only slight increases in CEC. Corresponding to the changes in CEC, ageing of biochars also increased the amount of acid functional groups with increases being in average about 2-fold higher in CD biochars than in PC biochars. Further and in contrast to other studies, the surface areas of biochars increased during ageing.Changes in CEC and surface acidity of CD biochar were more pronounced after incubation in the control soil, while surface area increase was higher in the kiln soil. Since the two acidic forest soils used in this study did not greatly differ in physical or chemical properties, the main process for inducing these differences in the buried biochar most likely is related to the differences in dissolved organic carbon (DOC). Although the kiln soil contained about 50% more soil organic carbon due to the presence of charcoal particles, extractable DOC was lower and less aromatic than in the adjacent control soil, likely due to strong sorption of dissolved organic matter (DOM) onto charcoal particles. We suggest that higher sorption of DOM onto the surface of biochar in the control soil provided additional acid functional groups and thus increased the surface charge to a greater extent than in the DOC poorer kiln soil. Hence, biochars incubated in the kiln soil showed less changes in CEC and surface acidity. Higher availability of DOM in the control soil could also stimulate microbial activity to a larger extent, resulting in higher oxidation rates of biochars incubated in the control soil.

Plant Macro- and Micronutrient Dynamics in a Biochar-Amended Wetland Muck

Biochar is an organic carbon (OC) and plant nutrient-rich substance that may be an ideal amendment for bolstering soil organic matter and nutrient contents. Two biochars were produced by pyrolysis at 350 °C from pine chips (Pinus taeda) and swine manure solids (Sus scrofa domesticus). The biochar total elemental composition was quantified using inductively coupled plasma spectrometer and their surface chemical composition examined using a combination of scanning electron microscopy (SEM) and electron dispersive spectroscopy (EDS). The biochars were mixed into triplicate pots containing Lauderhill muck (Euic, hyperthermic Lithic Haplosaprist) at 0, 2.5, 5, and 10 % (dry mass). Four simulated water infiltration events were conducted during the 124-day incubation to assess the potential alteration in the leaching potential of soluble soil nutrients. At termination, the muck’s fertility characteristics were assessed, and dissolved cations were measured in water leachates. Neither biochars significantly increased the muck’s OC contents. Swine manure biochar contained higher K, Mg, Na, and P concentrations, and these differences were observable in SEM and EDS as differing amounts of surface-precipitated Mg and K salts. Correspondingly, swine manure biochar at all three applications rates significantly increased Mehlich 1-s K, P, Mg, and Na concentrations. Pine chip biochar only improved the Mehlich 1-extractable K concentration but did reduce soluble P concentrations. Water leachates from swine manure biochar treated wetland soil contained significantly higher soluble P concentrations that could create water quality issue in downstream ecosystems.

Impact of pine chip biochar on trace greenhouse gas emissions and soil nutrient dynamics in an annual ryegrass system in California

Manure generated by dairy cattle is a useful soil amendment but contributes to greenhouse gas (GHG) emissions and water pollution from nutrient leaching. In order to assess the impact of pine chip biochar produced at a peak temperature of 550°C when added to a dairy grassland system, a one-year field study was conducted on a sandy loam soil under annual ryegrass (Lolium multiflorum Lam.) grown for silage in Petaluma, California. Manure was applied to all plots at a rate of ca. 150m3ha−1 (410kgNha−1). Control plots received no biochar, high application biochar plots (HB) received biochar (with a 17% ash content) at a rate of 18.8tha−1, and low application biochar plots (LB) received the same biochar at 5.7tha−1. Although the HB plots demonstrated the lowest cumulative nitrous oxide (N2O) and methane (CH4) emissions, there was no significant difference between treatments (p=0.152 and p=0.496, respectively). Soil pH results from samples collected throughout the year indicated a significant treatment effect (p=0.046), though Tukey test results indicated that there was no difference between mean values. Soil total carbon was significantly higher in HB plots at the end of the experiment (p=0.025) and nitrate (NO3−) intensity throughout the year (which expresses potential exposure of NO3− to the soil microbial community) was significantly lower in HB plots compared to the control (p=0.001). Annual cumulative potassium (K+) loss from HB plots was significantly higher than from the other treatments (p=0.018). HB plots also demonstrated a short-term increase in phosphorus (P) and ammonium (NH4+) in leachate during the first rainfall event following manure and biochar application (p<0.0001 and p=0.0002, respectively) as well as a short-term decrease of NO3− in leachate during a heavy rainfall event following a long dry spell (p=0.036), though differences between treatments for cumulative nutrient losses were not significant (p=0.210, p=0.061, and p=0.295, respectively for P, NH4+, and NO3−). These data indicate that biochar produced from pine wood chips at 550°C having high ash content (17%) is not likely to impact GHG emissions in systems with high manure application rates. Further research should be conducted in order to investigate the impact of biochar amendment on the dynamics and mobility of nutrients applied in subsequent repeated applications of dairy manure.

Biochar does not mitigate field-scale N2O emissions in a Northern California vineyard: An assessment across two years

Biochar amendment to soil has been proposed as a mechanism to mitigate climate change through an array of mechanisms; one being the mitigation of soil nitrous oxide (N2O) emissions. Yet the extent and mechanisms through which this may be achieved in temperate agroecosystems is uncertain. We used a pine chip biochar produced at a moderate temperature (550°C, PC biochar) and a walnut shell biochar produced at a higher temperature (900°C, WS biochar). Biochar was applied at 10Mgha−1 to a working commercial wine grape system in North-Central California. The effects of biochar were assessed over two years at two distinct functional locations: the berm and row, which differed in N application and irrigation. N2O emissions and ancillary soil properties (NH4+, NO3, water filled pore space (WFPS), and pH) were closely monitored following management and precipitation events. Soil bulk density, cover crop yield and soil C and N were measured annually to address longer term changes in cropping system and soil properties. In the PC biochar treatment, annual cumulative N2O emissions were significantly higher than the control treatment each year (p<0.05); 4.14±1.14kg N2O-Nha−1yr−1 versus 2.00±0.66kg N2O-Nha−1yr−1 in year one, and 4.24±0.74kg N2O-Nha−1yr−1 versus 1.60±0.28kg N2O-Nha−1yr−1 in year two. Emissions of N2O in the WS biochar treatment were also higher than the control each year, but differences were not significant. The effect of biochar on N2O emissions was more pronounced in the row location where annual emissions were significantly higher than the control in one and both years for the WS and PC biochars, respectively (p<0.05). In the PC biochar treatment, we observed increased N2O emissions at both functional locations, however increases were more pronounced in the row location where they were in part attributable to increased cover crop N inputs. Differences between treatments in NH4+, NO3− and WFPS were mostly not significant. The WS biochar significantly raised soil pH relative to the control (p<0.05), however in the berm location only, and increased soil pH in this treatment did not correspond to changes in N2O emissions. Since neither biochar amendment reduced N2O emissions, our results demonstrate the need to evaluate N2O emissions at a cropping system scale (e.g. encompassing changes in N inputs and cycling) and in systems where nitrification processes may dominate emissions.

Transport of , , and microspheres in biochar-amended soils with different textures.

The incorporation of biochar into soils has been proposed as a means to sequester carbon from the atmosphere. An added environmental benefit is that biochar has been shown to increase soil retention of agrochemicals, and recent research has indicated that biochar may be effective in increasing soil retention of bacteria. In this study we investigate the transport behavior of O157:H7, serovar Typhimurium, and carboxylated polystyrene microspheres in water-saturated column experiments for two soils (fine sand and sandy loam) amended with 2% poultry litter or pine chip biochars pyrolyzed at 350 and 700°C. Adding poultry litter biochar pyrolyzed at 350°C did not improve soil retention of either bacteria in fine sand and even facilitated their transport in sandy loam. Addition of either biochar pyrolyzed at 700°C generally improved retention of bacteria in fine sand, with the pine chip biochars being more effective in limiting their transport. Results from the column studies and auxiliary batch studies suggest that changes in cell retention after biochar amendments were likely due to changes in bacterial attachment in the column and not to physical straining or changes in survivability. We also found that changes in bacterial hydrophobicity after biochar amendments were generally correlated with changes in bacterial retention. The influence of biochar amendment in increasing retention of both bacteria was generally more pronounced in fine sand and indicates that soil texture affects the transport behavior of bacteria through biochar-amended soils.

Atrazine leaching from biochar-amended soils

The herbicide atrazine is used extensively throughout the United States, and is a widespread groundwater and surface water contaminant. Biochar has been shown to strongly sorb organic compounds and could be used to reduce atrazine leaching. We used lab and field experiments to determine biochar impacts on atrazine leaching under increasingly heterogeneous soil conditions. Application of pine chip biochar (commercially pyrolyzed between 300 and 550°C) reduced cumulative atrazine leaching by 52% in homogenized (packed) soil columns (p=0.0298). Biochar additions in undisturbed soil columns did not significantly (p>0.05) reduce atrazine leaching. Mean peak groundwater atrazine concentrations were 53% lower in a field experiment after additions of 10tha−1 acidified biochar (p=0.0056) relative to no biochar additions. Equivalent peat applications by dry mass had no effect on atrazine leaching. Plots receiving a peat-biochar mixture showed no reduction, suggesting that the peat organic matter may compete with atrazine for biochar sorption sites. Several individual measurement values outside the 99% confidence interval in perched groundwater concentrations indicate that macropore structure could contribute to rare, large leaching events that are not effectively reduced by biochar. We conclude that biochar application has the potential to decrease peak atrazine leaching, but heterogeneous soil conditions, especially preferential flow paths, may reduce this impact. Long-term atrazine leaching reductions are also uncertain.

Characterization and Mineralization Rates of Low Temperature Peanut Hull and Pine Chip Biochars

Biochar can potentially increase soil fertility and sequester carbon by incorporating nutrients and stable black carbon into the soil; however its effect on soil nitrogen (N) and carbon (C) processes is not well understood. A defined methodology to characterize biochar is necessary to predict how specific biochars will affect C and N mineralization. We amended a Tifton soil (Fine-loamy, siliceous, thermic Plinthic Kandiudults) with peanut hull (Arachis hypogaea; PH; 2.1% N) and pine chip (Pinus taeda; PC: 0.4% N) biochar at application rates of 1% and 2% (w/w) and performed a 136-day mineralization study. A companion 24-day mineralization study amended Tifton soil with PH and PC biochar at 2% and their respective feedstocks at equal C rates. Soil C mineralization rates were monitored periodically throughout each study and total N mineralization rates were also measured. In addition, we characterized each biochar using thermogravimetric analysis with mass spectrometer (TGA-MS), proximate analysis, Fourier transform infrared spectroscopy (FTIR), and total mineral analysis to identify biochar characteristics that might correlate with mineralization properties. Limited C (&lt;2%) mineralized from both biochars, but mineralization rates of soil amended with PH biochar were higher than PC biochar. Carbon mineralization correlated well with estimated aliphatic content determined by TGA-MS but not with volatile content indicated by proximate analysis. Nitrogen was not mineralized from either biochar, indicating that plant-based biochar should not be considered a source of N for plant growth. The N in biochar may be contained in the stable aromatic structure of the biochar, as indicated by TGA-MS, and not available to soil microbes.

Influence of Feedstock and Pyrolysis Temperature of Biochar Amendments on Transport ofEscherichia coliin Saturated and Unsaturated Soil

The effects of biochar feedstock, pyrolysis temperature, and application rate (1 and 2%) on the transport of two Escherichia coli isolates through a fine sand soil under water-saturated and partially saturated conditions were investigated in column experiments. Biochars from two feedstocks (poultry litter and pine chips) and pyrolyzed at two temperatures (350 and 700 °C) were evaluated. Both biochars pyrolyzed at 700 °C resulted in significant reductions in E. coli transport, with greater reductions observed with the pine chip biochars. For the low temperature biochars, increased transport was observed for the poultry litter biochar whereas reduced transport was observed for the pine chip biochar. In general, the effect of biochar application on E. coli transport was more pronounced in the unsaturated soils and for the 2% application rates. Large differences were also observed between the two isolates indicating that bacterial surface properties play a role in how biochar affects E. coli transport.

Effect of Peanut Hull and Pine Chip Biochar on Soil Nutrients, Corn Nutrient Status, and Yield

Pyrolysis is the anaerobic thermal conversion of biomass for energy production. It offers an option of returning carbon and nutrients to the soil while producing energy. The Ultisols in the southeastern United States have inherently low soil organic carbon and fertility, and may benefit from the addition of biochar from pyrolysis. Our objectives were to evaluate the effect of peanut hull and pine chip biochars on soil nutrients, corn (Zea mays L.) nutrient status and yield in a Kandiudult for two growing seasons (2006 and 2007). Experiments for each biochar source were conducted as completely randomized designs with the biochar applied at 0, 11, and 22 Mg ha−1 with and without N fertilizer. Nitrogen in the peanut hull biochar (209 kg ha−1 at 11 Mg ha−1 rate) was not available during the study based on corn tissue concentrations. The peanut hull biochar linearly increased Mehlich I K, Ca, and Mg in the surface soil (0–15 cm). The increased available K was reflected in the plant tissue analysis at corn stage R1 in 2006, but not in 2007. Pine chip biochar decreased soil pH, but had no effect on other nutrients except Mehlich I Ca. In the peanut hull biochar experiment, grain yields decreased at the 22 Mg ha−1 rate in the fertilized treatments. In the pine chip biochar experiment, grain yields decreased linearly with application rate in 2006, but this did not persist in 2007. Overall yield responses to biochar were smaller than expected based on previous studies.

Effect of Low-Temperature Pyrolysis Conditions on Biochar for Agricultural Use

The removal of crop residues for bio-energy production reduces the formation of soil organic carbon (SOC) and therefore can have negative impacts on soil fertility. Pyrolysis (thermoconversion of biomass under anaerobic conditions) generates liquid or gaseous fuels and a char (biochar) recalcitrant against decomposition. Biochar can be used to increase SOC and cycle nutrients back into agricultural fields. In this case, crop residues can be used as a potential energy source as well as to sequester carbon (C) and improve soil quality. To evaluate the agronomic potential of biochar, we analyzed biochar produced from poultry litter, peanut hulls, and pine chips produced at 400°C and 500°C with or without steam activation. The C content of the biochar ranged from 40% in the poultry litter (PL) biochar to 78% in the pine chip (PC) biochar. The total and Mehlich I extractable nutrient concentrations in the biochar were strongly influenced by feedstock. Feedstock nutrients (P, K, Ca, Mg) were concentrated in the biochar and were significantly higher in the biochars produced at 500°C. A large proportion of N was conserved in the biochar, ranging from 27.4% in the PL biochar to 89.6% in the PC biochar. The amount of N conserved was inversely proportional to the feedstock N concentration. The cation exchange capacity was significantly higher in biochar produced at lower temperature. The results indicate that, depending on feedstock, some biochars have potential to serve as nutrient sources as well as sequester C.