Biochar Application Rate Research Articles

Biochar-induced variations in crop yield are closely associated with the abundance and diversity of keystone species

Biochar application has widely been used to improve crop yield, but its effectiveness is uncertain. Soil microbial communities may play critical roles, but we lack experimental evidences on the relationships between these communities and crop yield following biochar application. Here, we used cooccurrence networks to demonstrate the importance of ecological clusters (cooccurring taxa of soil microbes including bacteria and fungi) and to identify specific keystone species that were closely connected with the variations in crop yield in a pot experiment. The experiment included two soils (i.e., red soil and yellow-cinnamon soil) for wheat growth, with each soil receiving three biochar application rate. The grain yield in the red soil significantly increased while that in the yellow-cinnamon soil significantly decreased with the biochar application rate. Generally, the grain yield from the two soils showed close correlations with the relative abundance as well as with the diversity of keystone species within major clusters rather than with the soil properties and enzyme activities. This contrasting effectiveness was mainly associated with the enrichment of beneficial and suppression of detrimental keystone species in the red soil and the suppression of beneficial and enrichment of detrimental keystone species in the yellow-cinnamon soil. These species together mainly accounted for the variation in the relative abundance of keystone species within major clusters of each soil, suggesting their potential to affect crop yield following biochar application.

Selection of suitable type and application rate of biochar for alfalfa (Medicago sativa L.) productivity in ridge-furrow rainwater-harvesting in semiarid regions of China

Ridge-furrow rainwater-harvesting (RFRH) has emerged as an effective technology to mitigate drought stress, control soil erosion, and increase crop yield in semiarid regions of China. However, the use of plastic film mulch in RFRH makes this technology impractical. A field experiment was conducted for three consecutive years in a randomized complete block design to determine 1) the runoff coefficient for ridges compacted with soil mixed with two types of biochar (rice straw biochar and cow dung biochar) at two application rates (single application rate i.e., 3 × 104 kg ha−1; and double application rate i.e., 6 × 104 kg ha−1; and 2) the effects of the ridges compacted with soil mixed with two types of biochar at two application rates on soil physico-chemical properties, economic benefit, fodder yield and water use efficiency (WUE) of alfalfa, and ridges compacted with soil (no biochar) as control. The average runoff coefficient for NB, SRSB, DRSB, SCDB, and DCDB (NB, SRSB, DRSB, SCDB, and DCDB were ridges compacted with soil, compacted with soil mixed with single rice straw biochar application, double rice straw biochar application, single cow dung biochar application, and double cow dung biochar application, respectively) over these three years was 31%, 28%, 27%, 22%, and 21%, respectively. Ridges compacted with soil-biochar crust had lower runoff coefficients, soil water storage, net income, and higher soil nutrients, when compared to ridges compacted with soil. The topsoil temperature at ridge tops was affected by the ridges compacted with soil-biochar crust, but the topsoil temperature at furrow bottoms was not affected. Compared to ridges compacted with soil mixed with cow dung biochar, ridges compacted with soil mixed with rice straw biochar had lower soil nutrients, and higher soil water storage resulting in higher fodder yield and WUE of alfalfa. With runoff, the nutrients in biochar flowed from ridges to furrows, becoming usable for plants. Ridges compacted with soil-biochar crust increased topsoil nutrients, especially soil organic matter ranging from 15% to 34%, resulting in high fodder yield and WUE of alfalfa. Compared to NB, annual fodder yield for SRSB, DRSB, SCDB, and DCDB increased by 9.0%, 5.9%, 4.4%, and 3.8%, respectively, over three years, while WUE for the same treatments increased by 2.81, 1.95, 0.65, and 0.45 kg ha−1 mm−1. Rice straw biochar at an application rate of 3 × 104 kg ha−1 was found to be suitable type of biochar for increase in fodder yield and WUE of alfalfa in RFRH. Future studies should be conducted in the form of long-term field study to determine economic benefits of biochar application.

Effect of Biochar Application Rate on Physical and Hydro-physical Properties of A Dystric Cambisol

The field trial evaluating the effect of biochar on physical and hydro-physical properties of a Dystric Cambisol was carried out at the Research Grassland Station VatĂ­n. The observed variants of the biochar experiment were as follows: 1) the control without biochar, 2) the biochar rate of 15 t/ha applied to the topsoil, 3) the biochar rate of 30 t/ha applied to the topsoil and 4) the biochar rate of 45 t/ha applied to the topsoil. It was found out that even the highest rate of biochar 45 t/ha did not affect saturated hydraulic conductivity of the topsoil at the depth of 0.05-0.20 m. When monitoring bulk density, it was confirmed that the biochar rate of 45 t/ha significantly reduced bulk density from 1218 kg/m3 to 1169 kg/m3. In the crop rotation without manure and clover growing the application of biochar at the rate of 45 t/ha resulted in the relevant decline in the average value of bulk density from 1197 kg/m3 to 1138 kg/m3. In the Norfolk crop rotation there were the inconclusive differences in bulk density. The rate of 45 t/ha had a highly noticeable impact on porosity. It increased from 53.75% (0 t/ha) to 55.60%. The biochar doses did not affect the value of field capacity. The application of biochar at the rate of 45 t/ha caused the significant increase in the average value of aeration from 31.90% to 34.45%.

Rice husk and melaleuca biochar additions reduce soil CH 4 and N 2O emissions and increase soil physicochemical properties.

Background: Biochar is a promising material in mitigating greenhouse gases (GHGs) emissions from paddy fields due to its remarkable structural properties. Rice husk biochar (RhB) and melaleuca biochar (MB) are amendment materials that could be used to potentially reduce emissions in the Vietnamese Mekong Delta (VMD). However, their effects on CH 4 and N 2O emissions and soil under local water management and conventional rice cultivation have not been thoroughly investigated. Methods: We conducted a field experiment using biochar additions to the topsoil layer (0-20 cm). Five treatments comprising 0 t ha -1 (CT0); 5 t ha -1 (RhB5) and 10 t ha -1 (RhB10), and 5 t ha -1 (MB5) and 10 t ha -1 (MB10) were designed plot-by-plot (20 m 2) in triplicates. Results: The results showed that biochar application from 5 to 10 t ha -1 significantly decreased cumulative CH 4 (24.2-28.0%, RhB; 22.0-14.1%, MB) and N 2O (25.6-41.0%, RhB; 38.4-56.4%, MB) fluxes without a reduction in grain yield. Increasing the biochar application rate further did not decrease significantly total CH 4 and N 2O fluxes but was seen to significantly reduce the global warming potential (GWP) and yield-scale GWP in the RhB treatments. Biochar application improved soil Eh but had no effects on soil pH. Whereas CH 4 flux correlated negatively with soil Eh ( P <0.001; r 2 = 0.552, RhB; P <0.001; r 2 = 0.502, MB). Ameliorating soil aeration and functions by adding RhB and MB resulted in improving soil physicochemical properties, especially significant SOM and AN boosting, which indicate better soil health, structure, and fertility. Conclusions: Biochar supplementation significantly reduced CH 4 and N 2O fluxes and improved soil mineralization and physicochemical properties toward beneficial for rice plants. The results suggest that the optimal combination of biochar-application rates and effective water-irrigation techniques for soil types in the MD should be further studied in future works.

Biochar Addition Inhibits Nitrification by Shifting Community Structure of Ammonia-Oxidizing Microorganisms in Salt-Affected Irrigation-Silting Soil.

Biochar has been widely recognized as an effective and eco-friendly ameliorant for saline soils, but information about the mechanism of how biochar influences nitrification in salt-affected agroecosystem remains fragmented. An incubation experiment was performed on the salt-affected soil collected from a three-consecutive-year experiment at biochar application gradients of 7.5 t⋅ha−1, 15 t⋅ha−1 and 30⋅t ha−1 and under nitrogen (N) fertilization. Responses of the nitrification rate (NR), numbers of ammonia monooxygenase (amoA) gene copies, and community structures of ammonia-oxidizing bacteria (AOB) and archaea (AOA) to biochar application were investigated. The results indicated that, under N fertilization, the NR and numbers of amoA-AOB and amoA-AOA gene copies negatively responded to biochar addition. Biochar application increased the community diversity of AOB but decreased that of AOA. Biochar addition and N fertilization shifted the AOB community from Nitrosospira-dominated to Nitrosospira and Nitrosomonas-dominated, and altered the AOA community from Nitrososphaera-dominated to Nitrososphaera and Nitrosopumilus-dominated. The relative abundance of Nitrosospira, Nitrosomonas and Nitrosopumilus decreased, and that of Nitrosovibrio and Nitrososphaera increased with biochar application rate. Soil SOC, pH and NO3−-N explained 87.1% of the variation in the AOB community, and 78.1% of the variation in the AOA community was explanatory by soil pH and SOC. The SOC and NO3−-N influenced NR through Nitrosovibrio, Nitrosomonas, Norank_c_environmental_samples_p_Crenarchaeota and amoA-AOB and amoA-AOA gene abundance. Therefore, biochar addition inhibited nitrification in salt-affected irrigation-silting soil by shifting the community structures of AOB and AOA and reducing the relative abundance of dominant functional ammonia-oxidizers, such as Nitrosospira, Nitrosomonas and Nitrosopumilus.

Opportunities and challenges of applying biochar to boost agricultural output and repair salt-damaged soils

Soil salinization is recognized as a serious form of soil degradation, affecting crop production and compromising food security. It is crucial to remediate the negative impacts of soil salinization to improve the associated soil functions. Biochar amendments are used to reclaim the salt-affected lands. Therefore, the main objective of the present paper was to review and discuss the recent studies investigating a role of biochar in improving soil properties and plant growth in salt-affected soils. Recently, biochar (solid carbonaceous residue, produced under oxygen-free or oxygen-limited conditions at temperatures ranging from 300 to 1000 C) has attracted considerable attention as a soil amendment. An emerging pool of knowledge shows that biochar addition is effective in improving physical, chemical and biological properties of salt-affected soils. Biochar amendments improve not soil properties but also support plant growth and ameliorate soil problems. However, some studies have also found an increase in soil salinity with biochar application at high rates. Further, the high cost associated with production of biochar and high application rates remains a significant challenge to its widespread use in areas affected by salinity. Therefore, the underlying mechanisms of such beneficial effects provided by biochar amendment of soils are highly complex. Therefore, more in-depth studies are needed to understand biochar interactions with soil organisms under extreme environments, which would help achieve maximum benefits of biochar under saline soil conditions.

Rice husk and melaleuca biochar additions reduce soil CH 4 and N 2O emissions and increase soil physicochemical properties

Background: Biochar is a promising material in mitigating greenhouse gases (GHGs) emissions from paddy fields due to its remarkable structural properties. Rice husk biochar (RhB) and melaleuca biochar (MB) are amendment materials that could be used to potentially reduce emissions in the Vietnamese Mekong Delta (VMD). However, their effects on CH 4 and N 2O emissions and soil under local water management and conventional rice cultivation have not been thoroughly investigated. Methods: We conducted a field experiment using biochar additions to the topsoil layer (0-20 cm). Five treatments comprising 0 t ha -1 (CT0); 5 t ha -1 (RhB5) and 10 t ha -1 (RhB10), and 5 t ha -1 (MB5) and 10 t ha -1 (MB10) were designed plot-by-plot (20 m 2) in triplicates. Results: The results showed that biochar application from 5 to 10 t ha -1 significantly decreased cumulative CH 4 (24.2-28.0%, RhB; 22.0-14.1%, MB) and N 2O (25.6-41.0%, RhB; 38.4–56.4%, MB) fluxes without a reduction in grain yield. Increasing the biochar application rate further did not decrease significantly total CH 4 and N 2O fluxes but was seen to significantly reduce the global warming potential (GWP) and yield-scale GWP in the RhB treatments. Biochar application improved soil Eh but had no effects on soil pH. Whereas CH 4 flux correlated negatively with soil Eh ( P < 0.001; r 2 = 0.552, RhB; P < 0.001; r 2 = 0.502, MB). Ameliorating soil aeration and functions by adding RhB and MB resulted in improving soil physicochemical properties, especially significant SOM and AN boosting, which indicate better soil health, structure, and fertility. Conclusions: Biochar supplementation significantly reduced CH 4 and N 2O fluxes and improved soil mineralization and physicochemical properties toward beneficial for rice plants. The results suggest that the optimal combination of biochar-application rates and effective water-irrigation techniques for soil types in the MD should be further studied in future works.

Biochar impacts on the soil environment of soybean root systems

Biochar has been widely studied as a soil amendment, but little is known about the “biochar-freeze-thaw soil-crop root system” interface in seasonally frozen soil areas. In the second year after the application of biochar, we conducted research on the morphological characteristic indicators of the soybean root system and the nutrient migration of the soil in the root zone under different biochar application periods (spring and autumn mixed, autumn, and spring biochar application) and different biochar application rates (3 kg·m−2, 6 kg·m−2, 9 kg·m−2, and 12 kg·m−2). The effects of different biochar treatments on the growth and development of soybean roots were examined. The soil organic carbon, ammonium nitrogen and nitrate nitrogen contents of the soil were measured at different locations in the root zone, and the migration processes of these nutrients in the soil were explored. The conclusions drawn from the experiments are as follows. (i) The biochar application rate and application method together determine the root morphological characteristic indicators of soybean plants. During long freeze-thaw periods, the freeze-thaw cycles change the internal environment of the biochar-freeze-thaw soil complex. (ii) Biochar tends to move towards the root system, which can increase soil organic carbon content, but the effect of biochar on root characteristics is not caused by the change in soil organic carbon content. (iii) Biochar promotes nitrogen cycling in the soil and the migration of soil nitrogen to the root sheath, increasing the number of nitrogen compounds that can be directly absorbed and utilized by crops. (iv) From a comparison of the effects of various biochar treatments on crop roots and farmland soils, we suggest that the 9 kg·m−2 biochar application rate under spring and autumn mixed biochar application is the optimal treatment.

Integrated Application of Thiourea and Biochar Improves Maize Growth, Antioxidant Activity and Reduces Cadmium Bioavailability in Cadmium-Contaminated Soil.

Cadmium (Cd) contamination of croplands jeopardizes sustainable crop production and human health. However, curtailing Cd transfer and mobility in the rhizosphere-plant system is challenging. Sole application of biochar (BC) and thiourea (TU) has been reported to restrain Cd toxicity and uptake in plants. However, the combined applications of BC and TU in mitigating the harmful effects of Cd on plants have not yet been thoroughly investigated. Therefore, this study attempts to explore the integrated impact of three maize stalk BC application rates [B0 (0% w/w), B1 (2.5% w/w), and B2 (5% w/w)] and three TU foliar application rates [T0 (0 mg L–1), T1 (600 mg L–1), and T2 (1,200 mg L–1)] in remediating the adverse effects of Cd on maize growth, development, and physiology. Results demonstrated that Cd concentration in soil inhibited plant growth by reducing leaf area, photosynthesis activity, and enhanced oxidative stress in maize. Nevertheless, BC and TU application in combination (B2T2) improved the fresh biomass, shoot height, leaf area, and photosynthesis rate of maize plants by 27, 42, 36, and 15%, respectively, compared with control (B0T0). Additionally, the oxidative stress values [malondialdehyde (MDA), hydrogen peroxide (H2O2), and electrolyte leakage (EL)] were minimized by 26, 20, and 21%, respectively, under B2T2 as compared with B0T0. Antioxidant enzyme activities [superoxide dismutase (SOD) and catalase (CAT)] were 81 and 58%, respectively, higher in B2T2 than in B0T0. Besides, the shoot and root Cd concentrations were decreased by 42 and 49%, respectively, under B2T2 compared with B0T0. The recent study showed that the integrated effects of BC and TU have significant potential to improve the growth of maize on Cd-contaminated soil by reducing Cd content in plant organs (shoots and roots).

Effects of wetland plant biochars on heavy metal immobilization and enzyme activity in soils from the Yellow River estuary.

The purpose of this study was to assess the effects of wetland plant biochars on the enzyme activity in heavy metal contaminated soil. The biochars were produced from Phragmites australis (PB), Suaeda salsa (SB), and Tamarix chinensis (TB) under different pyrolysis temperatures and times. The detected pyrolysis products showed that the ash, pH, electrical conductivity, and carbon content of the biochars increased significantly, while the production rate of the biochars decreased with increasing pyrolysis temperature and time. The results of the adsorption experiments indicated that biochar addition could effectively reduce the concentration of Pb and/or Cd in the Pb2+/Cd2+ single or mixed solutions, but the Pb2+ and Cd2+ in the mixed solution indicated a competitive adsorption. A 30-day incubation experiment was conducted using salt marsh soil amended with different biochar application rates to investigate the short-term effects of biochar addition on Pb and Cd immobilization. The PB and SB significantly immobilized Pb within the first 15days, but Pb remobilized within the next 15-day period. In contrast, TB addition did not significantly fix Pb. Moreover, biochar addition promoted the conversion of Cd from the residue to the less immobile fractions. The addition of three types of plant biochar had no significant effect on the urease activity in wetland soil but significantly increased soil sucrase activity. PB and SB significantly promoted catalase activity, while TB significantly inhibited soil catalase activity. According to the adsorption effect, the fixation effect, and the promotion of enzyme activities, the Suaeda salsa biochars are suitable for the remediation of heavy metal pollution in wetland soils.

Biochar can reduce N2O production potential from rhizosphere of fertilized agricultural soils by suppressing bacterial denitrification

Biochar-fertilizer combination is a promising strategy to improve environmental quality while maintaining agronomic performance. Yet, its effect on soil nitrification and denitrification and their causal pathways remains less explored. Here in a pot experiment growing pakchoi (Brassica Chinensis) under two nitrogen (N) fertilizer rates (100 and 200 mg N kg−1) in combination with four biochar levels (0%, 0.5%, 1% and 2% w/w), we investigated the potential of N2O production-related bacterial and fungal nitrification and denitrification from both non-rhizosphere and rhizosphere, as well as the abundance of bacterial and fungal genes associated with N2O production. Results revealed strong inorganic fertilizer and biochar-driven changes in the potential of N2O production as well as the gene abundance associated with these processes. However, bacteria and fungi showed distinct responses to inorganic fertilizer and biochar amendment. Greater N fertilization rates increased the abundance of bacterial genes and bacterial-related nitrification and denitrification potential by 89 ± 2.3% and 70 ± 4.1%, respectively; but did not affect fungal gene abundance or activities. By contrast, the increased application rate of biochar, although increased fungal activities overall by 21 ± 1.8%, resulted in a decline of the abundance of N-cycle bacterial genes and bacterial-related nitrification and denitrification, especially in the rhizosphere, a hotspot of soil microbial activities and greenhouse gas emissions. As a result, the N2O production potential from denitrification increased in the non-rhizosphere but decreased in the rhizosphere with biochar application. Also, structural equation modeling showed a greater bacterial contribution to total denitrification than that of fungi in the non-rhizosphere but showed an opposite trend in the rhizosphere soil. These findings, together with greater soil C content but lower NO3−-N with the increased rate of biochar application, suggest that partially substituting inorganic fertilizers with biochar can reduce potential N2O production from bacterial nitrification and denitrification.

The Potential of Biochar to Enhance the Water Retention Properties of Sandy Agricultural Soils

The impact of climate change has become increasingly severe in drylands, resulting in heat stress and water deficiency and, consequently, reducing agricultural production. Biochar plays an important role in improving soil fertility. The properties of sandy soils where water deficiency occurs with a greater frequency need to be enhanced by biochar amendments to increase the water retention capacity (WRC). Few studies have reported the effects of biochar on the readily available water (RAW) of these soils or an evaluation of the optimal application rate of the biochar. In this study, we aimed to assess the effect of different biochar types and application rates on the soil properties related to water retention. Under laboratory conditions, we amended sandy soil with four different types of biochar (woodchip (WBC), waterweed of Ludwigia grandiflora (WWBC), poultry litter (PLBC) and bagasse (BBC)) at rates of 0%, 5%, 10%, 15%, 25%, 50%, 75% and 100%. Soils treated with zeolite and perlite, both conventional materials, were arranged for a comparative study. The water content in the amended soils was recorded at saturation, field capacity, wilting point and oven-dry. Our results show a reduction in the bulk density by increasing the amendment rate across all biochar types. Although the WRC increased with the application rate, the RAW reduced and peaked at a 5% (v/v) biochar content for almost all the biochar types. WBC and WWBC showed the highest RAW increments of 165% and 191%, respectively, at a 10% (v/v) rate. In most cases, higher rates (such as 75% (v/v) of PLBC) caused negative effects on the RAW. Following these results, it is clear that both the biochar type and the application rate significantly influence the hydrological properties and the RAW capacity of sandy soils. A 5% (v/v) biochar amendment could significantly improve the readily available water to mitigate drought in sandy agricultural soils.

The impact of biochar on the activities of soil nutrients acquisition enzymes is potentially controlled by the pyrolysis temperature: A meta-analysis

Understanding the responses of soil enzymes that catalyze the decomposition of organic matter is critical for understanding the mechanisms of biochar effects in agricultural soils. In this study, we conducted a global meta-analysis based on 1354-paired observations extracted from 125 published and 4 unpublished articles to explore the effects of biochar on the activities of soil nutrients-acquisition enzymatic groups. The meta-analysis revealed contrasting responses of soil enzymes to biochar amendment at the individual and group levels. Pyrolysis temperature was the dominant factor determining the effects of biochar on soil enzyme activities. Low-temperature biochar produced at < 500 ℃ enhanced the activities of almost all soil enzymatic groups involved in carbon (C), nitrogen (N), and phosphorus (P) acquisition extracellular soil enzymes, and dehydrogenase (DHA) with mean effect sizes of 4%, 23%, 12%, and 22%, respectively. A significant role of different parameters associated with low-temperature biochar, soil, and experimental conditions was evident on the activity of C-acquisition enzymes. In contrast, N and P-acquisition enzymes showed consistently positive responses to low-temperature biochar addition regardless of other parameters. High-temperature biochar produced ≥ 500 ℃ showed negligible effect on C-, N-, P- acquisition enzymes and DHA activity with mean effect sizes of 2%, 6%, 1%, and 0.5%, respectively. Soil pH, texture, C contents, and biochar application rates were the dominant factors influencing biochar effects on soil enzyme activities. The long-term field experiments usually showed different responses to biochar addition from lab incubation and short-term field experiments. Overall, the present meta-analysis provides comprehensive information elucidating the effects of low and high-temperature biochars on soil enzymes in agroecosystems to enhance C sequestration or soil fertility.

不同改良剂对黄土高原丘陵区山地果园土壤质量的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 不同改良剂对黄土高原丘陵区山地果园土壤质量的影响 DOI: 10.5846/stxb202106091529 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划项目（2021YFD1900700）；国家自然科学基金项目（42125705）；唐仲英基金会项目；陕西省重点研发计划项目（2020ZDLNY07-04） Effect evaluation of soil amendments on soil quantity of mountain apple orchards in the hilly region of Loess Plateau, China Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:土壤质量是影响黄土高原丘陵区山地果园健康可持续发展的关键因素之一。针对黄土高原目前存在的土壤保水能力差，肥力低及微生物群落结构单一等问题，选取保水剂、生物炭和植物根际促生菌三种改良剂，研究其对土壤质量的影响。研究设置5个处理，分别为：生物炭处理(BC)，施用量为5%；枯草芽孢杆菌处理(PGBS)，施用量为0.25%；胶质芽孢杆菌处理(PGBM)，施用量为0.25%；腐殖酸型保水剂处理(SAP)，施用量为0.1%，不施用土壤改良剂作为对照(CK)。通过主成分分析法和最小数据集法筛选出相关指标，分别与对照处理(CK)进行对比，并进行综合评价。结果表明：土壤全氮、速效磷、β-1，4-葡萄糖苷酶、真菌Chao1指数、纤维素酶和细菌Chao1指数对土壤质量的影响较大；同时土壤改良剂的施用可以明显提高果园土壤质量。通过综合评价，发现不同改良剂改善土壤质量效果为：生物炭(BC)>保水剂(SAP)>枯草芽孢杆菌(PGBS)>胶质芽孢杆菌(PGBM)。综合考虑土壤质量和改良成本，保水剂在黄土高原山地果园土壤改良方面的适用性最好，若农林废弃物可资源化则生物炭在黄土高原土壤改良方面具有很大的应用潜力。 Abstract:Soil quality is the main bottleneck restricting the healthy and sustainable development of mountain orchards in the hilly region of Loess Plateau. In order to solve the problems of poor soil water holding capacity, low fertility and single microbial community structure in the Loess Plateau, three amendments were selected and five treatments were set up in this study:biochar application rate was at 5% of soil weight (BC), bacillus subtilis application rate was at 0.25% of soil weight (PGBS), bacillus glia application rate was at 0.25% of soil weight (PGBM), humic acid water retaining agent application rate was at 0.1% of soil weight (SAP), and not application any amendment as a control (CK). The relevant indexes were selected by principal component analysis (PCA) and minimum data set (MDS) to comprehensively evaluate soil quality. The results showed that soil total nitrogen, available phosphorus, β-1,4-glucosidase, fungal Chao1 index, cellulase and bacterial Chao1 index had a significant effect on soil quality, and application of soil amendments could significantly improve the soil quality in apple orchards. The improvement effects of different amendments on soil quality as follows:BC > SAP> PGBS > PGBM through a comprehensive evaluation. Considering soil quality and cost, water retaining agent is more suitable for soil quality improvement in mountain apple orchards in the hilly region of Loess Plateau. Biochar has great application potential in soil amendment, if agricultural and forestry wastes can be recycled. 参考文献 相似文献 引证文献

Impacts of eucalyptus biochar application on greenhouse gas emission from an upland rice–sugarcane cropping system on sandy soil

Summary An on-farm field experiment was conducted in northeastern Thailand to assess the effects of different eucalyptus biochar (BC) application rates, in combination with mineral fertilizers, on upland rice and a succeeding crop of sugarcane on sandy soil. Soil mineral N and greenhouse gas emissions were also evaluated. The field experiment consisted of three treatments: no biochar (BC0), 3.1 Mg ha−1 of biochar (BC1), and 6.2 Mg ha−1 of biochar (BC2). All treatments received the same recommended fertilizer rate. Soil mineral N, and emissions of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) were monitored after BC application. The results revealed that the BC2 treatment caused lower soil mineral N content than that of the BC0 treatment during the upland rice period. During the sugarcane period, the BC2 treatment induced a greater soil mineral N content than the BC1 treatment but had no significant difference from the BC0 treatment. The BC2 treatment resulted in significantly lower cumulative CH4 and N2O emissions than the BC0 treatment during the upland rice period. In conclusion, we found that the BC2 treatment alleviated the global warming potential from CH4 and N2O emissions throughout the experiment, causing slight changes in soil N availability in the upland rice–sugarcane cropping system.

Comparison of long-term effects of biochar application on soil organic carbon and its fractions in two ecological sites in karst regions

Biochar (BC) is widely used in soil to increase carbon sequestration. However, the long-term effects of BC application on the soil organic carbon (SOC) and labile organic carbon (LOC) fractions are unclear, especially in karst regions. In order to address this issue, two field experiments were designed to observe the changes in the SOC and its fractions after two years of BC application. In this study, we chose karst regions with two different ecological types, Linquan and Heishitou towns in Bijie City, China. Five BC treatment plots were established, with application rates of 0, 5, 15, 20, and 40 t·ha−1 (CK, B5, B15, B20, and B40, respectively). Compared with CK, the contents of SOC, readily oxidizable organic carbon (ROC), particulate organic carbon (POC) and recalcitrant carbon (RC) under the BC treatments in Linquan increased by 7.09–38.08%, 1.62–39.80%, 9.52–62.30% and 8.66–58.14%, respectively. In Heishitou, the increases in these contents were 3.60–38.58%, 4.40–115.23%, 19.57–50.98% and 10.94–53.87%, respectively. There are significant positive relationships between the SOC content and the ROC, POC and RC contents. However, the application of BC had no significant effect on the DOC content in the two ecological regions. In addition, the soil carbon pool index (CPI) and carbon pool management index (CPMI) increased with increasing BC application rate due to its unique physicochemical properties and nutrients. These results indicate that long-term BC amendment significantly improves the soil quality and carbon sequestration in karst regions by increasing SOC and its LOC fractions.

Global soil organic carbon changes and economic revenues with biochar application

AbstractBiochar has been proposed as a promising negative CO2 emission technology to mitigate future climate change with the additional benefit of increasing agricultural production. However, the spatial responses of soil organic carbon (SOC) to biochar addition in cropland are still uncertain, and the economic feasibility of large‐scale biochar implementation remains unclear. Here, we analyzed the response of SOC to biochar addition using 389 paired field measurements. The results show that biochar addition significantly increased SOC by 45.8% on average with large regional variations. Using a random forest model trained with soil, climate, biotic, biochar, and management factors, we found that the response of SOC to biochar addition was mainly dependent on biochar application rates, initial SOC, edaphic (e.g., pH), and climatic (e.g., mean annual precipitation) variables. Combined with the predicted SOC changes to biochar addition on the global cropland, we assessed the revenue of the biochar system based on the current and potential pyrolysis plants in the world using the life‐cycle analysis. Net revenue of the currently existing 144 pyrolysis plants increases with larger plant capacity and higher carbon price. Potential revenue of building new plants is high in regions like America and Europe but low in regions with infertile soil, low crop residues availability, and inconvenient transportation. The global CO2 removal of biochar application is 6.6 Tg CO2e (CO2 equivalent) year−1 with a net revenue of $ 177 million dollars at a carbon price of $ 50 t−1 CO2 for current pyrolysis plants with a biomass‐processing capacity of 20,000 t year−1. Our study provides a full economic assessment of idealized biochar addition scenarios and identifies the locations with maximal potential revenues with new pyrolysis plants.

Significance of Pyrolytic Temperature, Particle Size, and Application Rate of Biochar in Improving Hydro-Physical Properties of Calcareous Sandy Soil

Water management and irrigation conservation in calcareous sandy soil are of significant importance for sustaining agricultural production, especially in arid and semi-arid region that facing scarcity of water resources. The changes in hydro-physical characteristics of calcareous sand soil were investigated after date palm waste-derived biochar application in column trials. Significance of pyrolysis temperature (300 °C, 500 °C, and 700 °C), particle size [&lt;0.5 mm (D0.5), 0.5–1 mm (D1), and 1–2 mm (D2)], and application rate (1%, 2.5%, and 5%) were studied. Variations in infiltration rate, intermittent evaporation, and saturated hydraulic conductivity as a function of aforementioned factors were investigated. After amending the top 10-cm soil layer with different biochar and application rates, the columns were subjected to six wetting and drying cycles by applying 25 cm3 tap water per week over a 6-week period. Overall, biochar application resulted in decreased saturated hydraulic conductivity, while improved cumulative evaporation. Specifically, biochar produced at 300 °C and 500 °C demonstrated 10.2% and 13.3% higher cumulative evaporation, respectively., whereas, biochar produced at 700 °C with 5% application rate resulted in decreased cumulative evaporation. Cumulative evaporation increased by 5.0%, 7.7% and, 7.8% for D0.5, D1 and D2 (mm) on average, respectively, as compared with the untreated soil. Thus, biochar with particle size 0.5–1 mm significantly improved hydro-physical properties when applied at 1%. Generally, using biochar produced at medium temperature and small particle size with appropriate application rates could improve the soil hydro-physical properties.

Integrating Tank Model and adsorption/desorption characteristics of filter media to simulate outflow water quantity and quality of a bioretention basin: A case study of biochar-based bioretention basin

Reliable approaches for accurately assessing the performance of stormwater treatment systems is essential for their effective design, including filter media selection which can be a significant constituent in stormwater treatment systems. This study presents an innovative modelling approach integrating the Tank Model with the adsorption-desorption characteristics of the filter media. The resulting modelling approach was applied to simulate a field-scale bioretention basin where biochar was used as filter media with over ten years of rainfall records. The resulting outflow and overflow volumes were compared with observed data for calibration. The Stormwater Treatment Tank Model (STTM) was validated using the Leave-One-Out-Cross-Validation (LOOCV) method. The simulation outcomes include water outflow and overflow (quantity) from the bioretention basin as well as outflow water quality represented by three heavy metals (Pb, Cu, and Zn). The modelling approach developed was found to be capable of accurately simulating outflow and overflow volumes, with outlet water quantity being significantly influenced by the total rainfall depth. The modeling results also suggested that a sole treatment system would not be adequate, particularly for large rainfall events (>100 mm) and a treatment train would be more effective. Simulating long-term (over ten years) pollutant removal performance in the bioretention basin indicated that heavy metals outflow event mean concentration (EMCs) values calculated using simulated results of 30% biochar application rate generated the best pollutant removal with consistent values (2.7 μg/L, 3.0 μg/L, 17.2 μg/L for Pb, Cu, and Zn, respectively). These results confirm that the modelling approach is reliable for assessing long-term treatment performance, as well as a robust tool able to contribute to more effective treatment system design, particularly filter media selection and evaluation.

Combined application of biochar and N fertilizer shifted nitrification rate and amoA gene abundance of ammonia-oxidizing microorganisms in salt-affected anthropogenic-alluvial soil

Biochar has been globally recognized as a novel and eco-friendly soil ameliorant to mitigate hazardous effects of salinization on soil health, and mediate carbon and nitrogen (N) nutrient cycling in agricultural ecosystems. However, knowledge pertaining to the regulatory mechanism of biochar application on nitrification in the salt-affected soil is limited. In this study, field plot experiment for three consecutive years and an aerobic incubation experiment with three biochar application rates (7.5, 15, and 30 ton ha−1) and N fertilizer (225 kg N ha−1 yr−1) were conducted. We investigated the effect of combined application of biochar and N fertilizer on soil chemical and microbial properties, nitrification kinetic parameters, and the abundance of ammonia monooxygenase (subunit A, amoA) gene of ammonia-oxidizing bacteria (AOB) and archaea (AOA). Our results showed that biochar addition increased soil pH, cation exchange capacity, available potassium, and microbial biomass carbon, and decreased the numbers of amoA-AOB gene in the salt-affected soil applied with N fertilizer. The nitrification process and fitted kinetic parameters were negatively responsive to the combined application of biochar and N fertilizer, which reduced the nitrification potential and potential nitrification rate, and prolonged the duration of nitrification. The nitrification rate and abundance of amoA-AOB and amoA-AOA genes decreased under biochar and N fertilizer addition, and biochar played the predominant role in the inhibiting effect, which aggravated with the increase of biochar rate. The AOB dominated the autotrophic nitrification with the nitrification rate having higher positive correlation with abundance of amoA-AOB gene than with that of amoA-AOA gene. The abundance of both amoA-AOB and amoA-AOA genes showed significantly negative correlation with nitrate nitrogen (NO3−-N) concentration. In conclusion, biochar and N fertilizer addition inhibited the autotrophic nitrification rate mainly by greatly reducing the abundance of amoA-AOB gene, which was adaptive to the changing soil microhabitat traits induced by biochar application and N fertilization.