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Introduction: Soil organic carbon (SOC) content can vary significantly across a given plot. Therefore, a representative sampling is a prerequisite to obtain meaningful results from analysis and of utter importance when SOC quantification is used to quantify (temporary) carbon dioxide removal (CDR). However, certain management practices aiming to increase SOC further increase the level of heterogeneity and may challenge representative sampling schemes. This includes concentrated root-zone application of biochar, which immediately increases SOC with the input of biochar-C and may promote the local enrichment of non-biochar SOC over time. Methods: Here, we used numerical modelling to quantify the number of single sampling points (soil cores) needed to achieve a representative sample of biochar-C and total SOC on a plot after application of biochar in rows, e.g., for growing vegetables, or in the circumference of trees in agroforestry systems. Results: After row application of 5 t ha-1 biochar in soil with rather low SOC content (26 t ha-1), 140 soil cores (per 0.25 ha plot) where necessary to achieve representative sampling of C-stocks (±5% error) in 90% of the repeated sampling simulation cases. Compared to realistic and cost-effective soil sampling scenarios in agronomic practice, we conclude that concentrated root zone application of biochar makes representative sampling for quantification of SOC in soils with low baseline C-stocks virtually impossible. Discussion: This finding calls into question the soil-sampling and SOC-analysisbased ("result-based") monitoring of SOC as a (temporary) CDR when biochar might have been applied. Considering the rapid scaling of biochar production and use in agriculture, this is a considerable challenge for SOC certification. Instead, action-based incentives, rewarding farmers for carrying out specific practices, could be applied to promote carbon farming practices. [ABSTRACT FROM AUTHOR]

Introduction: Compost heat recovery systems (CHRS) represent an emerging technology to recover residual woody biomass from agroforestry and forestry activities and use the heat that is naturally produced during aerobic biodegradation (composting). However, a low oxygen concentration in the gas phase and self-drying and compaction of the compost body often limit efficient oxidation by microbial communities. Woodchip-derived biochar has often been proposed as a bulking agent and improver of water retention and of oxygen accessibility in the composting process, but the literature reporting its effects in the CHRS is scarce. Methods: Here, biochar (average particle size of 10 mm) was added at 10% (on weight basis) to chipped pruning residues into two bench-scale-controlled reactors (0.2 m3), operated in parallel for 57 days. Results and Discussion: The addition of 10% (w/w) biochar to the composting body increased biodegradation yields by approximately 50% and improved oxidation rates over readily biodegradable organic fractions (addition of cheese whey). Temperatures were on average 1.34°C higher, and heat extraction flux was also improved in the presence of biochar (0.3kW/m3) versus in its absence (0.1 kW/m3). The organic matter mass balance resulted in approximately 50% higher biodegradation yield and improved oxidation rates over readily biodegradable organic fractions. Microbial analysis highlighted a higher concentration of thermophilic species and a lower concentration of well- known pathogenic and antibiotic-resistant genera in the presence of biochar. [ABSTRACT FROM AUTHOR]

Water availability is the main challenge for the growth and development of woody species in drylands. Application of biochar under deficit irrigation can enhance seedling growth in arid regions. The growth of commercial woody species seedlings was monitored for approximately two years using the combined effect of biochar and deficit irrigation treatments. Biochar was applied to the plantation pits during plantation at a rate of 38 g kg−1 of soil. The applied deficit irrigation per season covered 60% (459 mm) and 35% (459 mm) of the dry season crop evapotranspiration for Citrus sinensis and Yushinia alpina, respectively. We found statistically clear effects of biochar and deficit irrigation on the growth of both species with combined application. Compared to control treatment, the combined application of biochar and deficit irrigation significantly (P < 0.05) increased new culms of Y. alpina by 44%. Moreover, the combined application of biochar and deficit irrigation significantly (P < 0.05) affected the height and diameter relative growth rates (RGRs) of both species by enhancing soil moisture and which in turn increased the photosynthesis and transpiration rates of the species. Compared to Y. alpina, C. sinensis had significantly (P < 0.05) higher height and diameter RGRs and higher transpiration rate. The maximum height RGRs of Y. alpina (0.142) and C. sinensis (0.108 cm month−1) were attained at the end of the rainy season. The highest and significant increment (266.5%) of biomass of Y. alpina was recorded in the plants subjected to combined application of biochar and deficit irrigation However, we could not confirm a significant effect of B alone on the growth parameters of the species. Hence, the integration of biochar and deficit irrigation would be essential for the successful establishment of C. sinensis and Y. alpina seedlings in farmlands of dried region. [ABSTRACT FROM AUTHOR]

Dellavalle Soil Science Scholarship Cohen Hunter Cohen Hunter is a high school graduate pursuing a future in agriculture. Nicole Plenty Nicole Plenty is a student at the University of Wisconsin-Platteville majoring in Soil and Crop Science with an emphasis in Plant Breeding and Genetics and a minor in Biotechnology. Corinne Lee Cori Lee is a senior at The Ohio State University majoring in Sustainable Plant Systems Agronomy with a minor in Agribusiness. International Soil Science Award Hailin Zhang Hailin Zhang is a regents professor of soil science in the Department of Plant and Soil Sciences at Oklahoma State University. [Extracted from the article]

Gliricidia sepium (Jacq.) Walp is a well-known agroforestry leguminous tree that provides multiple benefits in different agroecological zones. Its apparent versatility is seen in improving animal feed, cleaning environmental wastes, and healing inflammations. It was also found to have significant benefits in agroforestry due to its ability to enhance soil fertility through nitrogen fixation and green manure. However, this article reviews the use of Gliricidia sepium to improve soil fertility and crop agronomic and nutritional properties. Google Scholar, PubMed, and Science Direct were the databases consulted for the relevant articles used in this review. Trees and leaves of G. sepium, either used as mulch, biochar, or intercropped, have enhanced soil fertility indicators, such as total soil carbon, nitrogen, phosphorus, available phosphorus, pH, cation exchange capacity, and soil organic matter in different farming systems. Its immense positive performance in improving the yield of crops led to an economic advantage for low-income farmers. G. sepium can also lower the use of mineral fertilizer as its adoption grows, leading to a greener environment in the agricultural sector. The review concluded that there is a plethora of research on the effect of Gliricidia on maize yield enhancement; hence further investigations should be conducted on using Gliricidia sepium as a green fertilizer to improve yields and the nutritional properties of other crops. [ABSTRACT FROM AUTHOR]

By affecting 10% of the world’s total arable land, soil salinity has become a potential threat to feeding the exploding population. As per the current scenario, among 1,125 million hectares of salt-affected land, nearly 76 million hectares are seriously affected due to human-induced salinization. Due to soil salinization, crop productivity is being hampered. In order to enhance productivity, there is an urgent need to shift from traditional methods to advanced 3E (efficient, economic, and environmentally sound) technology for soil salinity reclamation and management to achieve better soil health and sustainable crop production. The detailed mechanism of salt interference with various pathways involved in plant growth and development needs to be understood. This article critically reviews the mechanism of harmful salt interference with nutrient dynamics in soil and various physiological pathways involved in crop growth to apply various soil-oriented (crop residue management, biochar application, and agroforestry system) and plant-oriented [plant growth-promoting microbes (PGPMs), plant growth regulators, and nanotechnology] promising reclamation and rehabilitation approaches to mitigate its hazardous effect on soil salinity. The monitoring and assessment of salt-affected soils through remote sensing (RS) and geographical information systems (GISs) are pivotal in the management and framing of long-term policies to confront alarming threats to crop productivity and sustainability. This study provides an insight into recent developments in soil salinity management and proposes futuristic solutions that could ameliorate soil salinity to attain crop sustainability under adverse environmental conditions.

In northwestern Ethiopia, a conventional teff (Eragrostis tef (Zucc.) Trotter) monoculture was converted into a rotational agroforestry system (teff-Acacia agroforestry), which consists of the sequence i) teff-Acacia decurrens intercropping (1st year), ii) grass-A. decurrens silvopasture (2nd year), iii) A. decurrens plantation (3rd–4th year), and iv) on-site charcoal production from A. decurrens (end of 4th year). This study is the first one to comprehensively show how the agroforestry system affects soil organic carbon (SOC) and soil nutrients. Soil samples were collected from the teff-Acacia agroforestry and conventional teff fields at two different sites (site I and II) and they were used to determine soil pH, black carbon, SOC, soil total nitrogen (STN), extractable phosphorus (P), potassium (K), magnesium (Mg), sodium (Na), and calcium (Ca) contents. At site I (0–10 cm soil depth), charcoal production spots in teff-Acacia agroforestry had higher soil pH (20%), black carbon (164%), SOC (48%), P (687%), and K (788%) contents compared to outside charcoal production spots. Soil organic carbon and STN contents in the 1st and 2nd teff-Acacia agroforestry rotations were significantly higher (SOC: 112–169%, STN: 100–131%) than teff fields. At site II, SOC stocks (0–100 cm) in the 1st agroforestry rotation were not significantly different from teff fields. However, they were 159% and 244% greater in the 2nd and 3rd agroforestry rotations, respectively, compared to teff fields. Conversion of teff fields to teff-Acacia agroforestry for a 12-year period increased SOC stocks by 21 Mg C ha–1 per year. Our results demonstrated that locally adopted agroforestry practices can increase SOC and nutrients in the long term, thereby contributing to enhanced soil fertility and improved climate change mitigation strategies via carbon sequestration. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cell (SOFC) has the potential to convert biomass to electrical power cleanly and efficiently by integrating with in situ gasification of biomass. It is necessary to keep a balance between maximizing the power output of fuel cells and minimizing the pretreatment of biomass. Herein, we report the comparison of output performance between the apple tree branches (ATB) dried at 110°C and the one pyrolyzed at 500°C in SOFCs. The results show that the peak power densities (PPD) of SOFCs operated at 850°C were 157 and 238 mW cm−2 for the dried and the pyrolyzed samples, respectively. And the corresponding apparent fuel utilizations for them were 18.1% and 24.6%, respectively. However, if counting the pyrolysis yield (~28 wt%), the overall fuel utilization of the pyrolyzed sample declined from 24.6% to ~6.9%. In addition, if loading the steel slag (SS)‐based catalyst catalyst to the dried sample, its PPD at 850°C were almost doubled to 303 mW cm−2, but the fuel utilization reduced to 9.2%. Meanwhile, SOFCs using the medium‐density fiberboard (MDF) as fuel exhibited the parallel trends in electrochemical performance and fuel utilization. [ABSTRACT FROM AUTHOR]

Gliricidia sepium (Jacq.) Walp is a well-known agroforestry leguminous tree that provides multiple benefits in different agroecological zones. Its apparent versatility is seen in improving animal feed, cleaning environmental wastes, and healing inflammations. It was also found to have significant benefits in agroforestry due to its ability to enhance soil fertility through nitrogen fixation and green manure. However, this article reviews the use of Gliricidia sepium to improve soil fertility and crop agronomic and nutritional properties. Google Scholar, PubMed, and Science Direct were the databases consulted for the relevant articles used in this review. Trees and leaves of G. sepium, either used as mulch, biochar, or intercropped, have enhanced soil fertility indicators, such as total soil carbon, nitrogen, phosphorus, available phosphorus, pH, cation exchange capacity, and soil organic matter in different farming systems. Its immense positive performance in improving the yield of crops led to an economic advantage for low-income farmers. G. sepium can also lower the use of mineral fertilizer as its adoption grows, leading to a greener environment in the agricultural sector. The review concluded that there is a plethora of research on the effect of Gliricidia on maize yield enhancement; hence further investigations should be conducted on using Gliricidia sepium as a green fertilizer to improve yields and the nutritional properties of other crops.

Effective and efficient nutrient management is central to best-practice agriculture, facilitating sustainable intensification while reducing negative externalities. The application of biochar-based fertilizers (BBF) in tropical agronomy has the potential to improve nutrient management by enhancing nutrient availability and uptake. Here, we performed pot-trials with Theobroma cacao L. seedlings planted in an Oxisol with critically low phosphorus levels. Four fertilizer levels were deployed, including BBFs using micro-dosed biochar (16 g plant−1 i.e., 0.3% soil amendment w/w) charged with mineral fertilizer. Three different fertilizer-placement levels (topsoil, root-zone hotspot and root-zone layer) were evaluated. The results from the topsoil application of mineral fertilizer (farmer practice) served as the reference data. The root-zone layer application of BBF increased the aboveground biomass, total leaf area and chlorophyll content index by 56%, 222%, and 140% respectively. Foliar phosphorus levels were also significantly elevated by 53%. The N:P ratio of the foliar tissue was improved, indicating the potential of BBF to ameliorate P limitations. Thus, low dosages of biochar, which is upgraded to BBF, can considerably improve plant nutrition. Small scale technology to produce biochar can be easily adopted and integrated in T. cacao systems. We suggest that BBF production and application within tropical, perennial systems can contribute to achieving a range of sustainable development goals (SDGs), including climate action. [ABSTRACT FROM AUTHOR]

Long-term high intensity utilization leads to the degradation of black soil in Northeast China and the serious loss of organic carbon. Biochar has great potential for improving the carbon storage capacity of agroforestry ecosystems and reducing greenhouse gas (GHG) emissions. However, the effectiveness of biochar application depends on pedoclimatic factors, and few studies have explored the effects of biochar and its modified biochars on the net ecosystem economic benefit (NEEB) of black soil farmland. To increase the environmental benefits of carbon sequestration and emission reduction and to improve farmer profits, this study modified biochars by physical, chemical and biological methods, and studied the effects of different types of modified biochars on soil properties, crop yield and GHG emissions in black soil farmland through field experiments. The NEEB of different treatments was evaluated by combining carbon cost, yield benefit and biochar cost. A total of 6 treatments were used in the experiment: normal fertilization (CK), fertilization + raw biochar (BC), fertilization + physically modified biochar (PBC), fertilization + acid-modified biochar (HBC), fertilization + magnetically modified biochar (MBC), and fertilization+ biologically modified biochar (BBC) treatments. Compared with the control (CK), the application of biochar increased the content of soil organic matter by 18.76–42.57% and improved the soil fertility. The raw biochar had no significant effect on soybean yield and increased the global warming potential by 41.18%. Soybean yields significantly increased with decreasing GHG emission intensity when modified biochars were applied. Due to the high cost of biochar and the current low carbon price, the effect of biochar on crop yield is crucial for increasing the NEEB. The NEEB in the HBC treatment was the highest, 57.86% higher than that in the CK treatment and was an effective strategy for increasing crop yield while reducing GHG emissions. The results of this study could provide a theoretical basis and technical support for soybean farmland carbon sequestration, emission reduction, soil improvement and yield improvement in the black soil region of Northeast China. [Display omitted] • Raw biochar stimulated soil CO 2 emissions and reduced the potential for CH 4 sinks. • Modified biochar increased yield while reducing GHG emission intensity. • Crop yield and biochar cost are vital for the large-scale application of biochar. • Acid-modified biochar application enhances NEEB by 424.64 $/ha in soybean fields. [ABSTRACT FROM AUTHOR]

Biochar is used to improve soil fertility and control nitrogen loss in soil. This study aimed to evaluate the difference between biochar sources, namely Melaleuca cajuputi waste and rice husk, for controlled nitrogen loss in hybrid maize planted between Melaleuca cajuputi stands. A split-plot design with three replications was used. The main plot was composed of biochar sources (BS), i.e., without biochar application (WB), Melaleuca cajuputi biochar (MCB), and rice husk biochar (RHB). The subplot was the urea fertilizer dosage, i.e., 0, 150, 300, and 450 kg/ha. The observation parameters were nitrate reductase activity (NRA), total chlorophyll (TC), leaf photosynthesis rate (LPR), nitrogen loss (NL), nitrogen use efficiency (NUE), and seed yield per hectare (SY). The data were analyzed with ANCOVA and LS-means. The results showed that there was no significant difference between mixing MCB or RHB in UF for all hybrid maize parameters, whereas significant differences were observed with WB. The NL values of MCB and RHB were 13.85 and 13.08 kg/ha N, i.e., NL was significantly reduced by 70.90% and 72.51%, and the percentage of SY increased by 28.60% and 37.94% compared to WB, respectively. [ABSTRACT FROM AUTHOR]

Salinity is a global issue and afforestation of degraded soils is the most sustainable approach to combat salt toxicity but trees have to suffer during their early growth in these soils. Under local set of climatic conditions, organic soil amendments are reported to enhance the yield of cultivated crops but their effects and efficiency on trees during their establishment in saline soils is not reported yet. This study was designed to check the transferability of the effect of different organic amendments on tree establishment in salt affected soils. In the present study, various organic amendments applied at early growth stages, to assess the survival rate, morphological and physiological attributes of three selected agroforestry species: Eucalyptus camaldulensis Dehnh., Vachellia nilotica (L.) PJ.H.Hurter & Mabb. and Dalbergia sissoo Roxb., in saline field conditions. Six different types of organic amendments: farmyard manure (FYM), poultry manure (PM), slurry (SL), sugarcane bagasse biochar (SCB), woodchips biochar (WCB) and farmyard manure biochar (FYMB), were applied to check the response of selected tree species against salinity in field conditions. Survival rate was observed in the order of E. camaldulensis > V. nilotica > D. sissoo against all applied organic amendments. Maximum height increment was observed for FYMB in all tree species under saline conditions: 46.22 cm (E. camaldulensis), 18.63 cm (V. nilotica), 8.50 cm (D. sissoo) as compared to other treatments. Photosynthetic and transpiration rates were greater for FYM and were maximum in E. camaldulensis and minimum in D sissoo whereas chlorophyll contents and stomatal conductance were higher for FYMB in E. camaldulensis as compared to other species and treatments. Higher amounts (mg g-1) of leaf Na+ and K+ were observed for control (6- 8.6) and FYMB (6.3-8.06), respectively as compared to other treatments. All types of biochar treatments showed more promising results and can be recommended for future afforestation programs. [ABSTRACT FROM AUTHOR]

The choice of Neolamarckia cadamba for reforestation and agroforestry programs in Nigeria could be constrained with lack of basic knowledge on the species-management in relation to its sensitivity to water and growth on low fertile soil. Hence, growth of the species as influence by watering regimes and bamboo biochar was evaluated. Treatments involved three watering frequencies (watering thrice a week, twice a week and once a week) and five levels of biochar (0, 1, 2, 3, and 4 tons/ha) combined in a factorial arrangement. These were laid out in a randomised complete block design with five replicates. Municipal-waste compost was basally applied at 160 kg N/ha. Growth in terms of shoot length, stem girth, number of leaves, dry matter and relative growth rate were evaluated. The results showed that not significant (p = 0.05) highest growth was obtained from seedlings watered thrice a week with 4 tons of biochar/ha in stem girth (10.67 mm), total dry matter (23.15 g/pot), allocated biomass in stem (7.44 g/pot), leaves (9.51 g/pot) and shoot (16.95 g/pot), shoot RGR (0.022 g/g/day) and total RGR (0.025 g/g/day). Main effect of biochar was only significant (p = 0.05) at 4 tons/ha on stem girth (9.38 mm), higher than control and other rates. These results indicated that with adequate nutrient-supply from organic source like compost and proper soil-management such as biochar inclusion, N. cadamba seedlings could survive and grow well under low or high watering frequency in the range of once to three times a week (420 mm to 1260 mm rainfall/ha respectively). [ABSTRACT FROM AUTHOR]

Salinity is a global issue and Eucalyptus camaldulensis Dehnh. is one of the most planted agroforestry tree species on saline soils in Pakistan. Organic amendments are reported to ameliorate plant growth in saline sodic soils. This study was designed to examine the effects of different organic amendments on the growth of E. camaldulensis grown in saline soil. A pot experiment was performed and seedlings of E. camaldulensis were grown in soil having pH (8.5) and EC(e) 20.5dS/m. Four types of organic amendments were used: farmyard manure, poultry manure, slurry and biochar. The maximum plant total biomass (132.12 g), root length (24.67 cm) and shoot length (174.33 cm) were recorded in the plants grown in soils amended with farmyard manure. The minimum plant total biomass (36.05 g), root length (9.44 cm) and shoot length (68.0 cm) were found in plants without any amendment. Plants treated with farmyard manure and biochar showed the best results for chlorophyll contents, photosynthetic rate and stomatal conductance. Sodium contents in the shoots and roots of plants treated with organic amendments were decreased whereas potassium contents were increased. Maximum sodium contents were found in the shoot (5.70 mg/g DW) and root (7.71 mg/g DW) of un-amended plants, whereas, maximum potassium contents were in the shoots (7.81 mg/g DW) and roots 6.33 mg/g DW) of plants treated with biochar. Biochar was found to be best amendment to improve physicochemical characteristics of soil by improving organic matter (%) and saturation (%) as well as decreasing EC and SAR values of saline soils. Findings of this experiment suggested that organic amendments are useful in enhancing the early stage growth of E. camaldulensis in saline soils. [ABSTRACT FROM AUTHOR]

Degraded soils in humid tropics are characterized by low fertility and high soil erosion potential. Hence, field experiments were conducted during 2018 and 2019 cropping seasons on an Alfisol at Owo in the forest–savanna transition zone of southwest Nigeria to evaluate the effects of the application of biochar (B) produced from waste wood of trees on physicochemical characteristics, erosion potential, and maize yield. Four treatments considered were control (no biochar application, 10 t ha−1 B, 20 t ha−1 B and 30 t ha−1 B). The treatments were laid out in a randomized complete block design with three replications. Results in both years indicated that B application significantly improved grain yield of maize and soil chemical properties, and reduced bulk density (BD) and penetration resistance (PR), and increased porosity (PO), moisture content (MC), and the mean weight diameter (MWD) of soil aggregates. Pooled over 2 years, B applied at 10, 20 and 30 t ha−1 increased grain yield of maize by 44.4%, 66.7%, and 88.9%, respectively, compared with the control. Averaged over 2 years, incorporating B into the soil significantly reduced soil loss (SL) by 32.3%, 56.9%, and 69.7% at 10, 20, and 30 t ha−1 application rates, respectively, compared with the control. The formation of macroaggregates in the B-amended soils is the critical factor to improve soil erosion potential. Therefore, the application rate of 30 t ha−1 B is considered as suitable for severely degraded soil because this application rate efficiently improves maize yield and soil properties and reduces SL. [ABSTRACT FROM AUTHOR]

Biochar, or pyrolyzed organic matter intended for use as a soil amendment, has a variety of properties of interest from the perspective of agroforestry, in particular its potential to increase soil C sequestration and enhance yields by increased retention of soil mineral nutrients. Nitrogen-fixing legumes commonly show large growth responses to biochar, and we hypothesized that combinations of legumes and non-legumes would show increased enhancement of yields in mixture due to enhanced facilitation related to increased nutrient retention. This hypothesis was tested in a glasshouse pot trial involving the leguminous tree leucaena (Leucaena leucocephala), and maize (Zea mays) grown for 120 days in mixture and monoculture in both an unamended soil and soil amended with a slow-pyrolysis coconut husk biochar at 10 t/ha. Responses were quantified in terms of biomass production and partitioning, leaf-level gas-exchange, leaf chlorophyll content, and (for leucaena) root nodule formation. Consistent with predictions, leucaena showed more pronounced growth and physiological responses to biochar than did maize. The system also showed increased total biomass yields relative to monocultures in the two-species mixtures with biochar (relative yield in mixture [RYM] = 1.69; 95% CI 1.41–1.81), but not in the control treatment (RYM = 1.25; 95% CI 0.93–1.76), and positive effects of biochar on yield were generally greater for both species when grown in mixture. Growth responses to biochar were most pronounced for stem and root biomass, and growth responses were consistent with changes in leaf-level photosynthesis and chlorophyll content. In addition, biochar had large effects on biomass partitioning, enhancing stem allocation in both species. Our results suggest that biochar additions may augment facilitative interactions in agroforestry and intercropped systems on acidic, nutrient-deficient soils by enhancing system nutrient retention. [ABSTRACT FROM AUTHOR]

The biomass type is one of the most important factors that affects biochar properties, but the relationship between the major constituents of different biomasses and the properties of the derived biochars, especially the pH, is still unclear. In this study, the cellulose, hemicellulose, lignin, and ash contents of 30 representative agro-forestry biomasses and the pH, surface acid functional groups, and carbonates of 150 resultant biochars prepared with different heat treatment temperatures (HTTs) were examined. The results showed that the lignin content of the biomass had a strong negative correlation with the biochar pH (r = -0.428, P < 0.01). When the HTT was 300 °C, a high lignin content in the biomass was found to have increased the acid functional groups in the biochar, which resulted in a relatively low pH. When the HTT was greater than or equal to 400 °C, the high lignin content in the biomass negatively correlated to the carbonates, which led to a low biochar pH. It was concluded that the lignin content of agroforestry biomass affects the biochar pH negatively, and the acid functional groups and carbonates have different effects at different HTTs. [ABSTRACT FROM AUTHOR]

Biochar has been identified as a media amendment to improve nutrient removal from wastewater, and N retention and plant growth in agroforestry. It therefore has the potential for treating domestic wastewater. The aim of this research was to compare nitrogen removal and plant growth in pure sand and sand amended with biochar, in wetland mesocosms (240 L) receiving sewage. There were seven media treatments based on the proportions of biochar in the sand media (100% sand, sand and coir peat, 5, 10, 15, 20, 25% biochar). The plant species were Paperback tree ( Melaleuca quinquenervia ) and Lemongrass ( Cymbopogon citratus ). The mesocosms were continuously loaded for 8 months with secondary clarified wastewater (SCW) (16 L/day). Septage was then intermittently loaded (20 L/2 days) for a further 8 months. Inflow and outflow samples were monitored for TN, NH 4 -N, and NO x -N. All treatments showed good nitrogen removal efficiency. Average removal efficiencies of TN, NO x -N and NH 4 -N in the mesocosms loaded with SCW ranged from 71 to 87%, 81 to 93% and 65 to 79%, for 100% Sand to 25% Biochar respectively. For septage, the removal efficiencies ranged from 63 to 81%, 69 to 87% and 66 to 81%, for 100% Sand to 25% Biochar respectively. Significant differences of nitrogen outflow concentrations were observed between pure sand and sand amended with biochar. Physical chemical properties of the biochar would have facilitated microbial processes and adsorption. Strong positive correlations were observed between biochar content in the media and nitrogen removal rates. The increased nitrogen removal may be attributed to higher mineralisation of organic nitrogen and NH 4 -N, especially in the case of septage where strong correlation was observed between BOD 5 and TN removal. Total N biomass in the plants harvested after 21 months ranged from 13.4–14.0 g N. The addition of biochar did not increase plant N biomass in either species. [ABSTRACT FROM AUTHOR]

Research Highlights: We find that biochar plus fertilizer has synergistic and positive effects on seedling growth and robustness, but slightly lowers early seedling survival. Biochar plus fertilizer has the potential to greatly decrease costs associated with afforestation as compared to traditional fertilization and gives better results. Background and Objectives: Biochar can improve soil fertility and plant yield in crops. However, there is little information regarding the effects of biochar on trees, even though reforestation/afforestation projects are increasing and are often unsuccessful due to soil fertility limitations. This study aims to increase knowledge of biochar use as a reforestation tool. Materials and Methods: We measured survival and growth in an early ((Guazuma crinita Mart. [n = 240])) and a late (Terminalia amazonia (J.F. Gmel.) Exell. [n = 240]) successional species under 6 different biochar treatments in a 6-month nursery experiment. Results: (i) Survival was highest in the 1 t/ha biochar treatment, while treatments containing fertilizers or biochar at 5 t/ha lowered the survival rate of both species compared to the control; (ii) simultaneous addition of biochar and fertilizer lead to significant increases in height, diameter, total number of leaves, and aboveground and belowground biomass of both species as compared to other treatments; (iii) biochar treatment containing 1 t/ha with and without fertilizer showed significantly better results than applications of 5 t/ha; and (iv) Guazuma crinita responded more strongly to treatments containing biochar and fertilizers compared to Terminalia amazonia, which is suggestive of greater synergetic effects of biochar and fertilizer addition on early successional tree species. Conclusions: Applying biochar and fertilizer is synergistic and outperforms any single treatment, as well as the control, in terms of plant performance. This case study suggests that biochar can greatly improve reforestation/afforestation projects by increasing plant performance while substantially reducing fertilizer and labor maintenance costs. Field experiments and testing of additional species is needed to generalize the findings.

Climate change is an unprecedented global threat to fundamental life-supporting systems and people's livelihoods and is expected to aggravate development challenges. Subsistence-oriented smallholder farmers of developing regions, such as those in sub-Saharan Africa, are highly vulnerable to these changes given their lower adaptive capacity. In this context, building a climate-resilient agricultural society is an essential requirement to protect livelihoods. Hence, there is a need for spreading the climate-resilient sustainable agricultural (CRSA) practices by replicating the proven ones to larger areas (scaling-up). Fostering widespread adoption of such practices needs consideration of their social, ecological, economic, and institutional appropriateness in target areas. This article reports the application of a tool 'ScalA' that generates information on a multitude of aspects and assesses the local suitability of CRSA practices among sub-Saharan smallholders. It also briefly presents other state-of-the-art tools that can be used for similar purposes. In the first case study, the tool is used to assess appropriateness of agroforestry, biochar application, and rainwater harvesting in Fulwe village of Morogoro, Tanzania, for enhancing resilience capacity. In another case study, the potential of fertilizer management is assessed for two different villages, i.e., Fulwe and Mlali. Analytically, appropriateness of interventions is assessed by the deviation of the actual factor constellation of the scaling-up process with an optimal constellation that will foster the wider adoption of the given practice. [ABSTRACT FROM AUTHOR]

A pressing challenge facing poor farmers is how to maintain yields in swidden-fallow systems when confronting growing land scarcity and declining soil fertility. The objective of this research is to document the innovative use of biochar and biochar-rich kiln soils on charcoal kiln sites by Amazonian peasant farmers for annual and perennial crop production as part of their swidden-fallow agroforestry cycle. The study was undertaken in a riverside community near Iquitos, Peru, where the availability of primary forest land has decreased significantly over the past 30 years. Charcoal production is a long-standing, near ubiquitous local activity, drawing on wood primarily from secondary forest fallows. Data were collected in 2011 through household interviews (n = 36) and an extensive survey of upland kiln sites (n = 500). Results indicate this innovation, dubbed 'kiln site agriculture' (KSA), evolved endogenously within the study community as an adaptation to growing land scarcity. Current landholdings were found to negatively correlate with both the number of crops households (n = 32) cultivated per kiln site ( r = −0.3483, p = 0.0254) and the proportion of those sites cultivated with manioc, the local staple crop ( r = −0.5441, p = 0.0006), suggesting that land-poor households rely on KSA harvests to supplement subsistence. This study provides evidence charcoal production need not be a rapacious forest use and can, through KSA and biochar, offer an affordable opportunity to peasant farmers who practice swidden-fallow agroforestry where new land in primary forest is scarce and the productivity of their weathered soils is falling. [ABSTRACT FROM AUTHOR]

Heavy metal pollution and global climate change caused by increased greenhouse gas emissions are two important challenges to sustainable development. Various strategies have been implemented to mitigate both heavy metal pollution and global climate change, including the use of biochar obtained from biorefinery of agroforestry biowaste. This study was conducted to clarify how nitrous oxide (N 2 O) emission and soil cadmium (Cd) contamination respond to mitigation strategies, aiming to understand which strategy will be efficient in mitigating both N 2 O emissions and Cd contamination. Effects of three soil conditioners (biochar; modified biochar, MB; hydroxyapatite, HAP) and Cd on N 2 O emissions from acid soil of Camellia oleifera plantations with nitrogen, and microbial functional genes related to N 2 O productions were examined. The results showed that Cd was decreased by 73.4% and 64.9% by HAP in control and fertilized soil, respectively. HAP reduced both Cd and N 2 O emissions more efficient compare to MB and biochar, which strongly associated with increased pH. Soil N 2 O emissions from fertilized soil without Cd were reduced by 91.0%, 34.3% and 25.8% by HAP, MB and biochar, respectively. However, soil N 2 O emissions with Cd were reduced by 67.3% and 24.6% by HAP and MB, respectively, while they were increased by 56.7% by biochar. Cd inhibited N 2 O emissions, via decreasing abundance of ammonia-oxidizing archaea in fertilized soil. Thereby, MB should be considered in amelioration of Cd-contaminated common soil, while HAP could be used in highly acid Cd-contaminated soil, which largely increase soil pH and simultaneously mitigated N 2 O emissions. [Display omitted] • Both Cd contamination and N 2 O emissions are environmental issues need to control. • Both biochar and hydroxyapatite decrease and increase soil Cd and pH, respectively. • Modified biochar has stronger adsorption and ion exchange capacity than biochar. • Modified biochar mitigates more N 2 O emissions than common biochar. • HAP mitigated soil Cd contamination and N 2 O emission, and largely increase soil pH. [ABSTRACT FROM AUTHOR]

Kayu putih (Melaleuca cajuputi) waste has the potential via in situ biochar briquettes to overcome the low availability of nitrogen in soil. This study evaluated the short-term effects of in situ biochar briquettes on nitrogen loss reduction and determined an optimum scenario for hybrid rice grown in an agroforestry system among kayu putih stands. This three-year experiment (2019–2021) was conducted using a randomised complete block design factorial with three blocks as replications. The treatments included biochar briquettes made from kayu putih waste (0-, 2-, 4-, and 6-grain plant−1 or 0, 5, 10, and 15 tonnes ha−1) and urea fertiliser (0, 100, 200, and 300 kg ha−1). The results demonstrated that the eco–environmental scenario was the most efficient strategy that improved the soil quality, the physiological characteristics, and the yield of the hybrid rice with the optimum application of the biochar briquettes at 5.54-grain plant−1 and the urea fertiliser at 230.08 kg ha−1. This alternative approach illustrated a reduction in both the usage of urea fertiliser and the loss of nitrogen by 23.31% and 26.28%, respectively, while increasing the yield of the hybrid rice by 24.73%, as compared to a single application of 300 kg urea ha−1 without biochar briquettes. [ABSTRACT FROM AUTHOR]

In this study, the adsorption of a multicomponent mixture of active pharmaceutical compounds, such as Venlafaxine (VLX), Trazodone (TRZ) and Fluoxetine (FLX), was studied in a biochar fixed-bed column. The selection of appropriate biochar (eucalyptus, grapevine cane and holm tree biochar) as an adsorbent was carried out through batch assays. An insight into the adsorption mechanism and its correlation with the chosen biochars was performed, showing that electron donor/acceptor interaction is the main mechanism involved. Equilibrium and kinetic batch adsorption experiments were performed and the results demonstrated that eucalyptus biochar was the most viable option for the removal of the pollutants, individually and combined. Column adsorption experiments were performed and Thomas, Yoon-Nelson and Yan models were adjusted to the breakthrough curves. This multicomponent system exhibited a synergetic behavior for TRZ and an antagonist for VLX and FLX, when compared to the single and multicomponent systems previously evaluated in batch assays. The treatment of real wastewaters, spiked with pollutants, has demonstrated the removal efficiency of multicomponent mixtures. Finally, the adsorbent regeneration by elution in different solutions was also investigated and methanol proved to be the most effective eluent for the column regeneration. [Display omitted] • Efficient individual removal of pharmaceuticals by Eucalyptus biochar was proved. • An extensive adsorption mechanism analysis was performed. • Feasible continuous treatment system for removal of a mixture of pharmaceuticals. • Successful removal of pharmaceutical mixture both in synthetic and real wastewater. [ABSTRACT FROM AUTHOR]

Agroforestry, an integration of farming system with woody perennials leads to the generation of potential agroforestry residues. The conventional treatment of agroforestry waste includes landfilling, thermal management, and decomposition which is accompanied with their own share of disadvantages. The ample amount of residues and products needs effective management to reap the economic and environmental benefits. The channel of waste collection, transportation, and recycle or valorization into products like biofuel, fertilizers, biochar, industrial chemicals is essential to maintain a circular sustainable bioeconomy. Global market value of biowaste to bioenergy (BtB) technology is roughly US $25.32 billion and is projected to enhance to US $40 billion by 2023. Employment of an appropriate pretreatment technology such as fermentation, hydrolysis, gasification etc. is going to elevate the degree of valorization along with surpassing the mobilization barrier. The sustainability assessment of the management process can be achieved with multiple models including technoeconomic analysis, life cycle assessment and multi criteria approach which are dependent on both hard and soft indices. Additionally, the loopholes of the agroforestry sectors would be managed by the introduction of appropriate policies which are undertaken globally by the Orlando and Lugo declarations, food and agriculture organization, Millennium Development Goals, Global Research Alliance and Guidelines for Sustainable Agriculture and Rural Development. The present review envisaged the agroforestry waste management strategy and its sustainability assessment primarily based upon Social, Economic and Environmental parameters without tormenting the future generations. [Display omitted] • The valorization of agroforestry waste for value-added products in biorefineries. • Bioeconomic potential along with the discussion of sustainability indices. • Existing laws and policies for effective agroforestry waste management. • Social, economic, and environmental aspects of waste management are studied. [ABSTRACT FROM AUTHOR]

This work comparatively studied the pyrolysis of agroforestry bio-wastes in the presence of alkaline-earth-metal (AEM) oxides or carbonates (i.e., CaO, CaCO 3 , MgO and MgCO 3). Particularly, the Ca- and Mg-enriched biochars were evaluated for the retention capacity improvement of soil water and nutrient (i.e., K+, PO 4 3−). In general, the Ca-enriched biochars exhibited higher retention capacity of soil water than the Mg-enriched biochars. However, the Mg-enriched biochars showed a much higher adsorption capacity of K+ and PO 4 3−. The MgO-enriched biochar with small specific surface area had a relatively high adsorption capacity on both K+ and PO 4 3−, since the adsorption of nutrient towards biochar was mainly controlled by the chemisorption process. The rapid releasing of PO 4 3− adsorbed in the MgO-enriched biochar indicated its low PO 4 3− retention capacity. In summary, MgCO 3 would be an appropriate candidate for production of biochar composite as a good soil conditioner during the pyrolysis valorization of lignocellulosic biomass. • Pyrolysis of agroforestry bio-wastes with Ca/Mg oxide and carbonate was studied. • MgCO 3 showed the significant effect on reducing the apparent activation energy. • The CaO-enriched biochar improved the soil water retention capacity. • The MgO-enriched biochar improved the nutrient adsorption and retention capacity. [ABSTRACT FROM AUTHOR]

• Oat hull biochar has a significantly higher N, P, K content than Pine bark biochar. • Biochar significantly improved shoot and root biomass of T. aestivum. • Biochar promotes changes in soil fungal and bacterial communities. • The biochar stimulates positively the indigenous AM fungi propagules. • The treatments assayed enhance some soil quality properties in a volcanic soil. Biochar (BC) production from agroforestry wastes and mycorrhizal fungi are potentially important agricultural practices for improving crops yields and increasing phosphorus (P) in volcanic soils. This study aimed to test the effect of BC application on wheat biomass and grain yield production, indigenous arbuscular mycorrhizal (AM) fungi propagules and soil microbial community and related to soil quality properties of an Andisol in Southern Chile. Biochars (BCs) were produced from oat hulls (OBC) and pine bark (PBC). Doses of 0, 5, 10, and 20 Mg ha−1 of BCs were applied on soil using wheat as the test crop. Wheat biomass (root and shoot portion) and grain yield, AM root colonization, spore, mycelium density, and glomalin content (glomalin related soil protein, EE-GRSP) were measured and related with soil quality properties such as bulk density, water-stable aggregates (WSA), and water holding capacity (WHC). The OBC had a significantly higher macronutrients content (N, P, K) than PBC. The highest dose of both BCs significantly improved shoot and root biomass and wheat grain yield. Application of 20 Mg ha−1 of OBC and PBC increased AM spore density and root colonization relative to control treatment. In the same way, the BC application significantly affects the AM mycelium density. The results showed that the application of higher BC dose changed the soil microbial community. The use of BCs in this volcanic soil is an effective strategy to increase wheat biomass, increase grain yield production, stimulate the indigenous AM fungi activity, enhance soil quality properties, and increase the sustainability levels of agricultural systems. [ABSTRACT FROM AUTHOR]

Biochar from agroforestry biomass residues is an alternative source of fertilizers for improving the soil fertility. In Costa Rica, Cedrela odorata is planted in pure plantations and agroforestry systems and different types of substrates are used in the nursery to enhance the growth and performance of the young saplings. The main objective of the present study was to evaluate the growth (in height, diameter, biomass) and distribution of carbon (C), hydrogen (H), and nitrogen (N) for C. odorata plants in a nursery with different application rates of biochar produced from Tectona grandis wood residues. The results showed that the above-measured variables were statistically affected by different application rates of the biochar. The stem diameter, total height, number of leaves, and height increment were statistically significantly higher in the substrate with an application rate of 25–50 tons/ha, in contrast to the 0 and 75 tons/ha application rates, which were statistically the lowest. As for the levels of C, H, and N, there were differences, with the highest values of N and C being in the leaves and stem with the 50 tons/ha application rate and the highest values of H for the 75 tons/ha application rate. The above results showed that applying biochar obtained from T. grandis residues improved soil conditions, resulting in better growth of C. odorata saplings with an application rate of 25 and 50 tons/ha. [ABSTRACT FROM AUTHOR]

In East Africa, soil nutrient depletion and low yields jeopardise the food security of smallholder farming families and exacerbate poverty. The main reasons for the depletion of soil nutrients are overuse due to population growth, limited land, and increasing uncertainty in agricultural production caused by climate change. This study aims to analyse and optimise nutrient flows and stocks in the homegardens of smallholder banana-coffee-based farming systems in the Kagera region in NW Tanzania. The plant nutrients nitrogen (N), phosphorus (P), and potassium (K) in plant-based biomass and organic farm waste are under investigation. We used data from a farm household survey (150 households) and from focus group discussions with 22 trainers who had been training about 750 farm households in sustainable land management (SLM) at a local farmer field school. In total, we identified six farm household types and calculated a nutrient balance (NB) for the homegardens of each household type. The NB was calculated for the following five management scenarios: S0: business as usual; S1: the use of 80% of the available human urine; S2: the incorporation of 0.5 t yr−1 of the herbaceous legume species Crotalaria grahamiana into the soil; S3: the production of 5 m3 yr−1 CaSa-compost (human excreta and biochar) and its application on 600 m2 land; and S4: a combination of S1, S2, and S3. The results show that the NB varies considerably depending on whether farmers have implemented the SLM training, apply nutrient-preserving manure collection and storage methods, and purchase fodder (imported nutrients), or whether they do not collect manure or do not purchase fodder. Trained farm households are more likely to have a positive NB than untrained households because they have already improved the nutrient management of their farms through the successful implementation of SLM practices. Untrained households would improve the NB in their homegardens under all management scenarios. However, the NB depends on labour-intensive manure collection and compost production, labour shortages, prolonged dry seasons, and socio-economic imbalances. As long as these constraints remain, nutrient deficiencies will not be overcome with mineral fertilisers alone, because soils have to be further enriched with organic matter first. In this paper, we also emphasise the importance of the system boundary, because only a complete NB can give an estimate of actual nutrient removal and the resulting nutrient demand (including removals by fodder and trees). Further improvements in the SLM training may be achieved by (i) measuring the current nutrient status of soils, (ii) analysing the need for the coexistence of free-range livestock on the grassland and zero-grazing in trained households, and (iii) conducting an in-depth analysis of the socio-economic differences between successful and unsuccessful households. In conclusion, if smallholder farmers were to integrate further improved SLM training and optimised nutrient management (S1 to S4), we assume that the NB would turn positive. Last but not least, the SLM training by the farmer field school may serve as a best-practice example for training and policy recommendations made by government institutions. [ABSTRACT FROM AUTHOR]

Research Highlights: We find that biochar plus fertilizer has synergistic and positive effects on seedling growth and robustness, but slightly lowers early seedling survival. Biochar plus fertilizer has the potential to greatly decrease costs associated with afforestation as compared to traditional fertilization and gives better results. Background and Objectives: Biochar can improve soil fertility and plant yield in crops. However, there is little information regarding the effects of biochar on trees, even though reforestation/afforestation projects are increasing and are often unsuccessful due to soil fertility limitations. This study aims to increase knowledge of biochar use as a reforestation tool. Materials and Methods: We measured survival and growth in an early ((Guazuma crinita Mart. [n = 240])) and a late (Terminalia amazonia (J.F. Gmel.) Exell. [n = 240]) successional species under 6 different biochar treatments in a 6-month nursery experiment. Results: (i) Survival was highest in the 1 t/ha biochar treatment, while treatments containing fertilizers or biochar at 5 t/ha lowered the survival rate of both species compared to the control; (ii) simultaneous addition of biochar and fertilizer lead to significant increases in height, diameter, total number of leaves, and aboveground and belowground biomass of both species as compared to other treatments; (iii) biochar treatment containing 1 t/ha with and without fertilizer showed significantly better results than applications of 5 t/ha; and (iv) Guazuma crinita responded more strongly to treatments containing biochar and fertilizers compared to Terminalia amazonia, which is suggestive of greater synergetic effects of biochar and fertilizer addition on early successional tree species. Conclusions: Applying biochar and fertilizer is synergistic and outperforms any single treatment, as well as the control, in terms of plant performance. This case study suggests that biochar can greatly improve reforestation/afforestation projects by increasing plant performance while substantially reducing fertilizer and labor maintenance costs. Field experiments and testing of additional species is needed to generalize the findings. [ABSTRACT FROM AUTHOR]