Studies document increases in biological nitrogen fixation (BNF) following applications of biochar. However, the underlying mechanisms for this response remain elusive. Greenhouse experiments were conducted to test the effects of biochar mineral nutrients, pH, and volatile matter (VM) on BNF in common beans (Phaseolus vulgaris L.). Biochars were produced from seven feedstocks pyrolyzed at either 350 or 550 °C. Biochars were treated with acid to reduce mineral nutrient contents, with acetone to remove acetone-soluble VM, with steam to reduce both the mineral and VM contents, or left untreated. The biochar additions at a rate of 15 t ha1 resulted in an average 262 % increase in shoot biomass, 164 % increase in root biomass, 3575 % increase in nodule biomass, and a 2126 % increase in N derived from atmosphere (Ndfa) over the control. Simple mineral nutrients and soil acidity amelioration from the biochar were only to a minimal extent responsible for these increases (r2=0.03; P=0.0298, n=201). Plant growth and Ndfa were significantly correlated with plant P uptake (r2=0.22; P0.05). Improved P nutrition resulted from 360 % greater mycorrhizal colonization with biochar additions. Removal of acetone-soluble VM increased plant growth and Ndfa, and VM extracted from the biochar produced at 350 °C reduced the growth of rhizobia in yeast extract mannitol agar (YMA) medium. In contrast, acetone-soluble VM extracted from seven biochars produced at 550 °C increased the growth of rhizobium in the YMA compared to an acetone-residue control, suggesting differential effects of VM forms on rhizobia.
Tag: biochar
The Effect of Biochar Amendment, Microbiome Inoculation, Crop Mixture and Planting Density on Post-Mining Restoration
Ecological restoration with a multispecies and multifunctional approach can accelerate the re-establishment of numerous ecosystem services. The challenges with land that is degraded, damaged, or destroyed post-mining are the low productivity of soil and the high potential for contaminants. Herein, we evaluated the multispecies and multifunctional approach to restoration strategy through a mixture of woody and herbaceous species, microsymbiont and biochar amendments, and plant spacing. The experiments were conducted using greenhouse and field trials located in Quebec, Canada. We used a mixture of tree species (Alnus viridis (Chaix) DC. ssp. crispa (Aiton) Turrill, Picea glauca (Moench) Voss, Populus tremuloides Michx. and Salix arbusculoides Andersson) and herbaceous species (Avena sativa L., Festuca rubra L. and Trifolium repens L.) on two types of gold-mine waste materials (fine tailing and waste rock). The biochar amendment and microbial inoculation were applied on both greenhouse and field trials. We found both positive and negative effects of plant spacing, biochar amendment and inoculation depending on their interactions. The net positive effect was shown by combining high plantation density, biochar, and inoculation factors on Alnus viridis ssp. crispa. Overall, plantation density was shown to be the most important factor in generating the net positive effect. We suggest that the mechanism was correlated with the improvement in microclimate through soil plant water conservation and microbial activity enhancement over soil temperature modification. Hence, we propose to put emphasis on microclimate improvement for accelerating the restoration processes, along with other combined factors, including microbial inoculation and biochar amendment.
Using biochar and deficit irrigation enhanced the growth of commercial agroforestry woody species seedlings in drylands (a case study in Saz, northern Ethiopia)
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.
Use of biochar and Moringa oleifera in greywater treatment to remove heavy metals and contaminants of emerging concern
This study investigated the combination of biochar derived from carbonized local feedstock and Moringa oleifera seed extract-based flocculant, a novel combination in the context of greywater treatment missed in the previous studies, with a focus on the removal of organic contaminants (caffeine, chloramphenicol, trimethoprim, carbamazepine, diclofenac, and bisphenol A) and heavy metals (Cr(VI), As(III), Co(II), Ni(II), Cu(II), Zn(II), and Pb(II)). The research focused on the optimization of dosage, application procedure, and relevance to greywater (presence of humic acids, clay, and surfactants).
Biochar stoves for socio-ecological resilience
Soils, sinks, and smallholder farmers: Examining the benefits of biochar energy transitions in Kenya
Besides reducing fuel demands and indoor air pollution, pyrolytic cooking stoves produce a by-product (biochar) that can improve soil fertility and serve as a sink for carbon sequestration. Most smallholder farmers in Africa depend on wood for fuel, suffer from exposure to smoke and soils in their cultivated farms are deteriorating. Biochar (bio-charcoal) production has potentials to reduce energy requirement, diminish exposure to smoke, improve soil health and ease household activities traditionally associated with female labour. However, introducing new technologies and behaviours that tackle existing problems without creating new ones is a complex endeavour. Transitions need to be anticipatory, comprehensive and inclusive. Having this in mind, a trans-disciplinary study was conducted from 2013 to 2019 with 150 households in three agro-ecological zones of Kenya. The socio-economic conditions, the uses of fuels and stoves, the crops grown and fertilizers used, as well as the labour division within households were documented. Selected households were given pyrolitic cooking stoves and trained in applying biochar to the soil. After two years of using the cooking stoves and applying biochar, studies were conducted to assess the feasibility and preliminary impacts based on the households own perceptions and experiences. The results showed that the strategy represented a viable option to deal with fuel use efficiency, exposure to indoor smoke and soil degradation, as well as easing the burden on female labour.
Biochar production and use provides multiple benefits for smallholder agroecosystems.
Biochar from cookstoves reduces greenhouse gas emissions from smallholder farms in Africa
Biochar produced in cookstoves has the potential to contribute to negative carbon emissions through sequestration of biomass carbon while also providing other benefits for sustainable development, including provision of clean renewable energy and increased yields in tropical agriculture. The aim of the reported research was to estimate effects on food production, household energy access and life cycle climate impact from introduction of biochar-producing cookstoves on smallholder farms in Kenya. Participatory research on biochar production and use was undertaken with 150 Kenyan smallholder farming households. Gasifier cookstove functionality, fuel efficiency and emissions were measured, as well as biochar effects on agricultural yields after application to soil. Cookstoves provided benefits through reduced smoke, fuel wood savings and char production, but challenges were found related to labour for fuel preparation, lighting and refilling. On-farm trials with varying rates of biochar inputs, in combination with and without mineral fertilizers, have led to a sustained increase of maize yields following one-time application. The climate impact in a life cycle perspective was considerably lower for the system with cookstove production of biochar and use of biochar in agriculture than for current cooking practices. Climate benefits from biochar production and use are thus possible on smallholder farms in sub-Saharan Africa, through reduced use of biomass in cooking, reduced emissions of products of incomplete combustion and sequestration of stable biochar carbon in soils. Biochar-producing cookstoves can be implemented as a climate change mitigation method in rural sub-Saharan Africa. Successful implementation will require changes in cooking systems including fuel supply, as well as farming systems, which, in turn, requires an understanding of local socio-cultural conditions, including power relations and gender aspects.
Short-term casting activity of earthworm Pontoscolex corethrurus (Oligochaeta: Glossoscolecidae) after biochar additions
Exploring biochar and Moringa oleifera seed proteins for greywater remediation on small farms
This study investigated the potential of using biochar and Moringa oleifera seed proteins for sustainable greywater treatment in rural Kenya. Greywater samples from washing clothes were collected from households in the Kenyan counties of Kwale and Siaya. Two treatment methods, batch stirring and filtration, were used to assess the effectiveness of using biochar and Moringa oleifera seed protein extract together to treat greywater at a household level. Both methods achieved a significant reduction in contaminants: colour was reduced by up to 43% in Kwale and 67% in Siaya, turbidity decreased by 91–98%, and surfactant levels were lowered by 89–93%. There were increases in total organic carbon and total dissolved solids post-treatment, but both methods effectively reduced levels of phosphates, nitrates and iron. This research highlights the potential of using locally available materials for greywater treatment and provides insights into sustainable water management nature-based solutions in the Global South.