| 1. |
- Abiven, Samuel, et al.
(författare)
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Biochar amendment increases maize root surface areas and branching : a shovelomics study in Zambia
- 2015
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 395:1-2, s. 45-55
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Tidskriftsartikel (refereegranskat)abstract
- Positive crop yield effects from biochar are likely explained by chemical, physical and/or biological factors. However, studies describing plant allometric changes are scarcer, but may be crucial to understand the biochar effect. The main aim of the present study is to investigate the effect of biochar on root architecture under field conditions in a tropical setting. The presented work describes a shovelomics (i.e., description of root traits in the field) study on the effect of biochar on maize root architecture. Four field experiments we carried out at two different locations in Zambia, exhibiting non-fertile to relatively fertile soils. Roots of maize crop (Zea mays L.) were sampled from treatments with fertilizer (control) and with a combination of fertilizer and 4 t.ha(-1) maize biochar application incorporated in the soil. For the four sites, the average grain yield increase upon biochar addition was 45 +/- 14 % relative to the fertilized control (from 2.1-6.0 to 3.1-9.1 ton ha(-1)). The root biomass was approximately twice as large for biochar-amended plots. More extensive root systems (especially characterized by a larger root opening angle (+14 +/- 11 %) and wider root systems (+20 +/- 15 %)) were observed at all biochar-amended sites. Root systems exhibited significantly higher specific surface areas (+54 +/- 14 %), branching and fine roots: +70 +/- 56 %) in the presence of biochar. Biochar amendment resulted in more developed root systems and larger yields. The more extensive root systems may have contributed to the observed yield increases, e.g., by improving immobile nutrients uptake in soils that are unfertile or in areas with prolonged dry spells.
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| 2. |
- Alling, Vanja, et al.
(författare)
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The role of biochar in retaining nutrients in amended tropical soils
- 2014
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Ingår i: Journal of Plant Nutrition And Soil Science/Zeitschrift für Pflanzenernahrung und Bodenkunde. - : Wiley. - 1436-8730 .- 1522-2624. ; 177:5, s. 671-680
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the effect of biochar amendments on the retention and availability of plant nutrients and Al in seven acidic tropical soils from Zambia and Indonesia. The experiments carried out investigated whether the adsorption capacity of NH4+ in the soils increased upon the addition of biochar and which effect biochar had on available concentrations of NO3-, K+, Mn2+, Mg2+, PO43-, and Al3+. These nutrients were selected as they represent those important to plant growth and soil quality. No significant increases or decreases in aqueous NH4+-N concentration with additions of biochar were detected. The Gaines-Thomas model was used in order to calculate selectivity coefficients for NH4+ exchange (K-gt values). Following the addition of biochar to soil, K-gt values decreased showing a reduction in the selective binding of NH4+ in the biochar amended soil compared to the control. The concentration of NO3- increased following the addition of biochar to the soils. The addition of 5 and 10% biochar to the Indonesian soil did not significantly alter (t-test confidence level 0.05) the sorption of PO43- to the soil-biochar mixtures as compared to the soil alone. However, the addition of biochar to the soil from Zambia increased the sorption of PO43- compared to the soil alone. The concentrations of K+ and Mg2+ were significantly increased for almost all soils (t-test at the 0.05 confidence level) following the addition of biochar. Addition of biochar to all but two soils significantly decreased (t-test confidence level 0.05) Mn2+ concentrations. The concentration of Al3+ in the soils decreased exponentially significantly (t-test confidence level 0.05) following the amendment of biochar in accordance with the increase in pH observed when biochar was added to the soil. These results show that biochar has the ability to release essential plant growth nutrients as well as alleviate Al toxicity in these soils.
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| 3. |
- Hale, Sarah E., et al.
(författare)
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Short-Term Effect of the Soil Amendments Activated Carbon, Biochar, and Ferric Oxyhydroxide on Bacteria and Invertebrates
- 2013
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 47:15, s. 8674-8683
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to evaluate the secondary ecotoxicological effects of soil amendment materials that can be added to contaminated soils in order to sequester harmful pollutants. To this end, a nonpolluted agricultural soil was amended with 0.5, 2, and 5% of the following four amendments: powder activated carbon (PAC), granular activated carbon, corn stover biochar, and ferric oxyhydroxide powder, which have previously been proven to sequester pollutants in soil. The resulting immediate effects (i.e., without aging the mixtures before carrying out tests) on the springtail Folsomia candida, the earthworm species Aporectodea caliginosa and Eisenia fetida, the marine bacteria Vibrio fischeri, a suite of ten prokaryotic species, and a eukaryote (the yeast species Pichia anomalia) were investigated. Reproduction of F. candida was significantly increased compared to the unamended soil when 2% biochar was added to it. None of the treatments caused a negative effect on reproduction. All amendments had a deleterious effect on the growth of A. caliginosa when compared to the unamended soil, except the 0.5% amendment of biochar. In avoidance tests, E. fetida preferred biochar compared to all other amendments including the unamended soil. All amendments reduced the inhibition of luminescence to V. fischeri, i.e., were beneficial for the bacteria, with PAC showing the greatest improvement. The effects of the amendments on the suite of prokaryotic species and the eukaryote were variable, but overall the 2% biochar dose provided the most frequent positive effect on growth. It is concluded that the four soil amendments had variable but never strongly deleterious effects on the bacteria and invertebrates studied here during the respective recommended experimental test periods.
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| 4. |
- Martinsen, Vegard, et al.
(författare)
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Farmer-led maize biochar trials : Effect on crop yield and soil nutrients under conservation farming
- 2014
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Ingår i: Journal of Plant Nutrition And Soil Science/Zeitschrift für Pflanzenernahrung und Bodenkunde. - : Wiley. - 1436-8730 .- 1522-2624. ; 177:5, s. 681-695
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Tidskriftsartikel (refereegranskat)abstract
- In extensive farmer-led trials practicing conservation farming (CF) in three regions of Zambia (Mongu: sandy soils; Kaoma: sandy or loamy sand soils; Mkushi: sandy loam or loamy soils), we studied the effects of biochar made of maize cobs (0, 2, and 6 t ha(-1) corresponding to 0, 0.8, and 2.5% per basin) at different fertilizer rates of NPK and urea on crop yield of maize (Zea mays) and groundnuts (Arachis hypogaea). Conservation farming in this case combines minimum tillage (how basins), crop rotation and residue retention. For the first time, the effect of biochar on in situ soil nutrient supply rates [determined by buried Plant Root Simulator (PRS (TM)) exchange resins] was studied, as well as the effects of biochar on elemental composition of maize. Effects of 0-10% (w:w) biochar addition on soil physical and soil chemical properties were determined in the laboratory. At all sites there was a consistent positive response in crop yield upon the addition of biochar. However, due to a great variability between farms there were no significant differences in absolute yields between the treatments. In the sandy soils at Mongu, relative yields (i.e., percentage yield with biochar relative to the same fertilizer rate without biochar) of maize grains and maize stover were significantly increased at recommended fertilizer rates (232 +/- 60%) and at half the recommended rate (128 +/- 6%), respectively. In addition, biochar significantly increased concentrations of K and P in maize stover. In situ soil nutrient supply rates as measured by PRS (TM)-probes were highly spatially variable with no consistent effects of the different treatments in the three regions. By contrast, the fraction of plant available water (Vol.-%) significantly increased upon the addition of biochar in all three soils. The increase caused by 10% biochar addition was of factor 2.5 in Mongu (from 4.5% to 11.2%) and 1.2 in both Kaoma (from 14.7% to 18.2%) and Mkushi (from 18.2% to 22.7%). Cation exchange capacity, pH, and exchangeable K significantly increased upon the addition of 10% (w: w) biochar in all three regions with a subsequent increase in base saturation and decrease of available Al3+. Our findings suggest that the addition of biochar in combination with CF might have a positive impact on crop growth and that this positive effect is mainly caused by increases in plant-available water and decreased available Al.
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| 5. |
- Obia, Alfred, et al.
(författare)
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In situ effects of biochar on aggregation, water retention and porosity in light-textured tropical soils
- 2016
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Ingår i: Soil & Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 155, s. 35-44
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Tidskriftsartikel (refereegranskat)abstract
- Biochar (BC) has been reported to improve soil physical properties mainly in laboratory and greenhouse pot experiments. Here we study, under field conditions, the effect of BC and its particle sizes on soil aggregate stability, bulk density (BD), water retention, and pore size distribution in two experiments in Zambia. A) Farmer practice experiment in sandy loam with maize cob BC in conservation farming planting basins under maize and soybeans crops. B) Maize cob and rice husk BC particle size experiments (<= 0.5, 0.5-1 and 1-5 mm particle sizes) in loamy sand and sand. In the farmer practice experiment, BC increased aggregate stability by 7-9% and 17-20% per percent BC added under maize and soybeans crops respectively (p < 0.05) after two growing seasons. Total porosity and available water capacity (AWC) increased by 2 and 3% respectively per percent BC added (p < 0.05) under both crops, whereas BD decreased by 3-5% per percent BC added (p < 0.01). In the maize cob BC particle size experiment after one growing season, dose was a more important factor than particle size across the soils tested. Particle size of BC was more important in loamy sand than in sand, with <= 0.5 and 1-5 mm sizes producing the strongest effects on the measured properties. For example, BD decreased while total porosity increased (p < 0.01) for all BC particle sizes in sand whereas only 1-5 mm BC significantly decreased BD and increased total porosity in loamy sand (p < 0.05). However, AWC was significantly increased by only <= 0.5 and 1-5 mm BCs by 7-9% per percent BC added in both loamy sand and sand. Rice husk BC effect after one year followed similar pattern as maize cob BC but less effective in affecting soil physical properties. Overall, reduced density of soil due to BC-induced soil aggregation may aid root growth and with more water available, can increase crop growth and yields.
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| 6. |
- Obia, Alfred, et al.
(författare)
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Vertical and lateral transport of biochar in light-textured tropical soils
- 2017
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Ingår i: Soil & Tillage Research. - : Elsevier BV. - 0167-1987 .- 1879-3444. ; 165, s. 34-40
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Tidskriftsartikel (refereegranskat)abstract
- Field experiments were conducted in Arenosols (loamy fine sand) and Acrisols (sandy loam) in Zambia to quantify vertical and lateral transport of biochar (BC) using the BC and soil C-13 isotope signatures and total organic carbon contents. There were three experimental treatments composing of no BC, <= 0.5 and 0.5-1 mm BCs each with three replicates arranged in completely randomized design. The applied BCs were made from rice husk, except 0.5-1 mm BC in sandy loam, which was from maize cob. One year after mixing BC homogeneously in the 0-5 cm surface layer, soil down to 20 cm depth was sampled. The downward migration of BC was significant down to 8 cm depth in sandy loam and down to 6 cm in loamy fine sand. Below these depths, there was no significant difference in BC amounts between the BC amended and the reference plots. There was a general tendency for greater downward migration for the <= 0.5 mm than for 0.5-1 mm BC. Total BC recovery at 0-5 cm depth in the BC-treated soils amounted to 45-66% of the total applied amount of BC. As only 10-20% was recovered in the deeper soil layers, 24-45% of the applied BC could not be accounted for in the soil profile. Although, decomposition and downward migration to below 20 cm depth may contribute to the loss of BC from the surface soil, much can be attributed to lateral transfer through erosion. This is the first study that explicitly focuses on the theme of BC dispersion and shows that in Arenosols and Acrisols of the tropics, the downward migration of BC is limited.
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| 7. |
- Schmidt, Hans Peter, et al.
(författare)
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Fourfold Increase in Pumpkin Yield in Response to Low-Dosage Root Zone Application of Urine-Enhanced Biochar to a Fertile Tropical Soil
- 2015
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Ingår i: Agriculture (Basel). - : MDPI AG. - 2077-0472. ; 5:3, s. 723-741
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Tidskriftsartikel (refereegranskat)abstract
- A widely abundant and invasive forest shrub, Eupatorium adenophorum, was pyrolyzed in a cost- efficient flame curtain kiln to produce biochar. The resulting biochar fulfilled all the requirements for premium quality, according to the European Biochar Certificate. The biochar was either applied alone or mixed with fresh cow urine ( 1: 1 volume) to test its capacity to serve as slow release fertilizer in a pumpkin field trial in Nepal. Treatments included cow- manure compost combined with ( i) urine- only; ( ii) biochar- only or ( iii) urine- loaded biochar. All materials were applied directly to the root zone at a biochar dry matter content of 750 kg . ha- 1 before seeding. The urine- biochar treatment led to a pumpkin yield of 82.6 t . ha- 1, an increase of more than 300% compared with the treatment where only urine was applied, and an 85% increase compared with the biochar- only treatment. This study showed for the first time that a low- dosage root zone application of urine- enhanced biochar led to substantial yield increases in a fertile silt loam soil. This was tentatively explained by the formation of organic coating of inner pore biochar surfaces by the urine impregnation, which improved the capacity of the biochar to capture and exchange plant nutrients.
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| 8. |
- Sparrevik, Magnus, et al.
(författare)
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Emissions of gases and particles from charcoal/biochar production in rural areas using medium-sized traditional and improved retort kilns
- 2015
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 72, s. 65-73
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Tidskriftsartikel (refereegranskat)abstract
- Charcoal is used for cooking in many parts of the developing world. Charcoal from agricultural materials can also be used as a soil amendment to enhance agricultural production, and is often termed biochar in this case. Charcoal may be produced in various types and scales of systems, but for rural tropical areas, traditional kiln technologies without treatment of the pyrolysis gases dominate. Traditional charcoal industry is considered to be both inefficient and polluting, emitting harmful off-gases containing methane, carbon monoxide and particles. Retort kilns, which recirculate and combust the pyrolysis gases internally have been claimed to overcome this problem. Even though retort technology has frequently been discussed, this paper is the first study determining gas emission factors for operational retort kilns in rural tropical areas. The mean emission factors for the retort ldlns found in this study using identical feedstock were (in g kg(-1) charcoal); carbon dioxide (CO2) = 1950 +/- 209, carbon monoxide (CO) = 157 +/- 64, nonmethane volatile organic components (NMVOC) = 6.1 +/- 3.4, methane (CH4) = 24 +/- 17, total solid particles (TSP) = 12 +/- 18, products of incomplete combustion (plc) = 200 +/- 97 and nitric oxides (NOx) = 1.8 +/- 1.0. The corresponding value for the non-retort ldlns tested was in general higher; CO2 = 2380 +/- 973, CO = 480 +/- 141, NMVOC = 13 +/- 3.8, CH4 = 54 +/- 29, TSP = 7.9 +/- 2.6, PIC = 554 +/- 138 and NOx = 4.3 +/- 1.6. The difference between the kiln types was statistically significant (p < 0.05) for CO, NMVOC, PIC and NOx. However, the retort kilns consumed ignitable fuel such as wood in the start-up phase to reach pyrolysis temperature resulting in insignificant difference in yield between retort and non-retort kilns. In addition, retort kilns are more costly than traditional kilns, which may be challenging for implementation. It is therefore important to continue design development, especially with regard to wood consumption during the start-up phase.
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| 9. |
- Sparrevik, Magnus, et al.
(författare)
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Life Cycle Assessment to Evaluate the Environmental Impact of Biochar Implementation in Conservation Agriculture in Zambia
- 2013
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 47:3, s. 1206-1215
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Tidskriftsartikel (refereegranskat)abstract
- Biochar amendment to soil is a potential technology for carbon storage and climate change mitigation. It may, in addition, be a valuable soil fertility enhancer for agricultural purposes in sandy and/or weathered soils. A life cycle assessment including ecological, health and resource impacts has been conducted for field sites in Zambia to evaluate the overall impacts of biochar for agricultural use. The life cycle impacts from conservation farming using cultivation growth basins and precision fertilization with and without biochar addition were in the present study compared to conventional agricultural methods. Three different biochar production methods were evaluated: traditional earth-mound kilns, improved retort kilns, and micro top-lit updraft (TLUD) gasifier stoves. The results confirm that the use of biochar in conservation farming is beneficial for climate change mitigation purposes. However, when including health impacts from particle emissions originating from biochar production, conservation farming plus biochar from earth-mound kilns generally results in a larger negative effect over the whole life cycle than conservation farming without biochar addition. The use of cleaner technologies such as retort kilns or TLUDs can overcome this problem, mainly because fewer particles and less volatile organic compounds, methane and carbon monoxide are emitted. These results emphasize the need for a holistic view on biochar use in agricultural systems. Of special importance is the biochar production technique which has to be evaluated from both environmental/climate, health and social perspectives.
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