Effect of biochar amendment on sorption and leaching of nitrate, ammonium, and phosphate in a sandy soil

Department of Agricultural and Biological Engineering, University of Florida, Gainesville, FL 32611, United States.
Chemosphere (Impact Factor: 3.34). 07/2012; 89(11):1467-71. DOI: 10.1016/j.chemosphere.2012.06.002
Source: PubMed


When applied to soils, it is unclear whether and how biochar can affect soil nutrients. This has implications both to the availability of nutrients to plants or microbes, as well as to the question of whether biochar soil amendment may enhance or reduce the leaching of nutrients. In this work, a range of laboratory experiments were conducted to determine the effect of biochar amendment on sorption and leaching of nitrate, ammonium, and phosphate in a sandy soil. A total of thirteen biochars were tested in laboratory sorption experiments and most of them showed little/no ability to sorb nitrate or phosphate. However, nine biochars could remove ammonium from aqueous solution. Biochars made from Brazilian pepperwood and peanut hull at 600°C (PH600 and BP600, respectively) were used in a column leaching experiment to assess their ability to hold nutrients in a sandy soil. The BP600 biochar effectively reduced the total amount of nitrate, ammonium, and phosphate in the leachates by 34.0%, 34.7%, and 20.6%, respectively, relative to the soil alone. The PH600 biochar also reduced the leaching of nitrate and ammonium by 34% and 14%, respectively, but caused additional phosphate release from the soil columns. These results indicate that the effect of biochar on the leaching of agricultural nutrients in soils is not uniform and varies by biochar and nutrient type. Therefore, the nutrient sorption characteristics of a biochar should be studied prior to its use in a particular soil amendment project.

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Available from: Andrew R Zimmerman, Aug 29, 2014
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    • "In recent years evidence has been accumulated that biochars of various types may reduce N 2 O emissions from soils (Ameloot et al. 2013a; Case et al. 2012; Chintala et al. 2015; Kammann et al. 2012; Spokas and Reicosky 2009; Van Zwieten et al. 2009; Yanai et al. 2007). A number of mechanisms for this N 2 O emission reduction have been proposed, such as the capacity of biochar to shuttle electrons (Cayuela et al. 2013; Kappler et al. 2014), increase the soil pH (Van Zwieten et al. 2009), adsorb denitrification substrates (Clough et al. 2013; LeCroy et al. 2013; Yao et al. 2012) and change the soil structure (Van Zwieten et al. 2009; Yanai et al. 2007), without a clear conclusion to date. The mechanisms investigated in this paper involving a control of biochar over N 2 O emissions are twofold, viz. 1) biochar-induced improvements of soil aeration and 2) the stimulation of the last denitrificaiton step. "
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    ABSTRACT: Biochar addition to soils is heralded to reduce N2O emissions, but still, the explanatory mechanisms have not been resolved.Moreover, it is uncertain whether N2O emission reductions would persist after prolonged biochar incorporation in the field. In this study,we incorporated four biochar types in a loam textured cropland field and intact soil cores were sampled to investigate the physical control of biochar on denitrification after 7 months. During a first incubation experiment, we measured N2O emissions from undisturbed and disturbed (i.e. sieved (2 mm) and grounded) soil cores. Both in the disturbed and undisturbed soil cores biochar at water filled pore space (WFPS) of 80% reduced the N2O emissions by 50–90%, refuting the hypothesis that biochar exerts an indirect physical control over soil denitrification several months after incorporation. Secondly, we hypothesized that biochar creates denitrification ‘hotspots’ in soil, where complete reduction of N2O toN2 is promoted compared to non-amended soil. In these hotspots biochar particles could act as microlocations with local anaerobic conditions and local higher pH, stimulating in this way complete denitrification. Via the acetylene inhibition methodwe did not observe a reduction in the N2O/(N2O+N2) ratio, which could suggest that biochar did not promote the reduction of N2O toN2. Manipulations likely to promote labile C bioavailability, here either by glucose addition or by soil particulate OM disclosure after disruption of soil aggregates, resulted in the most prominent biocharinduced N2O emission reductions.
    Full-text · Article · Apr 2016 · Geoderma
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    • "The high release of cations and anions from BCs, especially those produced at 700 °C, could be related to the presence of soluble salts (as seen in high EC values in Table 2), since they were not subjected to washing after pyrolysis. Therefore, BCs can serve to replenish and retain exchangeable nutrient ions such as Ca, Mg, NO 3 , and PO 4 in the amended soils (Yao et al. 2012). "
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    ABSTRACT: Purpose Remediation of metal contaminated soil with biochar is attracting extensive interest in recent years. Understanding the significance of variable biochar properties and soil types helps elucidating the meticulous roles of biochar in immobilizing/mobilizing metals/metalloids in contaminated soils. Materials and methods Six biochars were produced from widely available agricultural wastes (i.e., soybean stover, peanut shells and pine needles) at two pyrolysis temperatures of 300 and 700 °C, respectively. The Pb-, Cu-, and Sb-contaminated shooting range soils and Pb-, Zn-, and As-contaminated agricultural soils were amended with the produced biochars. The mobility of metals/metalloids was assessed by the standard batch leaching test, principal component analysis and speciation modeling. Results and discussion The changes in soil properties were correlated to feedstock types and pyrolysis temperatures of biochars based on the principal component analysis. Biochars produced at 300 °C were more efficient in decreasing Pb and Cu mobility (>93 %) in alkaline shooting range soil via surface complexation with carboxyl groups and Fe-/Al-minerals of biochars as well as metal-phosphates precipitation. By contrast, biochars produced at 700 °C outperformed their counterparts in decreasing Pb and Zn mobility (100 %) in acidic agricultural soil by metal-hydroxides precipitation due to biochar-induced pH increase. However, Sb and As mobility in both soils was unfavorably increased by biochar amendment, possibly due to the enhanced electrostatic repulsion and competition with phosphate. Conclusions It is noteworthy that the application of biochars is not equally effective in immobilizing metals or mobilizing metalloids in different soils. We should apply biochar to multi-metal contaminated soil with great caution and tailor biochar production for achieving desired outcome and avoiding adverse impact on soil ecosystem.
    Full-text · Article · Jan 2016 · Journal of Soils and Sediments
    • "Several studies have examined nutrient retention by biochars produced from a range of parent materials (Lehmann et al., 2003; Ding et al., 2010; Laird et al., 2010; Yao et al., 2012). Thirteen different biochars showed little or no absorption of nitrate or phosphate , although nine of those tested removed aqueous ammonium from solution (Yao et al., 2012). "
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    ABSTRACT: Organic amendments such as peat moss and various composts are typically added to sand-based root zones to increase water and nutrient retention. However, these attributes are typically lost within a few years as these amendments decompose. Biochar is a high carbon, porous coproduct produced from the pyrolysis of phytobiomass. Its unique porosity gives it excellent water and nutrient retention properties. Additionally, unlike other organic amendments, biochar is extremely resistant to microbial decomposition. Pure calcareous sand (control) or mixtures of three different biochars and sand at 1, 5 and 10% volume biochar/total volume were tested. Bulk densities decreased while percent pore space increased with the addition of all three biochars at all of the addition rates. Water retention was greater than the control in all but one of the biochar treatments, and several of the biochar mixtures had values for compaction resistance similar to pure sand. Creeping bentgrass (Agrostis stolonifera L. 'Pure Distinction') plant heights, root lengths, and fresh and dry weights were evaluated in mixtures grown hydroponically in polyvinyl chloride tubes (112. mm outside diameter. × 99 mm inside diameter) filled 30 cm deep with 1 cm diameter pea gravel, over which 30 cm of either pure sand or sand/biochar mixtures were added to mimic a United States Golf Association root zone. Five weeks after seeding, plants grown in several of the biochar mixtures had significantly greater fresh and dry weights, shoot heights and root lengths than the control. Based on these results it appears that the addition of certain biochars would improve water retention and increase overall plant growth in sand-based root zones.
    No preview · Article · Oct 2015 · Scientia Horticulturae
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