Unintended effects of biochars on short-term plant growth in a calcareous soil

Marks E.A.N., Alcaniz J.M., Domene X. (2014) Unintended effects of biochars on short-term plant growth in a calcareous soil. Plant and Soil. : 0-0.
Link
Doi: 10.1007/s11104-014-2198-2

Abstract:

Background and aims Biochar has demonstrably improved crop yields in weathered and acidic soils, but studies in calcareous soils are particularly lacking, so biochar effects on plant growth was investigated under these conditions. Methods Six biochars were obtained from different feedstocks and production technologies. Chemical characterization of fresh biochars included total and extractable nutrients, labile carbon, and Fourier transform infrared spectroscopy. Extractable nutrients were also evaluated in biochar-soil mixtures with a basic (pH >8.2) test soil. Bioassays with lettuce and ryegrass were carried out to relate biochar chemical properties to effects on plant biomass. Results A sewage sludge slow pyrolysis char was stimulatory to plant growth, as was a slow pyrolysis pine wood char at an intermediate concentration, while gasification and fast-pyrolysis pine and poplar wood chars were strongly inhibitory, with reductions in biomass at realistic application rates of 5-19 t ha-1. Conclusions Statistical comparison of plant responses with biochar composition led to the assessment that plant responses were most correlated with volatile matter content and total P content, whose availability was likely regulated by pH and Ca content. Potential effects of phytotoxins were considered, but these were seen to be much less probable than effects due to nutrient availability. © 2014 Springer International Publishing Switzerland.

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Biochars provoke diverse soil mesofauna reproductive responses inlaboratory bioassays

Marks E.A.N., Mattana S., Alcaniz J.M., Domene X. (2014) Biochars provoke diverse soil mesofauna reproductive responses inlaboratory bioassays. European Journal of Soil Biology. 60: 104-111.
Link
Doi: 10.1016/j.ejsobi.2013.12.002

Abstract:

Biochar application to soil has the potential to improve soil fertility under certain conditions. However, potential ecological effects remain largely unexplored and poorly understood, particularly those on soil biota. Six biochars were tested on two soil-dwelling invertebrates in short-term bioassays to determine effects on survival and reproduction. A pine wood gasification char increased collembolan adult mortality at high concentrations. Wood slow and fast pyrolysis biochars had a strong stimulatory effect on collembolan reproduction, but no strong effect on enchytraeids. A sewage sludge char was slightly stimulatory for both organisms, and a pine gasification char was inhibitory in both cases. Inhibitory effects were associated with biochars with high carbonate and Ca content and pH. In light of the high stimulation of collembolan reproduction, potential explanations such as soil microbial community shifts or gut symbiont use of biochar are suggested. © 2013 Elsevier Masson SAS.

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