Short-term mesofauna responses to soil additions of corn stover biochar and the role of microbial biomass

Abstract

A B S T R A C TBiochar additions have been suggested to influence soil microbial communities that, through a cascade effect, may also impact soil fauna. In turn, any direct biochar effects on fauna can influence microbial communities through grazing, physical fragmentation of organic debris (and biochar) and modifying soil structure. If biochar creates a favorable environment for soil microorganisms, it is also plausible for fauna to be attracted to such microbially enriched habitats. However, how soil fauna respond to biochar addition to soil and what are the main factors that drive their behavior has rarely been experimentally addressed. Therefore, the behavior of two mesofauna species was assessed as a result of corn stover biochar (slow pyrolysis at 600 C) additions to a loamy temperate soil, after preincubation for 2, 17, 31 and 61 d, and related to variations in microbial biomass and activity. Microbial biomass increased by 5-56% and activity by 6-156% with increasing biochar rates for the different preincubation times. Over the incubation time, microbial biomass did not change or increased at most 15% with the different biochar rates, while in turn microbial activity decreased steadily (around 70-80% at day 61). Enchytraeids generally did not show avoidance or preference to biochar when provided with an alternative unamended soil, while collembolans often showed avoidance responses. However, collembolan avoidance to biochar decreased or disappeared in biochar mixtures with higher microbial biomass and water extractable NH 4 -N content, agreeing with the plausible role of microorganisms to potentially attract soil fauna after biochar applications. Avoidance response was mainly explained by environmental preferences of the test species and not by any toxic effect of the biochar in this study. However, avoidance after the application of biochar may still need to be considered due to the potential negative impacts of individuals' migration on soil ecosystem functioning.

Biochar to improve soil fertility. A review

“…Domene et al (2014) indicated that microbial abundance could increase from 366.1 (control) to 730.5 μg C g −1 after an addition of 30 t ha −1 biochar. Similarly, microbial abundance increased by 5-56 % with the increase of corn stover biochar rates (from 0 to 14 %) for the different preincubation times (2-61 days) (Domene et al 2015). Some possible reasons may be responsible for the increase of microbial abundance, such as higher availability of nutrients or labile organic matter on biochar surface (Pietikäinen et al 2000;Bruun et al 2012), less competition (Lehmann et al 2011), the enhanced habitat suitability and refuge (Pietikäinen et al 2000;Warnock et al 2007), the increased water retention and aeration (Wardle et al 1999;Schimel et al 2007), or positive priming (Zimmerman et al 2011).…”

Elaboration, characteristics and advantages of biochars for the management of contaminated soils with a specific overview on Miscanthus biochars

“…Another study conducted on collembolans (Protaphorura fimata) evaluated the effects of maize and wood biochars in a greenhouse experiment and revealed that P. fimata were not affected by the different biochars (Reibe et al, 2015). In Domene et al (2015), the behavior of two mesofauna species (enchytraeids and collembolan) was assessed as a result of corn stover biochar additions to a loamy soil. Enchytraeids did not show any avoidance or preference behavior compared to the unamended soil, while collembolans showed avoidance responses.…”

“…Few studies have investigated the meso-fauna (Domene et al, 2015;Lehmann et al, 2011), both in terms of abundance/community and evaluation of biochar toxicity. Zhang et al (2013a) observed no variation in total nematode abundance following a wheat straw biochar addition (2.4 t ha À1 ), although higher diversity with the biochar addition was observed as well as an increased abundance of fungivores.…”

Is There a Positive Synergistic Effect of Biochar and Compost Soil Amendments on Plant Growth and Physiological Performance?

“…If growth responses to BC and SMS treatments are mainly due to nutrient provision, then a saturation of plant nutrient demands will often result in a non-additive positive effect on plant growth (e.g., [63]), and may lead to a decline in plant growth at high levels [28] (p. 46). Alternatively, the combination of BC and SMS may have resulted in an oversupply of toxic elements (e.g., Al, Pb, Mn, As), or nutrients required at only very low levels (e.g., Mn, B) [3,23,25,64,65]. For example, high amounts of Mn are present in the BC used in our experiment (Table 1); while Mn is important for plant growth as a micronutrient [66], it can be toxic to plants at amounts that are highly variable between plant species [67] and environmental conditions [68][69][70].…”