Biochar in Mixtures - International Biochar Initiative
Biochar in Mixtures - International Biochar Initiative Biochar in Mixtures - International Biochar Initiative
Some researchers found better yield of peanuts and greater numbers and total biomass of nitrogen-fixing nodules on peanut roots when Bokashi was used instead of synthetic fertilizer (Yan and Xu, 2002). However, Formowitz et al. (2007) showed that the “effective microorganisms” were not likely responsible for beneficial effects of the material on plant growth, and similar observations were made in field crops grown over four years in central Europe (Mayer et al., 2008). However, the Bokashi made by Formowitz et al. (2007) did not include biochar, and the reports by Yan and Xu (2002) and Mayer et al. (2008) do not provide details on the materials used to make Bokashi and whether or not biochar was used. Thus while Bokashi was found to provide plant growth benefits in these studies, and these benefits could not be attributed to EM, there are no reports in the literature about the role of biochar in Bokashi mixtures. Nevertheless, biochar-containing Bokashi has been used successfully for over 15 years for growing vegetables in Costa Rica (IBI Practitioner Profile, 2010) and used by farmers in the Philippines, as outlined in Jensen et al (2006), as one example. Biochar as a medium for fungal inoculants Peat is commonly used as a carrier for rhizobial inoculant. Rhizobia are bacteria used to promote proper nodulation and biological nitrogen fixation in legume crops. However, peat is not available in all regions and is arguably not a renewable resource since its formation takes a very long time. Biochar can also be used as a carrier for microbial inoculants. Stephens and Rask (2000) indicate that carriers for microbial inoculants should, among other factors, support the growth of the target organisms, have high moisture holding and retention capacity, and be environmentally safe. Properly produced biochar has these characteristics. When testing the survival rate of rhizobial inoculum, charcoal performed similarly to peat, oil and other carriers (Kremer and Peterson, 1983). Similar results were found by Sparrow and Ham (1983), where rhizobial inoculant survival rates were greater in peat, charcoal and vermiculite than in peanut hulls or corn cobs. Mycorrhizae are another type of fungus which also forms symbiotic associations with plants, and soil-applied biochar has often been demonstrated to be beneficial to mycorrhizal fungi (reviewed by Warnock et al., 2007), although neutral effects have also been observed (Habte and Antal, 2010). Biochar as a “bulking agent” in compost Studies to date show that the composting process can be accelerated by adding biochar to poultry manure (Dias et al., 2009; Steiner et al., 2010). For example, maximum temperatures of the compost were reached faster when biochar was applied (Steiner et al., 2010) and the degree of humification of the resulting compost was greater (Dias et al. 2009) with biochar application. Steiner et al. (2010) assumed that biochar did not decompose during the 42 day trial, and found that the loss of poultry manure biomass was not different in cases where biochar was added as 0, 5 or 20% of the mixture on a dry weight basis. Dias et al. found that total mass loss in their 1:1 by wet weight mixture of biochar and poultry litter was intermediate compared to equivalent mixtures with coffee husks and sawdust (coffee husks as a bulking agent caused greater losses and sawdust caused lower losses relative to biochar), and alluded to the fact that biochar could have IBI Research Summary – Biochar in Mixtures – January 2011 page 2
undergone decomposition, although their data did not allow this to be determined. More research is needed on the effect of biochar on the C and mass balance during composting; however a faster “ripening” of compost as demonstrated by both authors is desirable for compost makers. Total nitrogen losses over 42 days of composting sewage sludge were reduced by 64% by adding 9% biochar to the sludge (Hua et al., 2009) as opposed to a control not receiving biochar. Adding 20% biochar to poultry litter reduced ammonia emissions by 64% over 42 days (Steiner et al. 2010) compared to a non-amended control. Dias et al. (2009) found that N losses when using biochar as a bulking agent were lower than when coffee husks were used, but greater than when sawdust was used as a bulking agent. These results are promising, especially considering the recalcitrance of biochar in soil compared to other bulking agents, and the potential for biochar to reduce odors in compost and retain inorganic N against leaching, after soil application. Indeed Steiner et al. (2007) found greater yield of maize and sorghum on an acid soil after four years when biochar was applied with compost as opposed to being applied with synthetic fertilizer. Dr Makoto Ogawa of the Osaka Institute of Technology in Japan states: “Making compost from litter and excretions has been common in Japan for a long time. In the 1980s, charcoal compost was made from fresh chicken dung and palm shell charcoal; the more charcoal used, the faster the composting process. Under aerobic conditions the Bacillus group became dominant and produced antibiotics that inhibited growth of soilborne pathogens and suppressed root diseases. Charcoal compost is now sold in Japan as a biological fungicide. Various other organic composts are now being been produced from livestock excretions and charcoal and sold commercially.” (Ogawa, 2009). Biochar and manure In a column study, Laird et al. (2010) found that the addition of biochar to manureamended soil reduced the leaching of nutrients. One method for mixing biochar with manure is to feed biochar directly to animals. While there are constraints on the amount of biochar which can be delivered to soil in this way, it can potentially provide other advantages. It has been known for a long time that adding charcoal or various zeolite-like materials to the feed of livestock improves their ability to utilize protein and assimilate protein-derived nitrogen from poor-quality (tannin-rich) fodder, most probably via control of loss of ammonia that is subsequently used for microbial protein synthesis in the rumen. Van et al. (2006) showed that growth rate was 20% greater, and final animal weight was 5% greater when goats fed tannin-rich Acacia sp. fodder were also fed less than 1 g bamboo charcoal per kg animal weight per day. This trial lasted 12 weeks. As suggested by Blackwell et al. (2009) and McHenry (2010), biochar can thus be “ecologically delivered” to soil as part of the animals’ manure. A technical bulletin from the Food and Fertilizer Technology Center (FFTC, year unknown) in Taiwan also proposes feeding bamboo charcoal to cattle, pigs and poultry to reduce smells in barns as well as providing other benefits to animal health. Similarly, the Brief Compend on American Agriculture (an agriculture handbook published in 1847) gives the following advice on keeping pigs: “If they are closely confined in pens give them as much charcoal IBI Research Summary – Biochar in Mixtures – January 2011 page 3
Some researchers found better yield of peanuts and greater numbers and total biomass of<br />
nitrogen-fix<strong>in</strong>g nodules on peanut roots when Bokashi was used <strong>in</strong>stead of synthetic<br />
fertilizer (Yan and Xu, 2002). However, Formowitz et al. (2007) showed that the<br />
“effective microorganisms” were not likely responsible for beneficial effects of the<br />
material on plant growth, and similar observations were made <strong>in</strong> field crops grown over<br />
four years <strong>in</strong> central Europe (Mayer et al., 2008). However, the Bokashi made by<br />
Formowitz et al. (2007) did not <strong>in</strong>clude biochar, and the reports by Yan and Xu (2002)<br />
and Mayer et al. (2008) do not provide details on the materials used to make Bokashi and<br />
whether or not biochar was used. Thus while Bokashi was found to provide plant growth<br />
benefits <strong>in</strong> these studies, and these benefits could not be attributed to EM, there are no<br />
reports <strong>in</strong> the literature about the role of biochar <strong>in</strong> Bokashi mixtures. Nevertheless,<br />
biochar-conta<strong>in</strong><strong>in</strong>g Bokashi has been used successfully for over 15 years for grow<strong>in</strong>g<br />
vegetables <strong>in</strong> Costa Rica (IBI Practitioner Profile, 2010) and used by farmers <strong>in</strong> the<br />
Philipp<strong>in</strong>es, as outl<strong>in</strong>ed <strong>in</strong> Jensen et al (2006), as one example.<br />
<strong>Biochar</strong> as a medium for fungal <strong>in</strong>oculants<br />
Peat is commonly used as a carrier for rhizobial <strong>in</strong>oculant. Rhizobia are bacteria used to<br />
promote proper nodulation and biological nitrogen fixation <strong>in</strong> legume crops. However,<br />
peat is not available <strong>in</strong> all regions and is arguably not a renewable resource s<strong>in</strong>ce its<br />
formation takes a very long time. <strong>Biochar</strong> can also be used as a carrier for microbial<br />
<strong>in</strong>oculants. Stephens and Rask (2000) <strong>in</strong>dicate that carriers for microbial <strong>in</strong>oculants<br />
should, among other factors, support the growth of the target organisms, have high<br />
moisture hold<strong>in</strong>g and retention capacity, and be environmentally safe. Properly produced<br />
biochar has these characteristics. When test<strong>in</strong>g the survival rate of rhizobial <strong>in</strong>oculum,<br />
charcoal performed similarly to peat, oil and other carriers (Kremer and Peterson, 1983).<br />
Similar results were found by Sparrow and Ham (1983), where rhizobial <strong>in</strong>oculant<br />
survival rates were greater <strong>in</strong> peat, charcoal and vermiculite than <strong>in</strong> peanut hulls or corn<br />
cobs. Mycorrhizae are another type of fungus which also forms symbiotic associations<br />
with plants, and soil-applied biochar has often been demonstrated to be beneficial to<br />
mycorrhizal fungi (reviewed by Warnock et al., 2007), although neutral effects have also<br />
been observed (Habte and Antal, 2010).<br />
<strong>Biochar</strong> as a “bulk<strong>in</strong>g agent” <strong>in</strong> compost<br />
Studies to date show that the compost<strong>in</strong>g process can be accelerated by add<strong>in</strong>g biochar to<br />
poultry manure (Dias et al., 2009; Ste<strong>in</strong>er et al., 2010). For example, maximum<br />
temperatures of the compost were reached faster when biochar was applied (Ste<strong>in</strong>er et al.,<br />
2010) and the degree of humification of the result<strong>in</strong>g compost was greater (Dias et al.<br />
2009) with biochar application. Ste<strong>in</strong>er et al. (2010) assumed that biochar did not<br />
decompose dur<strong>in</strong>g the 42 day trial, and found that the loss of poultry manure biomass was<br />
not different <strong>in</strong> cases where biochar was added as 0, 5 or 20% of the mixture on a dry<br />
weight basis. Dias et al. found that total mass loss <strong>in</strong> their 1:1 by wet weight mixture of<br />
biochar and poultry litter was <strong>in</strong>termediate compared to equivalent mixtures with coffee<br />
husks and sawdust (coffee husks as a bulk<strong>in</strong>g agent caused greater losses and sawdust<br />
caused lower losses relative to biochar), and alluded to the fact that biochar could have<br />
IBI Research Summary – <strong>Biochar</strong> <strong>in</strong> <strong>Mixtures</strong> – January 2011 page 2
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