Biochar Reduces Short-Term Nitrate Leaching from A Horizon in an Apple Orchard
Nitrogen leaching in croplands is a worldwide problem with implications both on human health and on the environment. Efforts should be taken to increase nutrient use efficiency and minimize N losses from terrestrial to water ecosystems. Soil-applied biochar has been reported to increase soil fertility and decrease nutrient leaching in tropical soils and under laboratory conditions. Our objective was to evaluate the effect of biochar addition on short-term N leaching from A soil horizon in a mature apple orchard growing on subalkaline soils located in the Po Valley (Italy). In spring 2009, 10 Mg of biochar per hectare was incorporated into the surface 20-cm soil layer by soil plowing. Cumulative nitrate (NO) and ammonium (NH) leaching was measured in treated and control plots 4 mo after the addition of biochar and the following year by using ion-exchange resin lysimeters installed below the plowed soil layer. Cumulative NO leaching was not affected by biochar after 4 mo, whereas in the following year it was significantly ( < 0.05) reduced by 75% over the control (from 5.5 to 1.4 kg ha). Conversely, NH leaching was very low and unaffected by soil biochar treatment. The present study shows that soil biochar addition can significantly decrease short-term nitrate leaching from the surface layer of a subalkaline soil under temperate climatic conditions.
Available from: Anita Maienza
- "Biochar is a recalcitrant material produced by biomass pyrolysis and its addition to agricultural soils has been proposed as a climate change mitigation strategy able to offset up to 12% of the current anthropogenic greenhouse gas emissions (Lehmann, 2007; Woolf et al., 2010). Moreover, biochar was proved to: increase soil water availability (Baronti et al., 2014; Glaser et al., 2002), improve macro-nutrient cycling (Ventura et al., 2013), increase crop yields (Jeffery et al., 2011) and preserve quality of agricultural productions (Genesio et al., 2015; Vaccari et al., 2011). Although a large literature focused on biochar effects in agriculture, the impacts on soil biota have received much less attention compared to other topics and the better understanding of the complex interplay between biochar and soil biology has been identified as an urgent research priority (Lehmann et al., 2011). "
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ABSTRACT: Biochar incorporation in agricultural soils has been proposed as a climate change mitigation strategy and has proved to substantially increase crop productivity via physical, chemical and biological mechanisms. The changes induced in soil properties are known to have a direct impact on soil ecosystem with consequences for soil biota community that, in turn, can influence biochar aging in soil. Despite several studies investigated in the interplay between biochar and soil microbiology, there is a clear lack of information on groups that live in the most superficial ground layers: soil meso and macro fauna. These groups are of great importance if we consider that biochar application should ideally be located in the soil's surface layer (0-30cm). Our study is the first attempt to investigate the interactions between biochar soil amendments and aboveground soil macro-meso fauna in a field crop. This was made setting-up a randomized-block experiment on a processing tomato crop in northern Italy, using three different biochar types and periodically monitoring soil parameters and fauna abundances along the crop growing cycle in summer 2013. Results show that the impact of biochar application on soil fauna as a whole is small when compared to that of agricultural management, suggesting that this amendment does not have short-term ecological interferences. Nevertheless, ants exhibited variations in abundances and distribution connected to properties of amended soils such as temperature, pH and humidity, proving that they can be effectively used as a target group in the study of interactions between biochar and soil biota.
Available from: Marcus Hardie
- "Toselli et al. (2011) reported that annual nitrate loss from the tree row of an apple orchard was up to 141 kg-N ha -1 , with average nitrate concentration in the leachate ranging from 10 to 40 mg L -1 . Ventura et al. (2013) found that cumulative nitrate and ammonium leaching from an apple orchard were up to 5.5 kg N ha -1 yr -1 , while Atucha et al. (2011) reported nitrogen fertilizer losses from subsoil leaching in an apple orchard were 5.2 to 20.9 kg ha -1 yr -1 or 18 to 22% of the applied fertilizer. "
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ABSTRACT: Nutrient leaching from agricultural soils is a worldwide problem that has been implicated in deleterious impacts on the environment. Application of biochar to soil has been proposed as a means to reduce nutrient leaching and improve fertilizer use efficiency. The potential for biochar to reduce nutrient leaching and increase fertilizer use efficiency was tested by applying 47 Mg ha hardwood biochar before replanting a commercial apple () orchard, in the Huon Valley, Tasmania. Passive wick flux meters were installed at the base of the A1 horizon at a depth of 25 cm to monitor leachate volume and the concentration of nutrients leached below the A1 soil horizon over a 38 mo period. Biochar application significantly increased the concentration of phosphorous in the leachate, while having no significant effect on nitrate or potassium concentration. The volume of leachate collected in the flux meters was significantly higher in the biochar treatment, which resulted in significantly higher amounts of potassium and phosphorous being leaching from the biochar treatment than the control. Biochar application had no significant effect on either the concentration or the flux of nitrate leached from the A1 horizon. Nonetheless, nutrient application was well in excess of tree requirements, such that between 53 to 78% of the applied nitrogen, 5 to 11% of the applied phosphate, and 69 to 112% of the applied potassium were leached below the A1 horizon.
- "The various proposed mechanisms are that enhanced nutrient retention due to cation and anion exchange reactions, immobilization of N due to labile C fraction of biochar, adsorption of organic N on biochar, etc. A large number of studies (Mizuta et al., 2004;Dempster et al., 2012b;Kameyama et al., 2012;Yao et al., 2012a, b;Chintala et al., 2013b;Ventura et al., 2013) have demonstrated decreases in leaching of nitrate (NO − 3 ) due to adsorption of NO − 3 on anion exchange surface of biochar. All these studies, however, have deemed high pyrolysis temperatures (> 600 @BULLET C) a prerequisite. "
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ABSTRACT: Biochar as a soil amendment is confronted with the challenge that it must benefit soil health as it can be by no means separated from soils once it is added. The available literature even though sparse and mostly based on short-term studies has been encouraging and the trend obtained so far has raised many hopes. Biochar has been reported to positively impact an array of soil processes ranging from benefiting soil biology, controlling soil-borne pathogens, enhancing nitrogen fixation, improving soil physical and chemical properties, decreasing nitrate (NO-3) leaching and nitrous oxide (N2O) emission to remediation of contaminated soils. However, very little biochar is still utilized as soil amendment mainly because these benefits are yet to be quantified, and also the mechanisms by which the soil health is improved are poorly understood. Due to the infancy of research regarding this subject, there are still more questions than answers. The future research efforts must focus on carrying out long-term experiments and uncover the mechanisms underlying these processes so that key concerns surrounding the use of biochar are addressed before its large scale application is recommended.
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