BIOCHAR - Fertilizers: Components, Uses in Agriculture and Environmental Impacts - page 109

indicators three years after chipped wood trunk biochar was applied to a sandy clay loam
Eutric Cambisol at rates of up to 50 Mg ha -1 (Quilliam et al., 2012; Quilliam et al., 2013a).
E FFECT OF B IOCHAR A PPLICATION ON C ROP Y IELD
The main positive effect of biochar on plant performances is through its liming potential
and its effect on soil pH. As assessed in meta-analysis studies, biochar application resulted in
moderate (10-15%), yet significant increase in crop productivity (Jeffery et al., 2011).
Positive response to biochar application occurred (1) on coarse texture soils more than on
soils of finer texture, (2) with increase in application rate, (3) when applied in combination
with fertilizers, (4) with increase in biochar alkalinity, and (5) when larger increase in soil pH
occurred in response to biochar application (Verheijen et al., 2009; Jeffery et al., 2011;
Biederman & Harpole, 2012). When biochar applications did not increase the native soil pH,
it resulted in no significant effect on crop yield; conversely, when biochar applications
increased the soil pH, it resulted in an increase in crop yield (Figure 5). Inasmuch as
increasing soil pH leads to decrease in nutrient availability and subsequent deficiencies at
high soil pHs (ca. pH>8), raising pH of acid soils ameliorates acid soils growth limiting
factors (Parker et al., 1988; Fox et al., 1991; He et al., 1999; Ritchey & Snuffer, 2002).
(Jeffery et al., 2011, Elsevier, with permission).
Figure 5. Percent changes in crop productivity as influenced by changes in soil pH upon addition of
biochar. Points show means of treatments, horizontal bars show 95% confidence intervals.