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Table 2 Mean concentration of nutrient elements extracted with aqua regia, H2SO4, vinegar, and water in charcoal and firewood ash from five cities in southern Ghana; probability values of a two-way ANOVA using ash type and city as factors

From: Characterization of charcoal and firewood ash for use in African peri-urban agriculture

 CharcoalFirewoodSDProbability valuesCV
(± %)
(mg g−1)Ash typeCityAsh type × city
Ca–aqua regia13112026NS0.01NS16
Ca–H2SO4706636NSNSNS45
Ca–vinegar16414838NS0.02NS18
Ca–water6.47.21.6NSNSNS22
Mg–aqua regia16.821.66.50.010.01NS25
Mg–H2SO415.920.26.10.020.04NS25
Mg–vinegar14.218.77.40.04NSNS31
Mg–water0.060.080.04NSNSNS34
K–aqua regia736922NS0.01NS26
K–H2SO4120100380.02 < 0.01 < 0.0117
K–vinegar13687740.020.02NS37
K–water24243NS0.050.038
Na–aqua regia3.94.22.7NS < 0.010.0549
Na–H2SO410.812.33.2NS0.01NS23
Na–vinegar10.111.54.3NS < 0.01NS21
Na–water3.84.41.7NS0.010.0431
P–aqua regia0.450.430.13NSNSNS29
P–H2SO40.420.380.12NSNSNS31
P–vinegar0.200.130.06 < 0.01NSNS39
P–water0.0020.0020.001NSNSNS59
  1. SD = standard deviation of the whole sample group (n = 40); CV = pooled coefficient of variation between replicate samples (n = 4)
  2. NS  not significant