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Soil fertility transience in the region of Masako in Democratic Republic (RD) of Congo remains a major challenge to sustainable agricultural production. Recently, biochar application as soil amendment has attracted attention of the people across the world owing to its potential to improve soil physicochemical properties, crop yield and carbon sequestration into the soil. A study was conducted in Masako to analyze the use of charcoal (biochar) as soil amendment and assess its effects on soil chemical performance and some biophysical parameters of maize crop. The experiment was set up using randomized complete block design with three replications of three treatments comprising ½ kg of sieved (small-sized particulate) charcoal per m 2 (C 1 ), 1 kg of sieved charcoal per m 2 (C 2 ) and control group without charcoal (C 0 ). Data were subjected to analysis of variance, Pearson's phenotypic correlation and regression analyses using genstat 12 th edition. The results of the analysis of variance showed non-significant variation for most physicochemical properties of soil and maize phenotypic traits, indicating that treatments had the same effects on soil composition suggesting that there was no clear impact of charcoal amendment as applied except for phosphorus content and collar diameter of the maize crop which were significantly (P ≤ 0.047 and P ≤ 0.043 respectively) influenced by the treatments. The results indicated that biochar improved the soil phosphorus availability by up to 72% as accounted for by the linear contribution of the treatment C 2 indicating that biochar could be recommended for use in soil with low level of phosphorous.

With respect to the pedosphere, human activities in the last 100 years have been the major driver of soil change. Despite human activities being one of the main soil forming factors recognized by soil scientists (in addition to climate, organisms, parent material, relief, groundwater, and time), the Canadian System of Soil Classification emphasizes soil as a natural body. We argue human-agricultural activities are direct and indirect drivers of significant changes to the carbon balance and cycling in A horizons of Gray Luvisolic soils in western Canada, resulting in changes to A horizon carbon stocks, structure, and micromorphology. Evidence from scientific literature, in-field soil profile observations and the National Pedon Database are presented in support of our argument. We propose a polygenetic, two-stage model of Gray Luvisol soil formation. The first stage is dominated by the climate forcing of the Holocene, resulting in a relatively stable boreal forest ecosystem including relatively minor perturbations from natural and human-induced wildfire and other disturbances. The second stage is dominated by direct, human-driven disturbances such as cultivation, release of exotic fauna (earthworms), and indirect human-driven disturbances associated with anthropogenic climate change. Further, we propose modest amendments to the Canadian System of Soil Classification to reflect a polygenetic model of soil genesis in Gray Luvisolic soils that preserve the balance between observation and interpretation inherent in the system.

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