Interactive effect of biochar levels and years on AMF root colonization (%) of maize crop. Biochar treatment 1 is control receiving no biochar in any season, 2 is receiving biochar at 20 t ha-1 each in summer and winter, 3 is receiving biochar at 40 t ha-1 in winter season and 4 is receiving biochar at 40 t ha-1 in summer season.