Interactive effect of biochar levels and years on AMF spores in soil after harvest of maize crop in year 1 (2015) and 2 (2016). 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.