high humus content causes the soil to be brown
humic_shale is humate. brown_root_rot_fungus is fungus. coarse_grained_soil_region is inorganic_soil_region. mud is very_wet_soil. if plow occurs then dig occurs. brown_rot is plant_disease. humus is soil. macowanites_americanus is fungus. high_plasticity_soil_region is fine_grained_soil_region. brown_rot_gummosis is brown_rot.