The issue of sequestration amounts and time are not explored in enough depth and may appear to be better solutions to a long term problem than they are.  Soil may retain 20% of the carbon but will become saturated in 20-30 years.  Trees have longer term sequestration and may retain that carbon for decades to centuries. The carbon that is being added by burning fossil fuels was sequestered in the order of thousands to millions of years. The use of shorter term sequestration may delay the problems but longer term sequestration must be found.