To remove the weeds... we might spend 10 hours per hectare. Whereas the guy who uses weed-killer... will only spend about an hour, using chemicals that kill everything. We may use a tractor about ten times longer... so we burn more fuel, etc... So our carbon footprint... is going to be bigger. But what do we want? Do we want to pollute our soil and people... or do we decide to have a bigger carbon footprint?