Define "isn't working that well". Are we not exceeding historical standards for agricultural productivity?
Here's the wheat yield per hectare: http://www.earth-policy.org/images/uploads/graphs_tables/upd...
And corn bushels per acre: http://4.bp.blogspot.com/-lvcQDaR56xg/Trfc71LwF3I/AAAAAAAAQK...
Genetic engineering, as well as more traditional agriculture knowledge, has hugely improved productivity.