Nothing new here.
What is happening in Cuba is the largest conversion in world history from conventional agriculture to organic or semi-organic farming. Empirical evidence from the United States and elsewhere demonstrates that it can take anywhere from three to seven years from the initiation of the conversion process to achieve the levels of productivity that prevailed beforehand. That is because it takes time to restore lost soil fertility and to re-establish natural controls of insect and disease populations. Yet Cuba does not have three to seven years - its population must be fed in the short term. Cuban scientists and planners are therefore attempting to shorten this process by bringing sophisticated biotechnology to bear on the development of new organic farming practices.
Organic Farming in Cuba
If the land can not sustain the people then there are too many people and birth control needs to be put in place before the land is destroyed and the people starve. The answer is not modified crops but modified behaviour that fixes the population problems. If a field has a yield of 100 tons per acre then you cant keep pushing it to produce 200 tons per acre without something breaking down, and this means many years of poor yields and even more famine.
Short term solutions never work