The article says quite literally that they did -
Rajapaksa’s government made good on that promise, imposing a nationwide ban on the importation and use of synthetic fertilizers and pesticides and ordering the country’s 2 million farmers to go organic
> So, this is not a failure of idealism. It is a failure of management.
Honestly, this sounds like the 'communism didnt work the last x times because nobody did it right'. I'm not saying you or your idea are wrong, to be clear, but it's impossible to say they did it wrong until a shining example proves that you -can- do it right.