[radford-neal]

"Sri Lanka banned the import of foreign fertilizers not because they were committed to being organic but because they had dire foreign exchange shortages"

In a free-market economy, the government is not in charge of importing things. It should make no difference whether the government has any foreign currency. Private actors can import things if they have the foreign currency to pay for them. Which they can get by exporting stuff.

I don't know what sort of deviations from a free-market economy are going on in Sri Lanka that led to this problem. But something is very wrong. Destroying your agricultural sector so the government can get more foreign currency is just obviously stupid. Unless, of course, you're benefiting from some corrupt scheme involving government control of foreign exchange...