Why is it difficult to stop the practice of tavy farming in madagascar?

It's a traditional practice and it's an economical need

Explanation:

The tavy farming is a slash and burn approach, where forest is cut to gain agricultural land to plant rice for example.  However, without trees, the land cannot be irrigated properly and that patch of land becomes useless quite rapidly.

Over the generations, that caused global devastation on this island nation.

Most people know it's wrong and it will have to end soon, by the simple fact that there won't be any trees left to cut in a generation or two.

However, tavy is deeply engrained into traditions and it's still the easiest way for farmers to earn a living to feed their families, in a country with an annual income of less than US$0.60 a day.