Assuming you mean "deserts", it depends on the type and what causes it to be a desert or plain (here, I assume you mean grassland). If these occur naturally, no. Deserts occur where the precipitation is less than 10"/year. At 10 to 40" inches, you get grassland. Tropical rain forest requires at least 80"/year. Where human intervention has caused the damage, it can be reversed to some extent by reforestation, which over the years, will slowly increase rainfall, so that irrigation will no longer be needed. An example is the Sahel. However, any attempt at reforestation will fail if the locals keep cutting pencil-thin seedlings for firewood. In short, possible in theory, not in practice.