Nepal is an agricultural country. According to Wikipedia, agriculture is accounted for, on average, about 60 percent of the GDP and approximately 75 percent of exports. A lot of Nepalese students take forestry(which falls under Agriculture and Veterinary)
If you are willing to study agriculture just so that you can comeback and do something in Nepal, that’s a great idea. The fun thing about studying agriculture in Australia is, even if you are planning to build your career in Australia instead, that’ll serve the purpose too. Australia is itself a major agricultural producer and exporter.
Australian government is looking for more agriculture manpower for the growing need of the Agriculture workforce which is expected to ease the visa process as well.