The correct answer is: All of the above.
The Imphal Valley is a fertile valley in the state of Manipur, India. It is surrounded by hills and mountains, and is drained by the Imphal River. The valley has a significant portion of land under irrigation, due to the presence of rivers, government schemes, and fertile soils.
The Imphal River is a major river in Manipur. It originates in the hills of Nagaland, and flows through the Imphal Valley before joining the Barak River in Assam. The river is a major source of water for irrigation in the valley.
The government of Manipur has implemented several schemes to improve irrigation in the Imphal Valley. These schemes include the construction of dams, canals, and wells. The government has also provided subsidies to farmers to help them install irrigation systems on their land.
The soils in the Imphal Valley are fertile. This is due to the presence of alluvial deposits from the Imphal River. The alluvial deposits are rich in nutrients, which makes the soil ideal for agriculture.
The combination of the presence of rivers, government schemes, and fertile soils has made the Imphal Valley a major agricultural region in India.