Consider the following statements regarding Black Soils (Regur Soil) of India:
1. They are highly argillaceous (clayey) and rich in lime, iron, magnesium, and alumina, but deficient in
nitrogen, phosphorus, and organic matter.
2. During dry seasons, these soils develop wide cracks, leading to a phenomenon known as 'self-ploughing'.
3. Black soil is primarily confined to river valleys and floodplains of the Indo-Gangetic belt.

Which of the statements given above are correct?