Primary succession is a method of bringing about fertility in infertile land that can not be cultivated. This method usually involves plant species known as "pioneer species", that do not rely heavily on soil nutrients but add nutrients to the soil. The land under the glacier is likely to be void of nutrients and infertile, so primary succession will be needed there the most.
Tilling agitates the topsoil and removes ‘unnecessary’ vegetation so the main crop can grow without competition. Tilling improves soil aeration and drainage for plants to grow well. Nonetheless, it can lead to other consequences such as soil erosion because it loosens the soil and makes it easy to be carried away by wind and water.
