During direct drilling, the seed is placed without any prior soil cultivation in the stubble of the previous crop. Direct drilling is used mainly in dry growing regions such as Canada, USA, Russia, Ukraine and Australia, and to some extent in other parts of the world.
Direct drilling (slit-seeding, zero tillage) and minimal cultivation techniques have now become alternatives to conventional cultivations on many farms and on a wide range of soil types, including difficult clays. Several types of special drills are available for direct drilling, using such developments as heavily weighted discs for cutting slits, strong cultivator tines or modified rotary cultivators. For it to be successful, direct drilling has relied on achieving a good straw and stubble burn to remove surface trash. Now that burning is banned, the practice has declined. With cereals it should only be used on very clean stubbles where the previous crop has been cut and the straw removed from the field. Even in these circumstances, there will be a small risk of disease spread from the stubble to the new crop. It can still be seriously considered for seeding grass and for crops such as kale. Minimal cultivation systems are those using various types of cultivators instead of the plough, and in such a way that only the minimum depth of soil is moved to allow drilling to take place.