With conventional tillage dating back to as early as 15th century, the method utilises the plough to fully turn the soil over, followed by multiple passes of secondary cultivation to loosen it before drilling.
Producing a clean seedbed, soil inversion brings fresh nutrients up to the surface, whilst burying weeds and previous crop residue. However, the practice also destroys the soil’s natural structure and disrupts its diverse ecosystem which serves many useful functions, from improving soil structure and aeration to helping plants absorb nutrients and fend disease. Heavy cultivation results in lower numbers of earthworms, beneficial fungi and microbial life.
Not only does ploughing bury the topsoil – the most fertile layer which is also abundant in beneficial micro-organisms,- it loses large amounts of nitrous oxide and carbon dioxide to the atmosphere, contributing to greenhouse gases.
Multiple machinery passes causes compaction whereas repetitive loosening of the top layer of soil may result in panning which restricts water movement and contributes towards waterlogging. Waterlogged ground favours grassweeds and presents less favourable conditions for commercial crops.
Yet one of the largest and most noticeable disadvantages is the loss of moisture and soil drying caused by intensive tillage. Conversely, in wet weather conditions, the residue-stripped ground can develop a crust and be prone to erosion.
Due to the number of passes required, seedbed preparation is slow, labour intensive and costly. For comparison, a typical plough-based system can use between 2.5 and 3 labour hours per hectare and approximately 124 litres of fuel per hectare compared with 0.4 hours per hectare and 18 litres of fuel per hectare with the Mzuri strip tillage system.