Abstract
AimsTo determine the effects of the long-term (44-years) tillage practices on wheat grain yield in a dryland farming system. MethodsEffects of tillage on soil quality and crop productivity were assessed between 1976 and 2020 in South Africa’s Mediterranean climate zone. Seven tillage treatments were investigated: continuous mouldboard (MB) ploughing to a depth of 200 mm, tine-tillage to 150 mm, shallow tine-tillage (ST) to 75 mm, no-tillage (NT), ST conducted once in two years (ST-NT), ST conducted once in three years (ST-NT-NT), and ST conducted once in four years (ST-NT-NT-NT). Two crop management systems were also investigated: wheat monoculture and crop rotation. We evaluated the long-term wheat grain yield responses from the trial and hypothesised that, with time, the (i) monoculture system will lead to reduced grain yield, (ii) MB sequence will lead to reduced grain yield, (iii) infrequent tillage practices will improve grain yield relative to continuous NT.ResultsThe monoculture system led to reduced grain yield over time due to increased weeds. Compared to other tillage treatments in the monoculture system, the MB sequence led to higher (P<0.05) grain yields. However, in the crop rotation system, the NT treatment was the best option as it led to high yield and lower fuel usage. The infrequent tillage sequences failed to significantly improve the grain yield relative to continuous NT.ConclusionsThe infrequent tillage sequences were no better than the NT practice. We recommend that farmers opt for NT and crop rotation to ensure sustainability and avoid intensive tillage.
THE REMOVAL OF PHOSPHORUS, THE GRAIN YIELD OF SPRING WHEAT AT MINIMIZATION OF PRIMARY TILLAGE