Tillage systems and stubble management in a Mediterranean-type environmentin relation to crop yield and soil moisture

The effect of tillage and crop rotations can only be seen over many crop ye ars. Crop yield and soil results are evaluated from two long-term trials, e stablished in 1978-79 and 1985-86 to investigate various forms of tillage a nd the timing of such operations in various wheat (Triticum aestivum)-based rotations on a Calcixcrollic Xerochrept in northern Syria. In a tillage sy stems trial involving two wheat-legume-watermelon (Citrullus lanatus) rotat ions, deep tillage showed no advantage over a shallow sweep-tillage system, either for soil moisture storage or yield increase of any crop. The zero-t ill system suited legume crops but gave lower productivity in wheat due to a build up of grassy weeds, and was nor suitable for watermelon. Minimum ti llage, with its higher energy-use efficiency and yield levels equal to or e ven slightly above those of deep-tillage systems, appears promising for the lowland areas of West Asia and North Africa. In a tillage timing trial, wh eat in a wheat-lentil (Lens culinaris) rotation yielded best after conventi onal deep disc-plough tillage, but lentil yields were higher in a zero-till system.