Effect of sheep grazing on forage yield, yield components and grain yield of local black barley, under rainfall conditions in Iraqi Kurdistan

Abstract

In Iraqi Kurdistan, farmers usually graze young barley if it sown early in fall and then let the crops recover for 
grain production. Barley field that was established from the seeds of harvest lost from the previous season (2008 
to 2009), due to poor adjustment of the combine harvester. The plant population density was 190/m² at 13-2-2010; 
this was close to the normal rate 200 /m². The field was exposed to different grazing intensity; including two and 
four ewes which were fixed by ropes and wedges in the centre of the circle plots of 2.82 m radius to form an area 
of 25 m²; for three and six hours grazing duration in addition to none grazing treatment. Results revealed that, 
grazing treatments reduced significantly all measured characters (excluding number of tillers with no spike). The 
effect of grazing duration was more obvious than that of grazing intensity by increasing the number of ewes per 
plot. Therefore, the lowest plant height value was recorded for the treatment of four ewes grazed six hours; this 
was true for spike length, number of grain per spike, grain yield/spike, number of spike/m², grain yield/m², 
biological yield and grain yield/donum. There were reverse results for harvest index; it was increased with 
increasing number of ewes and grazing hours or by stress on plants this was attributed to the fact that, reduction 
of straw was more drastic than that of grains. The amount of reduction of straw and grain from the treatment of 
four ewes and six hours grazing was 59.63 and 49.15%, respectively.