Weed management under different tillage systems in smallholder farming areas of Zimbabwe
1999
Mabasa, S. (Henderson Research Station, Mazowe (Zimbabwe)) | Shamudzarira, Z. (Agronomy Institute, Harare (Zimbabwe)) | Makanganise, A. (Henderson Research Station, Mazowe (Zimbabwe)) | Bwakaya, F. (Agronomy Institute, Harare (Zimbabwe)) | Sithole, T. (Soil Productivity Research Laboratory, Marondera (Zimbabwe))
Two tillage practices and seven weed management systems were evaluated for maize in farmer's fields at sites in Chihota, Nharira and Tjolotjo communal areas in the 1995/96 and 1996/97 seasons. The tillage treatments were conventional and reduced tillage. Conventional tillage used animal drawn mouldboard plough and involved winter ploughing + spring ploughing at Chihota, winter ploughing only at Nharira, and spring ploughing only at Tjolotjo. Reduced tillage involved opening the planting furrows using the mouldboard plough. Weed management systems involved combinations of hoe weeding, ox-cultivation, plough weeding and banded Atrazine at 0.9 kg a.i./ha. Atrazine efficacy on weeds was less satisfactory at one site due to low soil pH and low rainfall in the 1995/96 season. When soil pH was corrected through liming, and herbicide application was done under moist soil conditions, Atrazine efficacy was good at all sites in the 1996/97 season. Although the weed management systems that included, use of the herbicide were more efficient in suppressing weed populations than mechanical methods, maize grain yield was not significantly affected. Reduced tillage increased total weed population at Chihota in the 1996/97 season, Nharira in the 1996/97 season and Tjolotjo over the two seasons. Conventional tillage and reduced tillage increased the emergence of Richardia scabra and Eleusine indica, respectively. The Atrazine treatments had low labour requirements compared to mechanical methods. When ox-cultivation and hoe weeding were initiated at 2 and 6 weeks after crop emergence, labour decreased compared to the same operation being carried out at 4 and 6 weeks after crop emergence.
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