Assessment of weed infestation and economic returns of maize/cowpea intercrop under different tillage systems in northern Ghana
2003
Kombiok, J.M., Savanna Agricultural Research Institute, CSIR, P.D. Box 52, Tamale, Ghana | Safo, E.Y., Department of Crop Science, Faculty of Agriculture, KNUST, Kumasi, Ghana | Quansah, C., Department of Crop Science, Faculty of Agriculture, KNUST, Kumasi, Ghana | Ibana, S., Department of Agricultural Economics, University ofCalabar, Cross Rivers State, Nigeria)
The cost of crop production is mostly attributed to soil tillage and weed control. Against this background,.a field experiment was conducted at Nyankpala in the northern Ghanaian savanna ecology in 2000 and 2001 to assess the ~ffects of tillage and cropping systems (CRPSYT) on ,"eed infestation and economic returns of maize (Zea .nays L) intercropped with cowpea (Vigna unguiculata L Walp). The results showed that the tractor-ploughed conventional tillage system (Con) and bullock plough (BP) with tillage depths more than 12 cm significantly (P0.05) increased grain yields of both crops and also significantly reduced weed score, weed count, and the subsequent weed dry matter, probably through deep burying of weed seeds as compared to hand hoe (HH) and zero tillage (ZT) practices. Tillage systems did not influence weed flora, but cropping systems increased the grass composition in maize to about 70 per cent and significantly decreased the broad leaf weeds. The reverse situation was observed in the cowpea and the maize/cowpea intercrop. The predominant grass weed species found on the field were Eleusine iirdica and Digitaria spp., while the broad leaf weeds were Amaranthus spinosis and Tridax procumbens. The highest cost was incurred under ZT due to high cost of herbicides and labour for spraying while the least was in HH, but the highest net benefits and the highest benefit-cost ratio (BCR) were recorded under BP. The maize component yielded higher BCRs in the sole and the intercrops. However, poor rainfall distribution had negative impact on the yield of both crops, resulting in negative BCRs in the inter-row cropping systems in both years.
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