An Evaluation of Conservation Agriculture Weed Control Techniques in Sugar Bean Production at Hatcliffe, Harare, Zimbabwe

Abstract

Weed control is considered a major obstacle for Conservation Agriculture (CA) farmers in the smallholder sector of Zimbabwe. In most cases, losses caused by weeds exceed the losses from any category of agricultural pests. The research aims to evaluate different techniques of controlling weeds under CA practises on labour, cost of producing a tone of sugar beans, yield and weed biomass and density. The study was conducted at Hatcliff Institute of Agriculture , Harare which is located 17042’ S ad 310 0n6’E and at altitude of about 1500m above sea level. A randomized complete block design was used with four blocks and five treatments. The treatments were replicated four times. The weed control treatments were; were conventional (C), complete herbicides (CH), spot herbicides application plus hand pulling (SHC), spot herbicides application plus, hand pulling (SHHP). The sugar bean variety Kware was used. The trial was set up in January 2020.The weed density and biomass had no significant differences at the first two weeks after crop emergence but they showed significant differences at fourth and sixth week after crop emergence. Results indicated that there were significant differences in weed biomass and density (p<0.001), labour required (p<0.001) and cost of producing a ton of sugar beans (p<0.001). There was no significant difference in yield (p=0.478) across all treatments. The yields and production cost were 2.6 t/ha at US$18.62/t, 1.9 t/ha at US$ 12.56/t, 2.5 t/ha at US$38.31/t, 2.3 t/ha at US$64.97 t/ha, 2.2t/ha at US$19.45/t for the respective treatments. Outcomes from this study are that there are significant differences in labour and cost required in weed management of a sugar bean crop between CA and CT practices. These results do suggest that CA weed control techniques are a good basis for promoting CA in small holder farmers. These results show that CA weed control techniques have high efficacy in controlling weeds as they are more economic and provides effective timely weed control. The results imply that widespread adoption of CA weed control strategies will reduce labour requirements, improve timeliness of weed control during crop management which will result in improved yields and reduced production cost. On-farm farmer managed trials are necessary.