Understanding drivers of weed density and diversity is essential for the development of weed management strategies. Here, we compared temporal changes in weed density and diversity under no‐till (NT) and conventional (CONV) tillage systems in cotton–maize rotations on loam, clay loam and sandy loam soils immediately after transition to NT in Kadoma, Zimbabwe. The effect of tillage system on weed density varied through the growth season and was dependent upon soil type and species composition of the weed community. Although weed responses to tillage system varied amongst species, we identified general trend effects on weed density on specific soils. At 3 weeks after crop emergence (WACE), weed density on loam soils was 76% and 96% higher in NT than in CONV during the 2009/2010 and 2010/2011 seasons, respectively, and on clay loam soils it was 37% and 33% higher in NT than CONV, respectively. Weed densities in NT and CONV were similar across all soil types at 6 WACE during the 2009/2010 and 2010/2011 seasons and at 9 WACE in 2009/2010. Tillage system did not affect weed density during the growth season on sandy loam soils. Weed diversity (Shannon index) was at least 75% higher in NT than CONV on loam and clay loam soils at 3 WACE during both seasons. It is likely these increases in weed densities following conversion to NT will exacerbate already prevalent weed management problems in the smallholder sector. Earlier weeding is recommended to suppress weed emergence and reduce likely associated crop yield losses.

中文翻译：

---

津巴布韦小农户免耕模式过渡期间杂草群落对土壤类型的反应

了解杂草密度和多样性的驱动因素对于制定杂草管理策略至关重要。在这里，我们比较了在津巴布韦卡多玛过渡到NT以后，在免耕（NT）和常规（CONV）耕作制度下，棉壤-玉米轮作在壤土，黏土壤土和沙质壤土上的免耕法和杂草密度随时间的变化。耕作制度对杂草密度的影响随生长季节而变化，并取决于土壤类型和杂草群落的物种组成。尽管杂草对耕作系统的反应因物种而异，但我们确定了一般趋势对特定土壤上杂草密度的影响。在作物出苗（WACE）后的3周，新土在壤土上的杂草密度分别比2009/2010和2010/2011季节的CONV高76％和96％，在粘土壤土上，NT的含量分别比CONV高37％和33％。在所有土壤类型中，NT / CONV的杂草密度在2009/2010和2010/2011季节为6个WACE，而在2009/2010年为9 WACE。在砂壤土上，耕作制度在生长期不影响杂草密度。在两个季节中，在3个WACE的壤土和黏土壤土上，NT上的杂草多样性（Shannon指数）至少比CONV高75％。转换为新台币后，杂草密度的增加可能会加剧小农部门已经普遍存在的杂草管理问题。建议早期除草以抑制杂草的出现并减少可能的相关农作物减产。在所有土壤类型中，NT / CONV的杂草密度在2009/2010和2010/2011季节为6个WACE，而在2009/2010年为9 WACE。在砂壤土上，耕作制度在生长期不影响杂草密度。在两个季节中，在3个WACE的壤土和黏土壤土上，NT上的杂草多样性（Shannon指数）至少比CONV高75％。转换为新台币后，杂草密度的增加可能会加剧小农部门已经普遍存在的杂草管理问题。建议早期除草以抑制杂草的出现并减少可能的相关农作物减产。在所有土壤类型中，NT / CONV的杂草密度在2009/2010和2010/2011季节为6个WACE，而在2009/2010年为9 WACE。在砂壤土上，耕作制度在生长期不影响杂草密度。在两个季节中，在3个WACE的壤土和黏土壤土上，NT上的杂草多样性（Shannon指数）至少比CONV高75％。转换为新台币后，杂草密度的增加可能会加剧小农部门已经普遍存在的杂草管理问题。建议早期除草以抑制杂草的出现并减少可能的相关农作物减产。在两个季节中，在3个WACE的壤土和黏土壤土上，NT上的杂草多样性（Shannon指数）至少比CONV高75％。转换为新台币后，杂草密度的增加可能会加剧小农部门已经普遍存在的杂草管理问题。建议早期除草以抑制杂草的出现并减少可能的相关农作物减产。在两个季节中，在3个WACE的壤土和黏土壤土上，NT上的杂草多样性（Shannon指数）至少比CONV高75％。转换为新台币后，杂草密度的增加可能会加剧小农部门已经普遍存在的杂草管理问题。建议早期除草以抑制杂草的出现并减少可能的相关农作物减产。