Effects of Weed Control Methods on Weeds and Productivity of Range Grasses in Semi-Arid Kenya

Abstract

<p><strong>Background:</strong> Weeds are a common occurrence and challenge in different crops eventually influencing crop development and yields. Weed control and management are key in enhancing the productivity of cultivated pastures. In semi-arid Kenyan drylands, the main methods employed for weed management are manual cultural practices and recently, the application of commercial herbicides. <strong>Objective:</strong> To evaluate the effects of two weed control methods on weed characteristics and productivity of four rangeland grasses commonly used in reseeding and pasture improvement in a semi-arid environment. <strong>Methodology:</strong> In a randomized complete block design in a field experiment, we determined the effects of two weed control methods (manual and herbicide use) in four rangeland cultivated grasses. These are Buffel grass (<em>Cenchrus ciliaris</em>), Horsetail grass (<em>Chloris roxburghiana</em>), Masaai love grass (<em>Eragrostis superba</em>) and Bush rye (<em>Enteropogon macrostachyus</em>). Weed characteristics (species, density, diversity and weed biomass,) were evaluated, as well as the effectiveness of the weed control methods in the grasses. <strong>Results:</strong> Broad-leaved weeds and annual grasses were prevalent in the established grasses. Generally, higher grass dry matter yields were obtained in <em>Cenchrus ciliaris</em> grasses (2.05 t h<sup>-1</sup>) while lowest yields were in <em>Chloris roxburghiana</em> (1.2 ton ha<sup>-1</sup>). Weed management interventions increased biomass production in the grasses by a mean of 19% in general. The mean yield increase varied with species and weed control method ranging from 8-39%. Weed control methods significantly reduced weed density, diversity and eventually weed biomass within the grass species. The efficacy of manual weed control and chemical application was in the range of 27-74%. <strong>Implications: </strong>Weed control is, therefore, necessary if one is to realize higher productivity and returns in cultivated pasture and fodder systems in semi-arid environments. <strong>Conclusion:</strong> Both chemical and manual control methods of weed control are important and effective approaches to manage weeds in pasture systems in semi-arid environments.<strong> </strong></p>

Optimal Weeding Interval for Grevillea robusta Nursery Seedlings

“…Weeds creates a large mass of aboveground and underground organs which compete with the other plants for the available resources [5] such as light, water, nutrients [1,2,3,6]. Weeds can be propagated sexually from seeds or vegetative.…”

“…Weeds can be propagated sexually from seeds or vegetative. The spread is usually via agents such as animals, wind, water and man [4,5]. Weed damage to plants is considered as more adverse than that of diseases and pests combined.…”

“…Allelopathy can both inhibit [9] and stimulate seed germination, overall growth, development, reproduction, biosynthesis, division of cells as well as disease/weed management [10]. Additionally, weeds negatively affects the establishment and reseeding success in plants through competition [5]. They also result into inefficiency in land use, increased cost of production, problems in water management and inefficient labor utilization.…”

“…Even though there are diverse ways to control weeds, weeds are still a challenge [5]. Weed control in tree nurseries is one of the crucial factors in raising healthy seedlings [1].…”

“…Weed control in tree nurseries is one of the crucial factors in raising healthy seedlings [1]. Control practices includes; mechanical, which entail, ploughing [11], disking, tilling, weeding [5,7], farrowing, mowing [4], mulching [6]. Mulches destroy weeds through hindering the sprouting of its seeds [1,5] and are more safe, cheap and sustainable, and are more effective when used with cover crops [12,13,14,15,16].…”