Tag Archives: Derived Savanna

Mapping Of Weeds in Cassava Fields Using Geographic Information Systems (GIS) 1n Derived Savanna of Nigeria (Published)

The investigation of weed spectrum in cassava fields was carried out in Derived savanna agro-ecology (Ido Local Government Area) of southern Nigeria in 2017. Thirteen (13) cassava farms were surveyed. Coordinate points, elevation of the investigation sites and mapping were conducted with Geographic information system (GIS). Weed flora composition of each location was studied by sampling randomly using ’M’ pattern of quadrat placement and average from the samples was recorded. Results showed that thirty-six (36) weed species cutting across twenty-one (21) families were identified. This showed the richness and dominance of weed flora identified in the agro-ecology. Tridax procumbens, Talinum fruticosum, Euphorbia heterophylla, Chromolaena odorata and Ageratum conyzoides were the most frequent weed species and evidently showed their broader environmental tolerance. Weediness in cassava fields ranged from 4.67/10 to 8.33/10 across locations. Cultural practices and location might have influenced the weediness and weed flora composition.

Keywords: Derived Savanna, Geographic information System (GIS), Weed Flora Composition, Weediness, cassava

Survey and Mapping of Speargrass (Imperata Cylindrica (L.) Reauschel) Invasiveness Using Gis Techniques in Two Agro-Ecologies of Nigeria (Published)

Speargrass invasiveness in Derived Savanna (DS) and southern Guinea Savanna – northern fringe (SGS) is influenced by the rainfall amount and cultural practices (weed management methods, tillage method and plant spacing). Studies were conducted between 2015 and 2016 in Eruwa (DS) and Kishi (SGS), to investigate the problem of weed incidence in farmers’ fields and the influence of weed control methods adopted on invasiveness with structured questionnaire; the invasiveness of predominant weed [speargrass – Imperata cylindrica (L.) Reauschel]. The geographical analysis were carried out in an ArcGIS environment. Results showed that speargrass was the predominant weed identified by 100% and 90% of farmers in DS and SGS respectively. Other weeds identified were broadleaf (54%), grass (38%) and sedge (8%) in both locations. Manual weeding (slashing and hoe-weeding) was the most common weed control method used among respondent farmers in the two agro-ecologies. 60% and 50% of the farmers adopted manual weeding in DS and SGS respectively. This was followed by chemical weed control (DS 30% and SGS 40%) and manual + chemical was practiced by 10% each of farmers in both agro-ecologies. Frequently used weed control methods followed the order of Manual weeding (MW) > Chemical weeding (CW) > Manual + chemical weeding (MW + CW). Average speargrass density in DS was 140 stands/sq.m (0 – 288 stands/sq.m), while the mean was 39 stands/sq.m (0 – 160 stands/sq.m) in SGS. Speargrass covered 288.07 sq.km (79.80% of surveyed area) with <50 stands/m2 in SGS, while 231.74 sq.km (57.60% of surveyed area) with density of 150 stands/sq.m in DS. Weed management methods and locations might have influenced speargrass invasiveness.

Keywords: : GIS, Chemical Weeding, Derived Savanna, Invasiveness, Manual Weeding, Southern Guinea Savanna, Speargrass Density