Guinea Savanna Agro-ecological Zone Research Articles

Quantitative analysis of soil degradation in response to land use change in the Guinea savanna zone of Ghana

Soil degradation (SD) poses a significant challenge to tropical agricultural production systems due to its role in depleting soil nutrients. Recently, SD has threatened population growth by causing hunger and poverty among smallholder farmers in the Guinea savanna agro-ecological zone of Ghana. However, SD cannot be directly measured. Instead, assessment and modelling efforts rely on biological and physico-chemical indicators. This study sought to: (i) select a minimum dataset (MDS) using a multivariate statistical technique; (ii) identify SD processes, and evaluate the extent of degradation; and (iii) suggest strategies to monitor SD in the study area. Soil samples were collected using the Land Degradation Surveillance Framework (LDSF), specifically designed for sub-plot level (1000 m2) sampling. This scheme aligns well with the typical farm structure of smallholder farmers (<10 acres). Soil samples, taken from a depth of 0–20 cm, were analyzed to assess their physico-chemical properties. Principal component analysis (PCA) identified seven key SD processes: soil texture, pH, organic carbon (OC), total nitrogen (TN), available phosphorus (Av. P), base saturation (BS) and Effective Cation Exchange Capacity (ECEC). These identified processes lead to the loss of OC, deterioration of soil texture, reduction in soil nutrients, and increased soil acidity. There was a strong positive correlation (r = 0.70, p<0.05) between soil physical and chemical properties. PC1 explained 26.86% of the total variance, followed by PC2 at 15.31%, PC3 at 12.46%, and PC4 at 9.98%. Also, PC5, PC6, and PC7 accounted for 8.49%, 7.25% and 1.42% of the variance, respectively. The land-use systems we identified significantly affected the concentration of soil nutrients (p<0.001). In our computed Composite Soil Degradation Index (CSDI), CEC emerged as the most significant SD indicator with a weight of 0.328, followed by Si:CL ratio at 0.187. The results indicate that soil management activities should focus on increasing organic matter. Soil nutrient depletion primarily occurs through several processes. Land clearing and burning of organic materials during land preparation are primary causes. Furthermore, a total crop removal during harvest, inadequate manure application, and subsequent leaching and erosion aggravates SD, leading to nutrient-depleted soils. We conclude that the loss of nutrients, specifically CEC, OC, Ex. K and Av. P is the primary contributor to chemical SD. Therefore, implementing integrated soil fertility management (ISFM) strategies, such as applying organic (e.g., animal-based manures, green manure, crop residues, compost) and inorganic fertilizers (e.g., NPK + micronutrients) is crucial for increasing soil nutrient availability, enhancing SOM content, and promoting carbon sequestration in these farming systems. This study establishes a baseline for comparing and evaluating the effectiveness of land management interventions at the landscape level in northern Ghana. Consequently, soil nutrient management should be tailored to site-specific conditions, focusing on increasing the efficiency of N, P, K and micronutrient uptake by plants. Adopting such site-specific management strategies could significantly contribute to the sustainable intensification of agricultural production systems in the Guinea Savanna agro-ecological zone of Ghana.

Effect of Lambda-cyhalothrin + Carbofuran Application and Habitat Modification on Population Dynamics Of 0rseolia oryzivora (Diptera: Cecidomyiidae) in Relation to its Parasitoids On Rice

ABSTRACT This experiment was carried out between 2018 and 2019 at the experimental site of National Cereals Research Institute’s identified hot spot (Edozhigi) for Africa rice gall midge (0rseolia oryzivora) infestation in Nigeria. Edozhigi in Niger State is within the southern Guinea savanna agro-ecological zone at latitude 09°45' N, longitude 06°07' E, to test integrated inluence of habitat manipulation, lambda-cyhalothrin and carbofuran on population dynamics of 0. oryzivora in relation to its parasitoids on rice. The treatments were arranged in split-plot and laid out in a RCBD with three replicates. Data were collected on number of tiller / stand, plant height, days to 50 percent flowering, percent incidence, percent severity, percentage parasitism of 0. oryzivora, panicle per meter square, grains per panicle and yield of rice. Data collected were subjected to Analysis of Variance and significant means were separated using Student Newman Keuls Test, (SNK) at 5 % probability. The result showed that Rice plots treated with P. scrubiculatum + 0.38L/ha lambda-cyhalotrin +3.75kg/ha carbofuran had lower incidence (2.36) and severity (1.54) of 0. oryzivora compared with incidence (7.99) and severity (7.40) respectively found in untreated plots (control). It also had significantly higher yield (3263.95kg/ha) compared with the yield (2688.28kg/ha) in control plots. In conclusion, having P. scrobiculatum at boarder of net plots enhanced number of parasitoids and reduced attack of rice by 0. oryzivora. Integration of habitat modification with insecticide application offers better protection of rice against O. oryzivora. Key words: Habitat P. scrobiculatum, Infestation, Modification, Galls.

Assessment of Weathering Intensity and Pedogenesis of Lithosequence Located in Two Agroecological Zones of Nigeria

Elemental oxides can help to identify processes of soil formation and the degree of soil development. This study assessed soil development and weathering intensity in soils developed on schist and older granite in upland tropical rain forest and southern guinea savanna agro ecological zones of Nigeria. Soil profile samples were collected in each of the study locations. In the laboratory, total elemental oxides was determined using the energy dispersing X-ray Fluorescence (EDXRF) XRF SPEC (Minipal 4). The relative intensity of weathering of total elemental oxides was determined by choosing titanium as the suitable indexing element and the relative gain or loss of element was estimated using relative retained element (Ro) equation. Result obtained, revealed that SiO2 was the most abundant in the soils. Distribution of Al2O3 and CaO showed the direction of the pedogenic age. Older granite soil had higher values of Al2O3 and lower values of CaO. There was negative relationship of SiO2 with Al2O3 and Fe2O3. The trace elemental oxides were less than 1% and zirconium oxide was the most retained oxide in the soils. Soil which developed on schist retained more of the trace elements than soil on older granite. There was evidence of alitization, ferritization and desillication in the soils. Parent materials contributed to loss and gain of trace elemental oxides. Older granite soil was more weathered and pedologically older than schist derived soils.

Identifying drivers for variability in maize (Zea mays L.) yield in Ghana: A meta-regression approach

CONTEXTMaize is the main cereal crop in Ghana, but its production is adversely affected by various biotic and abiotic factors. OBJECTIVEThis study aimed to highlight the factors related to maize yield variability. To this end, yields from 978 data points within 3 agro-ecological zones (AEZs) were used in crop-based and statistical modelling. METHODSThe QUantitative Evaluation of the Fertility of Tropical Soils (QUEFTS) model, the Linear Mixed Effects Model (LMM), and the Random Forest (RF) model were used to evaluate multiple effect sizes. RESULTS AND CONCLUSIONSAnalyzing an entire set of yield data points with QUEFTS, and LMM explained 19%, and 26% of yield variability, respectively. Considering all data points in the RF model, nitrogen fertilizer (NF) rate, temperature, root zone depth, rainfall, and variety accounted for 27%, 15%, 13%, 10%, and 9% of yield variation, respectively. In Guinea Savanna (GS), Transition Zone (TZ), and Deciduous Forest (DF), QUEFTS explained 30%, 20%, and 4% of yield variability, respectively. LMM, however, explained 47%, 51%, and 79% of yield variability in those AEZs. LMM showed that the phosphorus fertilizer (PF) rate was very important and exceeded the importance of the NF rate in GS. LMM showed also that yield variability was significantly related to maize variety at the AEZ scale. In DF, soil chemistry (marginal R2 = R2m = 0.48) and environmental variables (R2m = 0.43) contributed more to explaining yield variability, whereas in GS and TZ, fertilizer rates (R2m = 0.35 in GS and 0.26 in TZ) and variety (R2m = 0.04 in GS and 0.20 in TZ) played a much larger role. In GS, TZ, and DF, the RF model explained 74%, 79%, and 84% of the variance in yield, respectively. These findings suggest low impact of fertilization on yield on the inherently fertile soils in the DF, while fertilization drives yield increase in the less fertile TZ and GS AEZs. We may conclude that QUEFTS was unable to capture yield variability and, according to RF and LMM analysis, the NF rate was the most important factor in explaining yield variability in the data. It can also be concluded that the factors responsible for yield variability are AEZ dependent. SIGNIFICANCEWe discuss the implications of these findings to uncover factors driving maize yield variability. It also provides information to guide and prioritize actions to be taken based on the importance of these factors in contributing to yield variability.

Soil properties affecting soil organic carbon stock of different land use types in two agro-ecological zones of Nigeria

Soil organic carbon (SOC) stock is the carbon proportion that is of biological origin stored with respect to soil depth. It is more prone to loss than soil inorganic carbon. High sequestration of SOC in soil is germane to the improvement of soil quality and mitigating impact of climate change. Thus, this study was carried out to evaluate soil properties affecting SOC stock in the two agro-ecological zones, namely Upland Rainforest (Ado-Ekiti) and southern Guinea Savanna (Kabba) agro-ecological zones of Nigeria, with respect to three selected land use types; arable, oil palm and wetland. Random collection of soil samples was carried out at four varying depths (0-15, 15-30, 30-45, and 45-60 cm) for evaluation of soil properties. The SOC stock regression models for the two agro-ecological zones showed that land use, SOC, pH, SOM (soil organic matter), Ex-K, Ex-Ca, Ex-Mg (exchangeable potassium, calcium, magnesium, respectively), BD (bulk density), and gravel content would predict variation in SOC stock in the two agro-ecological zones with coefficient of determination (R2) values of 0.952 and 0.996 for Kabba and Ado-Ekiti respectively. Principal component analysis identified that in the soil of the southern Guinea Savanna agro-ecological zone, SOC, CEC, EA, Ex-Na, land use, clay content, and soil depth with Eigenvalues &gt; 1 explained 80.58% of sample variance while in the soil of the Upland Rainforest agro-ecological zone, Ex-Ca, SOC, Ex-Na, EA, sand and silt contents with Eigenvalues &gt; 1 explained 78.81% of sample variance as potential determinants of SOC stock.

Biochar for Wastewater Treatment and Soil Improvement in Irrigated Urban Agriculture: Single and Combined Effects on Crop Yields and Soil Fertility

This work evaluated the agronomic and soil fertility effects of using municipal wastewater or anaerobically treated wastewater for irrigation and applying biochar to a soil from the Guinea savanna agroecological zone of Ghana. For this purpose, untreated municipal wastewater (WW), the effluent of an anaerobic wastewater filtration system (TWW), and clean water (CW) were used as irrigation water in a pot trial. Additionally, rice-husk biochar in the form of raw biochar (RB), water-washed biochar (WB), and biochar used as wastewater filter material (FB) were added to the soil, testing the influence on soil fertility and crop yield. Lettuce and carrot were selected for the pot study, grown on soil mixed with the biochar types at 20 t ha−1 and irrigated with either WW, TWW, or CW. Our results indicated higher crop growth morphology and yields (up to 90% increase) by WW and TWW than CW. The average yield of carrot (34.1 g pot−1) and lettuce (29.3 g pot−1) with TWW irrigation were the highest, followed by 31.2 and 27 g pot−1 with WW, then the lowest yields of 21.7 and 19.5 g pot−1 of carrot and lettuce irrigated with CW respectively. Compared to WW, TWW was more beneficial to plant development, causing an up to 10% increase in crop yields. Soils with FB and WB produced similar agronomic effects and plant nutrient concentrations but were lower than pots amended with RB. Nevertheless, combining RB with TWW showed increasing effects on pH, CEC, and P availability in the highly weathered acidic soil. The results suggest a beneficial effect of biochar-filtered wastewater on soil fertility and crop growth, offering the potential to enhance resource use efficiency in irrigated urban agroecosystems.

Antibiotic Resistance of Bacterial Isolates from Smallholder Poultry Droppings in the Guinea Savanna Zone of Nigeria.

There is a growing risk of antibiotic resistance (AR) in smallholder poultry (SP). This study, therefore, aimed to investigate AR pattern of bacterial isolates from SP in the Guinea Savanna agro-ecological zone of Nigeria. A total of 120 fresh poultry droppings were aseptically collected, randomly, from two tropically adapted (FUNAAB Alpha and Noiler) and local chickens. The chickens were raised either using ethnoveterinary medicines (n = 60) or antibiotics (n = 60). Bacterial isolates were characterized and analyzed using standard protocols, and appropriate statistical tools. Compared to Pseudomonas spp. (2.5%) and Klebsiella spp. (5.8%), Salmonella spp. (57.5%) and Escherichia coli (34.2%) were the most prevalent (χ2 = 96.67; p < 0.001). Prevalence of bacterial species was significantly (p = 0.024; Odds Ratio = 2.552) influenced by antibiotics usage. All four species were multi-drug resistant. In total, 30% of the isolates had a multiple AR index ≥ 0.2. Bacterial isolates from FUNAAB Alpha (58.0%) and Noiler (44.0%) were highly resistant to quinolones, while isolates from the local chickens (22.6%) were most resistant to aminoglycosides. Bacterial species isolated from FUNAAB Alpha and local chickens exhibited the lowest and highest percentage of AR, respectively. Clustering of isolates with similar antibiogram revealed inter-species dependence with possibility for inter-species gene transfer. These findings provide a background to investigate the metagenomics of local and improved chickens for AR.

EFFECT OF TRANSPLANTING DATES ON GROWTH AND YIELD COMPONENTS OF PEPPER (Capsicum Spp) IN BADEGGI, NIGERIA

Field experiment were conducted to determine the effects of transplanting date on growth and yield of pepper (Capsicum Spp) varieties at the irrigated Research farm of the National Cereal Research InstituteBadeggi, Niger State, Nigeria in 2018 and 2019 rainy seasons were assessed. The experiment was a 5 x 4 factorial laid out in a randomized complete block design with three replication and consisted of five pepper varieties (Tabasco, Bell pepper, Rocoto, Hottest pepper and South Africa pepper) and four transplanting dates (3rd June, 3rd July, 3rd August, and 3rd September). Result indicated significant differences (P&lt;0.05) among the pepper varieties and transplanting dates. Rocoto variety was the tallest variety in both years while Bell pepper was the shortest. Bell pepper had the largest leaf area (49.88, 41.90 and 41.19cm2 in 2018 and 46.78, 46.34 and 40.99cm2 in 2019 at 6, 9, 12 weeks after transplanting WAT respectively). Fresh and dry fruit yields from Rocoto variety superseded other variety by 21-82% and 22-85% in 2018 and 27-83% and 35-87% in 2019. Pepper transplanted in July and significantly (P&lt;0.05) higher number of leaves per plant, larger leaf area, number of branches per plant and taller plants than other transplanting dates. Also, transplanting dates had significant effects (P&lt;0.05) on pepper phonological and yield components. 3rd September transplanting attained 50% of flowering, fruiting and ripening earlier than other dates in both years. July transplanting date had the highest fresh (13.40 and 13.87t/ha-1) and dry (9.88 and 9.15 tha-1) fruit yields in both years. Fresh and dry fruit yields from plants transplanted in 3rd July susperseded other dates in both years. Findings from this experiment show that transplanting Rocoto variety in July would guarantee high productivity of pepper in Badeggi, Southern Guinea Savanna agro-ecological zone of Nigeria.

Assessing the Spatial Variability of Soil Properties to Delineate Nutrient Management Zones in Smallholder Maize-Based System of Nigeria

Spatially explicit information on soil variability is relevant for agronomic decisions; however, such information is limited in the northern Guinea savanna (NGS) agroecological zone of Nigeria. This study was conducted to delineate soil nutrient management zones (MZs), based on spatial variability of soils in the smallholder maize-based farming system within the NGS. Two hundred and eighty-nine soil samples were analyzed for some physical and chemical properties. Principal component analysis (PCA) was used to aggregate the soil properties into four principal components, which accounted for about 60% of the variation in the data, and spatial variability was assessed with a semivariogram. The ordinary kriging technique was used to predict soil properties at unsampled locations, while weighted overlay analysis was conducted to delineate nutrient management zones. Results showed that total nitrogen (0.06%), available phosphorus (5.6 mg kg−1), organic carbon (0.66%), and effective cation exchange capacity (5.6 cmol(+) kg−1) are below optimal requirement for maize production. Four MZs were identifiable in the region with the highest fertility (MZ3 and MZ4) associated with the northern area but covering a relatively small part (9.1%). The differences observed in soil properties among the MZs suggest that each zone requires different agronomic management, especially in relation to fertilizer application.

Evaluation and application of the CROPGRO-soybean model for determining optimum sowing windows of soybean in the Nigeria savannas

Soybean production is limited by poor soil fertility and unstable rainfall due to climate variability in the Nigeria savannas. There is a decline in the amount and duration of rainfall as one moves from the south to north of the savanna zones. The use of adapted soybean varieties and optimum sowing windows are avenues to increase productivity in the face of climate variability. Crop simulation models can be used as tools for the evaluation of alternative management options for a particular location, including fertilizer application rates, plant density, sowing dates and land use. In this study, we evaluated the performance of the Cropping System Model (CSM)-CROPGRO-Soybean to determine optimum sowing windows for three contrasting soybean varieties (TGX1835-10E, TGX1904-6F and TGX1951-3F) cultivated in the Nigeria savannas. The model was calibrated using data from ten field experiments conducted under optimal conditions at two sites (BUK and Dambatta) in Kano in the Sudan savanna (SS) agro-ecology over four growing seasons. Data for model evaluation were obtained from independent experiment for phosphorus (P) response trials conducted under rainfed conditions in two locations (Zaria and Doguwa) in the northern Guinea savanna (NGS) zone. The model calibration and evaluation results indicated good agreement between the simulated and observed values for the measured parameters. This suggests that the CROPGRO-Soybean model was able to accurately predict the performance of soybean in the Nigeria savannas. Results from long-term seasonal analysis showed significant differences among the agro-ecologies, sowing windows and the soybean varieties for grain yield. Higher yields are simulated among the soybean varieties in Zaria in the NGS than in Kano the SS and Jagiri in the southern Guinea savanna (SGS) agro-ecological zones. Sowing from June 1 to July 5 produced optimal yield of TGX1951-3F and TGX1835-10E beyond which yield declined in Kano. In Zaria and Jagiri the simulated results show that, sowing from June 1 to July 12 are appropriate for all the varieties. The variety TGX1951-3F performed better than TGX1904-6F and TGX1835-10E in all the agro-ecologies. The TGX1951-3F is, therefore, recommended for optimum grain yield in the savannas of northern Nigeria. However, the late maturing variety TGX1904-6F is not recommended for the SS due to the short growing season in this zone.

Influence of farm yard manure and N-levels on the growth, yield characters and yield of sesame (Sesamum indicum L.)

Field experiment was conducted at the Kogi State University Research and Demonstration Farm Anyigba, (Lat 7&deg; 291 and Long 70 111E). Anyigba lies in the Guinea Savanna Agro-ecological Zone. This experiment was conducted during the raining season of 2021 to evaluate the effect of Farm Yard Manure and Nitrogen levels on the growth, yield characters and seed yield of sesame (Sesamum indicum L.). Treatments consisted of three levels of Farm Yard Manure (0 t ha-1, 5 t ha-1, 10 tonsha-1and 15 t ha-1) respectively and Nitrogen fertilizer rates (0 tons Nha-1, 0.02 t N ha-1, 0.04 t N ha-1and 0.06 t N ha-1) respectively. Factorial combination of treatments gave a total number of 16 treatments which was laid in a Randomized Complete Block Design (RCBD) with three replicates. 48 plots were obtained in total. Results showed that application of Farm Yard Manure did not influence (p&ge;0.05) all parameters studied in the experiment except dry weight/plant, plant height and seed yield/ha. Nitrogen application significantly influenced (p&le;0.05) plant height and seed yield only. There was no significant interaction observed between Farm Yard Manure and Nitrogen levels in all parameters studied.

Effect of nitrogen and weeding regimes on yield and yield components of maize (Zea mays L.) in the derived guinea savanna Agro-ecological zone of Nigeria

Effect of nitrogen and weeding regimes on yield and yield components of maize (Zea mays L.) in the derived guinea savanna Agro-ecological zone of Nigeria

Effect of nitrogen and weeding regimes on yield and yield components of maize (Zea mays L.) in the derived guinea savanna Agro-ecological zone of Nigeria

In the 2017 and 2018 wet seasons, field trials were conducted at the Teaching and Research Farm of the Faculty of Agriculture, Kogi State University, Anyigba to determine the effect of nitrogen and weeding regime (period of weed interference) on the yield and yield components of maize. The experimental design used was a split-plot in a randomized complete block design replicated three times. The main plot was assigned to four different levels of nitrogen 0, 40, 80 and 120 kg N/ha while the sub-plot was assigned to different frequencies or regimes of weed control. The results obtained from the study revealed that the application of 120 kg N/ha produced the highest cob weight, 100-seed weight and grain yield per hectare in both years. The study also showed that all the rates of nitrogen application resulted into increased grain yield in comparison to where there was no nitrogen application. Maize plant kept weed-free for 9 and 12 weeks after planting (WAP) and those weed infested for 3 WAP produced cob dry weight, 100-seed weight and grain yield (kg/ha) comparable to those kept weed-free throughout. From the two-year study conducted, it was found out that keeping the field weed-free for only 3WAP did not provide a satisfactory weed control situation for optimum crop performance owing to imminent re-infestation. Conversely, plants weed infested for 3WAP could ward off whatever damage that might have been inflicted initially through subsequent re-growth which could translate into impressive yield as observed in this study.

Synergistic effects of liming and balanced fertilization on maize productivity in acid soils of the Guinea Savanna agroecological zone of Northern Ghana

Soil acidity and very low nutrient status are major production-limiting factors for maize production in most parts of the savanna agroecological zones (AEZ) of northern Ghana. Therefore, effective nutrient management is critical to increase productivity. During a two-year study across six locations in the Guinea Savanna AEZ in northern Ghana, we evaluated the interactive effects of liming and balanced fertilization on maize productivity in acid soils. Six fertilization strategies – (i) balanced (containing all essential limiting nutrients), (ii) balanced with sulfur omitted (minus-S), (iii) balanced with zinc omitted (minus-Zn), (iv) balanced with boron omitted (minus-B), (v) NPK-only, and (vi) control (no nutrients supplied) – were evaluated, each with or without liming. Applying only lime without fertilizer application increased maize yield from an average of ∼0.55 t ha − 1 to ∼0.92 t ha − 1. For NPK-only fertilization, liming led to an increase in yield from an average of ∼1.68 t ha − 1 to ∼2.84 t ha − 1. For balanced fertilization, lime application resulted in an additional maize grain yield of ∼53% compared to treatment without lime application. With liming, the minus-Zn treatment resulted in a significant yield decrease of an average of ∼30% compared to balanced fertilization, suggesting that combined application of lime and Zn should be advocated to better sustain crop productivity in this region. We conclude that, to improve maize productivity in acid soils in order to ensure increased profitability and improved household income, fertilizer recommendations that promote balanced fertilization must include liming as part of the nutrient application package.

English

The adoption of new and high yielding pearl millet (Pennisetum glaucum (L.) R. Br.) varieties can be boosted if they correspond to farmers&rsquo; preferences and answer the constraints prevailing in the production environments. Therefore, the focus of this study was to assess production constraints, farmers&rsquo; preferences and choices of varieties among pearl millet cultivating farmers using participatory rural appraisal (PRA) in the guinea savanna agro-ecological zone of Ghana where the crop is grown. Data collection was through mixed methods of focus group discussion (FGD) and individual interviews with 295 (45 for FGD and 250 for individual interviews) farmers covering 45 communities. Results indicated that the major constraints of production included low yields, bird damage, poor soils, erratic rainfall, downy mildew disease, head insects, and early maturity. Majority of pearl millet farmers depend on own seed source due to lack of access to and low knowledge of improved seeds. Breeding for high grain yield, earliness, resistance to downy mildew disease and bird attack varieties were the leading traits of preference that research should focus on. It is therefore anticipated that breeding program would integrate the product profiling proposed in this work for enhance adoption of new pearl millet varieties in Ghana. &nbsp; Key words: Participatory rural appraisal, constraint, pearl millet Guinea savanna, Ghana.

Pigeon pea (Cajanus cajan) fodder cutting management in the Guinea Savanna Agro-Ecological Zone of Ghana

This study evaluated the effect of cutting regime on biomass yield and nutrient composition of pigeon pea (Cajanus cajan (L) Millsp.) fodder in the Guinea Savanna Agro-Ecological Zone of Ghana. Three cutting regimes (12, 16 and 20 Week After Planting [WAP]) in RCBD were imposed on Cajanus cajan at both initial establishment and regrowth. At each harvest, biomass yield was estimated after which samples of the fodder were separated into leaf and stem botanical fractions for chemical composition and in vitro digestibility. Cutting regime significantly affected plant height, number of branches and stem diameter in both the initial establishment and regrowth. Biomass yield was significantly affected by cutting regime in the initial establishment but not the regrowth. The biomass yield was highest in the harvest at 20WAP (6515kgDM/ha) while 12WAP (3175 kg/ha) recorded the lowest biomass yield in the initial establishment. All chemical composition parameters were significantly affected by cutting regime and botanical fractions except hemicellulose in the initial establishment. Cutting regime also significantly affected DM, CP and ash concentrations in the regrowth with botanical fraction significantly (P < 0.05) influencing CP, NDF, ADF and ash. The highest CP was obtained in the leaf fraction harvested at 12 WAP and 20 WAP in the initial establishment and regrowth respectively. Cutting regime, botanical fraction and their interaction were significant in gas produced at 24 h, SCFA and ME in both the initial establishment and regrowth stages. In conclusion, harvest at 20WAP produced the highest biomass yield but lower CP in the initial establishment whiles in the regrowth, harvest at 20WAP produced higher biomass yield, CP and ME.

A nationwide survey of the tabanid fauna of Cameroon

BackgroundTabanids are a neglected group of haematophagous dipterans despite containing 4434 species, regrouped in > 144 genera. They are mechanical vectors of important pathogens, including viruses, bacteria and protozoa of humans and domesticated and wild animals. As it is > 50 years since the publication of a preliminary nationwide record of the tabanids of Cameroon identified 84 species, updated information is needed. The aim of this study was to provide current data on the species composition, abundance and distribution of tabanids in the five main agro-ecological zones (AEZs) of Cameroon.MethodsFrom 2015 to 2017, a systematic entomological study using Nzi, Vavoua, Biconical and Sevi traps (n = 106) was conducted in 604 trapping points over 11,448 trap-days in the five main AEZs of Cameroon.ResultsA total of 25,280 tabanids belonging to 25 species were collected, including eight species not previously documented in Cameroon, namely Tabanus latipes (1 female), Tabanus ricardae (1 female), Tabanus fasciatus (32 females and 6 males), Haematopota pluvialis (18 females), Haematopota decora (19 females and 3 males), Haematopota nigripennis (18 females), Chrysops distinctipennis (47 females and 5 males) and Ancala fasciata (34 females and 7 males). The distribution maps of the newly identified tabanids differed between AEZs, with most tabanids collected from the Guinean savanna. The highest apparent density of tabanids was recorded in the Sudan Savanna region, and the mean apparent densities of species with sites was statistically significantly different (Student t-test: 2.519, df = 24, P = 0.019). The highest species diversity was found in the rainforest.ConclusionsThis study increased the list of tabanids recorded in Cameroon from 84 species in the preliminary record to 92 species, with most of the newly identified species occurring in the Guinea Savanna AEZ. The high diversity and abundance of tabanids in the livestock/wildlife interface areas of the rain forests and Sudan Savanna AEZs, respectively, suggest risk of mechanical transmission of pathogens. Investigations of the microbiota of tabanids in the different AEZs to define their role as disease vectors are proposed.Graphical abstract

Effect of Fertilizer Application on Soil Properties and Yield of Sesame (sesamum indicum l.) Varieties in Southern Guinea and Sudan Savanna Agro-Ecological Zones of Nigeria

Field experiments were carried out in 2018 and 2019 cropping seasons to determine the effect of fertilizer application on soil properties and yield of sesame varieties in Southern Guinea and Sudan Savanna Agro-ecological Zones of Nigeria. Treatments consisted of three varieties of sesame (Jigida, NCRIBEN-01M and NCRIBEN-032) and four levels of NPK 15:15:15 fertilizer (0, 50,100 and 150 kg ha-1). Treatments were laid out in a randomized complete block design (RCBD) and replicated thrice. Prior to planting, surface (0-15 cm) soil samples were collected from eight points and bulked; post-harvest composite soil samples were also collected on the basis of treatments. All soil samples were analyzed using standard analytical procedures. Data on yield parameters collected include number of capsules per plant, number of seeds per capsule, length of capsule (cm), 1000 capsule weight (g), 1000 seeds weight (g) and seed yield (t ha-1). The crop data generated from the study were subjected to Analysis of Variance (ANOVA) using Genstat Release 10.3 DE after which significant means were separated using Least Significant Difference (LSD) at 5 % level of probability. Results indicated that the soils of both locations were inherently poor in essential plant nutrients. The improved varieties (NCRIBEN-01M and NCRIBEN-032) performed better than the local variety in terms of yields in both cropping seasons. Sesame yield increased with increase in fertilizer application rates up to 150 kg ha-1. The effect of varieties on soil properties did not differ significantly however, the improved varieties left lower essential nutrients in soil when compared with the local variety. Fertilizer application at 150 kg ha-1 favoured the retention of organic matter as well as other essential nutrient elements in soil. Location effect showed that the Potiskum soil had more nutrients than that of Makurdi. For sustainable sesame production and maintenance of soil fertility in both locations, application of 150 kg ha-1 of NPK 15:15:15 to sesame fields is recommended.

Defoliation Effects on Growth, Development and Yield of Okra (Abelmoschus esculentus) Under an Irrigation Regime

An experiment was conducted at Research and Demonstration Farm of Agricultural Science Department, Federal College of Education, Pankshin located in the Northern Guinea Savanna Agro-ecological Zone of Nigeria to investigate defoliation effects on morphological characters and yield attributes of okra (Abelmoschus esculentus) carried out during 2015 and 2016 dry season. The experiment comprised five levels of defoliation viz: 0% (control), 30%, 60%, 90%, and 100%. The experiment was laid out in identical Randomized Complete Block Design (RCBD) with six replications. Results revealed that defoliation had significant effect on the studied crop characters and yield. Most of the parameters like plant height, stem girth; number of leaves, leaf area, and yield parameters decreases which are a function of increasing defoliation levels intensity. Defoliation at 0% and 30% were tolerable for okra plant growth and development, while at 90% and 100% was detrimental to plant growth and yield. Hence, defoliation at 30% is recommended to meet farmers’ pod and leaf requirement.

Characterization of Groundnut (Arachis hypogaea L.) Test Locations Using Representative Testing Environments With Farmer-Preferred Traits.

In this study, the differential rankings of 36 groundnut genotypes under varying environmental conditions were studied at various levels of phenotype. Locations that are generally accepted by the crop- and soil-based research community to represent the entire Guinea and Sudan Savanna agro-ecological zones in Ghana were characterized, this time using a crop. The characterization was done based on four farmer-preferred traits (early and late leaf spot disease ratings, and haulm and pod yields) using three models (i.e., AMMI, GGE, and Finlay–Wilkinson regression). These models were used to capture specific levels of phenotype, namely, genotype-by-environment interaction (GE), genotype main effect plus GE (G+GE), and environment and genotype main effects plus GE (E+G+GE), respectively. The effect of three major environmental covariables was also determined using factorial regression. Location main effect was found to be highly significant (p < 0.001), confirming its importance in cultivar placement. However, unlike genotypes where the best is usually adjudged through statistical ranking, locations are judged against a benchmark, particularly when phenotyping for disease severity. It was also found that the locations represent one complex mega-environment, justifying the need to test new technologies, including genotypes in all of them before they can be approved for adoption nationally. Again, depending on the phenotypic level considered, genotypic rankings may change, causing environmental groupings to change. For instance, all locations clustered to form one group in 2017 for early and late leaf spot diseases and pod yield when GE was considered, but the groupings changed when G+GE was considered for the same traits in the same year. As a result, assessing genotypic performance at the various levels to arrive at a consensus decision is suggested. Genotypes ICGV-IS 141120 and ICGV-IS 13937 were found to be the best performing.