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The study was conducted to assess the influence of different agro-ecological zones and cropping seasons on the incidence and severity of maize streak disease (MSD) in Ghana. Field surveys were conducted in two districts each of the coastal savannah, forest, and transitional agro-ecological zones of the Volta region to assess the incidence and severity of MSD in farmers’ fields, during the 2014 minor and 2015 major cropping seasons. The disease assessment was carried out in 12 fields from each district, and for each field on both maize plants growing under tree shade and in open parts of the field. The plants were scored for disease severity based on a 1-5 visual scale (1=no infection and 5=very severe infection). Percentage total N, available P, exchangeable K, organic matter levels and pH were determined from soil samples collected from each of the fields surveyed. Incidence and severity of MSD on maize plants growing under tree shade and in open parts of the fields were significantly higher (P

African universities have to play a central role in Africa’s development through the provision of quality training, knowledge and innovations. This is particularly crucial in ensuring a food secure Africa through a knowledge-based transformation of agriculture and related activities. Information on the state and challenges of higher agricultural education can inform actions aimed at positioning institutions to play the roles expected of them. The overall objective of this study was to assess the current status of the higher education sector in Ghana to identify current challenges and gaps and develop specific recommendations towards enhancing its performance and contribution to science, technology and innovation. Focusing on the five main public universities in Ghana, the study comprised a desk research and interviews with key officials of selected institutions. The findings suggest low quality of service to students due to large gaps in funding, teaching staff, and academic facilities.The demand for higher education in general far exceeds the supply. The total number of applicants to agricultural programmes increased sluggishly between 2004 and 2014, with female applicants hovering around 20%. Funding gaps, low technical or infrastructural capacity and declining number of applicants to science, technology, engineering and mathematics programmes are key issues that require urgent attention.

Nitrous oxide emissions are usually increased following incorporation of crop residues or inorganic N fertiliser into soil, but the effect of combining these inputs at different proportions on N dynamics and NO emissions has 2 yet to be adequately examined. The interactive effect of combining crop residues barley (Hordereum vulgare) and clover (Trifolium pretense) and inorganic N fertiliser (NH4NO3) on N2O emission and mineral N dynamics under controlled laboratory conditions is reported. Emissions of NO were significantly higher from soils amended with 2 the low C:N ratio clover residues compared to the high C:N ratio barley residue treatments and was further increased, following combined application of crop residues and inorganic N fertiliser. Furthermore, the magnitude of emission was influenced by the proportions at which the residue-N and the fertiliser-N were combined with the 75:25 fertiliser:clover treatment emitting the highest (P < 0.05) amount of 65 mgN2O-N m-2 30 d-1. Incorporation of sole clover residues resulted in net N mineralization and addition of sole barley residues led to a net N immobilization. However, combined application of either residue with inorganic N fertiliser resulted in netNmineralisation. The results from the study demonstrated that whilst there is the potential for N2O emission to be controlled through varying ratios of residue:fertiliser input, the magnitude and direction of interactions between these N sources vary between different species as a result of their different qualities. This relationship should be verified under field conditions.

Although cocoa productivity has recently been increasing in Ghana, it is still low compared with that of other countries such as Cote d’Ivoire and Malaysia. This situation has been attributed to the low adoption of cocoa production technologies. The study was aimed at analysing the yield gap as well as some cocoa yield factors. Cross-sectional socio-economic survey was conducted in six (6) cocoa growing districts: Nkawie, Goaso, Enchi, Oda, Twifo Praso/Assin Fosu and Hohoe. A structured questionnaire was employed in the collection of data from 300 respondents who were randomly chosen with multi-stage cluster sampling technique. The yield gaps and their proportion to yield potentials were estimated using data from the survey and on-station trials. The findings indicated an experimental yield gap of 1 553.4 kg ha-1, accounting for 82.1% of the experimental yield potential whereas farmer-based yield gap was 1 537.2 kg ha-1, also accounting for 82.0% of the farmer (survey) yield potential. The Ordinary Least Square (OLS) regression analysis indicated that frequency of spraying fungicides against black pod disease, spraying insecticides against capsids, weeding of cocoa farms, cocoa variety planted by farmer, area of cocoa farm and total cocoa production variables had a significant impact on cocoa yield. It is recommended that the Government should encourage cocoa farmers, through pragmatic measures, to adopt improved technologies for enhancing productivity instead of focusing on excessive land expansion which eventually leads to low productivity.

Monthly samples of ripened improved robusta coffee berries from compact and large growth forms from three locations, which are representative of the main ecological zones where coffee is grown in Ghana, were taken for 3 years. The pulp and parchment and beans were analysed for N, P and K contents. The amounts of N, P and K removed from the soil in the harvested coffee berries were estimated from the concentrations of the nutrients in the pulp and parchment and beans, and the yield of coffee at each location. The mean NPK contents of the berries were 2.18, 0.08, 2.56 and 2.07, 0.08, 2.52 per cent for compact and large growth forms, respectively. The N and P concentrations in the pulp and parchment were lower than in the bean, while the K content was higher in the pulp and parchment than in the bean across the locations. The N, P and K concentrations of the coffee berries were not significantly different among the growth forms. Coffee berries from suitable and moderately suitable sites removed significantly (P

The effect of cocoa pod husk-based compost on growth and nutrient uptake of cocoa seedlings was compared with conventional NPK 15-15-15 fertilizer at the nursery in a randomized complete block design experiment. Poly bags were filled with either top soil or compost alone, and also with mixtures of top soil, compost and inorganic fertilizer in various ratios to provide the following treatments: soil alone, compost alone, 1 : 1 soil/compost, soil + fertilizer, 1 : 1 soil/compost + fertilizer, 1 : 2 soil/compost, 1 : 2 soil/compost + fertilizer, 2 : 1 soil/compost, 2 : 1 soil/compost + fertilizer. The fertilizer was added at the rate of 6 g per poly bag. Plant height, girth, leaf area, dry matter yield, and root volume of cocoa seedlings were significantly (P

Cropping systems have influence on the conservation of soil organic matter. Soil samples were taken from a long term experiment that was designed to study the impact of shade and cocoa plant densities on cocoa yields. The impact of the treatments on soil organic carbon sequestration rates and the gains or losses of soil organic carbon under the treatments with reference to adjacent undisturbed bush were assessed. The experiment was sited at the Bunso substation of the Cocoa Research Institute of Ghana on Rhodi-lixic ferralsol with annual precipitation of about 1500 mm. The shade was provided by forest trees of 18 trees ha-1 and no shade, while the cocoa densities were 1111, 1428 and 1667 trees ha-1. Shade effects on organic carbon pools within the top soil (0-30 cm) under cocoa were not significant (p=0.05). Cocoa plant densities per unit area influenced the soil organic carbon pools. The soil organic carbon pools were significantly lower (p=0.05) in the closely planted farms than in the widely spaced farms. There were no soil organic carbon sequestration in the highest cocoa plant density of 1667 trees ha-1 but 250 and 190 kg soil organic carbon ha-1 yr-1 in the top soil (0-15 cm) were sequestered in the soils under cocoa with density of 1111 trees ha-1 for shaded and unshaded farms respectively. Irrespective of the shade conditions, the net gains of carbon in the soils were higher in farms with lower cocoa plant density. The results suggest that cocoa planted at low plant density under shade stores more carbon per unit area of soil than an equivalent area of cocoa planted at high density without shade. It is concluded that cocoa farming could be an effective means to mitigate carbon dioxide emissions in cocoa growing countries.Key words: Soil organic carbon, sequestration rates, cocoa plant density, shade.

Cocoa production is bedevilled with low inherent soil fertility, pests and diseases, which cause substantial reduction in the potential yield of the crop. Despite these problems, farmers are often reluctant to use pesticides, due to lack of knowledge on the effect of the chemicals on non targeted organisms. The experiment is, therefore, aimed at finding out if Roundup (herbicide) and Benlate (fungicide), with Glyphosate and Benomyl, as their respective active ingredients r ecommended for use on cocoa plantations in Ghana, have any effect on nitrogen mineralization by affecting decomposition of plant litter. It is also to find out if the combined effects of the two pesticides are additive or interactive. Tomato served as a test plant, treated with three levels of each pesticide. A factorial experiment arranged in a completely randomized design with combinations of five incubation periods and 10 treatments was established. The 10 treatments were soil alone and nine factorial combinations of the fungicide and the herbicide at three levels each. The application rates of Roundup were 0, 1.2 and 12 kg Glyphosate ha–1, and those of Benlate were 0, 1.13 and 11.3 kg benomyl ha–1. The treated plant materials were dried, milled and incorporated into soils of Rowland series and incubated at 25 oC for 0, 7, 14, 28 and 42 days, after which NH4–-N and NO4–-N were determined. The results showed that increasing glyphosate concentration increased available NH4–-N concentration at the day of application. NH4–-N concentration at the day of application was significantly (P < 0.05) higher than those of days 7, 14, 28 and 42. Increasing glyphosate concentration increased nitrification. There was no net immobilization of soil mineral nitrogen at higher concentration of glyphosate treatment and their combinations. Benomyl treatment at normal concentration (1.13 kg benomyl h-1) depressed nitrification for a longer period (up to day 28) than that at higher concentration (up to day 14). Net mineral nitrogen at day 42 was higher in the glyphosate and the benomyl treatments than the control. It is concluded that pesticide application affected litter decomposition as indicated by changes in mineral nitrogen. There were positive interactive effects between Glyphosate and Benomyl in relation to nitrogen mineralization.

Cocoa production on degraded soils in Ghana is less sustainable and less competitive because of increasing plant nutrient depletion and consequent degradation of soil resource base. The need for supplementary plant nutrients has led to current introduction of recommended cocoa fertilizers like Asaase Wura (N:P:K 0:22:18 + 9CaO + 7S + 6 MgO), Cocofeed (N:P:K 0:30:20), Potassium Rich Sidalco Liquid fertilizers (N:P:K 6:0:20 + 1 MgO + trace elements) and Balanced Sidalco Liquid fertilizer (N:P:K 10:10:10 + 1MgO + trace elements)for farmers. For an effective and efficient intervention to the existing problem, there is the need to monitor the levels of degradation of cocoa soils in the different ecological zones and cropping systems. A study was therefore conducted by sampling and analyzing eight hundred soils from four great soil groups covering different areas of the Ghana cocoa belt - Acrisols (75%), Lixisols (10%), Ferralsols (9%) and Nitisol (3%), within four cocoa regions; Eastern, Ashanti, Western and Central. This paper discusses the ratios of the primary and secondary nutrients in addition to their soil reactions, and was compared with the established ratios of nutrient elements in a good cocoa soil. The results showed the need to add calcium and nitrogen to the soils to meet the standard ratio of K: Ca: Mg of 2:17:8, and to augment the low nitrogen to phosphorus ratio in the soils. There is also still the need to search for fertilizer formulations with nitrogen and calcium that will be in the right forms and ratio to suit the nutrient changes recommended for sustainable and competitive cocoa production for the Ghana cocoa belt.

The intensely weathered nature of soils used for cocoa production in Ghana, and the long history of nutrient depletion due to the absence of fertilization in this farming system have resulted in increased incidence of soil nutrient deficiencies in cocoa farms. The paper discusses the use of a soil diagnostic model combined with geographic information systems (GIS) to convert the current blanket fertilizer recommendations (0 N -165 P.O, -200 K.O kg ha1) into a more effective recommendation that accounts for local land resources and the actual nutrient requirements of cocoa trees. A digital map of cocoa nutrient requirements was created based on climatic and soil groups/associations data. The results showed that about 95% of the areas suitable for cocoa production are developed on only seven soil groups and four sub-groups (FAO classification). As inputs, 201 soil chemical analytic data were linked to land units to compute cocoa fertilizer formulae and doses. The number of fertilizer formulae was reduced to 32 using a fuzzy classification. Six fertilizer formulae would be sufficient to cover fertilizer recommendations for 52% of the cocoa growing areas, while 16 fertilizer formulae will cover 90% of the cocoa area. The current blanket fertilizer formula is only suitable for 6% of the cocoa growing areas in Ghana. In western Ghana, where rainfall is over 1800 mm, the climatic influence is predominant and high leaching of soils is probably responsible for greater needs for P, than for K, Ca, and Mg. In eastern Ghana, where soils have high exchangeable cation levels and base saturation, soil diagnostic method suggested application of N fertilizers. This integrated method could provide precision agriculture techniques for cocoa farmers in Ghana, and beyond, in order to sustain yields on cocoa farms.

Le cacao est la pierre angulaire de l'économie du Ghana depuis près de 75 ans. Depuis son introduction, le secteur cacaoyer a été basé sur l'exploitation de la fertilité des sols, accumulée sous la forêt. Ceci a donc entraîné peu à peu l'appauvrissement du sol en nutriments et la dégradation des terres. Actuellement, il existe de vastes surfaces de terres dans la ceinture cacaoyère où le type de sol serait idéal pour la cacaoculture, mais dont la situation est tout à fait inadaptée. Cette contribution évalue les effets à long terme de la production cacaoyère au Ghana sur une période de 75 ans, et notamment l'utilisation de l'azote, du phosphore et du potassium présents dans les sols. Les principaux nutriments extraits des sols sur cette période et les quantités équivalentes des divers types d'engrais ont été estimés et comparés aux revenus obtenus par les agriculteurs par la vente de leur production. Selon cette estimation, la production totale de fèves de cacao séchées sur la période de 75 ans, soit de 1930-31 à 2004-05 a été de 23,3 millions de tonnes, soit une moyenne de 311 000 tonnes par an. Les quantités d'azote, de phosphore et de potassium extraites du sol par les fèves ont été estimées à 655 400 t, 42 400 t et 144 600 t respectivement. Ceci équivaut à 655 400 tonnes, 100 300 tonnes et 173 500 tonnes de N, P2O5 et K2O respectivement. Selon ces estimations, 3,2 millions de tonnes de sulfate d'ammonium, 218 000 tonnes de superphosphate triple et 289 200 tonnes de chlorure de potassium, ou leurs équivalents, seraient nécessaires pour réapprovisionner le stock de nutriments appauvri. En plus de ces quantités, il faudrait appliquer chaque année au moins 42 667 tonnes de sulfate d'ammonium, 2 908 tonnes de superphosphate triple et 3 856 tonnes de chlorure de potassium (ou leurs équivalents) pour maintenir la production annuelle moyenne de 311 000 tonnes de fèves de cacao séchées par an. Bien que les mêmes quantités de nutriments soient extraites par l'enveloppe des cabosses de cacao, ces quantités reviennent dans le sol, puisque l'on laisse pourrir les enveloppes sur le sol des exploitations. À partir de ce bilan, la contribution analyse le besoin urgent de rétablir et de soutenir la fertilité des sols de cacaoculture au Ghana, afin de maintenir les niveaux de production actuels.