(S.A.O., E.O.K.O. & F.Y.O. : Animal Research Institute, CSIR, P.O. Box 20, Achimota, Ghana; P.G.: Department of Animal Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana; Y.A. : Department of Economics, University of Ghana, Legon,Ghana)

A survey was carried out in five districts on the Accra plains to characterize the peri-urban dairy system. Results of the survey indicated that about half of the farms visited had hired herd managers who were paid in kind with milk. The Fulani ethnic group constituted 58.2 per cent of the herdsmen encountered, followed by Ga, 20.9 per cent, Ewe, 12.0 per cent, and other mixed group, 8.9 per cent. The educational level of household heads was generally low; 49.1 per cent were illiterate, 22.0 per cent had Arabic education, while 18.0 and 10.9 per cent had primary and secondary education, respectively. Utility services, namely electricity, water and telephone, were non-existent. There were little or no farm

equipment and most farmers used hand dipping as a means of applying acaricide. Integration of crops and livestock production was very low. Tenancy was communal with no private grazing lands. It was concluded that the factors mentioned above were constraints to smallholder peri-urban dairy production and need to be addressed.

Original scientific paper. Received 10 Jun 96; revised 10 Jul 97.

(Akuro Adoki: Institute of Pollution Studies, Rivers State University of Science and Technology, P.M.B. 5080, Nkpolu - Oroworakwo, Port Harcourt, Nigeria; Abiye Adoki: Department of Geography, Rivers State College of Agricultural Science, P.M.B. 5936, Port

Harcourt, Nigeria)

During the preliminary phase of a process for the production of a protein-enriched feed supplement, a strain of Candida sp. was isolated from ripe banana pulp. Morphological and biochemical tests showed that the strain which was bipolar and elongated was not capable of growth at 37 oC but grew only on dextrose and fructose and was able to supply its amino acid requirements in culture. The efficiency of conversion of readily utilizable carbon sources in fruit wastes used for feed supplement production by the test strain was studied. Results obtained showed that reducing sugars were most readily utilized compared to other soluble carbohydrates. Conversion efficiencies were high and averaged about 75 per cent in unsupplemented substrates. Supplementation with organic and inorganic compounds resulted in greatly increased biomass yields.

Original scientific paper. Received 8 Sep 90; revised 22 Aug 97.

School of Agriculture, University of Cape Coast, Cape Coast, Ghana

A survey of the production of Frafra potato (Solenostemum rotundifolius Poir) in Ghana was conducted to collect baseline data on the crop and to identify constraints to production. In all, 100 farmers who were randomly selected from 16 villages and towns in five districts in the Upper East Region and Upper West Region were interviewed between August and November 1991. Results indicated that Frafra potato is an important crop in the districts of Builsa, Kassena-Nankani, Frafra, Lawra-Nandom, Jirapa-Lambussie, Nandawli, and Wa. It is usually cultivated as a monocrop but may sometimes be intercropped with yam, okro, maize, rice, sorghum, cowpea and bambara groundnut. It is usually grown on mounds and sometimes on ridges but not on the flat. Tubers are mostly used for propagation but softwood stem cuttings can also be used. Farm sizes range between 0.05 and 1.2 h. A wild type referred to as "Tug-piece", meaning shrub potato, has been identified by farmers. Constraints to production, in descending order of importance, include rapid tuber deterioration in storage, lack of adequate planting materials, pests and diseases, and insufficient soil moisture for maturing the crop.

Original scientific paper. Received 9 Jan 97; revised 25 Aug 97.

(E. N., G. N. D. & Y. A.: Department of Soil Science, University of Ghana, Legon, Ghana; A.R.M. & H. T.: Department of Soil Science, University of Saskatchewan, Saskatoon, Canada)

The variability in the properties of five Lixisols _Tingoli, Tolon and Kumayili series on toposequence 1; Kpelesawgu and Changnalili series on toposequence 2 _ was studied to ascertain the natural differences in the soils. The Tingoli and Tolon series accumulate more in situ formed nodules with greater bulk density. Moisture storage is greater in the toposequence 2 soils because of poor internal drainage. Kaolinite is the dominant clay mineral in the toposequence 1 soils. Illite is dominant in the toposequence 2 soils, especially in the Changnalili series, serving as K reserve source. The nodules have high concentrations of haematite and goethite, implying greater maturity. Soils on toposequence 1 are more weathered with more pronounced desilication. Organic carbon accumulation and effective CEC in the toposequence 2 soils are relatively greater because of poor internal drainage, which hinders organic matter decomposition.

The toposequence 1 soils show reddish colouration because of better internal drainage.

Original scientific paper. Received 12 Feb 97; revised 25 Sep 97.

Crops Research Institute, Council for Scientific and Industrial Research (CSIR), P.O. Box 3785, Kumasi, Ghana

The effects of urea and sulphate of ammonia applied at 0, 90, 120, 150 and 180 kg N ha-1 (from 1989 to 1992) and the time and rate of N application (1992) on the severity of Striga hermonthica infestation and maize yield were studied in order to compare the two sources of N fertilizer, commonly available to farmers in Ghana, in reducing S. hermonthica infestation, and to determine the rate and time of application that would minimise the deleterious effect of Striga on maize. The experiments were carried out under natural field infestations on farmers' fields (6-10 locations each year) in the Guinea Savanna zone of Ghana and replicated three times at each location on plots 5 m long and 3.6 m wide. In 1989 and 1992, higher S. hermonthica population density was recorded when urea was applied compared to sulphate of ammonia. However, there were no differences in Striga population density between the two sources of nitrogen from 1990 to 1991. Applying N at either 4 or 6 weeks after planting (WAP) maize did not affect the number of emerged Striga shoots. The rate of nitrogen applied did not influence the emergence of Striga from 1989 to 1991 as compared to 1992 when Striga population declined with increased rate of nitrogen fertilizer. Maize grain yield was unaffected by the source of nitrogen applied from 1989 to 1991. Similarly, applying N fertilizer at 4 or 6 WAP did not affect maize grain yield in 1992. However, the application of sulphate of ammonia resulted in higher maize yield compared to urea in 1992. Maize grain yield increased with increased nitrogen rate up to 90 kg ha-1 beyond which no appreciable increase was observed. A minimum of 90 kg N ha-1 is therefore required for any meaningful reduction in the deleterious effects of Striga on maize. In addition, to reduce the population of Striga in maize, it is essential to apply N fertilizers early.

Original scientific paper. Received 12 Feb 97; revised 26 Sep 97.

(E. N., G. N. D. and Y. A.: Department of Soil Science, University of Ghana, Legon, Ghana; A. R. M. and H.T.: Department of Soil Science, University of Saskatchewan, Saskatoon, Canada)

The forms and distribution of phosphorus in three well-drained and two poorly drained, widely cultivated Lixisols on two landscapes in the interior savanna zone of Ghana were studied. Total phosphorus (TP) and dithionite-citrate-bicarbonate extractable P (DCB-P) concentrations increase with depth in all the soils and are related to profile maturity in the well-drained soils. In the low-lying soils, however, the concentration is governed by drainage. The greatest amounts of TP occur in the topsoils of the Tingoli series on Catena 1, which were 132, 92, 744, and 700 mg/kg in the fine earth, silt, clay, and nodule fractions, respectively. The Kpelesawgu series on Catena 2, however, has the least TP accumulation of 78, 159, and 50 mg/kg in the fine earth, silt, and clay fractions, respectively. The large concentration of TP and DCB-P in the nodules and clays is due to their greater sesquioxide contents. The available P concentration is extremely low because of the low content of P-bearing parent material. The amounts of clay, silt, and DCB-P may be used to estimate the accumulation of TP concentration in the soils. Variations in TP saturation correspond with changes in clay accumulation in the soils on Catena 1 and in silt content in the Catena 2 soils.

Original scientific paper. Received 12 Feb 97; revised 29 Sep 97.

Food Research Institute, CSIR, P.O. Box M.20, Accra, Ghana

The quality of traditionally smoked-dry snail meat as it occurred on the open market in Ghana was investigated. Quality evaluation on representative samples of the product collected involved proximate composition, water rehydration capacity, microbiological and sensory analyses. A preliminary survey was also carried out to identify the processing procedure, raw material used, handling, packaging, and storage of smoked-dry snail meat. Results of the work indicated lack of hygienically controlled processing procedures, the use of poor quality snail meat for processing, and poor handling and storage procedures for the unpackaged smoked-dry product. The quality of the smoked-dry product was also generally poor based on results of microbiological and sensory evaluations. Recommendations for improving smoked-dry snail meat processing, including quality checks required to prevent recontamination and improve shelf-life and eating quality of the product, have been given.

Original scientific paper. Received 21 May 96; revised 7 Oct 97.

Crops Research Institute, Council for Scientific and Industrial Research (CSIR), P. O. Box 3785, Kumasi, Ghana

Plant density and nitrogen (N) fertilizer responses of one local and three improved open-pollinated cultivars of maize (Zea mays L.) developed in different eras of maize breeding were studied on sandy-loam Alfisols in the Guinea savanna zone of Ghana in 1992 and 1993. A split-plot design was used in which plant densities (30 000, 50 000, 70 000 plants/ha) were the main-plots and 12 combinations of N fertilizer levels (0, 80, 160 kg N/ha) and cultivars (Local, Composite 4, Dobidi, Okomasa) were the sub-plots in four replicates. A cross location analysis for grain yield showed environment, plant density, nitrogen and cultivar effects were highly significant (P<0.01). The environment W ultivar, environment W nitrogen, density W nitrogen, and nitrogen W cultivar interactions were also significant (P<0.05). The density W cultivar interaction and all second- and third-order interactions involving the three factors were not significant. The mean yields were 3.08 and 4.51 t/ha for the local and the improved cultivars, respectively. For all cultivars, yields increased by 10 per cent after each 20 000 plants/ha increase in plant density. Similar N response patterns were observed for all the improved cultivars. Estimated biological optimum N rates were 154 kg N/ha for the local cultivar and 183 kg N/ha for the improved cultivars. Grain yields at the optimum N levels were 3.50 t/ha for the local and 5.53 t/ha for the improved cultivars. The greatest yield response to N was observed at 80 kg N/ha for all cultivars. The data showed that (1) improved cultivars out-yielded the local cultivar at low as well as at higher levels of soil fertility, (2) breeding did not result in varieties that required higher N rates to produce high yields, and (3) the data support the current N fertilizer recommendations for the Guinea savanna zone of Ghana.

Original scientific paper. Received 8 May 97; revised 29 Oct 97.

(J. A. A.: Department of Crop Science, University of Ghana, P.O. Box 44, Legon, Ghana; G. L.W. : Department of Agriculture, University of Queensland, Brisbane, 4067, Australia)

Original scientific paper. Received 23 Oct 95; revised 29 Oct 97.

Original scientific paper. Received 10 Jun 97; revised 17 Nov 97.

Subject review article. Received 24 Jan 97; revised 4 Aug 97.