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Distribution and abundance of forest birds in Ghana
(Ostrich, 2000) Ntiamoa-Baidu, Y.; Owusu, E.H.; Asamoah, S.; Owusu-Boateng, K.
Forest reserves within the Ghanaian rain forest have been classified into categories (Condition I-VI) on the basis of their botanical importance and status of the vegetation. We present data on the distribution and abundance of avifauna of 28 Condition II and III forest reserves in southern Ghana based on line transect counts and mist-net captures. A total of 227 species were recorded for all the sites; species records for individual sites ranged from 78–119. The dominant groups in the overall survey were Muscicapidae (represented by 40 species), Pcynonotidae (21) and Cuculidae (12). The most abundant bird species in the Ghanaian forests were Yellow-whiskered Greenbul, Green Hylia, Green Pigeon and Olive Sunbird. Species encounter rates ranged from 16.7 to 50.7 species per km with individual bird encounter rates of 27.9 to 172.0 birds per km. Capture rates in mist-nets ranged from 1.2 to 3.9 birds per 100 metre net-hr (mnh). A total of 183 species were recorded in Condition II forest as compared with 167 in Condition III forests. The effects of forest condition and vegetation types on the total number of species recorded were, however, not statistically significant. The Similarity Index for bird communities within Condition II and III forests was 0.72. Bird species composition in the two forest types also differed: e.g., seven primary forest species, as well as 40% of the species associated with primary and matured secondary forest which were recorded in Condition II forests, were absent from Condition III forests. Bird communities of Moist Evergreen, Upland Evergreen and Moist semi-Deciduous were more similar than communities in the Wet Evergreen forest type. The implication of the results for conservation of the Ghana’s forests is discussed. © 2000, Taylor & Francis Group, LLC. All rights reserved.
Farmers‘ perceptions of constraints to plantain production in Ghana
(International Journal of Sustainable Development and World Ecology, 2000-01) Schill, P.F.; Afreh-Nuamah, K.; Gold, C.S.; Green, K.R.
Plantain (Musa AAB), a primary food crop in Ghana, is a key component in sustainable agricultural systems in high rainfall zones. Recently, there has been a substantial yield decline and reduction in plantation life. To elucidate the context in which intervention strategies should be developed, a Participatory Rural Appraisal (PRA) was conducted at five villages in the major plantain-producing belt of Ghana. The importance of plantain as a preferred food was confirmed, although farmers tended to sell plantain for cash income, using cheaper, less preferred alternatives for home consumption. Farmers identified decreasing soil fertility, the high cost of labour for weeding, pests and diseases, lack of good quality planting material and marketing-related issues as the major production constraints. Due to declining productivity in less fertile regions, plantain has been replaced with other food crops such as cassava and maize. Farmers overestimated the importance of insect pests but were unaware of the extensive damage that could be caused by nematodes and the foliar disease, black sigatoka. They observed, however, that pest damage is more severe when soil fertility is poor. Clearly, integrated pest management is likely to be most effective when practiced within the context of cropping systems management; sustainable strategies that are being developed for resource-limited plantain farmers in Ghana are discussed. © 2000 Taylor and Francis Group, LLC.
Nodulation of legumes in inland valley soils of Ghana
(Symbiosis, 2000-01) Dogbe, W.; Fening, J.O.; Danso, S.K.A.
Because most African farmers cannot afford the purchase of chemical fertilizers to correct soil nutrient deficiencies, alternatives such as increased use of biological nitrogen fixation are most useful. For best results, sound recommendations are needed on the use of different legumes, their rhizobial requirement and management for optimum nitrogen fixation. In West Africa however, except for the highly popular legumes such as cowpea, soybean and groundnut, few reliable data are available on the abilities of other legumes to nodulate and fix nitrogen with naturally occurring strains of rhizobia in various soils and thus on the need for rhizobial inoculation. A screen-house study was conducted at the University of Ghana, Legon, to assess the potential of 13 commonly grown legumes in Ghana to form nodules with native rhizobia from eight inland valley soils and to identify those for which further research would be needed to enhance their nodulation. Two of the soils had indigenous rhizobia that induced formation of nodules on all the legumes evaluated. Rhizobia in the remaining soils induced the formation of nodules on more than 75% of the legumes studied. However, numbers of nodules plant-1 on most of the legumes were low and were influenced by (i) the type of soil, (ii) legume and (iii) the soil x legume interaction. Population densities of rhizobia capable of forming nodules with legumes in the studied soils estimated by the most probable number method (MPN) ranged from very low (negligible to 1.7 x 101 cells g-1 soil for those that could form nodules with mucuna) to high (up to 1.7 x 105 cells g-1 soil and 3.1 x 105 cells g-1 soil for cowpea and green gram, respectively). Nodule number per plant correlated significantly with some important indices of soil fertility; namely %N, available NO3 - and % organic C, with r values of 0.39*, 0.60* and 0.40*, respectively. Inoculation of mucuna increased nodulation by between 3 to 20-fold and N2 fixation by 18 to 98 percent depending on the soil type. Non-inoculated mucuna absorbed a high proportion of its N (up to 60%) from the soil and may mine the soil of native N if harvested for seed. The low rhizobial populations and poor nodulation are indications for the necessity for inoculating many of these legumes in similar soils in West Africa.
Milk production of Tswana goats fed diets containing different levels of energy
(South African Journal of Animal Sciences, 2000-01) Adogla-Bessa, T.; Aganga, A.A.
The aim of this experiment was to characterize the milk yield of the Tswana goat of Botswana. Twenty-one Tswana goat does were allocated to one of three diets formulated to provide energy for maintenance and a milk yield of either 1.5 kg/d, 1.0 kg/d or 0.5 kg/d. Intake, milk yield and kid growth rate was monitored for 14 weeks. Dry matter intakes of up to 5% of body weight were recorded. Energy intake and milk yield differed between treatments (p < 0.01). Daily ME intake for the low, medium and high-energy diets was 1.01, 1.42 and 1.64 MJ ME/kg metabolic weight; the corresponding milk yields were 0.47, 0.53 and 0.72 kg/day. Kid birth weight ranged from 2.6 to 2.9 kg, and daily gains over the 14-week period were 95, 116 and 128 g/day for the low, medium and high energy diets respectively. Milk output accounted for 62% of the variation in kid growth rate. It was concluded that Tswana goats have the potential to respond to increasing levels of energy intake by increasing milk yield to relatively high levels.
Responses of Tswana goats to various lengths of water deprivation
(South African Journal of Animal Sciences, 2000-01) Adogla-Bessa, T.; Aganga, A.A.
The aim of this trial was to determine the water intake of Tswana goats and investigate the effects of short term water deprivation in summer or winter (6000 ml water offered either once every 72 h, 48 h, 24 h or ad libitum) on feed intake, dry matter digestibility, growth rate and health. Goats were fed a diet comprising 60% Cenchrus ciliaris hay and 40% Medicago sativa hay. Feed intake per kg metabolic weight was inversely related to water intake. Body weight gains decreased with longer watering intervals, rectal temperatures were unaffected but respiratory rate, packed cell volume, pulse rate, haemoglogin level and mean corpuscular haemoglobin concentration was highest with the 72 h watering interval. Feed intake and daily weight gains were higher in winter than summer, but animals drank more water in summer than in winter, and showed more signs of dehydration in summer. Dry matter digestibilities (%) were 66.8, 66.7, 64.2 and 65.2 for water intake intervals of ad lib, 24 h, 48 h and 72 h respectively; digestibilities of organic matter, crude protein and crude fibre followed the same trend. Urine output, faecal output per kg metabolic weight and faecal moisture content decreased with increased length of water deprivation. It was concluded that Tswana goats are well adapted to semi-arid zones and can be watered once in 72 h without severe dehydration.
Behavioural interactions between West African dwarf nanny goats and their single-born kids during the first 48 hours post-partum
(Applied Animal Behaviour Science, 2000-03) Addae, P.C.; Awotwi, E.K.; Oppong-Anane, K.; Oddoye, E.O.K.
West African dwarf nanny goats and their single-born kids were tested to find out their behavioural response to separation and their mutual recognition during the first 48 h post-partum. The tests were conducted at 18, 24, 36 or 48 h post partum. Chi-square analyses were used to determine whether age, sex and birth weight of kids as well as h partum and parity of dams had an effect on post-partum bahaviours. In a preliminary study where the kids were not prevented from sucking prior to the tests, the majority of kids (93%) and does (86%) exhibited apparant minimal concern to separation (i.e., had scores of less than 3) and also failed to seek each other. When the kids were prevented from sucking 2 h prior to the tests, the couple showed some response to separation and made attempts to seek each other. This suggests that in goats the state of the neonate's nourishment and the fullness of the dam's udder may be important factors that determine the willingness of the kid and the dam to seek each other when separated. The behavioural response of 48-h-old kids to separation from their dams when they had not sucked for 2 h was significantly higher (P < 0.05) than that of 18-h-old kids. The sex and birth-weight of 48-h-old kids did not affect their response to separation from their dams. Hours post-partum and parity of does did not affect their response to separation from their kids exhibiting even though the proportion of does the highest response was much higher in primiparous then multiparous animals (44% vs. 13%). Recognition of dams by kids was poor at 18 and 24 h with more than half (71%) the kids failing to recognize their dams. Dam recognition ability improved with age and at 48 h the majority of kids (88%) were able to recognize their dams. Does tested at 48 h post partum had better (P > 0.05) kid recognition than those tested at 18 and 24 h. The sex and birth weight of kids and the parity of dams had no effect on the mutual recognition of kids and their dams at 48 h post-partum. (C) 2000 Elsevier Science B.V.
On the simulation of root water extraction: Examination of a minimum energy hypothesis
(Soil Science, 2000-03) Adiku, S.G.K.; Rose, C.W.; Braddock, R.D.; Ozier-Lafontaine, H.
An alternative procedure for calculating root water extraction from different depths of a soil profile is proposed. The procedure is based on the concept that the root water extraction entails energy expenditure by the plant and that the plant seeks to minimize the total rate of energy expenditure during water uptake. The model, therefore, considers root water extraction to be a minimization problem whose solution can be sought using a dynamic programming framework. We tested the model by simulating the variations of the soil water content using the time and depth of a maize-sorghum intercrop experiment reported for an 8-day drying cycle by Ozier-Lafontaine et al. (Plant and Soil 204:183-201, 1998). Simulated patterns follow the observed water content distribution quite well. Furthermore, results from numerical experiments show that the model is capable of simulating a range of water extraction patterns in a realistic manner. Patterns of water extraction from uniformly wet soil profiles follow those of the root distribution with depth. The extraction rate is highest in the section where the root length density is also highest. Once the soil profile dries out, water extraction patterns cease to bear any similarity to root distribution. Model simulations also show increased root activity at greater depths when the top sections of the soil dry out. Generally, the model avoids the need to make any prior assumptions about the pattern of the root water extraction.
Ameliorating acid infertile rice soil with organic residue from nitrogen fixing trees
(Nutrient Cycling in Agroecosystems, 2000-06) Baggie, I.; Zapata, F.; Sanginga, N.; Danso, S.K.A.
Residues from two nitrogen fixing trees, Albizia zygia and Gliricidia sepium and one non nitrogen fixing tree Samania dinklagei and their combination with 50% of rice husk, were evaluated for their effect on growth and yield of rice (Oryza sativa) varieties (Rok 10 and Rok 23) grown in an Oxisol collected from a rice paddy in Inland valley swamps of Sierra Leone, West Africa. Ground and dried residues were mixed with soil and labelled with N15 ammonium sulfate (9.855% atom excess) at a rate of 10 mg N kg-1 soil. The 32P isotopic exchange method was used to determine the effect of organic residue incorporation on the bioavailable soil P status at five levels of P application. Albizia zygia and G. sepium had higher quality leaf litter (with relatively lower C/N, lignin/N and cellulose/N ratios) whereas Semania dinklagei and rice husk had high carbon. lignin and polyphenolic contents. Application of organic residue had positive effects on the soil available P status at varying degrees. Higher adsorption capacity, kinetic value and mean solution time of phosphates in solution were obtained with the A. zygia, and G. sepium residues. These values were lower with rice husk and S. dinklagei. Gliricidia sepium and A. zygia contributed more nitrogen derived from organic residue than rice husk and S. dinklagei but the mixture of A. zygia and G. sepium with rice husk enhanced N utilization.
An assessment of the safety of street foods in the Ga district, of Ghana; Implications for the spread of zoonoses
(Acta Tropica, 2000-07) King, L.K.; Awumbila, B.; Canacoo, E.A.; Ofosu-Amaah, S.
Street food refers to food and beverages prepared and sold by vendors in streets and other public places for immediate consumption. In Ghana street foods are sold at small eating places popularly known as 'chop bars'. Food safety studies were conducted on the premises of 160 'chop bars' in the Ga District of Ghana in July 1998. Only three (1.8%) of the proprietors met all the requirements (based on a five-point checklist) for basic hygiene. Twenty-four (15%) out of the 160 proprietors had access to potable water while the other 136 (85%) proprietors purchased water from vendors and six used pond water. These two latter sources of water were of poor microbiological quality (as shown by faecal coliform values which ranged from 1.0x102-1.9x105 cfu/ml). One hundred and five proprietors (65.6%) did not obtain their meat supply from an approved source. Factors influencing the purchase of meat from an approved source included the proximity of a chop bar to a slaughter facility, the conduct of meat inspection personnel and affordable user fees. Copyright (C) 2000 Elsevier Science B.V.
Behavioural interactions between West African dwarf nanny goats and their twin-born kids during the first 48 h post-partum
(Applied Animal Behaviour Science, 2000-07) Awotwi, E.K.; Oppong-Anane, K.; Addae, P.C.; Oddoye, E.O.K.
West African dwarf nanny goats and their twin-born kids were tested to determine their behavioural response to separation and their mutual recognition during the first 48 h post-partum. Does and their kids were given scores ranging from 1 to 5, depending on how they performed in the tests. Animals that showed maximum response and recognition ability were given a score of 5, while those with minimum response and recognition ability scored 1. The kids were prevented from sucking 2 h prior to the tests, which were carried out at 18, 24, 36 and 48 h post-partum. Chi-square procedure was used to determine whether age, sex and birthweight of kids as well as hours post-partum and parity of dams had any effect on these post-partum behaviours. Out of 48 twin-born kids tested, 32 (67%) responded actively to separation from dams (i.e. had scores of 3 or more). The age, sex and birthweight of kids did not significantly affect (P > 0.05) their response to separation from their dams. The hours post-partum and the parity of does also did not affect their response to separation from their kids. The dam recognition ability of twin-born kids was very poor. Out of a total of 48 kids tested, only 17 (35%) were able to recognize their dams (i.e. had scores of 3 or more). Even at 36 h, only four out of 14 (26%) could recognize their dams. It was only at 48 h that the majority of kids tested (i.e. 75%) successfully identified their dams. At 48 h, the dam recognition ability of kids was significantly better (P < 0.05) than that of 18-h-old kids. Sex and birthweight of 24-48-h-old twin-born kids did not significantly affect (P > 0.05) their ability to recognize their dams. The majority of does tested (i.e. 20 out of 24) were able to recognize their twin-born kids. The hour post-partum and parity of does did not significantly affect (P > 0.05) their kid recognition ability. (C) 2000 Elsevier Science B.V.
Yield of plantain alley cropped with Leucaena leucocephala and Flemingia macrophylla in Kumasi, Ghana
(Agroforestry Systems, 2000-07) Banful, B.; Dzietror, A.; Ofori, I.; Hemeng, O.B.
The decline in yield of plantain has partly been attributed to inadequate soil moisture and pests, particularly nematodes. The objectives of the study therefore were to determine the effect of mulch from Leucaena leucocephala and Flemingia macrophylla (Willd.) Merr. grown as hedgerows on (i) soil moisture and temperature (ii) growth and yield of plantain and (iii) pathogenic nematode populations. The study was conducted from 1991 to 1994 in Kumasi, Ghana. Treatments comprised of leguminous plants, L. leucocephala and F. macrophylla, and a control (no leguminous plants), arranged in a randomised complete block design with four replications. The leguminous plants were planted in 1991 while the plantain was planted in 1992. Results indicated that the highest biomass yield was produced by F. macrophylla. Mulching with prunings of F. macrophylla resulted in significantly (P < 0.05) higher retention of soil moisture and lower soil temperatures than mulching with prunings of L. leucocephala. Growth of plantain determined by plant height, leaf production, pseudostem girth and yield were significantly greater in F. macrophylla mulched plots than L. leucocephala treatment and control plots where no mulch was applied. Plant parasitic nematodes isolated were Meloidogyne spp., Pratylenchus spp., Paratylenchus spp., Helicotylenchus spp., and Rotylenchus spp. Three years after planting of hedgerows, significantly (P < 0.05) higher populations of Meloidogyne spp. (367 per 100 g soil), Paratylenchus spp. (92 per 100 g soil), Helicotylenchus spp. (8 per 100 g soil), and Rotylenchus spp. (308 per 100 g soil) were associated with L. leucocephala hedgerow than with Flemingia macrophylla hedgerow (42.0, 83.0 per 100 g soil) and the control (74.50, 41.0 per 100 g soil). F. macrophylla has qualities that suppress nematode populations. The results clearly indicated the superiority of Flemingia macrophylla over Leucaena leucocephala as much for plantain production.
The prevalence of anti-Toxoplasma gondii antibodies in Ghanaian sheep and goats
(Acta Tropica, 2000-07) Van Der Puije, W.N.A.; Bosompem, K.M.; Canacoo, E.A.; Wastling, J.M.; Akanmori, B.D.
The enzyme-linked immunosorbent assay (ELISA) was used to detect anti-Toxoplasma gondii antibodies in 1258 small ruminants (732 sheep and 526 goats) sampled from 28 different locations in the three ecological zones of Ghana. The animals sampled had an overall seroprevalence of 30.5% (384 of the total). Sheep had a higher overall prevalence (33.2%) compared to the goats (26.8%). Animals sampled from the Coastal Savannah and the Forest zones had prevalences of 39.4% and 39.1%, respectively, which were significantly higher (P<0.01) than the prevalence recorded for the drier Guinea Savannah zone (20%). Prevalence of antibodies in female animals (35.8%) was significantly higher (P<0.01) than that for males (21.1%). Significant differences were also observed between breeds and age groups. The ELISA was found to be both highly sensitive (92%) and specific (91%) when compared to the IFAT, which was used as a reference test. Copyright (C) 2000 Elsevier Science B.V.
The seroprevalence of toxoplasmosis in pigs in Ghana
(Acta Tropica, 2000-07) Arko-Mensah, J.; Bosompem, K.M.; Canacoo, E.A.; Wastling, J.M.; Akanmori, B.D.
A serological survey of toxoplasmosis in pigs in Ghana was carried out between October 1997 and April 1998 in the three ecological zones of Ghana: the Coastal Savannah, the Forest Belt and the Guinea Savannah. Antibody against Toxoplasma gondii was measured in pig serum using a microplate-ELISA which had a sensitivity and specificity of 90.2 and 92.3%, respectively when compared with IFAT. A national seroprevalence of 39% was obtained in pigs, with the ecological distribution being 43.9, 30.5 and 42.5% for the Coastal Savannah, the Forest Belt and the Guinea Savannah, respectively. The age of the animal, the breed, the environmental conditions and the management practices appeared to be the major determinants of prevalence of antibodies against T. gondii. The prevalence of anti-T. gondii antibodies was found to increase with age (P<0.05). Pigs from the two Savannah zones had a significantly higher (P<0.05) antibody prevalence than those sampled from the Forest belt. Antibody prevalence (46.8%) in crossbreed pigs was significantly higher (P<0.05) than that of the exotic Large White breed (38.8%). Copyright (C) 2000 Elsevier Science B.V.
Seroprevalence of brucellosis in cattle and humans in the Akwapim-South district of Ghana: Public health implications
(Acta Tropica, 2000-07) Kubuafor, D.K.; Awumbila, B.; Akanmori, B.D.
A total of 183 cattle comprising 54 bulls, 53 milking cows, 76 heifers and 44 calves in the Akwapim-South district of Ghana were tested for antibodies against Brucella abortus using the Rose Bengal plate test. The results indicated that cattle in the Akwapim-South district were infected with Brucella with a mean seroprevalence of 6.6%. There was no difference in the seroprevalence either between females 11/129 (8.5%) and males 1/54 (1.9%), or among the three different breeds of cattle (Sanga, West African short horn (WASH) and white Fulani) in the study area. However, there was a significant increase in seropositivity with respect to age. A significant association between antibodies against Brucella and a history of abortions and retained placenta in cows indicated that brucellosis might be responsible for significant economic losses to farmers in the area. However, no evidence of human brucellosis was detected by antibody screening in selected risk groups. Copyright (C) 2000 Elsevier Science B.V.
Human behavioural factors implicated in outbreaks of human anthrax in the Tamale municipality of northern Ghana
(Acta Tropica, 2000-07) Opare, C.; Nsiire, A.; Awumbilla, B.; Akanmori, B.D.
The knowledge, attitude, beliefs and practices of cattle owners, herdsmen, butchers and meat consumers about anthrax were used to provide a better understanding of the major factors responsible for the frequent outbreaks of human anthrax in the Tamale municipality of northern Ghana. A total of 96% of the respondents, made up of 50 cattle owners, 50 herdsmen, 25 butchers and 125 consumers, knew of anthrax and the clinical signs indicative of anthrax in cattle. However, very few knew the causative agent and many attributed the disease to the supernatural. Eight percent of the respondents believed that herbal preparations could protect against human anthrax, while 9% indicated that they would seek help from traditional practitioners or herbalists, if they suspected anthrax. A significant proportion of respondents were of the view that animals, which had died of unknown causes could be eaten because they served as a source of inexpensive meat for the community, especially if the meat was cooked with herbs which was commonly thought to prevent anthrax. These attitudes, taken together with the low income of the population studied, made the consumption of meat from animals, which had died of unknown causes, an attractive option. This increased the vulnerability to human anthrax in an area with frequent anthrax outbreaks in livestock. The results of this study suggest that a public education campaign involving both veterinary and local health personnel on the actual cause and prevention of anthrax could reduce outbreaks of anthrax in people. Copyright (C) 2000 Elsevier Science B.V.
Cereal producers and the structural adjustment programme (SAP) in Ghana: A welfare analysis of the first decade of SAP
(Development Southern Africa, 2000-10) Drafor, I.; Filson, G.; Goddard, E.W.
Small-scale food producers in Ghana produce about 90 per cent of the food in the country. Behaviourial patterns characteristic of these semi-commercial producers are complex, making it hard for policy makers to predict the consequences of policies on them. This study analyses the effects of the Structural Adjustment Programme on cereal producers in Ghana. A system of demand and supply equations was employed in a simulation analysis performed under three different scenarios to observe the aftermath of price increases; measure the impact of devaluation of the cedi; and gauge the effect of price increases and devaluation. The results show that cereal producers gain but consumers lose in terms of producer and consumer surplus. There is a net welfare loss as a result of the SAP.
Effects of Etiolated Slip Management on the Establishment, Fresh Tuber Yield and Yield-Related Attributes of White Guinea Yam, Dioscorea Rotundata Poir
(Discovery and Innovation, 2000-12) Gyansa-Easmon, C.E.
The "slip" of white guinea yam, Dioscorea rotundata Poir refer to the leafless sprout with the associated cormous structure that develops from the stored tuber when the dormancy period is over. Under dark storage conditions, these slips are etiolated, whitish or pale yellowish, being devoid of chlorophyll. At the end of 3 weeks of presprouting in topsoil, they attained a dry matter content of 58.9%, representing a net increase in "morphogenetic efficiency" (ME) of 340.3%, compared to the unpresprouted. A field experiment elicited no significant fresh tuber yield differences between the "directly planted" and "prerooted" slips at 5 months after transplanting or planting. The "presprouted" ones produced significantly higher fresh tuber yield of 19.3 t/ha. The directly-planted, produced significantly superior tuber size of 362.6g relative to the presprouted or prerooted, although its number of tubers per h. of 24,785 was significantly lower than the 103,910 of the presprouted. The directly-planted and presprouted produced tubers largely in the conventional seed yam range (200-1000g). This was an indication that the etiolated slips - the presprouted form, could be a new source of planting material for commercial seed yam production. The plants exhibited a "bushy" canopy architecture rather than viny and thus staking may not be necessary.
Variation in seed size, protein and tannin content of bambara groundnut (Vigna subterranea)
(Tropical Science, 2001-01) Ofori, K.; Kumaga, F.K.; Bimi, K.L.
Seed size and protein and tannin contents were determined on 25 accessions of bambara groundnut currently available in Ghana, using dried seeds 8-10 weeks after harvesting. The 100-seed weight varied from 34 to 63 g. The protein and tannin contents were 14.1 to 23.1% and 0.25 to 2.27% (dmb) respectively. Tannin concentration increased with increase in testa colour and eye pattern colour. Selecting accessions with high protein and low tannin, with large or medium seed size should improve the quality of bambara groundnut.
Simulation of the dry matter production and seed yield of common beans under varying soil water and salinity conditions
(Agricultural Water Management, 2001-02) Adiku, S.G.K.; Renger, M.; Wessolek, G.; Facklam, M.; Hecht-Bucholtz, C.
We present a model that simulates the effects of water and salinity stress on the growth of beans. The model derives a combined soil water/salinity stress factor from the total water potential (combination of the matric and the osmotic potentials) and uses this stress factor as a growth limiter in a growth model. The model was tested on data obtained from two greenhouse trials of beans (Phaseolus vulgaris) grown under a range of soil water and salinity conditions. The simulated dry weight of the bean generally followed those observed. In the first trial, the comparison between simulated and observed total dry weight and seed yield gave R2 values of 0.97 and 0.92, respectively. Comparison of the simulated to the observed dry weight for the second trial gave R2 values of 0.85 and 0.89, respectively. These indicate a good performance of the model in general. The principle of deriving a combined water/salinity stress from the matric and osmotic potentials is simple and can be included as a simple routine in many existing crop models without much difficulty. © 2001 Elsevier Science B.V.
Conceptual methodologies in agro-environmental systems
(Soil and Tillage Research, 2001-03) Rose, C.W.; Adiku, S.
When continuous measurement of relevant above- and below-ground environmental factors is made, and the dynamics of crop growth and phenology is followed, it is shown that small-plot agronomic experimentation can provide information vital to the development and testing of simulation models. Such models for crops of maize (Zea mays) and the legume cowpea (Vigna unguiculata), grown as sole crops and in an intercrop system, were used to simulate yield at two separate sites in the main savanna farming zones in Ghana, West Africa. Simulation was carried out for these three cropping systems using 20 years of historical rainfall data for the two sites, investigating the effect on yield of management options which included time of planting, rate of nitrogen fertilizer application, and crop planting density. The yield results of this series of simulations were then subject to two different types of analysis in order to assist the evaluation of agricultural options for the nation. The first analysis was an economic evaluation based on gross margins, but using the stochastic-dominance technique to rank the profitability of the alternative cropping and management systems. The second, more general methodology employed was multi-criteria analysis (MCA). This analysis covered economic returns and their variability, the amount and quality of residue returned to the soil, and the aerial cover provided by the crop. Other factors which could affect the sustainability of production in the long term, but which could only be evaluated qualitatively, were also included in the analysis, as allowed in MCA methodology. The MCA was then carried out for three scenarios in which different weightings were given to economic outcomes and to factors which are believed to encourage ecological sustainability. These scenarios allow recognition of different priorities which might be given by traditional subsistence farmers as compared to commercial producers. Outcomes of this broad analysis of development alternatives provided scientific support for the traditional Ghanaian practice of grain/legume intercropping which is also widespread in the tropics. The suite of methodologies illustrated by the case study appears to be suitable for the evaluation of alternative farming systems at the scale of a small nation such as Ghana. © 2001 Elsevier Science B.V.

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