Guinea Savannah Zone Of Ghana Research Articles

Accuracy of agricultural data and implications for policy: Evidence from maize farmer recall surveys and crop cuts in the Guinea Savannah zone of Ghana

CONTEXTThe need for accurate data in policy design aimed at agricultural transformation cannot be overemphasized. Unfortunately, the relevance of agricultural research in addressing the needs of farmers has been questioned due to debates about appropriate methodologies and approaches for establishing research activities and, in other instances, poorly reasoned premises and paltry delineation, definition, and understanding of the system being studied. For a country like Ghana, where agricultural transformation is a prerequisite for its sustainable development, an understanding of the accuracy of farm data measurement is necessary. OBJECTIVEThe objective of this study is to estimate the yield measurement error and to analyze the sources of such measurement errors among the farmers of the Guinea Savannah zone of Ghana. METHODSTwo years' data for both farmer recall surveys and crop cuts were used. Descriptive statistics, regression and sensitivity analyses were done to achieve the objectives of the study. RESULTS AND CONCLUSIONSOn average, farmers' recall of maize yields (1544.6 kg/ha) was lower than the estimated crop cut yields (2593.9 kg/ha), although about 11.2% of the farmers recalled higher yields than their estimated crop cut yields. The estimated average percentage error in yield measurement between crop cuts and farmer surveys was 36.4%. These yield measurement errors are due to systematic biases, including those involving the recall of farm size, and the socioeconomic conditions of the farmers. Although a crop cut is costly, it has limited bias in providing a better measure of yield than farmer recall surveys. Irrespective of the method used, however, more attention should be given to potential sources of systematic bias in the design and data collection. Moreover, for proper interpretation, yield estimates from recall surveys and crop cuts should be properly interpreted as economic yield and biological yields, respectively. SIGNIFICANCEThis paper provided clarity on the differences in maize yield estimates in Ghana and provided measures on how to improve precision in yield data.

Nitrogen uptake and grain yield of maize (Zea mays L.) as influenced by soil amendments of neem (Azadirachta indica L.) cake and oil extracts and NPK fertilizer in Guinea savannah zone of Ghana

Maize (Zea mays L.) has high response to N and the efficient uptake of N is a major factor influencing grain yield. The effect of inorganic NPK fertilizer and Neem cake and neem oil as soil amendments were examined on maize N uptake and grain yield. A 3 × 3 × 2 factorial experiment was laid out in a Randomized Complete Block Design with three replications at the University for Development Studies farms at Nyankpala near Tamale, in northern Ghana. The treatments consisted of combinations of three levels of neem cake (0, 200 and 400 kg ha-1), three levels of neem oil (0, 10 and 20 L ha-1) and two levels of NPK (0 and 250 kg ha-1). The results showed that NPK at 250 kg ha-1 combined with neem cake at 400 kg ha-1 significantly (p < 0.05) increased N uptake in maize by 31% (from 111.3 kg ha-1 to 146.9 kg ha-1) compared to the recommended NPK rate. Maize grain yield was significantly maximized by that treatment at 7,471 kg ha-1. Grain yield was significantly associated with N uptake; therefore 250 kg ha-1 NPK with 400 kg ha-1 neem cake could be recommended for maize farmers in the project area. In contrast, neem oil extracts significantly reduced N uptake. The results of the study posited important implications for soil fertility management and climate change mitigation strategies for enhanced maize production.

Gastrointestinal parasite infections in small ruminants relative to host sex, age and husbandry system under the guinea savannah vegetation

Despite raising animals mostly as scavengers in the guinea savannah zone of Ghana, there is still scanty scientific information on the effects of this system on the health of these animals. A study was conducted to document factors influencing the prevalence rate of gastrointestinal (GIT) parasites and their loads in 500 small ruminants (250 each of sheep and goats). Prevalence rate of about 86% was recorded in small ruminants. Sheep, however, had higher (P<0.05) overall GIT parasite burden than goats. In sheep, significantly (P<0.05) more females harboured strongyles than males. Similarly, tapeworm and GIT parasites in general, were more prevalent (P<0.05) in younger than older sheep. Strongyle population was higher (P<0.05) in growers than adults, while Eimeria spp populations were higher (P<0.05) in lambs and adults than growers. The overall GIT parasite load, however, was higher (P<0.05) in lambs than all other age groups. In goats, Eimeria spp infections, coinfections of Strongyloides spp/Eimeria spp, tapeworm/Emeria spp, and overall GIT parasite load were much higher (P<0.05) in the extensive than the semi-intensive systems of management. The overall parasite population was also higher (P<0.05) in growers than adults and kids. Coinfections of tapeworm/ Strongyloides spp increased (P<0.05) with increasing age. The prevalence rate of GIT parasites in small ruminants is high. However, higher GIT parasite burden was found in sheep than goats. Younger small ruminants and goats kept in the extensive system of management are more prone to GIT parasite infestation than those kept in the semi-intensive system and older ones, respectively.

Response of chilli pepper to different irrigation schedules and mulching technologies in semi-arid environments

The impacts of climate change on food security have increased interest in research and investments in irrigation technologies and agricultural water management. Agricultural practices such as mulching help to conserve soil moisture by reducing evaporation and mitigate the adverse effects of water stress on crops, especially in semi-arid environments. This study investigated the combined effects of irrigation schedules and different mulching technologies on the growth and yield of two varieties of chilli pepper – Legon 18 ( Capsicum frutescens L.) and Kpakpo shito ( Capsicum chinense ) – in the Guinea Savannah agro-ecological zone of Ghana. Soil temperature and moisture content as well as plant growth parameters were collected over the growth period. The number of days taken for first and 50% flowering and fruiting were also recorded. Total fruit yield and crop water productivity were estimated after harvest. Results show that the combination of irrigation at 100% E T c r o p every three days and rice straw mulch ensured optimal soil temperature and moisture content that improved vegetative growth, shortened the number of days to flowering and fruiting, and significantly improved yield and water use efficiency compared to the other treatment combinations. Fruit yield for this treatment combination was up to 19,042.2 kg/ha and 19,074.6 kg/ha whereas crop water productivity was up to 6.08 kg/m 3 and 6.09 kg/m 3 for Legon 18 and Kpakpo shito, respectively. Plastic film mulch under each irrigation schedule produced higher growth and yield-related parameters than no mulch treatments. Although findings from this study cannot be directly generalized for the entire Guinea Savannah agro-ecological zone of Ghana due to spatial variability of soil and other climatic variables, the combination of irrigation schedule at 100% E T c r o p every three days and rice straw mulch is recommended for improved yield and water use efficiency in dry season chilli pepper production in semi-arid environments with sandy loam soils. • We investigate the response of chilli pepper to different irrigation schedules and mulching in sandy-loam soils. • Rice straw mulch ensured optimum soil temperature and moisture retention. • Less frequent irrigation and more water shortened the number of days for flowering and fruiting. • Rice straw mulch and irrigation at 100% ET crop every 3 days produced the best CWP. • This combination is recommended for dry season chilli pepper production in the Guinea Savannah zone of Ghana.

Effect of Seed Coating and Burkina Rock Phosphate on the Growth and Yield of Rice

Purpose: Coordinated soil richness management innovation fits into the position of resource for poor cultivating on an Afisol in the Guinea savannah zone of Ghana. The research was conducted to determine the effect of seed coating and Burkina rock phosphate on the growth and yield of rice at University for Development Studies in Nyankpala near Tamale in the Northern Region of Ghana. The study aimed is to determine the interaction of Burkina rock phosphate and Triple superphosphate on the growth and yield of rice.Research Method: The experiment was a 2x3 factorial laid in randomized complete block design replicated six times. Factor one consisted of two levels such as, coated rice seed and non-coated rice seed whilst factor two consisted of three levels of (P) phosphate; (Burkina rock phosphate, Triple superphosphate and Non-Phosphate (control) were all treatments). The research was design to determine the interaction of coated seed and Burkina rock phosphate on the growth and yield of rice. However, treatment 1, 2, 3, 4, 5, 7 and 8 were the main plot whiles treatment 6, 9 and 10 were the sub-plots. The parameters measured included plant height, gravimetric soil moisture content, tiller count, effective tiller count, chlorophyll content, days to 50% flowering, plant height at harvest, straw biomass and grain yield.Findings: The outcome of the results obtained on treatment 1 shows significant on moisture content when coated seed of rice recorded highest among the treatments (Figure 02). Besides, similar results were obtained on plant height when coated seed of rice was compared with non-coated seed of rice on week after planting which confirmed significantly on 3, 6 (WAP) week after planting on Burkina rock phosphate and Triple superphosphate whiles non-coated seed of rice, Burkina rock phosphate and Triple superphosphate were significant on 6, 9 (WAP) week after planting (Figure 03 and Figure 04). Moreover, the results obtained gave similar outcomes when coated seed plus non-coated seeds of rice on treatment 1 and 4 were compared which shows significant on Burkina rock phosphate and Triple superphosphate on grain yield and straw weight (Figure 10 and Figure 11). However, among the treatment applied on tiller count phosphate (P2O5) was significant whiles Burkina rock phosphate and Triple superphosphate were significant on effective tiller count with coated seed plus non-coated seed of rice (Figure 05 and Figure 06). Comparatively under Burkina rock phosphate, coated seed of rice was significant in chlorophyll content whiles coated seed of rice shows significant among treatments on chlorophyll content at harvest (Figure 07 and Figure 08). Overall, results obtained on coated seed plus non-coated seed of rice on days to 50% flowering was significant on Burkina rock phosphate (BRP) and phosphate (P2O5) (Figure 09).Research Limitation: Deficiency of Burkina rock phosphate and Triple superphosphate resulted on the growth and yield.Originality/ Value: The experiment should further be repeated for confirmation of results on effect of coated seed and Burkina rock phosphate on the growth and yield of rice in the lowland ecology.

Productive Impact of Residual Nutrients (N and P) in Maize and Soybean Rotation

Agricultural intensification has resulted in severe soil nutrient depletion in Africa. Alternative agricultural practices have been promoted to restore and sustain soil fertility. Use of mineral fertilizer alongside different cropping systems has been particularly promising. This study was conducted in the Guinea savannah zone of Ghana during the 2015 and 2016 cropping season (July to November) to assess the performance of soybean and maize in a rotation system. In season one, using randomized complete block design the treatments were, soybean (without treatment), inoculated soybean, soybean with phosphorus application, inoculated soybean with phosphorus application and maize. During the second season, the first season experimental plots served as main-plots and divided into four sub-plots on which maize planted and treated with four nitrogen rates in a split plot design. The results show that soybean production leads to significant increase in residual soil nitrogen content of about 16kg/ha to 55kg/ha, which is about 28 folds higher than that observed in maize fields. The level of Residual N was enhanced with inoculation. Phosphorus application during the first season of maize cultivation led to increases in residual P levels, which had a positive impact on yield of soybean in the second season. Grain yield of maize that followed soybean in a rotation system performed better than maize that followed maize at various fertilizer rates. This shows that, the residual N and P helps maize and soybean respectively in a rotation system which makes it highly economical.

Groundnut (Arachis hypogaea L.) Response to Phosphorus and Weed Management in the Guinea Savannah Zone of Ghana

Reponse de l'arachide (Arachis hypogaea L.) a l'engrais phosphate et a la gestion des mauvaises herbes dans la zone de savane guineenne au Ghana Des essais ont ete menes pendant les saisons culturales de 2013 et 2014 a la station experimentale de l'Institut de recherche agricole de la savane CSIR-, Nyankpala, pour evaluer la reponse de l'arachide a l'engrais phosphate et au desherbage manuel. Un dispositif en bloc completement randomise, avec trois repetitions par traitement, a ete utilise. Douze traitements dont quatre doses de phosphore (0, 15, 30 et 45 kg.ha-1) et trois methodes de desherbage [presence de mauvaises herbes, absence de mauvaises herbes, et desherbage a 3 et 6 semaines apres le semis (SES)]. Les resultats ont montre une interaction entre le regime de desherbage et les doses de phosphore. Des differences significatives ont ete observees pendant les deux saisons pour differents parametres: la largeur de la canopee, la nodulation effective, les poids frais et sec des gousses, la biomasse des mauvaises herbes, le poids de 100 graines, le poids des fanes et la densite et les dommages causes par les arthropodes ravageurs du sol. Le desherbage a 3 et 6 SES plus 30 ou 45 kg.ha-1 de phosphore ont reduit l'activite des arthropodes dans le sol, au meme niveau que celui des parcelles exemptes de mauvaises herbes. Ces traitements ont ameliore tous les parametres de rendement. La largeur de la canopee, la nodulation effective et le rendement des gousses sont positivement correles (r = 0,72 a 0,95) au poids des fanes pendant les deux saisons. Malgre qu'une croissance et un developpement similaire ont ete observes dans les parcelles sans mauvaises herbes et ceux avec desherbage a 3 et 6 SES, pour des raisons de main-d'œuvre et de couts dans la pratique de l'agriculture sans mauvaises herbes, le desherbage a 3 et 6 SES et l'application de 45 kg P.ha-1 sont recommandes pour maximiser la production de l'arachide dans le nord du Ghana.

Effect of Age and Sex on Haematological Profiles in Indigenous Helmeted Guinea Fowl (Numida Meleagris) in the Guinea Savannah Zone of Ghana

Effect of Age and Sex on Haematological Profiles in Indigenous Helmeted Guinea Fowl (Numida Meleagris) in the Guinea Savannah Zone of Ghana

A new method for selecting sites for soil sampling, coupling global weighted principal component analysis and a cost-constrained conditioned Latin hypercube algorithm

Analysing spatial patterns of soil properties in a landscape requires a sampling strategy that adequately covers soil toposequences. In this context, we developed a hybrid methodology that couples global weighted principal component analysis (GWPCA) and cost-constrained conditioned Latin hypercube algorithm (cLHC). This methodology produce an optimized sampling stratification by analysing the local variability of the soil property, and the influence of environmental factors. The methodology captures the maximum local variances in the global auxiliary dataset with the GWPCA, and optimizes the selection of representative sampling locations for sampling with the cLHC. The methodology also suppresses the subsampling of auxiliary datasets from areas that are less representative of the soil property of interest. Consequently, the method stratifies the geographical space of interest in order to adequately represent the soil property. We present results on the tested method (R2 = 0.90 and RMSE = 0.18 m) from the Guinea savannah zone of Ghana.•It defines the local structure and accounts for localized spatial autocorrelation in explaining variability.•It suppresses the occurrence of model-selected sampling locations in areas that are less representative of the soil property of interest.

Effects of Integrated Use of Organic and Inorganic Fertilizer on Soil Chemical Properties in the Guinea Savannah Zone of Ghana

A two-year field experiment was conducted at Nyankpala, near Tamale during the 2014 cropping season and continued in 2015, to evaluate the effects of indigenous organic materials on soil chemical properties in the Guinea savannah zone of Ghana. The treatments included 4 organic materials (Biochar, Groundnut shells, Rice husk and Rice straw) applied at 3 rates (viz. 2.5, 5.0 and 7.5 t/ha on dry matter basis) and 3 fertilizer N rates using NPK (0,45-30-30, and 90-60-60 kg/ha) in 2014 and sulfan N (0,45 and 90 kg/ha) in 2015. The plots dimensions were 5m × 5m with maize planted at 40cm × 80cm to maturity stages in both years. The results after the second year revealed that the application rate of 2.5 t/ha groundnut shells without inorganic N supplement was superior in improving soil C, N, P and K but with addition of inorganic fertilizer the same soil nutrients increased most in biochar treated soils. Rice straw without fertilizer N improved the soil pH and Ca levels. The superior effects of groundnut shells and biochar were more pronounced at the application rate of 5 t/ha with or without sulfan N. Similarly, at 7.5 t/ha application of organic materials with or without fertilizer, groundnut shells and biochar enhanced the soil nutrients than the rice materials. The rice materials were found to affect more of soil pH and exchangeable Ca but for soil Mg, biochar appeared the most influential material. We conclude that, application of either groundnut shells or biochar could improve the soil nutrients of the savanna agroecology for crop production whilst with acidic soils and/or Ca deficient soils, rice materials are recommended for use.

Evaluation of System of Rice Intensification (SRI) for Enhanced Rice (Oryza sativa L.) Production in the Guinea Savannah Zone of Ghana

Field experiment was conducted in the dry season of 2014 in the Golinga Irrigation farm (Latitude 09°21'N and Longitude 0°56' W) at Golinga, in the Northern Region, Ghana. This was to evaluate the System of Rice Intensification (SRI) for enhanced grain yield, yield components and economic viability of Gbewaa rice variety production under irrigated conditions. The experiment was laid out in Randomized Complete Block Design with three replications. The treatments comprised four SRI and two Farmers’ Practice treatments viz: FP 1, SRI 1, SRI 2, SRI 3, SRI 4 and FP 2. Under all SRI treatments, seeds were nursed and seedlings were transplanted singly and widely (25 cm × 25 cm), irrigated intermittently and soil earthing up regularly. SRI 1 and FP 2 each received only 13 t ha-1 compost, SRI 2 and FP 1 each received an amount of 37.5 kg ha-1 each of N, P2O5 and K2O as basal application and 26.25 kg ha-1 of N as top dressing while SRI 3 and SRI 4 both received 13 t ha-1 compost followed by either 18.75 kg ha-1 each of N, P2O5 and K2O as basal application or 13.13 kg ha-1 of N as top dressing respectively. SRI 1 plants established best and took the longest days to flower. Higher number of grains per panicle was obtained in SRI 3. SRI 2 produced the highest plant height, panicle length, panicle weight, tiller count and plant biomass. SRI 2 also produced the highest yield (4026 kg ha-1) which was not statistically different from the yields produced in SRI 3 (3866 kg ha-1) and SRI 4 (3737 kg ha-1) as compared with the control – FP 1 (2410 kg ha-1). The benefit – cost analysis showed that SRI 2 (1.97) was the most profiting entry followed by SRI 4 (1.35) and SRI 3 (1.31). Where mineral fertilizers are available and affordable, SRI 2 could be chosen under irrigated condition.

English

The development of crops adapted to the semi-arid and arid regions would enhance food security in Africa. As part of research towards ensuring food security, field trials were carried out to evaluate the performance of sixteen hybrids of drought tolerant Quantitative trait loci (QTL) introgression lines of pearl millet in a Guinea-Savannah zone of Ghana, where the crop is one of the cereals popularly cultivated by farmers as a staple. The hybrids were obtained from ICRISAT in India and the validation trial was laid out in a randomized complete block design with (4) replicates. All the sixteen lines (843A × H77/833-2, ICML03048 × H77/833-2, ICML03050 × H77/833-2, ICML03051 × H77/833 -2, ICML03052 × H77/833-2, ICML03056 × H77/833-2, ICML03057 × H77/833-2, 841B × H77/833-2, 863B × H77/833-2, 843A × ICMR01029, 843A × ICMR01031, 843A × ICMR 01040, 843A × ICMR 01046, 843A × ICMR 01042, 843A × ICMR 01044 and 843A × PRLT2/89-33) were able to withstand the environmental conditions during the trial period. Three entries (843A × PRLT 2/89-33, 843A × ICMR 01046 and 843A × ICMR 01029) took fewer days to boot. Two hybrids (843A × H77/833-2 and 843A × PRLT 2/89-33) had the highest values of 100-seed weight. The hybrid 863B × H77/833-2 was outstanding in terms of plant height, fresh and dry stover weights, ear head length and diameter; 100-seed weight, head yield and grain yield. It is, therefore, concluded that marker-assisted selection could be used to breed for high yielding millet cultivars in drought prone savannah agro-ecological zones of northern Ghana to enhance yields and improve food security.

Dietary intakes and body mass indices of non-pregnant, non-lactating (NPNL) women from the Coastal and Guinea savannah zones of Ghana

Adequate maternal nutrition prior to pregnancy is important for maternal health and favourable pregnancy outcomes. However, information on the dietary intakes of NonPregnant, Non-Lactating (NPNL) women in Ghana is lacking. A cross-sectional survey was undertaken to compare the dietary intakes of NPNL women of children aged 2 to 5 years who are either living in the Coastal (n=79) or Guinea Savannah (n=89) zones. Data were collected using various methods namely interviewer administered socio-demographic questionnaire, 24hr dietary recall records, with data collected on one working and one non-working day within a week, and a 1-week food frequency questionnaire. Body mass index was derived from height and weight measurements. Women in the Coastal Savannah zone had significantly (p=0.05) more formal education (3.9 ± 2.5 years) and earned a higher (p<0.001) weekly income (Gh¢ 6.8 ± 2.7) than women in the Guinea Savannah zone with educational level and incomes of 2.2±1.6 years and Gh¢ 3.9±2.4 respectively. More women in the Coastal zone had significantly (p<0.05) fewer births and were heads of their households. Cereal-based foods were consumed daily by all women during the two-day observation period. Fish was the predominant animal source food in the diet in both zones. Significantly (p<0.05) more women in the Guinea Savannah zone did not meet their Estimated Average Requirements (EAR) for protein (81%), vitamin A (94.4%), and vitamin C (72%) compared to women in the Coastal zone (44%, 22%, and 31% respectively).The diets of both groups of women were low in calcium. Generally, women in the Coastal zone had a significantly (p<0.001) higher BMI (24.2 ± 4.6 kg/m2) than their counterparts in the Guinea Savannah zone (21.3± 2.4 kg/m2).The overall quality of dietary intakes and nutritional status of women in the Guinea Savannah zone was poorer than that of Coastal women. Dietary deficiencies are also present in NPNL women in Ghana. Efforts are needed to improve diet quality and to increase access to resources especially for women in the Guinea Savannah zone of Ghana.

Above-ground biomass, nutrients, and persistence of an early and a late maturing Mucuna variety in the Forest–Savannah Transitional Zone of Ghana

Abstract Many farmers in West Africa have adopted the herbaceous legume, Mucuna pruriens, as a fallow species to control weeds and to increase soil fertility on crop lands. This paper presents the biomass, nutrient content, and persistence results of farmer managed trials with late maturing M. pruriens var. utilis (L.) D.C. and an early maturing unclassified Mucuna cultivar relative to a short season natural fallow (control). From August until December 1998 and from June 1999 until March 2000, research was conducted at different farm locations in the Forest–Savannah Transitional Zone and in the Guinea Savannah Zone of Ghana. The following parameters were evaluated: (1) accumulation of above-ground Mucuna biomass during the short rainy season; (2) atmospheric N2 fixation during the same period; (3) Mucuna seed yield components; (4) persistence of above-ground Mucuna and natural fallow biomass throughout the dry season; (5) nutrient concentration and nutrient accumulation of Mucuna and natural fallow at the beginning and the end of the dry season; and (6) percentage ground cover by various biomass components throughout the dry season. During the first 2 months of establishment, M. pruriens grew slowly, producing 163 kg ha−1 above-ground biomass after 30 days and 1472 kg ha−1 after 60 days, but produced 4003 kg dry matter ha−1 after 90 days. Atmospheric nitrogen (N2) fixed by late maturing M. pruriens was estimated at 107.7 kg ha−1 but only 46.1 kg ha−1 for the early maturing Mucuna cultivar. The estimated amount of N2 fixed was significantly correlated with the amount of Mucuna biomass produced with R2 = 0.75 for the early maturing cultivar and R2 = 0.69 for M. pruriens. The nutrient uptake of macronutrients other than N in the Mucuna fallow did not differ significantly from that of the natural fallow treatment for either cultivar. Following a linear regression model, total above-ground biomass on M. pruriens plots declined by 503 kg ha−1 every 4 weeks from November until March, while the biomass on plots planted with the early maturing Mucuna cultivar declined by 911 kg ha−1. While ground coverage (including weeds and crop residues) on fields planted with M. pruriens was still 89.7% at the end of the dry season, coverage on fields planted with the early maturing Mucuna variety averaged only 72%. It was concluded that late maturing Mucuna varieties planted as a relay intercrop in maize (Zea mays) in June can be more easily integrated into existing farming systems than early maturing ones planted in August/September because Mucuna planting does not compete with other farming activities but can be combined with the second weeding of maize. Moreover, it is suggested that the major advantage of a Mucuna fallow is based on the option of not having to burn vegetation in preparation for the next cropping season. The few emerging weeds can be easily slashed as compared to a natural fallow which produces large amounts of lignified plant material. Therefore, this slash-and-mulch technology leads to reduced nutrient losses.

Improving Maize Yield in the Guinea Savannah Zone of Ghana with Leguminous Cover Crops and PK Fertilization

Improving Maize Yield in the Guinea Savannah Zone of Ghana with Leguminous Cover Crops and PK Fertilization

Recovery of cover-crop-N in the soil-plant system in the Guinea savannah zone of Ghana

In order to understand the efficiency of residue-N use and to estimate the minimum input required to obtain a reasonable level of crop response, it is important to quantify the fate of the applied organic-N. The recovery of N from 15N-labelled Crotalaria juncea was followed in the soil and the succeeding maize crop. Apparent N recovery (ANR) by maize from unlabelled Crotalaria juncea, Crotalaria retusa, Calopogonium mucunoides, Mucuna pruriens and mineral fertilizer at three locations were also evaluated. The maize crop recovered 4.7% and 7.3% of the 15N-labelled C. juncea-N at 42 days after sowing (DAS) and at final harvest, respectively. The corresponding 15N recovery from the soil was 92.4% and 58.5%. The highest mean ANR of 57.4% was with mineral fertilizer, whereas the mean ANR of 14.3% from C. retusa was the lowest. A large pool substitution and added-N interaction effect was observed when comparing N recovery from the labelled and unlabelled C. juncea. The amount of residue-N accounted for by the isotope dilution method at 42 DAS was 97.1% and at final harvest 65.8%. The large residue-N recovery in the soil organic-N pool explains the residual effect usually observed with organic residue application.

Correlation and Path Coefficient Analyses of Yield and Yield Components in Pigeonpea

Growth and yield components on which selection for high grain yield could be based among early maturing pigeonpea varieties were investigated in field trials conducted in the Guinea savannah zone of Ghana. Ten genotypes were tested during the 1996, 1997 and 1998 cropping seasons for their yield performance. The trial for each year was arranged in a randomised complete block design with 4 replications. Significant differences (P # 0.05) were found among genotypes for grain yield for each of the years. Relative yield ranking of genotypes did not shift significantly between years. Investigation of yield differences between genotypes using phenotypic correlation and path coefficient analyses have shown that crop growth rate, harvest index and number of pods per plant are the most effective secondary traits to select for high grain yielding varieties in Northern Ghana. A significant positive linear correlation (P # 0.05) was found between each of these traits and grain yield and between pairs of traits. Each of these traits showed a large positive direct effect on grain yield as well as large positive indirect effects through each other on grain yield.

Phosphorus adsorption by surface samples of five ironpan soils of Ghana

Phosphorus adsorption by surface samples of five ironpan soils (Kumayili, Kpelesawgu, Nyankpala, Wenchi and Changnalili series) within the Guinea Savannah zone of Ghana were studied. The samples differed in their capacity to adsorb added inorganic P. Per cent adsorbed P decreased as P additions and equilibrium P concentrations increased. P adsorption isotherms obtained were in two parts, and approximately 25 and 40% of the total adsorption was represented by the first lower part of the Langmuir isotherm. Phosphorus adsorbed correlated with percentage organic matter, oxalate-extractable Al and dithionite-HCl-extractable Fe but not with percentage clay, pH and dithionite-citrate-extractable Fe. Fractionation following six days of equilibration showed that added inorganic P was retained mostly as Al-P rather than as Fe-P. It was found that samples of three of the ironpan soils, the Kumayili, ?Kpelesawgu and Nyankpala series, have low P adsorption capacities.