Relative efficacy of cocoa pod husk-based compost on growth and nutrient uptake of cocoa seedlings in the nursery

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<0.05) affected by the potting media at 24 weeks after sowing. Potting media with the fertilizer additions significantly (P<0.05) produced shorter seedlings with smaller stems and narrower leaves. Root volumes and total dry matter yield of seedlings positively correlated (r = 0.733), and were significantly (P<0.05) higher in soil/compost mixtures than in treatments with fertilizer additions. Irrespective of the potting media, the uptake of N by the seedlings was higher than P and K. However, the addition of fertilizer to the potting media with compost resulted in lower N uptake by the seedlings. The use of compost developed from cocoa pod husk as potting medium or soil amendment for nursing cocoa seedlings enhanced better seedling growth than when used in combination with NPK 15-15-15 fertilizer

Boron levels in soils cropped to coffee and their relationships to some soil properties in Ghana

Studies on boron levels in soils cropped to coffee were carried out in Ghana due to widespread reports on boron deficiency in soils of some coffee producing countries. Leaves and soils were sampled from Cocobod coffeeplantations at Bogoso, Suhuma, Manso-Mim, Bunso and Bepong, which represent the main coffee growing areas in the Western, Ashanti and Eastern regions of Ghana. Also determined were percent OC and Ca, pH, texture and statistical relationships established for both leaf and soil boron contents and the soil properties. The results showed that availableB in the 0-30 cm depth ranged from 0.77 to 1.54 mg B kg-1 soil. Surface soil pH values ranged from 5.4 to 6.8 and the subsurface soil from 5.1 to 6.7. Leaf B was between 28.7 and 42.5 mg B kg-1. The leaf Ca/B ratio used as index of B deficiency was between 331.4 and 398.8; values high enough to suggest that boron was low compared to Ca concentrations in the leaves, a condition which implies that available B in the soils was below the levels required to support coffee plants. All locations of sampling indicated that there was positive correlation between percent OC,calcium and available B in the surface soils. Similarly, the relationship between percent clay, calcium and available B in the subsurface soils was positively correlated. Soil available B at 0–30 cm depth was highly influenced by percent OC and pH. Coffee leaf B content and soil pH was negatively correlated at pH above 5.8, but was positive when the pHwas below 5.8. Boron levels in the coffee leaves were within the critical range of 2–40 mg B kg-1 although soil available B appeared low

Impact of shade and cocoa plant densities on soil organic carbon sequestration rates in a cocoa growing soil of Ghana

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

Amounts of NPK removed from soil in harvested coffee berries as guiding baseline for planning fertilizer requirements of coffee in Ghana

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<0.05) higher amounts of N and K than the berries from the marginally suitable site, while the P contents of the berries were significantly (P<0.05) lower than N and K across the locations. Regardless of the coffee growth forms, the demand for N and K may be higher than P. A fertilizer rate of 30 kg N, 1 kg P, and 33 kg K ha-1 may serve as a basis for planning fertilizer requirements of mature coffee in Ghana

Effect of weed control methods on some soil properties of a newly planted cocoa farm

Weed control constitutes a high percentage of the total field maintenance cost of newly planted cocoa. Soil samples were collected from an experiment that was designed to evaluate some weed control methods during cocoa establishment. The objective of the experiment was to assess the effect of the weed control methods on microbial biomass and extractable N and P contents of the cocoa-growing soil during cocoa establishment. The weed control treatments were clean weeding, two times per year; clean weeding, three times per year; clean weeding, four times per year (recommended practice); high slashing, four times per year; clean weeding (1 m wide), three times per year plus Mucuna pruriens cover crop; clean weeding, three times per year plus Flemingia congesta mulch; Gramoxone 1.5 l ha-1, four times per year; and Roundup 1.5 l ha-1, three times per year arranged in a randomized complete block design. Microbial biomass N content ranged from 10.8 to 42.5 mg N kg–1 soil. Microbial biomass N was significantly higher (

Cooperative management and its effects on shade tree diversity, soil properties and ecosystem services of coffee plantations in western El Salvador

We compared how management approaches affected shade tree diversity, soil properties, and provisioning and carbon sequestration ecosystem services in three shade coffee cooperatives. Collectively managed cooperatives utilized less diverse shade, and pruned coffee and shade trees more intensively, than individual farms. Soil properties showed significant differences among the cooperatives, with the following properties contributing to differentiation: N, pH, P, K, and Ca. Higher tree richness was associated with higher soil pH, CEC, Ca, and Mg, and lower K. Higher tree densities were associated with lower N, K, and organic matter. Although we found differences in the incidence of provisioning services (e.g., fruit), all plantations generated products other than coffee. No differences were observed between C-stocks. The history and institutional arrangements of cooperatives can influence management approaches, which affect ecosystem properties and services. Our study corroborates that interdisciplinary investigations are essential to understand the socio-ecological context of tropical shade coffee landscapes

The Effects of Benomyl and Glyphosate Treated Plant Litter on Nitrogen Mineralization in Mollisols

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

Evaluation of fertilizer application on some peasant cocoa farms in Ghana

Low soil fertility has been identified as a major cause of decline in yield of cocoa (Theobroma cacao L.) on peasant farms in Ghana. The objective of the trial is to evaluate the effect of fertilizer application on yields of cocoa (T. cacao L.) under peasant farmers' management in Ghana with the aim of introducing fertilizers to farmers. This paper presents the results for 4 years of fertilizer trials on peasant farms. Triple or single superphosphate and muriate of potash at the rate of 129 kg P205 and 76.5 kg K2O ha-1 yr1, respectively, were applied to one half of 1.6-ha plot whilst the other half did not receive fertilizers. Generally, the fertilized plots on all the farms showed an increase in yield over the unfertilised plots during the 4-year period. The gross yields of the fertilized plots exceeded those of unfertilised plots by 61.7 per cent in the 1st year, 99.8 per cent in the 2nd year, 116.0 per cent in the 3rd year, and 106.0 per cent in the 4th year. At the end of the 4th year, 75 per cent of the farms had yields more than 1000 kg/ha. There were no significant differences between the age of the farms and variety of cocoa with fertilizer responses. Furthermore, there was no direct relationship between fertilizer treatment and incidence of diseases and pests. Substantial yields of over 1000 kg/ha could be obtained by adopting proper agronomic practices and the use of fertilizer compared to 280 kg/ha no produced in Ghana. Economic analysis of results indicated that the use of fertilizers on small-holder cocoa farms was profitable. Evaluation d'application d'engrais chimique sur quelques petits champs de cacao paysans au Ghana Résumé La fertilité basse du sol a été identifiée comme la cause principale de diminution en rendement de cacao (Theobroma cacao L.) sur les petits champs paysans au Ghana. Le but de l' essai est d'évaluer l'effet de l'application d'engrais chimique sur les rendements de cacao (T. cacao L.) sous l'exploitation des petits cultivateurs paysans au Ghana avec l'objectif de l'introduction des engrais chimiques aux cultivateurs. Les résultats pour les 4 années des essais d'engrais chimique sur les petits champs paysans sont prisentés dans cet article. Le superphosphate triple et simple en plus de muriate de potasse à la proportion de 129 kg P2O5 et 76.5 kg K2O par ha/an respectivement étaient appliqués à une demie de 1.6ha de lot alors que la demie autre n'avait pas regu des engrais chimiques. Dans l'ensemble les lots fertilisés sur tous les champs montraient une augmentation en rendement par rapport aux lots non fertilisés pendant la période de 4 années. Les rendements bruts des lots fertilisés dépassaient ceux des lots non fertilisés par 61.7 pour cent dans la première année, 99.8 dans la 2e année, 116.0 pour cent dans la 3e année, et 106.0 pour cent dans la 4e année. A la fin de la 4e année, 75 pour cent des champs avaient plus de 1000 kg/ha de rendements. Il n'y avait pas des différences considérables entre les âges des champs et la variété de cacao avec l'engrais chimique en ce qui concerne les réactions. Par ailleurs, il n' y avait pas de rapport direct entre le traitement d' engrais chimique et le taux des maladies et les insectes ravageurs. Des rendements substantiels de plus de 1000 kg/ha pourraient être obtenu par l'adoption des pratiques agronomiques appropriées et l' emploi d' engrais chimique en comparaison de celui de 280 kg/ha produit à présent au Ghana. L' analyse économique des résultats indiquait que l'emploi d' engrais chimique sur les champs de cacao des petits cultivateurs était rentable. Ghana Jnl agric. Sci. Vol.33(2) 2004: 183-19

The consequences of cocoa production on soil fertility in Ghana : A review

Cocoa cultivation over the past 20 years has been concentrated in the Western Region of Ghana where Most of the soils have been found to be unsuitable for the crop. During the 10-year period (1982-92), the estimated total amounts of major nutrients removed from the soil through the harvested beans alone were 76 000, 4 700 and 18 000 tonnes of NPK respectively. The non-use of fertilizer has led to decline in soil fertility with consequential decrease in production. The paper reviews and discusses the effects of cocoa production on soil fertility in Ghana and offers possible solution to the declined soil fertility. Ghana Jnl agric. Sci. Vol.30(2) 1997: 183-19