Yields are presented for a 54-week cutting experiment (1962–3) in which coastal bermuda (Cynodon dactylon sp.), pangola (Digitaria decumbens) and guinea (Panicum maximum) grasses were subjected to three cutting heights (1, 3 and 6 inches), four cutting intervals (1, 3, 6 and 9-weeks) and four nitrogen fertilizer regimes (0, 8, 16 and 32 cwt sulphate of ammonia per acre per annum). The results indicate that coastal bermuda and pangola grasses will tolerate severe cutting but not guinea grass. The highest dry matter yields were obtained from guinea grass, at 16½ tons/acre. Whereas the highest yields of coastal bermuda and pangola were 12½ and 12 tons/acre respecitvely. In the absence of measures of nutritive value it is impossible to say which is the best management system to adopt, but the facts presented may help to determine management practices.

After a review of previous work, experiments on cocoa seed storage at the West African Cocoa Research Institute are described. Although no definite recommendations are made as to the optimum methods of storing cocoa seed, the effects of temperature, fungicides, pre-storage in the pod after harvest, air-drying, and some minor factors are described and discussed.

In a factorial experiment with two spacings, four numbers of seedlings per hill, and two levels of nitrogen the highest numbers of shoots were produced in high nitrogen and high plant density plots. Increasing the number of seedlings per hill led to a rise in the number of shoots per plot and this was more pronounced in high than in low plant densities. Significant differences in shoot number between high and low nitrogen plots occurred only at the higher plant density, but high nitrogen and wide spacing led to an increase in the number of shoots per hill and per plant. Increasing the number of seedlings per hill resulted in an increase in the number of shoots per hill but a decrease in the number of shoots per plant. The effects of treatments on leaf blade area at ear emergence and on grain yields were similar to those on shoot number. The percentage increase in the yield of grain per unit area due to increasing the number of seedlings to three and four were 12 and 9 respectively. The percentage shoot mortality was greater in plots with low than with high plant density. Plants were higher in high nitrogen plots, especially at high plant density, while high nitrogen supply and four seedlings per hill increased the number of days from seeding to ear emergence. The former treatment also increased ear length. Low plant density and three seedlings per hill increased the ear to shoot dry weight ratio. The best combination of treatments for high grain yield was high nitrogen, 15 cm x 15 cm spacing, and four seedlings per hill.

Three Nigerian vegetables, Solanum melongena, Solanum nodiflorum and Vernonia amygdalina were analysed for oxalate, cyanide, minerals and food value. The edible leaves were low in oxalate and so involve no danger of oxalate toxicity, or decrease in their nutritive value due to the presence of oxalic acid. The content of hydrocyanic acid was also negligible and would, in any case, be lost during cooking. Aluminium contents were very high and could possibly be regarded as constituting a toxic level. The calcium content would provide about 4–7 per cent of the daily requirement for adults, who could depend solely on these vegetables for their daily iron requiretnents. The leaves were also good sources of protein. All these factors make the vegetables important dietary components in Nigeria and they could serve as a protein supplement, especially in villages where children can not get enough protein from meat, milk and cheese.

A simple but reliable type of drainage lysimeter was used to measure evaporation rates from lucerne and wheat and these were compared with calculated estimates of evaporation. Plant height was found to have an important effect on the amount of water lost from a plant cover, which also varied between two different species of crop of similar heights. Using two different soil types, maintained at a high moisture status, the rate of water loss was not influenced by the type of soil in which the plants were grown.

The results are reported of three field experiments conducted from 1955 to 1963 to investigate the effects of sunn green manuring in the sugar cane rotation. In a three-year rotation with sugar cane and wheat, green manuring twice was not superior to green manuring once, either in terms of sugar cane yield or the nitrogen and organic carbon status of the soil. Two experiments showed that the yield increase of cane was proportional to the weight of the green manure crop, irrespective of how the latter was disposed of, suggesting that the only factor with which yield increase was correlated was the weight of roots of sunn which were incorporated into the soil. The green manure effect is resolved into two components namely ‘green matter effect’ and ‘legume effect’, both of which are additive and nearly equal.

Measurements are reported on the influence of mulch on the chemical and physical characteristics of the soil and the chemical composition of the crop, together with growth measurements on an indicator crop in the greenhouse and on mature coffee in the field. Mulch reduced soil acidity; increased organic carbon, Kjeldahl nitrogen, exchangeable potassium and available phosphorus; and decreased exchangeable calcium and manganese. It increased total pore space, free-draining pore space and rate of rainfall acceptance in the top soil. Effects on the coffee were to increase phosphorus, potassium and in some cases nitrogen in the leaf, but reduce magnesium and calcium levels. Potassium and calcium levels were increased in feeder roots, whereas in the ripe cherry the phosphorus level was increased but nitrogen, calcium and magnesium levels were reduced. The soil effects were reflected in increased growth of the indicator crop and mulch improved the growth of the coffee tree in a year of seasonal drought.

An experiment is described on the establishment of cocoa on clear-felled land, using various ground covers on which 22 NP:KMg factorial treatments were later superimposed. Growth of cocoa was improved in mulched and clean-weeded plots and the unshaded trees began bearing two years after planting, which is exceptionally early for young cocoa in Ghana. In the third year responses to NP fertilizer were obtained and in the following year yields were very high, up to 2170 pounds dry cocoa per acre. This was partly responsible for K deficiency, particularly in plots without mulch and KMg, which led to declining yields especially on the NP plots. Significant increases were thence obtained from the KMg fertilized plots. Mulching at the rates used in this experiment is too expensive and uneconomic, but K fertilizer applied at rates higher than the present rate of 75 lb K2O/acre/annum may be needed on Ghanaian forest soils if they are clear-felled for growing unshaded cocoa.

The time and method of placement, and the distance from the plant at which fertilizers should be placed, was studied on sole-crop cowpeas. The development and yield of both early and late season crops were highest where fertilizers were applied at planting. It is suggested that it might be more advantageous to plough the fertilizers under before planting, so that the nutrients will become available to the seedlings from the time they emerge. Application of fertilizer in two bands gave the highest yields, but was not significantly superior to a less laborious method of application in one band. The distance at which the fertilizer was placed, and treatment interactions, did not show any definite trends.

The pattern of yield and productivity of a typical Raphia swamp is described and suggestions are made for improving the crop by selection

A detailed soil map of the Island of Barbados has recently been completed, and a number of factors make this area an interesting ‘laboratory‘ in which to investigate the uses to which such a map may be put. The map has already proved to be of considerable value in extension work by providing a more rational basis for advice about cultivations, growth and ripening patterns, crop diversification and the organization of simple dispersed-block trials. Because of the importance of available soil moisture and drainage, techniques have been developed to investigate these aspects in relation to the different soil types. The most rewarding feature, however, has been the enthusiastic response of plantation managers to the soil map as a basis for the exchange of information, the communication of the results of experimental work, the reorganization of field boundaries, and the introduction of new crops.

The effect of grass mulch on groundnut yield and shelling percentage has been studied at three locations in the Gambia. Yield increases have been mainly attributed to physical factors but residual increases were found for only one year after application. Mulching gave rise to significant increases in exchangeable soil potassium, in percentage potassium in the plant at harvest and in total potassium uptake by the plant. In the absence of response to potassium fertilizer, increased uptake was ascribed to luxury consumption. It was suggested that reduced shelling percentage from mulched plots was due to potassium-calcium antagonism.

As part of a project to introduce Virginian-type flue-cured tobacco varieties into a new area, a number of experiments on the effect of time of planting showed that returns declined according to the delay in planting after the start of the rains. This decline was not arrested by differential fertilization, soil fumigation or the use of quicker maturing varieties. The early plantings appeared to have a greater growth potential, which could often be more fully realised under improved cultural techniques. Thus, early plantings gave substantial positive responses to applications of nitrogen which had little effect on, or were detrimental to, later plantings. It is suggested that the responses noted were linked with weather conditions during the first few weeks after planting. The drier and more sunny these were, the better, and the possibility therefore arises of using rainfall probability data, with a minimum of field experimentation, in future problems of this nature.

Groundnuts (Arachis hypogaea L.) have been found to be one of the most promising additional cash crops for diversifying Sudan agriculture. Three hundred and thirteen agronomically distinct forms have been separated from 171 varietal samples, and 121 short-maturing upright bunch types and 49 long-maturing spreading bunch types have been tested in a series of trials over several years in four climatic regions. Among upright bunch varieties, PJ121070 and Large Natal 142 appeared to be the best selections as oil and confectionery types respectively, and among spreading bunch varieties, MH.372, Beladi Bunch and NJ37 for oil, confectionery kernels and unshelled nuts respectively. A hybridization programme was started in 1959 to improve the existing varieties of groundnuts and to produce non-germinating upright bunch varieties for growing in the heavy clay soils. Inheritance studies indicated the dominance of an alternate pattern of branching, prostrate plant habit and long maturity. Dominance of testa colours was in the order of purple–red–russet brown–light brown–white. Recessive albino seedlings were observed only in crosses involving different branching pattern. There appeared to be no association between the various characters studied except maturity period, which was related to branching pattern and growth habit.

In a trial carried out in 1958, aldrin applied as a fog with a swingfog machine at concentrations of 10 and 20 per cent in gas oil was more effective than dieldrin or chlordane at similar concentrations for control of Atta cephalotes. Two applications of 10 and 20 per cent benzene hexachloride and toxaphene failed to give complete control. In a subsequent trial, aldrin in concentrations ranging from 2·5 to 8·0 per cent was also found to be effective against A. cephalotes but against A. laevigata, aldrin and dieldrin were more effective than chlordane at concentrations of 5·0 and 2·5 per cent. In campaigns carried out from 1959 to 1963, 5000 nests were destroyed by fogging with 2·5 per cent aldrin in gas oil.

Suggested rules are given for the presentation of numerical data in a scientific agricultural journal. These are that all tables of numerical results should be sufficiently clear to render unnecessary any reference to the accompanying text; and that treatment means (and other statistics) should always be accompanied by their standard errors, rather than by least significant differences or by asterisks showing the results of significance texts. Examples are given of correct and incorrect presentation of results, and the graphical presentation of results is also discussed.

Use of substituted phenoxyacetic acids as yield stimulants for Hevea brasiliensis has been mainly limited to applications below the tapping cut rather than above. Although the above-cut application of these stimulants has exhibited some advantages with respect to yield, its use has been limited due to undesirable bark renewal characteristics. This paper describes studies with a method of above-cut application of stimulant which appears to eliminate the previous disadvantages. Reduced concentrations of growth regulator, applied at frequent intervals in combination with a disease preventive measure, resulted in favourable yield responses, bark renewal characteristics and application economics. Subsequent bark renewal was apparently directly proportional to the concentration of stimulant applied and it was thus possible to control the degree of bark regeneration. The above-cut method shows promise of being particularly effective with systems of reduced intensity tapping on certain clones.