Ethephon substantially increased pod numbers of a rust-susceptible cultivar, by inducing leaf fall and a second flowering, but had no such effect on a rust-resistant cultivar. The treatment reduced seed number per pod in both cultivars. B-9 increased pod number in the rust-resistant cv. but reduced mean pod weight and seed number per pod.

Precipitation in Western Nigeria is principally from thunderstorms with sharp, high-intensity rainfall peaks. The time of occurrence of the peak intensity period in a rainstorm has an influence on whether or not runoff occurs in smaller storms. Runoff and soil loss on bare, cultivated Iwo soil are closely related to an EI30 erosivity index, modified by the time-position of the peak intensity. The soil erodibility factor in the universal soil-loss equation could be reasonably estimated from easily measured soil parameters.

The results are reported of an experiment on the Lilongwe Plain to investigate the effects of under-sowing maize with a mixture of Rhodes grass and silverleaf desmodium. Undersowing caused no significant reduction in any component of maize yield, and mixed swards with a good legume content were established. Nitrogen application had no significant effect on yields of grain or pasture, but in the following year undersown swards outyielded those directly seeded. Some practical advantages of undersowing are discussed.

Groundnuts given a mixture of S35-labelled ground rock phosphate and sulphur at planting were radioactive 14 days later, when go per cent of the seedlings had emerged. Forty days after planting one-third of the total plant-S was from the fertilizer, and the mean recovery of fertilizer-S was 18 per cent by harvest. In field experiments the mixture outyielded ground rock phosphate and was as good as single superphosphate, though drought diminished yields generally. At three sites which were harvested the percentages of applied-S recovered were 12, 20 and 27 per cent. Significantly more P was taken up by the crop receiving the mixture than was recovered from the ground rock phosphate alone.

Different methods of undersowing maize with a mixture of Rhodes grass and silverleaf desmodium were compared, together with the effects of applied nitrogen, in an experiment on the Lilongwe Plain. Drilling the legume on the ridge or in the furrow was superior to broadcasting, and caused no substantial reductions in maize yield. Nitrogen application increased all aspects of maize production but slightly reduced legume yield. The data generally confirm previous findings that undersowing causes no appreciable and consistent reduction in maize yield, and results in the establishment of mixed swards with a high legume content.

This paper, concerned with agricultural development planning problems in the Sahelian and Sudanian (semi-desert and savanna) zones in Africa between 10 and 16° North, describes a plan for Darfur, Western Sudan. This aims to modernize a stagnant and primitive technology and out-dated land rights which, in the face of rapid population increase and climatic change, are reducing the long-term carrying capacity of the land. The development plan (H.T.S., 1974) has been based on a 2-year (1972–73) survey by a team of physical and social scientists, financed by the Overseas Development Administration of the United Kingdom and the Ministry of Agriculture in the Sudan.

Nitrogen fertilizer applied to the surface of the soil in the field did not increase the yield of Bragg soybeans, and at higher levels reduced it, but may or may not significantly reduce soybean nodulation and plant height. In a pot experiment, there was evidence that deeply applied N increased plant height and dry weight of a non-nodulating isoline of Clark soybeans 46 days after planting.

Effects of sowing dates, population, fertilizer, weeding and variety inputs on yield were measured, as well as labour required to apply the inputs. Sowing date was the most important, response to others being dependent upon this factor. Population was least important, but increased in value as fertilizer level was raised. Labour requirements were so increased by applying the ‘package’ that subsistence farmers, whose families are fully occupied as the sole source of labour, would be unable to cope without reducing the area under cultivation. Thus yield response to a package must be higher than hitherto considered acceptable, and the risk of not obtaining this increase probably contributes to the rejection of such recommendations by subsistence farmers.

Low and unreliable rainfall, combined with high summer evaporation rates, frequently lead to poor yields and crop failure in Botswana agriculture. Over three test years it has been shown that the soil can store up to 100 mm. of available moisture at planting time, which represents about half the water requirement of a crop of sorghum, and the balance is likely to be met (P = 0.05) during the current growing season. Sorghum grain yields have been doubled (2007 kg./ha.) after fallow compared with 1028 kg./ha. after non-fallowed pre-treatments. The advantages of a farming system based on a bare summer fallow are discussed, and reference is made to the implications of its wider adoption.

Effects are reported of some factors which may influence emergence and establishment of pigeon pea (Cajanus cajan (L.) Millsp.), including seeding depth, seed dressing, seed grading, seeding rate, variety and temperature. The effect of seeding rate was dependent on mean germination percentage in the field, but circumstantial observations on other factors of possible consequence in determining plant stand are also discussed.