For Muguga, in Kenya, confidence limits of expected ‘twenty-day’ rainfall may be reliably derived through a logarithmic transformation of the skew rainfall data. Frequency distributions of rainfall totals received during specific crop-growing seasons are examined for three widely separated Kenya sites. It is shown that confidence limits for such seasonal rainfall cannot be obtained by summation of the corresponding limits for the successive twenty-day intervals included within the season. Twenty-day limits should not therefore be accumulated in seasonal comparisons of crop water requirements and precipitation. Such assessments of agricultural site potential must take account of the year-to-year variability of precipitation, but are best undertaken with actual rainfall amounts.

Confidence limits of expected twenty-day rainfall have been computed for two widely separated maize-producing regions in Kenya. The 35-km. square survey areas were quite different topographically, and limits were derived for seven rainfall sites in each. Ratios of these limits to the corresponding long-term mean precipitations were evaluated for each site for each twenty-day period during the appropriate maize-growing seasons. For a particular period and confidence level, these ratios were almost constant for either group of seven sites. The variability computed for a single, well-chosen site is therefore representative of quite a large neighbourhood. Expected rainfall totals were also derived for a ‘fictitious’ site, simulating the average precipitation over the whole of the flatter of the two areas. The resulting limits were less extreme than those of any individual site, indicating that areal rainfall, as used in hydrology, is less variable than the agriculturally-important point rainfall.

Yields of sugar cane in low-silicon soils were significantly increased by the application of both calcium silicate and coral sand. Over and above the significant response to Ca and increase in soil pH, there was a highly significant response to Si. The overall response to the higher level of calcium silicate application (14·2 tons/ha.) over the control was 28·3 tons of cane per hectare. Neither calcium silicate nor coral sand influenced the sucrose content of the juice.

A crop of broad beans was subjected to different water treatments with a view to finding the most economical irrigation policy. Increments in yield were obtained from the sixth to ninth irrigation, but the relative significance of each irrigation after the sixth was dependent upon whether irrigation water was saved during the vegetative and early flowering phase, or during the phase of pod development. The influence of the different water regimes on yield components and on some attributes of growth was studied.

A uniformity trial was carried out at Banting, Selangor in West Malaysia to estimate optimal sampling rates for determining foliar nutrient contents of oil palms. The results suggest that the unit for sampling in this area is greater than 10 acres but less than 50. A comparison of the results with those obtained in Nigeria shows a large measure of agreement. Factors concerned in choosing a sampling rate are discussed. With the information available a rate of 2–3 per cent appears adequate.

Three methods of applying four fungicides were tested for controlling powdery mildew on roses. Best results were obtained by air blast application, with high-volume sprays providing better control than low-volume sprays. The former, unassisted by air blast, failed to give adequate control. Fluorescent tracers showed that performance of various modes of application depended on their ability to provide a satisfactory fungicide deposit on the lower leaf surface, which was particularly susceptible to the disease.

To assess the potentialities of Ph. vulgaris for haricot type bean production in Britain, a large collection of types was surveyed. One hundred varieties, mostly but not exclusively bush types, were grown both in the greenhouse and in the field. Characters of agronomic importance were evaluated. The morphological basis of the difference between the climbing and the bush habit was shown to be the interaction between two character contrasts, indeterminate versus determinate vegetative growth, and long versus short internodes. The four classes resulting from this interaction were identified and are described. Flowering habit, pod type and seed size were surveyed. Among the bush beans, wide variation in day length sensitivity in flowering was shown, and it is clear that day length neutral types can easily be selected. Among the determinate dwarfs, pods are either leathery or fleshy. Leathery types dry out readily, and do not dehisce freely in the field, and are therefore agronomically desirable in dry bean production. Fleshy pods are used for culinary purposes. The indeterminate bush types included in this survey have parchmented pods, which tend to dehisce when dry, and hence are subject to crop loss in the field. A wide range of seed size and seed colour is available for selection according to requirement. Two small variety trials yielded evidence that Colombian determinate bush types grow and crop satisfactorily within the limits of the growing season in eastern England. From two spacing trials, optimum within-row spacing was deduced.

A three-year study of the effects of sowing date, nitrogen application and seed rate on wheat showed that sowing in mid-October gave consistently greater grain yields than sowing in mid-September or mid-November because grains were larger and more numerous per head. Nitrogen increased yields but the effect decreased with later sowing. Nitrogen probably increased grain yield by increasing the number of ears, but this effect diminished with higher levels of nitrogen. Grain yield was only slightly influenced by seed rate, and the interaction of seed rate with sowing date or nitrogen was unimportant.

Nitrate content in the petiole of sugar beet (var. Polygrave) reaches its maximum three months after emergence of the seedling. There is a linear correlation between the final yields and the nitrate content of the petiole at the maximum stage. Nitrogen fertilization should be given in the first three months of the beet growth.

In Kenya, coffee growing east of the Great Rift Valley has its main flowering either in February–March or in October–November. These flowerings are mainly initiated from approximately August to December and June to September, respectively. Changes from an early to a late flowering rhythm and vice versa can be caused by (a) pruning, (b) the condition of the tree, and (c) the weather pattern, but more information is needed for a complete understanding of this problem.

Cross-inoculation tests among ten Acacia species and cowpea (Vigna sinensis) showed that eight Acacia spp were related to cowpea while two were independent and this agreed with the placement of Acacia in the cowpea group. The Acacia rhizobia showed certain cultural and physiological similarities to the cowpea Rhizobium and were resistant to high temperatures.