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Similar conclusions were reached in the case of sunflower seed, of which heated and unheated samples were sent by air and sea.
7. ALTERNATE CROP STUDIES
The original White Paper, on which the Scheme is based, suggested a rotation consisting of two consecutive years of groundnuts followed by two years of a grass ley. The ley was intended primarily to improve soil structure by root action, in accordance with the results of research in Uganda. From work at Ukiriguru, such, effects are less likely on the more sandy soil types which characterise a considerable part of the Corporation's areas in Tanganyika. Also, the economic use of the grass ley involves the building up of cattle herds and of water supplies. Nevertheless, on the heavier, compacting soils, crop residues and root action may have a considerable part to play.
It is also economically desirable to increase the proportion of cash crops in the rotation, and it was accordingly decided at an early stage to devote a con- siderable volume of work to studies of other rotation crops and to investigate the technical possibilities of rotations with a high proportion of cash crops. In the season under review, a wide range of crops and varieties was planted on experi- mental plots, mostly in the Kongwa Region.
Sunflower
At Kongwa, two mid-January plantings of the Hungarian dwarf variety yielded 1,160 and 1,320 lbs. seed per acre, and Pole Star and Saturn, also planted in mid-January, gave 1,255 and 1,153 lbs. per acre. Other varieties planted at the same time gave from 450 to nearly 800 lbs. Later plantings of Hungarian, towards the end of February, gave much poorer yields, probably due in part to drought.
A variety trial planted almost at the end of the rains in mid-March gave yields ranging from 350 (Hungarian) to 136 lbs. seed per acre (Sunrise). Pole Star gave 260 lbs. and Advance Hybrid 170 lbs. These results are not of direct economic interest except in so far as they confirm the greater suitability of Hungarian and Pole Star to the conditions of the Kongwa area.
A second late-planted experiment (8th March) compared drilling at 2 and 6 lbs. seed per acre with broadcasting at 371 and 75 lbs. per acre. All yields were low, the best being 280 lbs. per acre at the 6 lbs. level. Two lbs. of seed gave 217 lbs. per acre of crop, and the broadcast treatments gave 173 lbs. and 122 lbs. for 371 and 75 lbs. respectively. A larger scale broadcasting trial at similar rates gave 200 lbs. per acre.
In the 1947-48 season, all plantings at Kongwa later than mid-January gave poor results doubtless owing partly to the arid conditions throughout February, and the somewhat early cessation of the rains. It seems clear that even in normal seasons the results of March planting of sunflowers will be uncertain, except in so far as subsoil reserves of moisture can be built up, on which the crop can draw in April and May. It is known from Rhodesian experience that a good sunflower crop can be produced on as little as 6 ins. of rain on favourable sites. Much will depend on correct choice of variety and the determination of the optimum spacing.
At Urambo, sunflowers were planted on experimental plots on both red and grey soils. They all showed conspicuous signs, such as yellowing and early shedding of leaves, of nutritional, perhaps nitrogen, deficiency. Nevertheless, yields in excess of 600 lbs. per acre were obtained from Hungarian, Pole Star, Saturn and the grey and black seeded varieties. At Namanga, Saturn (359 lbs. per acre), Pole Star (382 lbs. per acre), and Black seeded (488 lbs. per acre) were promising. All plantings were late.
Oil content of sunflower varieties
It has not been possible to secure strictly comparable data for sunflower oil contents in thagam 40ayfab097 groundnuts (p. 116). Horrez40 ofsiderable 117
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