Total, dithionite-extractable (‘free’) and oxalate-extractable (amorphous) Fe as Fe2O3 forms were determined in eight Nigerian soil profiles selected to include four major parent materials and different drainage conditions.

Total Fe ranged from 1·98 to 15·01 % Fe2O3, the average contents being 4·40, 8·62, 12·59 and 13·49 Fe2O3 for soils derived from the coastal plain sands, basement complex rocks, shale and basalt, respectively. ‘Free’ Fe ranged from 0·08 to 12·28% Fe2O3, the basaltic soils having the highest content, and those on shale the least. Generally the poorly drained soils had low contents, the free Fe oxide constituting about 61 % of total Fe in well-drained soils, and only about 9% in poorly drained soils.

The oxalate-extractable or non-crystalline Fe oxide ranged from 0·04 to 1·21% Fe2O3. The proportion of amorphous iron oxide, indicated by the ‘active’ ratio ‘oxalate-Fe/DCB-Fe’, was higher in poorly drained than in well-drained soils.

The clay/DBC-Fe ratio remained constant in the well-drained soils but increased with depth in the poorly drained profiles, indicating a co-migration of free Fe oxide and clay in the former but not in the latter soils.

In general, the relative distribution of the different Fe forms appeared influenced by both the parent materials and the drainage of the soils.

Nutritional and other physiological factors are causes of variation in milk yield. In particular, the energy intake and the suckling stimulus of lambs greatly affect the milk yield of ewes in early lactation (Treacher, 1978; Hadjipanayiotou & Louca, 1976; Peart, Doney & MacDonald, 1975).

In most eastern Mediterranean countries ewes are milked after weaning and the weaning age and the suckling regime determine both the amount of saleable milk and the rate of growth of lambs. The aim of the present work was to study factors affecting the milk yield of Chios ewes fed ad libitum and the growth of their lambs.

A field experiment was made at the Indian Agricultural Research Institute, New Delhi to compare the efficiency of Mussoorie rock phosphate with ordinary superphosphate for two forage legumes, cowpea (Vigna sinensis Savi) and cluster beans (Cyamopsis tetragononoloba L.) and residual effects were studied in wheat (Triticum aestivum L.). For both the forage legumes Mussoorie rock phosphate was only 22% as effective as ordinary superphosphate (on soil of pH 7·1) and it had no significant residual effects on wheat even when the application rates supplied three times as much P as was supplied by ordinary superphosphate.

Tests were made to determine the juvenilizing effects of TH6040, JH-25, Altosid, Altozar, ZR-777 and ZR-619 on Culex pipiens L. using the IC50 value (dose to inhibit the emergence of 50% of adults) as a criterion. The descending order of activity was Altosid, TH6040, Altozar, ZR-777, JH-25 and ZR·619. Insignificant prolongations were recorded in the larval or pupal durations except in the case of TH6040 (Dimilin). The time lapse from larval treatment (early fourth instar) to adult emergence was prolonged by about 18·7% following treatment with 0·0001–0·1 μg/ml.

Juvenilizing effects of the tested compounds applied to the early fourth instar extended to the adult stage of Culex pipiens L. and affected the duration of the first gonotrophic cycle. The concentrations of TH6040, JH-25, Altosid, Altozar, ZR-777 and ZR-619 tested caused prolongation of the time between emergence and first oviposition by about 20–50% (at 0·0001–0·1 μg/ml), 3–26% (at 0·001–5μg/ml), 0–15% (at 0·1 × 10-8–0·001 μg/ml), 3-–23% (at 0·1 × 10-8–0·001 μg/ml), 9–27% (at 0·1 × 10-7–0·01 μg/ml), and 11–32% (at 0·1 × 10-7–0·01 μg/ml), respectively.

The results obtained indicated that the sex ratio of C. pipiensL. changed progressively in all treatments but with an inconsistent trend according to the concentration of each compound. This conclusion provides further evidence on the effect of juvenile hormone-like activity compounds on adults emerging from treated larvae. The numbers of females produced were increased by about 15–30%, 9–27%, 1–35%, 1–38%, 6–44% and 31–71% after treatment with 0·0001–0·1 μg TH6040, 0·001–5μg JH-25, 0·1x 10-8–0·001 μg Altosid, 0·1 x 10-8–0·001 μg Altozar, 0·1 x lO-7–O·Ol μg ZR-777 and 0·01 × 10-7–0·01 μg ZR-619‘sol;ml, respectively.

Potato cyst-nematode, Globodera rostochiensis, was controlled in peaty loam by growing the resistant potato cultivars Cara and Maris Piper, or by incorporating aldicarb or oxamyl granules in the seed bed before planting susceptible cultivars. In heavily infested soils, aldicarb or oxamyl increased tuber yields of susceptible cultivars and Maris Piper but did not increase tuber yields of Cara, which suggests that it is tolerant as well as resistant. Yield responses to oxamyl varied greatly among susceptible cultivars. In the top 20 cm of untreated soil, the nematodes increased twice as much on Bang Edward as on five other susceptible cultivars.

Body measurements and weights of animals of varying ages were recorded in White Fulani (Bunaji), Sokoto Gudali and N'dama breeds of cattle. Chest girth accounted for 86–96% of the variation in body weight in the three breeds. The linear regression coefficient of weight on chest girth in the N'dama differed significantly from the other two breeds. Within each breed, the regression coefficient of young animals was lower than those of older groups. The variables that contributed most to improving the prediction of weights when added to chest girth were rump length and body length. Animals with low body condition scores had lower regression coefficients of weight on chest girth than those with high scores.

Besides retarding somatic development, hypophysectomy markedly increases the deposition of subcutaneous fat in foetal lambs (Liggins & Kennedy, 1968). Two hypophysectomized (HX) and two pituitary stalk-sectioned (SX) foetuses became available for dissection during a study of the growth of normal Romney sheep (Broad & Davies, 1980a, b and unpublished). The present report supplements the existing information concerning the effects of altered hypophyseal function on the carcass composition of foetal lambs (Liggins & Kennedy, 1968; Alexander, 1978).

Previous studies have indicated that improved artificial drainage increases yields of winter wheat by as much as 1 t/ha (Armstrong 1978), and suggested that an important component of this improved yield was the more effective utilization of nitrogenous fertilizer. Further data to support this hypothesis are here presented from the longterm drainage economics experiment at the Drayton Experimental Husbandry Farm, Warwickshire, England (Trafford & Oliphant, 1977; Bee, Dennis & Marks, 1978; Armstrong, 1978). The soil of this site is a non-calcareous pelo-stagnogley of the Denchworth series, and the mean annual rainfall is 617 mm. Both the soil and the climate are typical of much of the English midlands. The results presented here are, however, restricted to a single site, and are consequently tentative.

Evans & Roberts (1979) considered that loworder polynomials such as mean, linear and quadratic were adequate to describe the trends that occur in treatment contrasts in long-term agricultural experiments. This conclusion was based on experience with experiments on levels of fertilizers and rates of stocking on similar pastures. In such experiments, the marked seasonal pattern in the data disappears when comparisons between treatments are followed. However, further experience with experiments comparing cultivars has shown that some comparisons still show a seasonal pattern. Such patterns may be accounted for by periodic regression (Bliss, 1970).

A number of attempts have been made, notably by workers in Australia (Nolan, 1975; Pilgrim et al. 1970) and Canada (Mathison & Milligan, 1971; Kennedy & Milligan, 1978a, b) to trace the metabolism of rumen ammonia-N in sheep.

Ergots are the sclerotia of Claviceps purpurea (Fr.) Tul., which periodically infects certain cereals especially wheat and rye, and frequently infects numerous grasses (Mantle, 1977a). The ergots are produced in the seeding heads of the plant and are harvested with, and thus contaminate, the grain, causing the mycotoxicosis known as ‘ergotism’ in livestock fed contaminated cereals, or in humans eating bread made from contaminated flour (Mantle, 19776). The disease is caused by certain alkaloid constituents of the ergots which are derived from lysergic acid. Symptoms in humans are hallucinations, convulsions, gangrene of the limbs and other extremities, and eventually death. Seven isomeric pairs of indole alkaloids have been isolated from ergot, ergocristine and ergocristinine, ergotamine and ergotaminine, ergocryptine and ergocryptinine, ergocornine and ergocorninine, ergosine and ergosinine, ergostine and ergostinine, and ergometrine and ergometrinine. The first named of each pair is derived from lysergic acid and is physiologically active, while the second is derived from isolysergic acid and has little physiological activity.