Three types of field instrument are described that are suitable for the automated and replicated in situ measurement of the soil properties: temperature, thermal conductivity and water pressure. Novel aspects of their design and construction are discussed, as are details of their installation and precautions necessary for successful use in the field. The principle of operation of each type of instrument is described and the method of controlling several instruments of the same type via a computer-based data acquisition system is indicated. Their accuracy and performance under field conditions are shown to be very adequate. Determination errors are approximately 0·1 K in the range 0–35 °C for temperature, 6–8% for thermal conductivity, and 1 mm water for water pressure, with a time constant of about 2 sec in a silty clay loam soil; reliability is measured as two sensor failures out of 236 over an operating period of several months. Examples are given of data collected during their deployment in an experiment to determine the physical effects of tillage on soil.

Four bruchid-susceptible and four bruchid-resistant cow-pea cultivars were crossed to produce 16 F1s and their reciprocals. From each cross, six generations, P1, P2, F1, F2, BC1, BC2, were obtained. Each cross was fitted to the additive-dominance model. Estimates of additive and dominance variances were obtained from the half and full sib analyses of the F1s and their reciprocals respectively. It was demonstrated that resistance to cow-pea weevils has additive, dominance and maternal components.

Use of generalized lattice designs instead of complete block designs in 244 cereal variety trials grown in the U.K. since 1975 has resulted in an average reduction of 30% in variances of varietal yield differences. The lattice designs were most effective when the number of varieties was more than 50 but worthwhile reductions in variance, averaging about 24%, were obtained in trials with fewer than 20 varieties. The data also provide guidance on the choice of block size and the potential for improvement by neighbour methods.

The seeds of a dwarf variety of pigeon pea (cv. Cita-1) were sown at 2, 4, 6 or 8 cm depths in three field trials in 1981 and 1982, in order to evaluate the effect of sowing depth on seedling emergence and the subsequent growth, development and yield of the crop.

In all trials, sowing pigeon-pea seeds deeper than 4 cm led to 1–2 days delay in seedling emergence, resulted in only 40–68% seedling emergence, reduced the development of the various growth and yield characters of the plant and significantly reduced seed yield. In two trials, plants from 4 cm sowing performed better than those from 2cm sowing in terms of development of growth and yield characters indicating that shallow sowing of pigeon pea prevents rapid and proper plant establishment.

The results therefore indicate that the optimum sowing depth for pigeon pea is 4 cm under the prevailing lowland humid tropical conditions.

In two field trials in 1982, the seeds of pigeon pea (cv. Cita-1) were planted at three configurationsof0·6 x 0·2m;0·4 x 0·3 m and 0·35 x 0·35m(on 14 April and 24 June)giving the same projected population density of 83 000 plants/ha for each configuration, in order to evaluate the best planting configuration for maximum productivity of the crop.

In the first trial, the 0·35 x 0·35 m configuration developed the highest magnitude of vegetative characters whilst the 0·4 x 0·3 m configuration had the highest number of seed-bearing pods, although seed yield was similar in all the treatments. In the second trial, the 0·4 x 0·3 m configuration developed the highest magnitude of growth and yield characters and thereby out-yielded the other two configurations.

The results show that in the early planting of pigeon pea, population density per se is most important in determining seed yield whereas planting configuration also becomes important in late planting where plant size is reduced as a consequence of the prevailing local conditions.

The analysis of two experiments involving the response of bread-making wheat to application of nitrogenous fertilizer is discussed. It is shown that a step function is required to determine the amount of applied N which optimizes the profit to be obtained from the crop. Varieties varied in their yield response to N and in the amount of applied N at which the ‘step’ took place and it is argued that trials of varieties at a common rate of N application or the reporting of results which are averaged over a number of rates cannot lead to very precise recommendations for growers.

The effect of field layout and the orientation of seed-production blocks on outcrossing rates was investigated in Indian mustard. The study incorporated three male:female combinations, i.e. 1:2, 1:3 and 2:4 laid in east–west, north–south and circular directions. The experimental material consisted of four test cultivars (RLM 198, RLM 514, Varuna and TM 4) in a split-plot design. Male sterility was achieved by spraying 0·25% (v/v) ethrel twice before the emergence of the first flowering shoots. The proportion of hybrid seed set was maximal in the 2:4 combination in a circular design. Outcrossing varied from 19 to 79%. Heterosis was evident in yield trials, but F1 hybrids showed carry-over effects due to ethrel treatment. It is argued that ethrelinduced male sterility has only a limited role in screening parental combinations for their yield assessment.

Glyceraldehyde-3-phosphate dehydrogenase (G-3-PDH), αglycerophosphate dehydrogenase (αGPDH), lactate dehydrogenase (LDH), alcohol dehydrogenase (ADH) and secondary-alcohol dehydrogenase (SADH) were histochemically located in the testes of buffaloes, goats and rams. Two forms of αGPDH were observed: (i) NAD-dependent or cytoplasmic αglycero-phosphate dehydrogenase (αGPDHC) and (ii) NAD-independent or mitochondrial αglycerophosphate dehydrogenase (α GPDHM). The basic pattern of distribution of the various enzymes was similar in the three species; species-specific variations were observed but cell-specific variations were more pronounced. The main activities of G-3-PDH and αGPDHM were observed in the seminiferous tubules; interstitial tissue showed moderate (G-3-PDH) and trace to weak (αGPDHM) activity. In contrast, αGPDHC activity was more marked in the interstitial tissue and less in the seminiferous tubules, especially in the mature germinal elements. LDH and ADH respectively showed strong and moderate activities in the interstitial tissue and seminiferous tubules. SADH was noticeable only in the interstitial tissue of buffalo. The activities of all enzymes other than αGPDHC increased during spermiogenesis. The physiological significance of the results is discussed in relation to the carbohydrate metabolism of the testis.

Experiments made for 2 years on a sandy-loam soil showed that previous grain crops of mung bean (Vigna radiata), cow pea (V. unguiculata) and black gram (V. mungo) increased the grain and straw yield of a subsequent crop of rice relative to previous fodder crops of maize or guar bean (Cyamopsis tetragonoloba) or a grain crop of Phaseolus bean (Phaseohcs vulgaris). The benefits from preceding crops of mung bean, cow pea or black gram were equivalent to 36–67 kg N/ha of chemical fertilizer applied to the rice crop following a cereal. The legumes improved yield-contributing characters such as number of productive tillers/m2, panicle length and number of grains/panicle. The yield increase from the preceding legumes was noted even when the rice crop was given increasing rates of fertilizer up to 90 kg N/ha.

A field experiment was made at the Indian Agricultural Research Institute, New Delhi, during the autumn-spring season of crop years 1979–80 and 1980–1 to study the effects of irrigation, pyrites and phosphobacteria on the efficiency of Mussoorie rock phosphate(north-western Himalayan deposits) for lentils (Lens culinaris Medic), and residual effects were studied in maize (Zea mays L.). Response to phosphate was observed only when the crop received irrigation. Mussoorie rock phosphate was only 40·5% as effective as ordinary superphosphate; its efficiency was increased to 50·4% when it was mixed with 25% (by weight) pyrites. When the lentil seeds were treated with the culture of Pseudomonas striata (phosphate solubilizing bacteria) the efficiency of rock phosphate was increased to 79·7%. Rock phosphate together with seed treatment with phosphobacteria also showed residual effects on the succeeding maize crop which were equal to those obtained with ordinary superphosphate. Our results thus show that use of phosphobacteria can considerably increase the efficiency of rock phosphate on neutral soils.

The blood composition of 45 cows with more than 20% fat in the liver (moderate fatty liver) was compared with that of 83 cows with less than 20% fat in the liver (mild fatty liver). The cows were sampled at 1 week after calving and were from three Friesian and one Guernsey herds. Blood concentrations of non-esterified fatty acids, bilirubin and aspartate amino-transferase were significantly elevated in cows with more than 20% in the liver whereas concentrations of glucose, cholesterol, albumin and magnesium were all significantly reduced. Blood samples from cows in two of the herds were analysed for ammonia, insulin and D(-)3-hydroxybutyrate. Cows with moderate fatty liver in these two herds had significantly lower insulin concentrations and higher D(-)3-hydroxybutyrate concentrations than those with mild fatty liver. Using an equation based on blood concentrations of non-esterified fatty acids, glucose and aspartate aminotransferase it was possible to assign correctly three out of four cows to either the mild or moderate fatty liver groups.

The moisture regimes of three soils under grassland in midland England were investigated using a neutron probe moisture meter from May 1976 until August 1978. The main aim of the experiments was to compare the differential build-up of moisture deficits in the three soils of different texture by monitoring moisture extraction down to 1·50 m depth. The moisture deficits measured by neutron probe were also compared with those predicted from meteorological data using the Grindley (1970) model.

The sandy (Newport) soil dried out more quickly and more completely than the clayey (Worcester) or fine loamy over clayey stagnogley (Salop) soil, particularly in 1976. This reflected the fact that the former had the smallest available water, most of which is held at low suctions, whereas the Salop soil, with much of its water bound at high suctions, continued to supply small amounts to plant roots when the available water in both the other soils was exhausted.

The soil moisture deficits determined from neutron probe measurements were much larger at all three sites in 1976 than in the following 2 years. The deficit increased more slowly in the Salop soil than in the other two in the early part of 1976 and more slowly than predicted by the Grindley model. However, during July and August of the same year, deficits in the Salop and Worcester soils increased more quickly than predicted and maximum deficits were in proportion to the available water capacities of the three soils. Deficits in 1978 were very small (less than 70 mm) in all three soils because of the wetter weather.

The results of this neutron probe study clearly show that the patterns of moisture extraction and the maximum deficits which developed in the three soils, particularly in 1976, are closely related to their physical properties, as determined from undisturbed soil cores.

Plant roots may extend as far or farther below the ground than the plant does above. Given ample space the root system of a single plant may have a total spread of 1·2 m in wheat and 2·4 m in maize. Although a major part of the nutrients are absorbed by crops from the surface soil, subsurfacesoil contributions are often substantial. Part of the nutrients applied to surface soil may leach down and accumulate in subsurface horizons which are often exploited by the deep-rooted crops in a crop rotation (Sparks, Martens & Zelazy, 1980). Lysimeter and soil sampling studies have shown a reduction of K movement when soils are cropped (Broadbent & Chapman, 1949; Singh & Brar, 1977). The amount of reduction varies with the crops. Volk (1940) found that losses of applied potassium on a sandy soil over an 8-year period were reduced by 20% by growing a winter legume in the rotation.

Earlier studies have reported a relationship between degree of fatty infiltration of the liver after calving and calving interval (Reid, Roberts & Manston, 1979; Reid, 1983). The aimof the present investigation was to relate the severity of fatty liver with cow reproductive physiology and performance.

A noticeable feature of mammalian skin surface lipids is the considerable variation in lipid and fatty acid compositions that exists between species (Nicolaides, Fu & Rice, 1968). The sebaceous lipids of oxen are characterized by the presence of relatively high levels of triglycerides, which, in contrast to those of other bovine tissues, contain a significant proportion (> 20%) of linoleic acid (Noble, Crouchman & Moore, 1974; Smith, Noble & Jenkinson, 1975; O'Kelly, Reich & Mills, 1980). The uniqueness of these highly unsaturated triglycerides has indicated possible roles in the chemical and biological defence systems of the skin surface for linoleic acid released by hydrolysis (Jenkinson, 1980). The skin surface triglycerides of calves do not attain the high levels of linoleic acid displayed by adults until 4–5 weeks after birth (Noble et al. 1975). It is, however, not known if a new-born calf compensates for this difference by an increase in sebum triglyceride concentration and output or, in view of the decreased availability of linoleic acid at this Stage, produces a sebum of widely different composition from the adult.

Controversy exists in the literature concerning the validity of the nylon bag technique for investigating the nutritive value of feeds (Pidgen, Balch & Graham, 1980; Marten, 1981). Avariety of factors have been implicated in affecting results such as sample size, fineness of grinding and positioning of bags in the rumen. In addition basal ration has been shown to affect results (Lindberg, 1981 a, b; Siddons & Paradine, 1981). ørskov & Hovell (1978) showed that rate of digestion of hay in nylon bags was faster when the animals were fed on Pangola (Digitaria decumbena) hay rather than on sugar cane with its high sucrose content. In further work Ganev, ørskov & Smart (1979) reported that vegetable proteins degraded at a faster rate when incubated in nylon bags in sheep receiving dried grass rather than whole barley as their basal ration.