1. Three experiments designed to investigate the effects of consolidation and aeration of soil beneath potato seed tubers before planting, and inter-row grubbing after planting, on the growth and yield of potatoes are described and the results discussed.

2. Consolidation of furrows beneath seed tubers by tractor wheels at planting had no effect on total weight of ware-size tubers produced but increased the weight of mis-shapen waresize tubers. It is argued that this effect was related to soil moisture content and tilth at planting time.

1. Two experiments have been described in which pigs were fed different levels of fibrous cellulose superimposed on a highly digestible purified basal ration. These experiments involved 24 hr. faecal collections and ultimate slaughter of the animals, together with analysis of faecal material and gut contents.

2. The results of these experiments, together with those from experiments described in the previous paper in this series, have provided the basis for a discussion of the effects of adding bran and cellulose to pig rations, and of the influence of the progress of the residues of feeds through the digestive tract, on the pattern of excretion and the dry matter content of the faeces.

Three short-term experiments on green-manuring are described. In the first, trefoil (T) and ryegrass given fertilizer N (RN) increased the yield of a following barley crop grown without fertilizer N by 500–900 kg/ha, but did not affect yield of barley given N. In the second, T and RN increased yield by 1400 kg/ha whether or not fertilizer N was given to the barley. Ryegrass without fertilizer N (R) had smaller effects in both experiments. The third experiment (with different treatments) suggested that the effect of trefoil was caused by the greenstuff turned in, not by any physical or microbiological change in the soil.

Seed treatments and methods of sowing sugar beet were tested in the laboratory and in field trials in 1975, 1976 and 1977 on a range of soil types including a sand, several loams and a peat.

‘Advancing’ the seed by controlled imbibition of water followed by drying before sowing, gave 2–3 % more emergence. Seedlings appeared 3–4 days earlier and were up to 50 % heavier at the four to six leaf stage, but by final harvest yields of sugar per unit area were similar from advanced and untreated seed. ‘Priming’ in osmotic solutions of salts or polyethylene glycol, to bring all seeds to the point of germination, before drying back and sowing gave inconsistent effects in the field with emergence percentage frequently being below that of the control. Steeping seed in water, aimed at removing germination inhibitors, improved germination and reduced the time to, and duration of, germination when tested in the laboratory but gave poorer results than the untreated control in the field. ‘Chitting’ the seed in the laboratory greatly improved emergence characteristics but treatment effects in the field were very variable. Chitted seeds were sown in carrier gels in the field to try to protect the radicles from damage but seedling establishment was no better from fluid drilling than from normal dry seed sown ‘raw’ or pelleted in clay, even when only chitted seeds were put into the fluid. Possible reasons for this are discussed.

Fluid-drilled seeds consistently gave quicker emergence and larger seedlings. Even when these were 30–50 % heavier, differences had usually become negligible by the end of the average 230 days long growing season, so that sugar yields were not consistently affected by the treatments tested.

Two samples of ammoniated sugar-beet pulp and one untreated sample have been examined. One sample was ammoniated at room temperature and an increase of 1·94 % in nitrogen content obtained. The other sample ammoniated at 10 atm. and 80° C. showed an increase of 3·47 % in nitrogen content. The total nitrogen contents were 3·30 and 4·83 % respectively.

Development was studied in winter wheat sown after rape or after oats in September 1984, 1985 and 1986, and in October 1985. N03-N residues from rape in October exceeded those from oats by 60, 50 and 40 kg N/ha respectively in the 3 years. Previous crops affected development only in the 1984–5 season. The first 12 apical primordia were initiated faster after rape; thereafter rates were similar, wheat after rape having two more primordia than wheat after oats. Final numbers of leaves and spikelets were each increased by one. The first five leaves appeared faster after rape so that from December onwards the number of emerged leaves was one more after rape than after oats. The double ridge and terminal spikelet stages occurred 8 and 4 days respectively earlier after rape than after oats. Development was unaffected by N fertilizer applied in November or at various times from February onwards, although growth and N uptake were increased. Drought during autumn 1985 delayed emergence of the September-sown wheat and slowed the rates of initiation of the first ten primordia and appearance of the first four leaves. Consequently the number of shoots per plant in December was only about three cf. six in the other 2 years.

The indirect estimation of intake of grazing animals is usually made from faecal index regression equations. Faecal nitrogen content or total faecal nitrogen are widely used to estimate intake. The most precise estimate of intake is obtained for a specific herbage (e.g. Phalaris) and condition (e.g. green, dry, etc,). Lambourne & Reardon (1963) found that the standard error of an estimate of the intake of a single animal, from a general regression equation, was 23%. Arnold & Dudzinski (1963) showed that the precision of estimates from general equations is improved by multiple regression including terms for faecal output. However, as regression relations are obtained from pen-feeding trials and are applied to field grazing, the following discrepancies axe likely to occur. We may have to extrapolate from low intakes in pens to higher intakes in the field; in addition selective grazing in the field can introduce a serious bias. To overcome the latter, when we are not sure about the exact condition of the forage eaten, as when green and dry herbage are both present, an average regression over two or more conditions has to be used. Naturally the precision of estimate then is much lower, because of the uncertainty as to what the animals are in fact selecting.

Seven-week-old White Rock males were exposed to step-wise increases in ambient temperatures from 7·7 to 37·7 °C in light and dark environments. Heart rate decreased with increasing ambient temperature with a quadratic slope (P ≤ 0·0001). Heart rate was lower during the dark period than during the light period (P ≤ 0·06). There was a positive linear correlation between heart rate and oxygen consumption (γ = 0·997) for ambient temperatures from 7·7 to 37·7 °C.

Body temperatures began to increase significantly when ambient temperature reached beyond 27·5 °C. The increases followed a quadratic slope (P ≤ 0·0001). Body temperatures during the light period were significantly higher than during the dark period (P ≤ 0·05).

The present study was initiated to investigate the effect of crude plant extracts as seed treatments on Phaseolus vulgaris (common bean) and Vigna unguiculata (cowpea) seed germination and emergence in the presence of Colletotrichum lindemuthianum and Colletotrichum dematium, respectively. Common bean and cowpea seeds were treated with crude water and acetone extracts of Agapanthus caulescens Spreng., Allium sativum L., Carica papaya L. and Syzygium cordatum Hochst.ex Krauss at 5 and 15 mg/ml concentrations. Seeds treated with the synthetic fungicide fludioxonil+mefenoxam (the commercial product Celest® XL) represented the positive control, whereas dimethyl sulphoxide and water-soaked seeds represented negative controls. The rolled paper towel method of the International Seed Testing Association was used to investigate the effect of the treatments on seed germination. Mean emergence time (MET) was determined using seed inoculated with the respective pathogens. The changes in the ultrastructure of embryonic roots and the connecting tissues of embryo-cotyledon of common bean and cowpea treated with Syzygium acetone extracts and Agapanthus water extracts were investigated using transmission electron microscopy (TEM). High germination percentages of >90% were observed in bean seeds from two production seasons treated with low concentrations of water extracts of Allium, Syzygium and Agapanthus and acetone extracts of Allium, Agapanthus and Carica. These treatments also recorded high emergence percentages with low MET values, which were similar to the water control. Cowpea seeds treated with Carica water extract had the highest germination and emergence. Syzygium acetone was the only extract that gave higher germination and emergence in both IT93K5132 and PAN 311 varieties. Therefore, Carica water and Syzygium acetone extracts can be considered as potential bean and cowpea seed treatments. Generally, there were inconsistencies in terms of correlations of germination with emergence percentages in both cowpea and bean seed treated with plant extracts used in the study, which could be due to differences in vigour. The TEM study of embryo-cotyledon tissue of both species revealed that Syzygium and Agapanthus extract seed treatment may accelerate metabolic processes as evidenced by the presence of vacuoles, many cristae and few lipid bodies.

In a factorial experiment, two protein concentrations and three patterns of feeding were administered to eighteen Large White × Wessex sows (three per treatment) in their second pregnancy. Treatments were repeated in their third pregnancy, when balance trials were conducted. The high protein diet (HP) (19·5% crude protein) contained 15% white-fish meal. The low protein diet (LP) (10·5% crude protein) contained protein of vegetable origin only. The pattern treatments involved intakes of 1·8 kg (L) 2·7 kg (C) and 3·6 kg (H) per day, the three pregnancy feeding patterns being HL, C and LH. Parturition results and lactation performance in the third reproductive cycle were similar to those recorded in the previous reproductive cycle (Pike & Boaz, 1969) reported earlier. Nitrogen retention in the third pregnancy was significantly higher in the HP sows(1606 g N)thaninthe LP sows(1082 g N) (P < 0·001). Intra-uterine nitrogen deposition in pregnancy was not affected by any of the treatments. Extra-uterine nitrogen deposition was significantly greater in the HP than the LP sows (P < 0·001). Dietary protein differences influenced extra-uterine rather than intra-uterine deposition of nitrogen in the pregnant sow, greater extra-uterine nitrogen deposition appearing to enhance subsequent lactation in this and the previous (Pike & Boaz, 1969) experiment. Protein utilization was more efficient in late than early pregnancy, suggesting that the feeding of higher levels of protein in late pregnancy should lead to greater efficiency over the whole pregnancy, provided energy intake is sufficient to promote optimum protein utilization.

An experiment, carried out over a 5-year period (1984–88) on medium–heavy textured soil at Athy (Ireland), tested the effect of five sowing dates (early September–early December) and four seed rates (c. 100, 150, 200 and 250 kg/ha) on the grain yield and protein content of winter barley (cv. Panda).

September-sown plots gave the greatest yields in all years. Plots sown in mid-October and later gave significantly reduced yields. Yield reductions over the 5-year period averaged 15, 24 and 34% for the mid-October, November and December sowing dates, respectively. Significant differences in yield between the smaller and larger seed rates were obtained, with the latter giving the greatest yields at all sowing dates from late September to December. Increasing the seed rate, however, did not compensate for the yield reduction due to delayed sowing. In the early September-sown plots, the higher seed rates gave reduced yields in four of the five years (1984–87) with the opposite result in 1988. In 1988 the early September-sown plots gave greater yields than the late September-sown plots.

Regression analysis showed a strong relationship between yield and log(ears/m2) in four of the five years (1984–87) but the relationship was poor in 1988 primarily due to the inexplicably low ear population of the early-sown plots. The inclusion of 1000-grain weight in the model gave a better fit and accounted for a high proportion (62–80%) of the yield variation.

The late September sowing date and the higher seed rates gave slightly lower protein levels in four of the five years. There was an inverse relationship between grain yield and protein for the same four years (1984–87).

Arginase (EC 3.5.3.1) catalyses the conversion of arginine to ornithine and urea, and is a key enzyme of the urea cycle. The enzyme is present in high activity in various mammalian red cells (Nishibe, 1973, 1974; Owczarczyk & Barej, 1975) and inherited arginase deficiencies have been found in two primate species (Shih et al. 1972; Terheggen, Lavinha & Colombo, 1972). The present paper describes an inherited arginase deficiency in the erythrocytes of certain sheep.

The growth of the tree legumes Leucaena leucocephala, Gliricidia sepium, Sesbania sesban, Sesbania grandiflora, Albizia falcataria and Calliandra calothyrsus was evaluated at four sites in Indonesia between 1984 and 1986. Tree seedlings were planted at 10000 trees/ha and, after an establishment period of 9–12 months, harvested every 3 months for a 2-year period.

At Bambu Apus, West Java (2040 mm annual rainfall, 1 month dry period, lowland, latosol with pH 5·6 decreasing with depth), G. sepium and C. calothyrsus produced 13 and 10 t/ha per year of leaf dry matter, respectively. Other species did not grow well at this site and fewer than 60% of the trees of these species survived until the end of the experimental period. At Sei Putih, North Sumatra (1550 mm annual rainfall, 3 months dry period, lowland, podzolic with pH 5·5 increasing with depth), no species produced > 6 t/ha per year of leaf dry matter. The highest yielding species were L. leucocephala and A. falcataria. At Cisarua, West Java (3340 mm annual rainfall, no dry periods, 925 m altitude, latosol with pH 5–6 increasing with depth) only C. calothyrsus grew well and produced 9 t/ha per year of leaf dry matter. At Grati, East Java (1500 mm annual rainfall, 6 months dry period, lowland, alluvial with pH 6·6 increasing with depth) L. leucocephala produced > 8 t·ha per year of leaf dry matter, while none of the C. calothyrsus and A. falcataria trees survived the first dry season.

Although L. leucocephala has been the most widely grown tree legume species in the tropics, C. calothyrsus and G. sepium performed better at the wetter sites and at high altitude.

The average numbers of females of all ages (herd size) in pedigree herds of Jerseys, Guernseys, and Red Polls in 1939 were found to be 25, 22 and 42 respectively. Of the herds listed, 15–20% made no herdbook entries and were of much smaller than average size. Excluding these, the average numbers become 29, 26 and 49. The number of females entered in the herdbook during 1939 was about 20% of the total number of females of all ages. The same proportion was found in all herd size groups except the smallest where it was lower. As a general guide, therefore, to breed and regional differences in herd size in all the major breeds, the average number of herdbook entries of females has been multiplied by 5.

An experiment comparing the yield at various stages of continuous wheat growing on heavy land, using two varieties and two rates of application of nitrogenous fertilizer, is described and the results from 1963 to 1974 discussed.

The yield of the second wheat crop was substantially less than that of the first following oats which followed beans, but there were no consistent yield differences between the second and later crops.

The major disease present was eyespot, but the differences in yield between Cappelle-Desprez and Hybrid 46 were little affected as wheat growing continued.

Increasing nitrogen application from 63 to 126 kg N/ha did not reduce the differences between first and later wheat crops.

Field experiments were conducted during the rainy seasons (June–October) of 1978 and 1979 in order to determine the effect of fertilizer N rates (0, 40, 80 and 120 kg N/ha) on yield and yield attributes of some new sorghum cultivars in northern India. Sorghum hybrid varieties yielded more than pure line varieties, hybrid CSH 5 outyielding all other cultivars including other hybrid varieties because of its greatest number of grains per panicle. Nitrogen application at 80 or 120 kg N/ha brought about significant improvement in number of grains per panicle and yield per ha.

Cultivar Χ N rate interactions were significant, in affecting the yield per ha and number of grains per panicle in 1978, whereas such differential response of sorghum cultivars to N rates did not occur in 1979. Sorghum hybrid varieties, even at lower N rates, produced identical yields to the pure line varieties supplied with higher N rates.

Teff (Eragrostis tef) was cut at various stages of growth and divided into leaf, stem (including leaf sheath) and inflorescence. Cell walls were isolated from the leaf and stem fractions and their composition determined. Acetyl groups and individual sugars were determined by gas-liquid chromatography.

Recoveries of cell walls from the same fresh weight of leaves or stems were similar at each stage of growth, but increased with maturity.

Throughout the growing season the leaf cell walls differed in composition from those of the stem. At the start of growth the leaves had a lower content of xylose and acetyl groups but were otherwise similar to the stems. However, with increasing maturity and the production of a flowering stem the stem cell wall composition changed much more than that of the leaf cell walls, with a marked decrease in the content of arabinose and an increase in the content of lignin and acetyl. Over the same period the leaf cell walls showed a smaller increase in acetyl content and decrease in arabinose and uronic acid, but were otherwise unchanged.

Digestion of the cell walls with a fungal cellulase preparation showed that although the two cell wall types were equally degradable while the grass was in the vegetative state, the digestibility of the stem cell walls decreased well below that of the leaves with the onset of maturity and the production of a flowering stem. This was confirmed by in vivo incubations of the cell walls in nylon bags.

Responses in body, skin and coat temperatures, cardio-respiratory frequencies and rate of moisture secretion of ewes of three breeds to the diurnal fluctuation in ambient temperature were recorded in the presence and absence of drinking water during the hottest part of the Rhodesian year.

1. At 7.0 a.m. body temperatures were: Merino 102·8° F.; Persian 102·2° F. and Native 101·5° F. Between 7·0 a.m. and 1·0 p.m. body temperature rose almost equally in Persians and Natives and fell slightly in Merinos. Change in body temperature between 7.0 a.m. and 1.0 p.m. was not affected significantly by availability of water nor age of ewe, but varied with type of thermal burden (i.e. solar insolation only v. solar insolation plus artificial heat) when water was not available. Although air temperature fell towards late afternoon body temperature of Merinos and Natives rose appreciably, that of Persians only slightly.

2. At 7·0 a.m. respiratory rates were (cyc./min.): Merino 59·6; Persian 43·0; Native 29·9. Increase in rate of respiration was the main thermolytic mechanism in all breeds. Merinos had a lower threshold of respiratory response to rising ambient temperature than either hair breed but increase in rate of respiration between 7.0 a.m. and 1.0 p.m. did not differ significantly with breed or age.

3. No breed appeared to use the peripheral blood system in thermoregulation. Cardio-frequency, as a measure of this blood flow, remained almost constant with a slight tendency to fall with rise in ambient temperature.

4. In all breeds skin temperature was related to ambient and body temperatures; consequently the diurnal fluctuation in skin temperature differed in wool and hair breeds. When thermal burden was greatest Merino skin temperature fell, that of hair breeds did not.

Except at 11.0 a.m. there was a gradient between rectal, skin and air temperatures. Direct elimination of heat was thus possible for 23 hr. each day.

5. In hair breeds moisture secretion depended on insensible perspiration; consequently, rate of moisture secretion changed with body and air temperatures. In Merinos moisture for skin surface evaporation was provided by sensible and insensible perspiration. Natives may be able to sweat at temperatures higher than those recorded but it is unlikely Persians have a sweating mechanism.

6. In all breeds coat temperature was related closely to ambient temperature and changes in solar conditions evoked immediate response in coat temperature. Merino fleece apparently stabilized skin temperature whereas Persian and Native hair did not.

Agriculture is a largely technical endeavour involving complicated managerial decision-making that affects crop performance. Farm-level modelling integrates crop models with agent behaviour to account for farmer decision-making and complete the representation of agricultural systems. To replicate an important part of agriculture in Central Europe a crop model was calibrated for a unique region's predominant crops: winter wheat, winter and spring barley, silage maize and winter rapeseed. Their cultivation was then simulated over multiple decades at daily resolution to test validity and stability, while adding the dimension of agent behaviour in relation to environmental and economic conditions. After validation against regional statistics, simulated future weather scenarios were used to forecast crop management and performance under anticipated global change. Farm management and crop genetics were treated as adaptive variables in the milieu of shifting climatic conditions to allow projections of agriculture in the study region into the coming decades.

A trial using a split-plot with blocks design was carried out at the INTA Balcarce Experimental Station, Argentina on a typic argiudol soil to evaluate N nutrition in wheat after different preceding crops and using two rates of N fertilization (0 and 90 kg N/ha).

Wheat (Triticum aestivum), soyabean (Glycine max), sunflower (Helianthus annuus) and maize (Zea mays) were grown in different combinations for two successive years (1984/85 and 1985/86).

No water stress was detected during either growing season. Nitrogen availability was altered by the previous crops grown, but the effect lasted only for one season. Wheat following maize yielded least with no N and responded most to N fertilization. The highest yields of wheat without N and the lowest response by wheat to N fertilization were found after crops of soyabean and sunflower.

Wheat after a fertilized wheat crop did not respond to N fertilization because of a serious attack of take-all (Gaeumannomyces graminis tritici).

The nitrate concentration in wheat stem bases was found to be a good estimator of the availability of soil N.