1. The methods of investigation of the effect of ground water-level on crop growth, together with tho field installations in use, are discussed.

2. Direct field experiments are handicapped by the difficulties of achieving close control on a sufficiently large scale, due to considerable variations of surface level and depth of peat within individual fields and to rapid fluctuations in rainfall and evaporation. Many recorded experiments are associated with climatic conditions of substantial precipitation during the growing season.

3. Seasonal fluctuations of ground water-level in Fen peat soils in England, in natural and agricultural conditions, are described.

4. The local soil conditions are outlined and the implications of profile variations are discussed.

5. The effective control of ground water-level on a field scale requires deep and commodious ditches and frequent large underdrains to ensure the movement of water underground with sufficient freedom to give rapid compensatory adjustment for marked disturbances of ground water-level following the incidence of heavy rain or excessive evaporation.

6. A working installation for a field experiment in ordinary farming conditions is described and the measure of control attained is indicated.

In one experiment, variety Kutsaga 51 was grown at inter- and intra-row spacings of 60, 80 and 100 cm. Both yield and quality of leaf were improved as plant density per unit area increased. The greatest yield and highest quality were obtained from the 60 x 60 and 80 x 60 cm spacings while the lowest yield and quality were obtained from the 100 x 100 and 100 x 80 cm spacings.

In a second experiment the same variety was subjected to three levels of N and four levels of K. Higher doses of N or K were not necessarily effective in increasing the yield or improving the quality of leaf; on the contrary rates higher than 42/ha reduced both yield and quality of the leaf. Progressively higher doses of K did not offset the ill effects of excessive N.

Yield of leaf was primarily a function of leaves per unit area in the plant density experiment and number of leaves per plant in the fertilizer experiment.

In recent years, processors in Tasmania have introduced Russet Burbank as the most desirable potato cultivar for processing into French fries. Malformed tubers, collectively known as second growth, have been observed in some commercial Russet Burbank crops with the main defect being knobby tubers. Second growth of potato tubers has been shown to occur when the plant suffers a period of stress during the growth of the tubers such as drought, high and low temperatures, restricted soil aeration, interference with water and carbohydrate translocation and fertility imbalance (Sparks, 1958; Bodlaender, Lugt & Marinus, 1964; Iritani, 1981; Holder & Cary, 1984) or a combination of both drought and high temperature stress (Ohms, 1968). If stress from these factors is relieved, the renewed growth of the tuber is often confined to the eyes, producing knobby tubers (Moorby, 1978). Moderate water stress during early tuber bulking can lead to pear-shaped tubers (pointed at the basal end) whilst water stress during the latter part of the season can lead to tubers pointed at the apical end (Iritani, 1981). Knobby tubers are undesirable because knobs are easily broken off leading to yield loss and the exposure of tissue to infection. Severely pointed tubers cannot be processed efficiently into French fries.

Silage maize variety testing systems usually evaluate new varieties within properly defined maturity groups; within a maturity group, all varieties are harvested on a single harvest date. In a small country like Belgium where growing conditions are similar across the maize growing areas, all tested silage maize varieties, comprising different maturity groups, are harvested on a single date. Under this testing system, only few varieties are harvested at the physiological stage where they theoretically show their optimal performance. In the current research, eight silage maize varieties were monitored from 25 to 40% whole-crop dry matter (DM) content at three locations in Belgium during the period 2007–2009. The optimal harvest date was calculated as the date where whole-crop DM yield, ear DM yield and organic matter digestibility were maximal. The variety rank at the optimal harvest date was compared with the variety rank at any studied single harvest date. Harvest dates where the variety rank was not statistically different to the rank at the optimal harvest date were pooled in a ‘harvest window’. Based on the current data, the harvest window comprised a flexible harvest period of about 14 days. It was therefore concluded that applying a single harvest date is scientifically justified for the ranking of silage maize varieties in Belgium, when the whole-crop DM content is between 28·1 and 40·6% with a maximum difference of 7·2% between all compared varieties.

Eight genotypes of groundnut and two of pigeon pea were evaluated in intercropping at the Indian Institute of Technology, Kharagpur, during the monsoon and winter seasons in 1985 and 1986, to identify plant characters associated with high yield in intercropping. The pod yield of groundnut decreased when intercropped with pigeon pea, the extent of the decline differing with groundnut and pigeon pea genotypes. The reduction in groundnut pod yield and the degree and duration of shading was less when grown with pigeon pea type ICPL87 than with LRG30. During the monsoon, pod yield among intercropped groundnut genotypes ranged between 47% and 88% of their yields under monocropping because of differences in growth pattern and duration (90–125 days). The groundnut type most suitable for intercropping had early vigour, early maturity and high partitioning and pod growth rate. However, variation in pod yield among groundnut genotypes was not observed during the winter season because they showed less variation in duration and growth and there was less shading by the associated pigeon pea.

1. Recordings of faecal organic matter (O.M.), faecal N% (O.M. basis) and live weight, were made over 52 consecutive weekly periods on ten Corriedale wethers grazing a pasture consisting mainly of Wimmera rye-grass (Lolium rigidum Gaud.) with some subterranean clover (Trifolium subterraneum) in a Mediterranean-type environment. The amount of available O.M. and its N% were also recorded.

2. By applying regressions of (i) the ratio of O.M. feed intake to O.M. faecal output on faecal N% and (ii) the N% in the O.M. intake on faecal N%, to the above observations it was possible to estimate the following quantities: O.M. and digestible organic matter (D.O.M.) intake, N and digestible N intake and O.M. digestibility percentage.

3. The patterns of O.M. and D.O.M. intake, and N and digestible N intake are described. Similar patterns exist for each of these quantities. Two maxima, a large one in the spring and a smaller one in the autumn, and two minima, one in the summer and one in the winter, are exhibited. The values for these various maxima and minima are presented in the text.

4. Attention is drawn to variations from the general pattern for these quantities and factors which could influence these patterns are mentioned.

A non-surgical device which collects a pre-determined proportion of the urine voided by free grazing male cattle is described. The behaviour of animals trained to wear the collection equipment was similar to that of their contemporaries without the equipment. The performance and maintenance of the device are discussed.

Three female pigs, one with bilateral and two with unilateral hernia inguinalis, from farms near Río Cuarto, Argentina were studied to assess the hypothesis of intersexuality due to porcine freemartinism. Karyotype analysis of lymphocyte cultures was carried out to look for XX/XY chromosome chimerism. Examination of anatomical and histological characteristics of sexual organs was also performed to describe possible sexual tract abnormalities. The animal with the bilateral hernia inguinalis was shown to be a case of true hermaphroditism. Externally it had female genitalia and inside the abdomen, on the left side, one mature ovary and one testis were located. On the right side of the hernia, a scrotal ovotestis was present. All cytogenetically analysed lymphocytes had the female karyotype. The two animals having unilateral hernia and lymphocyte sexual chromosome chimerism were porcine freemartin.

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.

In the foregoing communication on maize digestibility (i), reference has already been made to the early difficulties which arose as a consequence of attempting to make measurements on rations consisting wholly of maize and milk. During, the period in which a mixture of milk and flaked maize was being fed, the pigs developed constipation troubles, due, as subsequent results proved, to the almost complete digestion and assimilation of the ration by the animals. At the time, however, it was deemed expedient to alter somewhat the scheme of the experiment and to feed the maize along with a definite weight of coarse middlings. In this manner it was anticipated that the fibre of the coarse wheat offal would promote peristaltic activity in the intestinal tract and thus assist the passage of undigested food residues.

The introduction of the middlings into the experimental ration made necessary the determination of the digestibility of this feeding stuff. The results of this trial are given for convenience in this separate communication.

The results of these investigations show

1. The substances sold as “Phosphate of lime” and “Calcium Phosphas B.P.” are not pure tricalcic phosphate but are mixtures of di- and tricalcic phosphates.

2. Sodium phosphate (Na2HPO4) added to ammoniacal calcium chloride and the resulting precipitate washed with water yields a mixture of di- and tricalcic phosphate and calcium hydrate.

3. Bone ash dissolved in hydrochloric acid and precipitated with ammonia, the precipitate being well washed, yields also a mixture of di- and tricalcium phosphate and calcium hydrate.

4. When three equivalents of lime (3CaO) are made to act on one equivalent of phosphoric acid (P2O5) and the resulting precipitate removed with little delay pure tricalcium phosphate is obtained.

1. Four varieties of marrow stem kale in the first season, and thirteen in the second, were sampled on three occasions during the first half of the winter. Intervals between samplings were up to 1 month. The plants in the samples were divided into leaf, top half of the stem, and bottom half. The levels of dry matter, proximate constituents and minerals were determined in each sample.

2. The differences in composition between the three main fractions of the plant were highly significant for all the chemical constituents, except magnesium. The values for the chemical constituents in the top half of the stem were intermediate between those of the leaf and the bottom half of the stem for most constituents; it had the lowest values for dry matter and the highest for potassium and phosphorus. The distribution of chemical constituents between the whole stem and the leaf were similar to those reported previously.

The actual transpiration of Mexipak wheat (Triticum aestivium L.) was determined by the inflow-outflow method and by soil moisture determination by the use of a neutron probe and gravimetrically. Three irrigation treatments were used during the 1969 season, wet, medium and dry. Amounts of water given were 370, 310 and 255 mm for wet, medium and dry treatments respectively. One irrigation treatment was used during the 1971 and 1972 seasons in which 620 and 700 mm of water respectively was given. However, during the 1973 season, two wet irrigation treatments of 560 and 670 mm of water were used. Values of Et measured by different methods were closely related. Seasonal averages of Et were 2·55, 1·99 and 1·62 mm/day for wet, medium and dry treatments respectively. The empirical coefficient (f = Et/Eo) under wet treatment, was found to be higher than that given by Penman (1956) for short grasses and higher than that obtained by Boumans et al. (1963) for wheat and barley in Iraq. The empirical coefficient Kb in the Blaney-Criddle formula was less than the value given by Blaney & Criddle (1950) for an arid climate and less than the value obtained by Boumans et al. (1963) for wheat in Iraq. The water use efficiency for grain production was greater under dry than under wet treatment.

1. The availability of the calcium in three species of grass has been determined by a slaughter technique, using the rat as the experimental animal.

2. The calcium in both timothy and perennial rye-grass was found to be more available than that in cocksfoot, the differences between timothy and cocksfoot, and between perennial rye-grass and cocksfoot being of a significant order.

3. The grasses as a whole were found to be inferior to both the legumes and herbs in respect of calcium availability.

4. The significance of the high faecal calcium values found in rats receiving the cocksfoot diets has been discussed.

5. There was shown to be some indication of inverse relationships between fibre content and calcium availability, and between oxalic acid content and calcium availability.

No single one of the nine grassland plants so far investigated has proved to have a calcium availability which, when taken in conjunction with total calcium content, would be in the least likely to induce symptoms of deficiency in an animal fed on that species alone.

A total of 580 Friesian cows from four dairy farms selected at random were grouped by teat shape. The incidence of teat cup crawl was recorded at the time of afternoon milking.

Teat cup crawl was significantly higher (27·4%) in the cows with cylindrical shape teats than in cows with funnel shape teats (8·1%).

Milk yield was significantly higher in the cows with funnel shape teats than in cows with cylindrical shape teats. There was significant reduction in milk yield due to teat cup crawl in both groups of cows, the reduction in milk yield being higher in the cows with cylindrical shape teats.

The post absorptive state commences in the ruminant between 42 and 48 hours after the last food. If food is ingested before this time it becomes mixed with that already in the rumen and its decomposition by fermentation is thereby accelerated. The metabolism at 15 hours after the last food is about 23 per cent, above that in the post absorptive state. For about 36 hours after th commencement of the post absorptive state the R.Q. remains below that of fat oxidation and fermentation gases still continue to be excreted. Keasons are suggested by way of explanation for these phenomena in the causation of which absorption of gas from the rumen does not appear to play any appreciable part.

One thrust in increasing food security in Jamaica is expansion of cassava production. The multiple shoot removal technique (MSRT) for rapid propagation of cassava can help address limitations in planting material. Shoots sprouting from cuttings of hardwood stem are severed in such a way as to induce further sprouting, and then put to root for subsequent transfer to the field. The effects of age and fertilization of parent plants and nodal age of stems were studied. Six Colombian varieties were planted in fertilized and unfertilized field plots with similar growing conditions to provide stems for MSRT propagation. Volume of two-node cuttings increased from apical to basal nodal age, but cutting density was a better predictor of shoot production. On average, three to six viable shoots were produced per cutting over 3 months in a greenhouse. All nodal ages of stems from parent plants aged 6, 7 and 9 months were suitable if the quality of the planting stakes producing parent plants was adequate. If stake quality is uncertain, it is recommended that apical pieces are not used from parents younger than 9 months. The variety CM 6119-5 consistently produced most shoots, suggesting a strong genotypic effect, but other varieties, particularly CM 849, were less consistent, indicating the role of environmental interactions. The physiological status of cuttings as influenced by stem maturity, parent plant age, nutrition and growing conditions of both grandparent and parent stems was as important as genotypic characteristics in determining shoot production from two-node cuttings of cassava stem.

Hay was fed to an in vitro continuous culture of the rumen microbial population and to sheep kept in metabolism cages, and the effects of potassium chlorate addition on the rumen fermentation were studied. The compound was given for 8 days in vitro and for either 3 or 8 days in vivo.

Potassium chlorate addition in vitro (13·7 mg/g hay D.M.) depressed the production of CH4 and acetate, had little effect on propionate production and caused a small increase in the production of n-butyrate and n-valerate. The treatment also depressed cellulose digestion and the concentration of DNA in fermentor liquor, but increased the CO2:CH4 ratio in fermentor gas.

When given in vivo for 8 days at 6·7 mg/g hay D.M., potassium chlorate progressively depressed total VFA concentration in rumen fluid, had no effect on VFA molar proportions but caused a small increase in the CO2:CH4 ratio in rumen gas. When administered in vivo for 3 days at 14·4–15·3 mg/g hay D.M. the treatment increased the molar proportions of propionate and depressed those of acetate in rumen fluid without affecting total VFA concentration. There were considerable differences between animals in propionate response, and the maximum responses were generally obtained 2–5 days after dosing had ceased. Potassium chlorate addition also caused a temporary reduction in appetite with some sheep.

It was concluded that potassium chlorate was toxic to the rumen microbial population when given for 8 days, but that large doses given over 3 days could be used to increase the ratio of propionic acid relative to acetic and butyric acids produced from the rumen fermentation.

Casein in amounts ranging from 10 to 124 g/day was administered as an abomasal infusion to seven Merino wethers whose daily ration comprised 600–700 g of either chopped wheaten hay alone or a mixture of chopped wheaten and lucerne hays. Increases in both the length growth rate and diameter of the wool occurred at all levels of supplementation tested. When casein was infused at the rate of 100 g/day for a 20-day period the biggest increases in wool growth occurred during the first 4 days and there was little further change after the first 8 days.

There were marked wool growth responses to the infusion of up to 80 g casein per day. The results suggest that little further increase could be expected with the infusion of more than 120 g/day.

In experiments conducted between 1982/83 and 1984/85 on the winter barley cv. Igri, nitrogen, including slow release forms, applied at several growth stages in the autumn, increased vegetative growth, including vegetative tiller numbers, nitrogen content and greening, particularly in the early sown crops. By spring, these effects were less apparent and only very infrequently did autumn nitrogen applications result in an increase in fertile tiller number and yield, although the autumn nitrogen treatments had been tested in combination with several different sowing dates and spring nitrogen levels. Studies on leaf production over the winter showed that the additional leaf produced after nitrogen application was subsequently lost through leaf senescence (especially in the severe winter of 1984/85) and therefore the treated and untreated plots often recommenced growth in the spring with similar amounts of live leaf tissue. It is argued that the use of autumn nitrogen on winter cereals in the north of Scotland cannot be supported agronomically and may also be undesirable for environmental reasons.