1. Inoculated lucerne was grown in pots of sand and watered with nitrogen-free food solution. In some of the pots the lucerne was clipped once, in some twice and in some it was left unclipped. Pots were harvested on four dates at intervals of about three weeks. Counts and measurements of nodules were made and dry weights and nitrogen contents of tops and roots were obtained.

2. Clipping did not significantly alter the nodule numbers, their mean size, or the total nitrogen contents of the plants, i.e. in tops, including clippings, plus roots.

3. Clipping, however, resulted in a decrease in the nitrogen content of the roots of about 40 per cent, as compared with undipped plants. This nitrogen was transferred to the tops where it was removed in the clippings.

In field experiments, infections by okra mosaic virus (OMV) and okra leaf curl virus (OLCV) reduced trie growth of okra more than when the plants were infected singly by either virus. The critical growth component responsible for low performance was leaf area in OLCV-infected plants and chlorophyll content in OMV-infected plants. However, the two viruses had a synergistic effect in mixed infection.

Expressed as percentage yield loss, mixed infections significantly reduced edible fresh fruit weight more than single infections in all okra cultivars. In single infections, OLCV caused higher yield loss than OMV. Since both viruses cause more damage in mixed infections, it may be preferable to breed for combined resistance, particularly if the genes for resistance are linked.

The errors of 454 cereal experiments organized by the National Institute for Agricultural Botany between 1956 and 1960 are examined in relation to block size. All the experiments used long, narrow plots and were harvested by combine. The most important conclusion is that the gain in efficiency by using small blocks in cereal experiments is as great now as it was before combine-harvesting and long, narrow plots were introduced. An empirical rule is that the variance per plot is roughly proportional to n½, where n is the number of plots per block.

Visceral organs play an important role in animals' energy requirements, so their growth must be well understood. The objective of the current study was to fit and compare growth curves that best describe body and visceral organ growth over time in Saanen goats of different sexes. Data were synthesized from seven studies in which curves were fitted to visceral organ growth over time for female, intact male and castrated male Saanen goats from 5 to 45 kg body weight. The liver, pancreas, spleen, rumen–reticulum, omasum, abomasum, small intestine, large intestine and mesenteric adipose tissue (MAT) data were fitted to eight models: simple linear regression, quadratic, monomolecular, Brody, Von Bertalanffy, logistic, Gompertz and Richards. The best-fit model was chosen based on the corrected Akaike information criterion and the concordance correlation coefficient. Model parameters for each sex were compared. Overall, the model that best described visceral organ growth was the logistic model. Sex did not influence the parameters that predicted organ growth (g), except for MAT, where females presented a lower tissue deposition rate and greater inflection point than males. Irrespective of sex, at the beginning of the growth curve, the liver accounted for 28 ± 1.1 g/kg of empty body weight, and the inflection point occurred at 1.7 months. The rumen–reticulum and large intestine presented higher growth rates in the first 2 months of life. Knowledge of the visceral organ growth curve is useful in improving the understanding of the effect of nutritional requirements for goats and must be used to optimize the nutritional plans.

Ten single-sire mating groups of 13 Horro ewes per ram were used to study the effects of mating on liveweight, body condition and scrotal circumference changes and their relationships with level of sexual activity at different stages of the joining period, and effects of sexual activity and pre-joining liveweight and scrotal circumference on fertility. Mating had adverse effects on liveweight, body condition and scrotal circumference. There was a tendency for mean daily liveweight loss to increase with increasing number of services during the period of peak sexual activity and over the whole joining period. Changes in scrotal circumference were non-significantly correlated with sexual activity. Pre-joining liveweight and scrotal circumference had no significant effects on the proportion of ewes served, rate of return to first service and fertility. High losses of liveweight and scrotal circumference were observed during the stage of peak sexual activity, and it could be suggested that more supplementary feed should be provided to working rams at this stage, especially if the ewe[ratio ]ram ratio is to be increased. There is no significant benefit to be gained by increasing ram mating weight and scrotal circumference from 30 kg and 27 cm to 40 kg and 31 cm respectively in Horro sheep.

Records of plant development in some twenty-five multifactorial experiments were collected with the object of analysing the effects of nutrient level, density, spatial arrangement and variety on seed production in linseed. By sampling techniques estimates were made of plant density, the extent of basal branching, the number of capsules per stem, the number of seeds per capsule and the seed weight. The expected plot yields, calculated from these data, were in good agreement with the harvested yields.

In factorial trials, involving additions of nitrogen, phosphorus and potassium, only a change in the nitrogen level increased the yield of seed, and this gain was largely determined by an increase in the production of capsules and not by any alteration in either the number of seeds per capsule or the seed weight.

Over a range of density of thirty to eighty plants per square foot the number of capsules produced per plant was inversely correlated with density. When the distance between drills was maintained at 6–7 in. and the density varied by changing the seed rate then—on an area basis—both capsule production and seed yield were rarely affected since the product of plant number and capsules per plant remained relatively constant. On the other hand, if the rate of seed delivery in the drill was kept the same and the distance between the drills was the variable for density then with a narrow width of drill (4 in.) the increase in plant density more than offset the fall in capsules per plant.

Further experiments comparing drilling and crossdrilling did not wholly confirm the importance of spatial arrangement. There was, however, evidence that at densities over eighty plants per square foot, besides a further reduction in capsules per plant, the number of seeds per capsule was depressed. Varieties were characterized by differences in seed size, the number of seeds per capsule, capsules per plant and the ability to produce more capsules at high levels of nitrogen. The superiority of the yielding capacity of Royal could be ascribed to the high rate of capsule production. Such varietal differences in capsule production have not been reported previously, and since the number of capsules per plant is greatly influenced by varying density, the common practice of basing selection on spaced plants, may not give a true assessment of capsule formation at densities optimal for seed production.

Factors which could be expected to influence levels of ammonia in the rumen were compared in sheep maintained on diets providing 11·4 or 20·7 g N/day.

The ruminal fluid volume in sheep given the lower-N ration was 78% of that in sheep maintained on the higher-N diet. The effect of this in diluting rumen ammonia from recycled urea is discussed.

Ruminal urease activity was higher in sheep given the lower-N diet, and was confined to the particulate fraction of rumen liquor in animals given either diet. At least 95% of the maximum activity occurred in the range of pH 5·4–7·05, and pH 6·0–7·25 in sheep maintained on the lower- and higher-N diets respectively. Small variations in activity were observed between the morning and evening meals.

In vitro rates of net ammonia production in samples of rumen liquor were similar in sheep given either diet; a positive correlation with the initial ammonia concentration was evident. Net utilization of ammonia was detected in some experiments in samples from sheep maintained on the lower-N diet. Starvation for 1 day was associated with increased rates of production and initial concentrations of ammonia.

Cellulose, as cotton thread, was digested at similar rates in vivo in sheep given the different diets. This is discussed in relation to the demand for ammonia by cellulolytic bacteria.

Extending the duration of the late reproductive phase in wheat has been proposed as a possible avenue to improve spike fertility. There is a positive correlation between the number of fertile florets and the duration of the stem elongation phase when this phase is varied by extended photoperiod. Photoperiod treatments imposed during the vegetative period also influence the duration of stem elongation. The present study analysed the effect of long photoperiod (19 h) of different duration (10, 12, 14, 18 or 22 d) imposed before the onset of stem elongation on floret fertility in wheat. It was found that the length of the stem elongation phase was modified by earlier ‘historic’ photoperiod treatments imposed during previous phases. However, neither the number of fertile florets per spike nor the spikelet fertility was affected significantly by these historic treatments. The results of the study therefore showed that an increased duration of the late reproductive phase was ineffective in increasing the number of fertile florets, unless the length of that phase was directly altered by current photoperiod.

In a glasshouse pot experiment in Athens, Greece in 1989, 85Sr to calcium observed ratios (OR) based on the values of exchangeable Ca instead of soil Ca (ORexCa), were determined for crops or plant parts grown in eight soils widely differing in their physical and chemical properties. Compared to the values of concentration ratio (CRs) the values of ORexCa did not show as wide variation with the soil type. They were relatively constant and usually not related to soil properties. The ORexCa values were essentially the same as OR values for the non-calcareous soils and much smaller than the OR values for calcareous soils, considering as soil Ca in the calculation of OR, the sum exchangeable, watersoluble and CaCO3 Ca.

The values of 85Sr/Ca + Mg observed ratios (ORexCaMg) were just as good as the ORexCa values, while those of 85Sr/Ca + Mg + K + Na (ORex bases) showed more variation.

Highly significant (P <0·01) correlations were observed between the fractions of the observed ratios ORexCa, ORexCaMg and ORex bases, for each crop or plant part tested.

Statistics are presented to illustrate the influence of growing season and location on the accuracy of NIR testing of hard red spring wheat for protein. The influence of season was greater than that of growing location, and highly significant errors are likely to occur if protein is predicted in samples from one growing season using a calibration based on samples from another season. The same was true to a lesser extent if samples from one growing location were analysed using calibrations based on samples drawn from different areas. There was evidence that some growing areas were less susceptible than others to the seasonal influence, whereas certain seasons (e.g. 1976) exerted more influence than others. Errors in predicting protein were considerably greater than errors in predicting moisture. The development and use of universal constants incorporating samples from a wide range of location and several seasons effectively counteracted the influences of both season and location, and universal constants have been developed for use in the NIR instruments of leading manufacturers, for hard red spring and durum wheats, and barley. The concept and principle of 2·point calibration using normalized mathematical treatment of the log 1/R signal is discussed and its efficiency in providing a stable calibration for the prediction of protein in hard red spring wheat has been demonstrated.

1. It has been shown that the direct counting method for soil protozoa devised by Kopeloff and Coleman for use in liquid media gives results entirely comparable with those obtained by a dilution method.

2. The factors governing the relation between the protozoa and the soil particles are those of surface action, and the capacity of various substances, sand, soil and clay, for retaining these organisms is specific and constant.

3. Coarse sand is capable of withdrawing per gram approximately 145,000 amoebae and flagellates per c.c. from a suspension of any strength. Fine sand withdraws approximately 980,000 per c.c: soil and partially sterilised soil 1,650,000, ignited soil 1,500,000 and clay 2,450,000.

4. These figures are constant for given material and organisms and are independent of the concentration of the suspension, the time of action, or whether the suspension contains cysts or active forms of the amoebae and flagellates investigated. Also the action is the same when the experiment is performed with a suspension of living or dead organisms.

5. Experiments with the ciliate—Colpoda cucullus—show that coarse sand per gram retains 27,000 per c.c.; fine sand per gram 185,000 per c.c; soil and partially sterilised soil 280,000 per c.c; ignited soil 270,000 per c.c. and clay 450,000 per c.c.

Identification of climate-smart nutrient management practices will overcome the ill effects of extreme climate variability on agricultural production under projected climate change scenarios. The rice–wheat cropping system is the major system used in India: using long-term yield data from Integrated Nutrient Management experiments on this system, the present study analysed trends in weather parameters and grain yield under different nutrient management practices. Twelve treatments with different combinations of inorganic (chemical fertilizer) and organic (farmyard manure (FYM), green manure (GM) and crop residue) sources of nutrients were compared with farmers’ conventional practices. A significant increasing trend was noticed for rainfall during the rice season at Kalyani and Navsari, of the order of 137·7 and 154·2 mm/decade, respectively. The highest increase in maximum temperature was seen at Palampur (1·62 °C/decade) followed by Ludhiana (1·14 °C/decade). At all the sites except Ludhiana and Kanpur, the yield of the rice–wheat system showed an increasing trend ranging from 0·08 t/ha/year in Jabalpur to 0·011 t/ha/year in Navsari, under the recommended dose of inorganic fertilizer application. A significant decreasing trend of 0·055 t/ha was found in Ludhiana. For most of the sites, a combination of half the recommended dose of inorganic fertilizer and either FYM or GM to provide the remainder of the N required was sufficient to maintain productivity. The top three climate-resilient integrated nutrient management practices were identified for all the study sites. Thus, the present study highlights the adaptive capacity of different integrated nutrient management practices to rainfall and temperature extremes under rice–wheat cropping system in distinctive agro-ecological zones of India.

The current study assessed ruminal fermentation parameters and bacterial community, nutrient intake, nutrient digestibility and nitrogen balance of goats fed diets containing buffel grass hay and ruminal ammonia nitrogen (N-NH3). Five rumen-cannulated mixed-breed castrated adult goats (45 ± 2.3 kg) were used in a 5 × 5 Latin square design represented by five N-NH3 levels (3.43, 9.95, 17.2, 23.0 and 33.7 mg/dl). Control animals were fed hay exclusively. Other treatments were represented by ruminal infusion composed of a mixture containing urea, ammonium sulphate and casein. The increasing N-NH3 concentrations did not affect rumen fluid pH, which averaged 6.43. Rumen ammoniacal nitrogen increased linearly in response to N-NH3. Volatile fatty acids were not affected by increasing N-NH3 concentrations. A higher abundance of Ruminococcaceae (Ruminococcus 1, Ruminococcaceae UCG-014 and Ruminococcaceae NK4A214 group) was observed in the rumen of goats infused with higher concentrations of N-NH3 (17.2 and 33.7 mg/dl N-NH3). There was a quadratic effect (P < 0.050) of N-NH3 levels on neutral detergent fibre intake with maximum values estimated at 13.7 mg/dl N-NH3. Nutrient intake, nitrogen excretion and nitrogen balance presented a positive linear effect (P < 0.050). In conclusion, 3.43 mg/dl of N-NH3 is the minimum level to maintain microbial activity, whereas the recommended level to optimize the microbial community is 14.5 mg/dl of N-NH3 in the rumen of goats fed buffel grass.

The phosphorus effects of several nitrophosphates were compared with those of superphosphate and dicalcium phosphate in field experiments in 1954 and 1955. In both years immediate effects were measured on radishes, and in 1954 residual effects were measured on a crop of ryegrass which was cut twice.

None of the nitrophosphates tested were more than one-third as efficient as superphosphate for radishes. The residual effects of nitrophosphate (relative to superphosphate) for grass were much larger than their corresponding immediate effects on radish; several materials were as good as superphosphate for increasing the yields of the second cut of grass. The immediate effects of nitrophosphates were much increased by preparing finely ground powders from commercial granulated products.

In both years dicalcium phosphate was equivalent to superphosphate and gave significantly higher yields of radish than any of the granulated nitro-phosphates. At the second cutting of grass in the 1954 experiment there were no significant differences between yields given by dicalcium phosphate and the nitrophosphates.

The solubilities of the phosphorus of nitrophosphates in solutions of citric acid, neutral ammonium citrate, and alkaline ammonium citrate, were of little value in estimating immediate effects of granulated products. It is suggested that physical properties of the granules affect the rate at which phosphate ions can diffuse and so complicate the interpretation of solubility tests.

A comparison was made of six different methods of inoculation with Cercosporella herpotrichoidesFron on field plots of the spring barley variety Impala. All inoculation treatments produced significant differences in terms of disease incidence and grain yield compared with the uninoculated controls. Significant differences were found between treatments in terms of disease incidence, disease severity, mean yield/head and 1000 grain weights. The time of inoculation was also found to be significant. The earlier inoculation caused a reduction in yield of approximately 66 % compared with 50 % at the later inoculation. The application of these methods is discussed.

Studies were conducted on the quantity and distribution of fat in 104 half-sib Angus steers which had received various combinations of hay, corn silage, and corn concentrate. Groups were slaughtered at live weights of 216, 284, 340, 409, and 454 kg. The weights of mesenteric, cod, pelvic, kidney and total excess carcass fat were determined. Four linear measurements of subcutaneous fat, three cross-sectional area measurements of intermuscular fat, and the intramuscular fat in seven muscles were observed. The results showed that the feeding regimes had marked influences on the quantity and location of fat, particularly during the early feeding period (216–340 kg live wt.). Feeding hay during this period generally resulted in less fat deposition than feeding corn silage, but the suppression of intramuscular fat deposition was not evident until the animals were subsequently fed higher energy rations to heavier weights (409 and 454 kg). The results indicated that it may be possible to design dietary regimens that suppress waste fat but allow intramuscular fat to be deposited.

The results described above imply that one might influence the deposition of intramuscular fat by proper design of the diet in the early feeding period. Although this possibility exists, it is noted that quantities of chemically extractable fat are not identical with quantities of marbling fat and hence changes in the former may not alter the visible quality of the meat.

Measurements of the gaseous metabolism of sheep in this laboratory are conducted by drawing air through a sealed chamber that contains the animal, sampling the effluent air, and analysing the sample for its carbon dioxide increase and its oxygen deficit. As the analysis is dependent upon the measured fraction of nitrogen with rare gases, and particularly in respect of the oxygen deficiency this fraction must be known rather precisely. It is of course assumed that the animal in no way changes the quantities of nitrogen and rare gases passing through the chamber, but the analysis is incomplete if any gases or vapours other than carbon dioxide and water are given off.

It is well known that considerable quantities of methane, and possibly some hydrogen, are produced by ruminants, and some forms of gas analysis apparatus include a device designed to measure the concentration of methane in the sample. The device, as used in the apparatus of Carpenter & Fox (1926), consists of a platinum spiral heated electrically, the carbon dioxide resulting from combustion being measured volumetrically in the ordinary way, together with the O2 consumed. Experience with the device in this laboratory has led to its abandonment and gravimetric methods are now employed instead.

The effectiveness of 20 strains of Rhizobium leguminosarum bv. trifolii was evaluated with Trifolium semipilosum and T. burchellianum grown in a Vertisol soil in the glasshouse at the International Livestock Research Institute (ILRI) in Addis Ababa. Several effective strains were identified for both species. In T. semipilosum, inoculation significantly increased nodule DM and root N yield over the uninoculated control; Ethiopian Rhizobium isolates outperformed isolates from other sources for shoot DM and N yield. In T. burchellianum, contrast analysis revealed that there was no significant response to inoculation, although one effective strain was identified. Inoculant strains failed to overcome the competitive dominance of indigenous strains as reflected in mean nodule occupancies by inoculant strains of 15 and 7% in T. semipilosum and T. burchellianum, respectively. The 20 strains showed variable persistence following a 5-week drought period; only two of eight (T. semipilosum) and six of eight (T. burchellianum) strains were recovered from nodules on seedlings planted in the soil following the drought period. Overcoming the constraints of low nodule occupancy and variable persistence will require further understanding of the competitive interaction and the factors affecting access to nodule infection sites if superior Rhizobium–clover combinations are to be identified and developed.

The current study evaluated the effect of sowing date (early, mid-August or timely, mid-September) on two winter wheat (Triticum aestivum L.) cultivars (Hereford, Mariboss) with different rates of nitrogen (N) (0–225 kg total N/ha) applied as animal manure (AM; cattle slurry) or mineral fertilizers (N: phosphorus: potassium; NPK). Overwinter plant N uptake and soil mineral N content were determined during 2014/15, while harvest yields (grain, straw, N content) were determined during 2014/15 and 2015/16. Overwinter uptake of N was 14 kg N/ha higher in early than in timely-sown wheat. Despite very different yield levels in 2015 and 2016 harvests, the advantage of early sowing on grain yields was similar (1.1 and 0.9 t/ha); straw yield benefits were greater in 2015 (1.7 t/ha more) than in 2016 (0.4 t/ha more). In 2015 and 2016, N offtake was 35 and 17 kg N/ha higher in early than in timely-sown wheat, respectively. The mineral N fertilizer value of cattle slurry averaged 50%. Early sowing increased the apparent N recovery (ANR) for wheat regardless of nutrient source. However, ANR was substantially higher for NPK (82% in 2015; 52% in 2016) than for AM (39% in 2015; 27% in 2016). Performance of the two cultivars did not differ consistently with respect to the effect of early sowing on crop yield, N concentration and offtake, or ANR. Within the north-west European climatic region, moving the sowing time of winter wheat from mid-September to mid-August provides a significant yield and N offtake benefit.

1. Monthly aqueous extracts of soils which have been under wheat and barley cropping on the Woburn light sandy loam soils, with various manuring show very great similarity in the amount and character of the materials extracted in the wheat and the barley soils.

2. Water-soluble phosphoric acid and potash are in extremely small amount where these manures have not been applied during the fifty years’ treatment, but, in spite of this, the amount of these constituents does not appear to be a limiting factor in determining the yield of either wheat or barley. The phosphoric acid is much higher in the plots treated with phosphatic manures, and the potash is slightly higher in those treated with potash manures, but these facts do not seem to have secured a seriously higher yield.