The influence of growing plants on nitrification in the soil was studied by means of small lysimeters of which four were planted to a perennial grass, four to an annual millet crop and four were left fallow.

Nitrification was entirely repressed under the grass from the second season after its establishment onwards, and did not take place even when the grass was dormant in winter. This was due to a direct influence of the living root, since in the fallow soil which was treated similarly, nitrification took place freely throughout the winter. Under the annual crop a repression of nitrification could be detected only towards maturity of the crop and the soil solution was completely depleted of nitrates at this period. Nitrification was resumed, however, immediately after the crop was ripe and had died off and continued through the winter.

During the period that nitrification was depressed replaceable ammonia made its appearance in the soil in more than normal quantities. This fact is hold to indicate that the plant exerts its influence on the mineralization of nitrogen in the soil by paralysing the autotrophic dehydrogenase system of the nitrifying organisms without interfering with the process of ammonification and not, as has been claimed, by excreting such quantities of carbonaceous matter that nitrates are reassimilated by micro-organisms.

By virtue of the constancy of the carbon-nitrogen ratio in soils this influence of plants on the mineralization of nitrogen has a very important bearing on the conservation of soil humus and consequently on any system of alternate husbandry. Some of its implications were discussed with particular reference to local fertilizer practice and field experience.

Quinoa cultivation in Chile presents an ancient and active complex of geographic, climatic, social and cultural interactions that has determined its current biodiversity in the three main growing zones (north, central and south). Importantly, these interactions involve the participation of farmers, whose activities are at the base of seed exchange networks due to their knowledge and in situ conservation of genetic diversity. The present study reports how a better understanding of farmers’ seed exchanges and local production practices could impact the genetic structure and diversity of quinoa at national scale in Chile. Using field interviews and characterization of 20 microsatellite genetic markers in a multi-origin set of 34 quinoa accessions representative of Chile and the South American region, the phenetic analysis of germplasm was consistent with the current classification of quinoa ecotypes present in Chile and Andean zone. This allowed the identification of five populations, which were represented by quinoa of Salares (northern Chile), Coastal/Lowlands (central and southern Chile), Highlands (Peru, Bolivia and Argentina) and Inter-Andean Valleys (Ecuador and Colombia). The highly informative quality of the markers used revealed a wide genetic diversity among main growing areas in Chile, which correlated well with natural geographical–edaphic–climatic and social–linguistic context to the expansion of quinoa biodiversity. Additionally, in addition to ancient seed exchanges, this process is still governed by the diverse agricultural practices of Andean farmers. Genetic erosion is considered an imminent risk due to small-scale farming, where the influence of increased migration of people to urban systems and export-driven changes to the agro-ecosystems may further reduce the diversity of quinoa plants in cultivation.

Eight flushing experiments were conducted with grazing sheep over a 4-year period, the responses being measured at lambing. In the first 2 years mobs of 600-750 ewes were employed. Those experiments were designed to separate, identify and measure the two components postulated as comprising the flushing response—a static live-weight effect not specifically related in time to the mating period, and a dynamic effect of the rising or falling body condition which is specific to the mating period.

1. Three groups of mature ewes were fed during pregnancy and lactation on rations differing in their calcium content. The mean daily intakes of calcium were 1·4 g. (group A), 4·5 g. (group B), and 7·4 g. (group C). Blood samples were analysed monthly for calcium and inorganic phosphorus. The ewes were killed at approximately 100 days after parturition and the skeletons isolated. Individual bones, either whole or divided into definite fractions, were analysed.

2. The level of calcium intake was without effect on the number of lambs born, birth weight, or growth while milk fed.

3. Blood calcium was significantly lower in group A than in groups B and C, but blood inorganic phosphorus was unaltered.

4. The resorption of bone substance was greater in group A than in groups B and C.

5. The severity of resorption varied between bones, and in regions within certain bones. Resorption was most severe in the vertebrae and pelvis, and only slight in the metacarpal, the metatarsal and the shafts of other long bones. Resorption of intermediate magnitude was found for the remainder of the skeleton.

6. Resorption was accompanied by reductions in the percentages of ash in bones, but this effect was proportionately less than the ash weight reduction.

7. Radiological observations made on flesh-free bones at the end of the experiment gave a picture of resorption similar to that presented by the data for ash weights and percentages of ash, namely that resorption was much greater in group A than in groups B and C.

1. The oxygen consumption of young pigs from 1 to 37 days of age has been measured in a closed circuit respiratory metabolism chamber, over the environmental temperature range 4–37° C.

2. The values obtained for single pigs alone in the chamber have been compared with the results of measurements on groups of pigs 3–6 days of age taken together.

3. It has been found that as environmental temperature falls below 30° C. and the grouped pigs huddle together, oxygen consumption per kg. for the group becomes smaller than values for single pigs of the same individual weight, and corresponds more with results from the larger single pig.

4. Rectal temperature is maintained in pigs of the group at a lower energy cost than that required for the single pig, the saving in energy expenditure becoming proportionately greater as ambient temperature falls.

5. These results are discussed in relation to body size and skin temperature.

1. An investigation concerning the weights twenty-four beef steers (three breeds—Hereford, Dairy Shorthorn and Friesians—on four planes nutrition), their grades, weights of organs, carcasses, tissues, etc., together with the chemical composition of their muscular and fatty tissues has been carried out.

2. The resultant data have been used to calculate—mainly by an analysis of variance—the effect of breed and level of nutrition. Only statistically significant differences are dealt with in this summary.

Eleven widely used crop simulation models (APSIM, CERES, CROPSYST, COUP, DAISY, EPIC, FASSET, HERMES, MONICA, STICS and WOFOST) were tested using spring barley (Hordeum vulgare L.) data set under varying nitrogen (N) fertilizer rates from three experimental years in the boreal climate of Jokioinen, Finland. This is the largest standardized crop model inter-comparison under different levels of N supply to date. The models were calibrated using data from 2002 and 2008, of which 2008 included six N rates ranging from 0 to 150 kg N/ha. Calibration data consisted of weather, soil, phenology, leaf area index (LAI) and yield observations. The models were then tested against new data for 2009 and their performance was assessed and compared with both the two calibration years and the test year. For the calibration period, root mean square error between measurements and simulated grain dry matter yields ranged from 170 to 870 kg/ha. During the test year 2009, most models failed to accurately reproduce the observed low yield without N fertilizer as well as the steep yield response to N applications. The multi-model predictions were closer to observations than most single-model predictions, but multi-model mean could not correct systematic errors in model simulations. Variation in soil N mineralization and LAI development due to differences in weather not captured by the models most likely was the main reason for their unsatisfactory performance. This suggests the need for model improvement in soil N mineralization as a function of soil temperature and moisture. Furthermore, specific weather event impacts such as low temperatures after emergence in 2009, tending to enhance tillering, and a high precipitation event just before harvest in 2008, causing possible yield penalties, were not captured by any of the models compared in the current study.

Inclusion in the diet of concentrations of vitamin E and selenium (Se) above requirement is associated with variable improvements in animal performance and immune function. At the cellular and molecular level, research in the last decade has produced a clearer understanding of the mechanisms underlying the multiple functions of vitamin E and Se and it is apparent that these functions extend beyond antioxidant protection. This paper reviews recent research relating to the functionality of vitamin E and Se in relation to the ewe and her lambs and attempts to relate this understanding to the whole animal level. Important aspects of this improved understanding are descriptions of three groups of seleno-proteins and the appreciation that there is a hierarchy in both the distribution of selenium between tissues and in the synthesis of different enzymes within tissues. In addition, there is diversity in the effects of vitamin E and Se derivatives on immune cell function. Given this heterogeneity in function it is not surprising that published responses for the production and health of ewes and lambs to supplementary vitamin E and selenium are variable and not always positive. Coupled with information on factors influencing variability in supply of vitamin E and Se from fresh and conserved forages and concentrate supplements, this review highlights the need for greater awareness of the importance of adequate supplementation of ewe and lamb diets with vitamin E and Se.

The nitrate nitrogen content of the soil (0–90 cm) was measured immediately after the harvest of winter wheat at eight sites in central and eastern England in 1987 and 1988. On average, 50% of the total nitrate detected was in the 0–30 cm, 30% in the 30–60 cm and 20% in the 60–90 cm soil horizon. Although soil nitrate N increased with the amount of N fertilizer applied, it was not a linear relationship. There were small nonsignificant increases in soil nitrate up to the optimum fertilizer rate for yield but, once the optimum was reached, further addition of fertilizer increased nitrate contents significantly.

Therefore, applying the correct quantity of N for high grain yield did not significantly increase soil nitrate residues after harvest compared with the no-fertilizer treatment. This emphasizes the importance of applying the appropriate rate of N for each crop, because applying too much is not only uneconomic but also significantly increases the amount of mineral N which could be subsequently leached over the winter.

The cellulolytic activity of cell-free extracts of 15 species of entodiniomorphid protozoa grown in vitro and under two conditions in vitrohas been measured using six different assays with substrates varying in complexity from carboxymethylcellulose to microcrystalline cellulose. Although there were differences between the assays, the highest activities were found in Eudiplodinium maggii, Epidinium ecaudatum caudatum and Ostracodinium obtusum bilobum with little or no activity in five Entodiniumspp. There was no consistent effect of growth conditions on cellulase content although with protozoa grown in vitro those grown on grass alone tended to contain more cellulase than those grown on starch and grass.

A survey of methods for the release of cellulase from other rumen fractions was made and mild treatment with ultrasound of the fraction suspended in water gave the maximal release of enzyme with the highest specific activity. Using this method 62% of the total rumen cellulase was found in the protozoal fraction and 27% was associated with the plant debris in a normal sheep, fed on hay and oats, with an A-type protozoal population.

The present paper presents a meta-analysis of the economic and agronomic performance of genetically modified (GM) crops worldwide. Bayesian, classical and non-parametric approaches were used to evaluate the performance of GM crops v. their conventional counterparts. The two main GM crop traits (herbicide tolerant (HT) and insect resistant (Bt)) and three of the main GM crops produced worldwide (Bt cotton, HT soybean and Bt maize) were analysed in terms of yield, production cost and gross margin. The scope of the analysis covers developing and developed countries, six world regions, and all countries combined. Results from the statistical analyses indicate that GM crops perform better than their conventional counterparts in agronomic and economic (gross margin) terms. Regarding countries’ level of development, GM crops tend to perform better in developing countries than in developed countries, with Bt cotton being the most profitable crop grown.

1. Experiments with two sheep are described in which energy retention was measured at different levels of food intake and the losses of energy incidental to food consumption measured.

2. Attainment of reasonably stable values for energy losses occurred after 72 hr. of fast. On realimentation stable values were not attained until 10 days had elapsed. Methane production was resumed relatively slowly.

3. The accuracy of the mean estimates of energy retention was high, and duplicate determinations of metabolism after lapses of time gave excellent agreement.

4. It is shown that the assumption of linearity of the relationship between energy retention and food intake expressed as metabolizable energy is incorrect.

5. An exponential relationship between energy retention, and food intake was employed to describe the data. This resulted in a reduction of the residual sum of squares compared with a linear regression.

6. It is shown that net energy values (starch equivalents) measured by Kellner, Armsby and Forbes have entirely different meanings, and that the correction employed by Wood reflects these facts.

7. The exponential relationship has been generalized to take into account body-size variation and has been examined as far as it affects concepts of efficiency of food utilization, and of nutritional plane.

8. Nutritional plane has been rigidly defined in such a way that it is independent of body size and of food quality, and it enables net energy values to be predicted at other planes of nutrition once the net energy value at one nutritional plane is known.

9. A simple and rational scheme for the feeding of livestock to take into account the decline in net energy value (starch equivalent) with nutritional plane has been devised.

10. Analysis of the energy losses in relation to nutritional plane shows that losses of energy in faeces, urine and as heat per unit food ingested tend to rise with increasing nutritional plane. Methane losses fall. These results suggest that the prediction of net energy values from measurement of energy losses in faeces, or from estimates of metabolizable energy, can give rise to extremely unreliable results.

11. The results have been discussed in relation to previous work in this field. It is pointed out that the exponential relationships employed are a convenient method of describing a very complex situation and facilitating its analysis.

On crossing immune and susceptible varieties the resulting offspring is susceptible.

On self-fertilization these susceptible individuals produce immune and susceptible descendants in the proportion of one of the former to three of the latter. The degree of susceptibility is variable.

Where the degree of susceptibility differs in the two parents the hybrid resembles the more susceptible parent in that respect. Among the descendants of such hybrids the two degrees of susceptibility appear in the usual Mendelian ratio of one slightly to three very susceptible individuals.

The relatively immune forms breed true to this characteristic in the succeeding generations.

Immunity is independent of any discernible morphological character, and it is practicable to breed varieties morphologically similar to one another, but immune or susceptible to the attacks of certain parasitic fungi.

The effects of plant density on the growth and yield of winter oilseed rape (Brassica napus) were examined in a series of five multifactorial experiments at Rothamsted Experimental Station between 1984 and 1989. Plant densities, manipulated by changing the seed rate and row spacing, or because of overwinter losses, ranged from 13·5 to 372 plants/m2. Normalized yields for the multifactorial plots increased with densities up to 50–60 plants/m2. In very high density plots in 1987/88, yield decreased as density increased >150 plants/m2. Plants grown at high density had fewer pod-bearing branches per plant but produced more branches/m2. Branch dry matter (DM) per plant was decreased by 42%, the number of fertile pods per plant and pod DM/plant by 37%. There was no effect of density on the number or DM of pods/m2. Over 74% of the fertile pods were carried on the terminal and uppermost branches of plants grown at high density in 1987/88 compared with only 34% in plants grown at low density in 1988/89. Seed DM/plant decreased with increase in density but seed size (1000-seed weight) increased. There was no effect of density on seed glucosinolate or oil contents.

The extent to which condensed tannins (CT) in Lotus corniculatus were able to affect protein degradation and the nutritive value of pasture were evaluated at Palmerston North, New Zealand in 1992 in an indoor feeding trial with sheep and using in vitro incubations. The feeding trial involved three groups of seven young wether sheep held indoors in metabolism crates for the 32-day experimental period with one group fed freshly cut ryegrass/clover pasture (Pasture group) whilst the other two groups received a mixture of c. 37% freshly cut Lotus corniculatus and 63% pasture (dry matter (DM) basis). One of the latter groups was given twice daily oral drenches of polyethylene glycol (PEG) to bind with and remove the effects of the CT (PEG group) whilst the remaining sheep (Tannin group) were not drenched. Intakes of sheep given the mixed diets were constrained to that of the pasture group. The CT concentration in the lotus was 26·1 g/kg DM so that the mixed diets contained c. 10g CT/kg DM. Effects of CT on digestion and sheep performance were minimal. Apparent digestibility of N was lower in the Tannin group (76·4%) than PEG (79·8%) or Pasture (79·4%) sheep (P<0·001), but there were no differences in DM digestibility (75%) or wool growth from mid-side patches. Rumen ammonia and soluble protein concentrations appeared to be similar in PEG and Tannin sheep and volatile fatty acid (VFA) concentrations were similar in all groups (100 mmol/l).

For incubations in vitro, several ratios of Lotus corniculatus: pasture were used to determine the effects of CT on precipitation of soluble proteins and the net yield of ammonia and gas with and without PEG. Homogenates of Lotus corniculatus leaves and pasture showed that 50% of soluble protein was precipitated by 1·3% CT in homogenate DM and there was a substantial decrease in in vitro degradation to ammonia when lotus leaf accounted for 33% or more of DM with pasture. This work emphasises the need for caution when extrapolating from in vitro to the in vivo situation and suggests that 1% CT from Lotus corniculatus may be insufficient to affect the nutritive value of fresh forages for sheep.

The colonization of Lactobacillus spp., enterobacteria and facultatively anaerobic gram-positive cocci was monitored in intestinal samples of growing broiler chicks from 24 h to 28 days of age. Rapid bacterial growth occurred within the first week, followed by stabilization and decline of colony forming units (CFU). Xylanase supplementation led to significantly lower CFU per gram of wet weight for total presumptive enterobacteria and total gram-positive cocci in luminal and tissue samples in the first 3 weeks. Lactobacillus spp. colony counts from tissue samples were higher for animals with the xylanase-supplemented diet, but luminal CFU were not. The composition of dominant Lactobacillus spp. strains was different in duodenal and jejunal tissues, but distribution of Lactobacillus spp. colony forms was unaffected by xylanase treatment. Mucosa-associated Enterococcus spp. displaced the dominant gram-positive cocci in the jejunal samples. d- and l-lactic acid and acetic acid concentrations were significantly higher in ileal samples from the control group on days 7 and 14, while butyric acid concentrations were higher in the xylanase-treated group. It is concluded that the less viscous intestinal environment caused by the xylanase slowed proliferation of gram-positive cocci and presumptive enterobacteria in enzyme-supplemented animals in the first 3 weeks of life.

Relations between yield, water use and pre-anthesis growth were analysed for cropsof barley grown for three seasons at several sites in northern Syria. The relations obtained were compared with those for other cereal crops grown in similar regions of Mediterranean climates.

Phosphorus fertilizer application increased the rate of crop development from emergence to floral initiation and advanced anthesis by up to 11 days. Grain and total shoot dry-matter yields were increased by fertilizer (nitrogen + phosphorus) applications at all sites in all years, in most cases without increasing total evapotranspiration. The increased dry matter at anthesis was produced without having used a larger proportion of the total evapotranspiration in the whole season. Consequently, the ratio of grain yield to total above-ground dry-matter yield (harvest index) and kernel weight were also relatively stable between sites and years, despite some very low amounts of post-anthesis water use. Grain yield appeared to be largely determined by anthesis and there were strong linear relationships between grain yield or total dry-matter yield and number of kernels. Differences in water use efficiency of crops given fertilizer between sites and years were closely related to the differences in amounts of winter growth.

Some responses differed from those predicted from models of growth, water use and yield developed in other regions with similar climates. It is concluded that agronomists and breeders should increase amounts of early growth thereby increasing grain and dry-matter yields. Future research emphasis should also be on the development of dynamic simulation models of pre-anthesis growth and water use.

1. The utilization of the energy of the same ration by sheep and by cattle was measured using three steers and three sheep in twenty-one and twentyfour experiments, respectively. Five different amounts of the ration were given to each steer and six different amounts to each sheep.

2. No differences of any magnitude were found in the percentage losses of dietary energy in faeces, in urine or as methane if comparisons were made at comparable nutritional levels. Faecal energy losses increased and urine energy losses and methane production fell with increase in feeding level, the feeding level being defined as the ratio of food intake to that required to attain an energy retention of zero.

3. The net availability of metabolizable energy for maintenance was the same in both species at 80·4%. The net availability of energy for the production of fat was 53·5 ± 1·4 in sheep and 51·4 ± 2·6 in cattle.

4. The results are discussed in relation to the effect of the amount of food given on the utilization of its energy. It is pointed out that net energy per unit of food declines with increasing intake, due firstly to a decline in digestibility and secondly to the fact that oxidative processes operative at and below maintenance are more efficient processes than is the synthesis of fat.

1. Twenty-one varieties of pasture grasses, including ten bred varieties, were grown on fertile soil for 3 years. Figures are presented of the rate of production of herbage cut every 3or4 weeks. Plots were cut in staggered sequence to permit growth intervals to overlap and to allow frequent assessments of the rate of production.

During the early period of infestation of winter rape, pollen beetles and seed weevils were mainly feeding and attaining sexual maturity. Before a crop flowered pollen beetles fed on buds but only some of those which they had perforated to obtain pollen dropped off. When flowering started adults obtained pollen from flowers rather than from buds. They laid their eggs in the buds but not in the flowers. Larvae moved from flower to flower up the raceme and caused no damage. Probably many podless stalks have been wrongly attributed to pollen beetle damage.

Overwintered seed weevils caused no damage by feeding on rape pods. New generation seed weevils caused some loss of seed weight and viability when feeding on pods of spring rape; this is probably unimportant on a field scale.

Pollen beetles and seed weevils mated from mid-May until the emergence of new generation adults; these did not mate before hibernating.