The effects of direct drilling, shallow cultivation and ploughing on the growth of winter cereals (wheat and oats) are reported for the first 4 years of long-term experiments on two non-calcareous clay soils (stagnogleys), representative of soils occupying a large proportion of the cereal growing area of the U.K. These 4 years have been characterized by extreme contrasts in rainfall and wetness of the soil.

On a Lawford series soil, with 35% clay, although the treatments affected average grain yields none of the differences was large. With additional nitrogen fertilizer, the yield after direct drilling was significantly heavier by 6% than after ploughing. On the Denchworth series, with 50% clay, 4 year average yields were also similar after direct drilling and ploughing, but in individual years the treatments had large effects. In two wet years grain yields after direct drilling were 89 and 82% of those after ploughing, but in another year they exceeded by 16% those after ploughing, where lodging had restricted grain filling. In the unusually dry season of 1975–6 yields of winter wheat after direct drilling exceeded those after ploughing (by 14 and 6% on the Lawford and Denchworth soils respectively) and this was attributed to greater availability of water and deeper rooting in the spring. In a year of heavy wheat yields (1977–8) about 10t/ha was achieved on both soils irrespective of the method of cultivation. In this year, after prolonged wet soil conditions in winter, the response to additional nitrogen fertilizer was greater after direct drilling and shallow cultivation than after ploughing.

The concentration of nitrogen in the crops tended to be smaller throughout the growing season after direct drilling than after ploughing, especially on the Denchworth soil in the wettest season. The method of cultivation had no effect on the uptake of either phosphorus or potassium except on the heavier soil in the wettest year, when potassium uptake was restricted after direct drilling.

The results are discussed in relation to information on soil conditions and root growth also being obtained in these experiments.

1. Previous observations on the calcium and phosphorus metabolism of the pullet are confirmed.

2. Calcium and phosphorus retention are shown to be related to the amount of sodium chloride in the food.

3. The extra phosphorus excretion which accompanies egg laying involves no marked concomitant change of the amount of potassium in the droppings. Small concomitant increases in the sodium in the droppings were observed where the food contained only small amounts of sodium and chloride; potassium retention was observed on the succeeding day in every case but one.

The nitrogen (N) cycle is one of the best studied elemental cycles. However, the N flows and transformations, in particular in aggregated soils, at small scales and in plant–soil systems are not yet fully understood. Analytical and molecular techniques are now available to address N dynamics at small scales. The methodological advances should go hand in hand with the development of suitable mathematical models addressing the small scale and the full complexity of the many interacting effects. The importance of denitrification within the N cycle is highlighted and used as an example of the progress achieved in recent times. Research gaps and possible research pathways are outlined.

A technique is described which uses the ratio of the natural 12C and 13C isotopes of carbon to calculate the proportions of Calvin pathway (or C3) species and C4 dicarboxylic acid pathway (or C4) species in mixed samples of shoots, roots or seeds. Mean percentage of a particular component can be predicted to within ± 2% of actual values with average standard errors of less than 1% with two component mixtures under good conditions using threefold replication. The technique is particularly useful for estimating the proportion of C3 and C4 species in samples of visually indistinguishable, intermingled root systems from mixed field communities or from competition experiments. The proportion of C3 and C4 species in both oesophageal fistula and feed samples can be obtained using this technique, and it is proposed that data from fistula and pasture samples could be used to determine the extent to which animals selectively eat C3 or C4 species. The advantages and disadvantages of the technique are discussed.

1. The amounts of amino sugar-N present in acid hydrolysates of six soils with nitrogen contents ranging from 0·17 to 2·82% have been estimated by colorimetric and alkaline decomposition methods.

2. Recovery of amino sugar-N after hydrolysis of chitin or glucosamine was found to be unaffected by the presence of soil during hydrolysis.

3. Substances known to interfere with the methods of amino sugar analysis employed were not detectable in the soil hydrolysates.

4. From the amounts of amino sugar-N liberated by acid hydrolysis it is deduced that 5·10% of the total-nitrogen of the soils examined was in the form of amino sugars.

5. The decomposition of amino sugars in soil has been studied by comparing the rates of decomposition of chitin, glucosamine, casein and yeast nucleic acid when incubated with soil under conditions found to produce rapid nitrification of ammonium sulphate.

6. Glucosamine and chitin are readily decomposed by soil micro-organisms but not so rapidly as casein or yeast nucleic acid.

In seeking better predictions of grain yield under light-limited conditions, shading was applied to field-grown winter wheat cv. Slejpner during each of five consecutive phases (canopy expansion, ear expansion, pre-flowering, grain expansion and grain filling). Absolute measures were taken of solar radiation and its effects on growth in three seasons, at a site where water and nutrient supplies were not limiting. Replicate mobile shades automatically occluded 0·80 of incident light when mean total solar radiation exceeded 250 J/m2 per s. Mean effects over seasons of shading on incident total solar radiation were −296, −139, −78, −157 and −357 MJ/m2 for the five phases respectively, and corresponding effects on shoot dry weight were −236, −184, −58, −122 and −105 g/m2. Estimated efficiency of radiation use after flowering was 1·2 g/MJ unshaded, tending to increase with shading. Shading in all phases reduced grain dry matter yield: mean effects over seasons were −106, −64, −61, −93 and −281 g/m2 for the five consecutive shading periods. Shading from GS31–39 increased mean maximum area of the two top leaves from 2700 to 3100 mm2 per leaf but, with fewer stems, canopy size remained unaffected. This and the next shading, from GS39–55, reduced specific leaf weight from 42 g/m2 by 4 and 3 g/m2 respectively, but effects on shoot dry weight were largely due to stem and ear. By flowering, stem weights, and especially their reserves of water-soluble carbohydrates, had partially recovered. Effects on yield of shading from GS31–39 were explained by a reduction in grains/m2 of 3070 from 26109. Shading from GS39–55 reduced grains/m2 by 4211 due to fewer grains per ear, whilst mean weight per grain increased in compensation. Shading from GS55–61 decreased grains/ear by 2·5. Shading from GS61–71 decreased ear growth and reduced stem weight, and at harvest resulted in 4·3 less grains/ear. Effects of the final shading from GS71–87 were fully explained by a reduction in mean dry weight/grain of 10·3 mg. Except for shading from GS71–87, source- and sink-based explanations of grain yield both proved feasible, within the precision of the measurements. Constraints to accurate comparison of source- and sink-based approaches are identified, and the implications for yield forecasting are discussed.

Losses of NH3 from a number of swards grazed by cattle were measured through 2 (1986–87) grazing years using a mass balance micrometeorological method. Comparisons were made of grass swards receiving 420 or 210 kg fertilizer N/ha per year and a grass-clover sward (GC) dependent upon fixation under rotational grazing managements. In one year a continuously grazed sward was also examined. Rates of NH3 loss were usually greatest whilst animals were present, especially during early and late season. This was not always the case, however, and losses sometimes continued into the next grazing period; there were also large day-to-day variations in fluxes. Seasonal trends were also not distinct, but losses tended to be lower during early and late grazings.

The annual losses from 420 and 210 kg N/ha and GC treatments were 25, 10 and 7 kg N/ha, respectively, and the differences between treatments were still marked when losses were expressed on a per animal basis. Total loss under continuous grazing was 61 % of that under the rotational system. Although the losses represent only 7·8, 5·6 and 3·7% of the inputs to420N, 2 ION and GC treatments, there was a good relationship between inputs and total losses, and also between the concentration of N in the herbage and losses per animal. The effects of the measured rates of loss on the input of NH3 from grazed grassland to the atmosphere are discussed.

Two poorly digested materials, barley straw and grass cell wall residues recovered from sheep faeces, were treated with sodium ethoxide, methoxide or hydroxide under various conditions and the effects on their digestibilities studied by the nylon bag technique in the sheep rumen.

Acetyl groups were removed during these treatments and the degree of deacetylation could be controlled by adjusting the amounts of reagents used, about 25 m-mole of base/g being required to produce the maximum effect. Sodium ethoxide in ethanol was the least effective of the reagents used: it did not remove acetyl groups from barley straw and left a larger proportion untouched in faeces cell walls than did sodium methoxide in methanol.

Irrespective of the reagent employed digestibility increased with the progress of deacetylation and the two processes reached a maximum together, but there was not a linear relation between acetyl content and digestibility. In the case of straw treated with sodium hydroxide there appeared to be a linear relationship between digestibility and the amount of reagent applied, up to 20 m-moles/g straw.

Phenolic ester groups were less susceptible to the reagents tested than acetyl groups. It is concluded that the action of the basic reagents is probably upon polysaccharides other than cellulose, that access to some regions of the cell walls may be limited by the solvent present, and that the linkages that restrict digestibility have a sensitivity to basic reagents similar to that of the acetyl ester groups present.

A description is given of the statistical procedure appropriate for the analysis of a Latin square having missing the whole of one row, one column or one treatment, or one row and one column, or either and a treatment. These are the only types of incomplete Latin squares (except those which can be dealt with by the missing plot technique) for which a neat statistical analysis is possible.

It is shown that incomplete Latin squares of these types give unbiased estimates of error and are therefore valid experimental arrangements. They are consequently likely to be of use when the experimental material is such as to preclude the use of a complete Latin square owing to the fact that the number in one or both of the natural groups is one less than the number of treatments to be tested.

Wheat nitrogen-use efficiency in the Yaqui Valley has been estimated at about 0·31. The nitrogen that is not recovered by the crop has important environmental costs that have regional and global consequences. In addition, these nitrogen losses represent an important reduction in farm income. The objective of the present work was to validate a technology that includes the use of N-rich strips together with the GreenSeeker™ sensor and a crop algorithm in farmers' fields with the ultimate goal of improving nitrogen-use efficiency through site-specific nitrogen management in irrigated spring wheat. During the wheat crop cycle 2002/03 and 2003/04, 13 validation experiments of c. 1 ha each were established in farmers' fields in the Yaqui Valley. After the validation phase, during the wheat crop cycle 2005/06, eight technology transfer trials were established in farmers' fields; these had on an average an area of 10 ha each. Both the validation and technology transfer trials compared the farmers' conventional nitrogen management use v. the use of the N-rich strip together with the Green Seeker™ sensor and a crop algorithm to derive N recommendations for each individual field. The results of the validation trials showed that on an average over all locations, farmers were able to save 69 kg N/ha, without any yield reduction. At the price of US$0.9 per unit of N in the valley when these experiments were established, this represented savings to the farmers of US$62/ha. The technology transfer trials demonstrated that, in large commercial areas with an average size of 10 ha, farmers could improve their farm income by US$50/ha, when using sensor based N management. The combination of the N-rich strip, together with the use of the sensor and a crop algorithm to interpret the results from the sensor, allowed farmers to obtain significant savings in N use and thus in farm profits. Farm income was increased by US$56/ha, when averaged over all trials in all years.

The C and N in the biomass of soils from eight grassland field experiments where lime had been applied was determined by the chloroform fumigation method. Lime application increased C and N in the biomass by approximately 30% overall, although there was no effect at two sites. In the unlimed plots basal CO2 production, biomass C, and flush of mineral N production (FN) increased with soil pH. Biomass C and FN were correlated with total N content but not with organic C.

Differences in the apparent C/N ratio of the biomass were found in unlimed soils of pH ≤ 4·5 and in those of pH > 4·5, the ratios being 4·2 and 5·8 respectively. For limed soils the ratio was 5·2. It is probable that the chloroform fumigation method is not suited to soils of very low pH, and that the C/N ratio obtained in soils of pH < 4·5 is artificially low.

Significant differences were found in the flavour characteristics of stewed minces from lambs raised on either lucerne or phalaris pastures. The meat from lambs raised on lucerne had a more intense ‘sharp’ and ‘sickly’ aroma and flavour and a significantly lower flavour acceptability. These characteristics were not significantly alter when the lambs were starved for up to 3 days before slaughter. However, the flavour of meat from lambs transferred from lucerne to phalaris 7 or 14 days before slaughter was not significantly different from that of lambs grazed solely on phalaris.

Field experiments, using Vicia faba cvs Herz Freya and/or Maris Bead were made in 1972–5. Population densities were varied and shading treatments were applied. Soil moisture content was monitored throughout. Maximum dry-matter production per plant and per unit area were similar in 1973 and 1974, but lower in 1975. Variations in growth were associated with variations in soil moisture content. When pods began to fill, plants reached maximum total water content and root growth ceased.

Increasing density enhanced, and shading retarded both leaf senescence and seed maturation. Maximum potential seed yield (5–6 t/ha) in 1974 was obtained at 32plants/m2. In 1975, yields of 7–9 t/ha were obtained at 66 plants/m2, probably as a result of retention of many pods by the plants. Since total dry-matter production was lower in 1975 than in 1974 we conclude that photosynthetic potential did not limit yield in the earlier year.

From the patterns of rainfall, soil moisture and plant water content, we suggest that water supply may be a more important factor controlling yield than either solar radiation or plant competition, with the period following pod setting being especially vital. At this time plant water requirement may often be in excess of supply.

1. The object of this investigation has been to advance knowledge of the methods necessary for the practical application of the transplantation of fertilized ova in cattle.

2. The induction of ovulation at any specific time can be produced by squeezing out the corpus luteum per rectum. Oestrus occurs from 2 to 4 days afterwards; this is accompanied by ovulation and the ova so produced are readily fertilized. The onset of oestrus after the expression of the corpus luteum is hastened by previous treatment with P.M.S.

3. The induction of multiple ovulations is necessary to produce an augmented supply of fertilized ova, but it is of primary importance that the ova so produced are fertilized, viable and capable of full development. Four methods of doing this have been tested.

Nutrient inflows, that is the amount of nutrient absorbed per unit root length per unit time, have been determined for several winter wheat crops (cv. Hustler) with grain yields in the range 8–11 t/ha (85% D.m.). Inflows reached a maximum in April or May with values in the range 13–34, 0·5–1·6, 3·5–13, 0·9–1·8 and 0·35–0·60 × 10–14 mol/cm root/sec for N, P, K, Ca and Mg respectively. The concentration in the soil solution necessary to maintain inflows by diffusion of nutrient through the soil was calculated using a nutrient uptake model. For an October-sown crop the model predicted that soil solution concentrations of 165 μΜ N, 14 μΜ P and 56 μΜ K were needed to sustain the observed maximum inflows, whereas for a September-sown crop, with a larger root system, even lower values of 106 μΜ N, 8 μΜ P and 36 μΜ K were needed. It appears that nutrient transport is unlikely to limit uptake by winter wheat crops growing in moist, well fertilized soils, at least for crops up to about 17 t/ha of total dry matter.

Leaf and tiller production, ear development and ear growth were measured on a two-row and a six-row spring barley genotype, on the F1 between them and on the first backcrosses.

Among the developmental differences between the parental genotypes the following appeared to be of particular significance: the two-row genotype bore more leaves on the main shoot than the six-row genotype and these were initiated more slowly, but emerged more rapidly; the two-row genotype had a proportionately longer ear initiation phase than the six-row; the apical dome was bigger in the six-row than in t he tworow; the two-row genotype produced more tillers.

The association of characteristics with ear type may depend on a pleiotropic effect of the ear type (V – v) locus or, alternatively, some of these characteristics may be under independent genetic control. The latter hypothesis was supported by the developmental pattern of the F1.

It may be that well-adapted two-row and six-row genotypes have patterns of development balanced for the particular ear type. Hybridization between ear types may disrupt these balanced developmental patterns producing a high frequency of poorly adapted genotypes in the progeny.

Iron toxicity is a nutrient disorder associated with high concentrations of iron in soil solutions. Deficiencies of other nutrients, such as P, K, Ca, Mg and Zn, have been implicated in its occurrence in rice plants. Field experiments were carried out in 1992 and 1993 in Ivory Coast to evaluate the iron toxicity tolerance of promising rice cultivars available in West Africa, and to provide additional information for selecting breeding materials. Two sites, differing in their potential to cause iron toxicity, were used. Glasshouse and field studies were also conducted to test the role of other nutrients in the occurrence of iron toxicity. The results showed that genetic tolerance to iron toxicity can significantly improve rice production in iron-toxic soils, with some cultivars producing yields in excess of 5 t/ha. The application of N, P, K and Zn in the field decreased the uptake of iron in rice tops, and this can be a significant factor in the iron-toxicity tolerance of the cultivars.

The aim of the present study was to use data from herds to demonstrate the degree of seasonal influence on litter size at birth in gilts compared to sow parities 2, 3–5 and older (parities ⩾6) in a conventional, open-housing system for commercial pig herds in the northeastern part of Thailand. Data were obtained during a 3-year period from July 2005 to June 2008. The data analysed included observations on 25 835 litters from 8100 sows. Total number of piglets born per litter (TB), number of piglets born alive per litter (BA), proportion of stillborn piglets per litter (SB) and proportion of mummified fetuses per litter (MF) were analysed using a general linear mixed model procedure. The influence of temperature, relative humidity and temperature-humidity index (THI) on TB, BA, MF and SB were also analysed. The meteorological data were merged with the reproductive data and the means of temperature, relative humidity and THI during 115 days before farrowing were calculated and included in the statistical models. The results revealed that sows that farrowed in the hot season had a larger TB and BA than sows that farrowed in the rainy (P<0·001) and cool seasons (P<0·001). The difference of TB and BA among seasons was more pronounced in the gilt litters than the sow litters, insofar as the gilts that farrowed in the rainy season had 0·7 TB fewer than gilts that farrowed in the hot season (P<0·001). By contrast, sows of parities 2, 3–5 and ⩾6 that farrowed in the rainy season had 0·4 (P=0·01), 0·3 (P=0·003) and 0·3 (P=0·02) TB fewer than those that farrowed in the hot season. In the first parity, MF increased from 0·022 to 0·042 when the mean temperature during gestation increased from 26 to 29°C (P<0·001). On average, a reduction of 0·8 TB and 0·7 BA were found when the humidity during gestation increased from 50 to 80% (P<0·001). The influence of THI on TB, BA and SB differed among herds. When THI increased from 71/72 to ⩾81, a decrease of 0·4 TB were observed in herd A (P<0·001) and a decrease of 0·9 TB were observed in herd B (P<0·001), but not in herds C and D (P>0·05). In conclusion, inferior litter size at birth was observed in sows that farrowed in either rainy or cool seasons. High temperature, high relative humidity and/or high THI during gestation significantly reduced the number of total piglets born per litter. The influence of season, temperature, relative humidity and/or THI on litter size at birth was more evident in the gilts than the sows. These data indicated that various strategies to reduce temperature in the open-housing system for pregnant gilts and sows in Thailand are not adequate and the proper housing of pregnant gilts should be emphasized.

1. An analysis has been made of milk records from 3109 cattle of the six main dairy breeds in England and Wales.

2. The correlation between measurements on separate lactations declined as the time interval between the lactations increased. The average correlation was 0·38 for 70 days' milk yield and 0·48 and 0·55 respectively for milk yield and fat content in the 305-day lactation.

3. The heritabilities of the three measurements measured by daughter-dam regression were found for heifer lactations to be 0·36, 0·43 and 0·43 respectively. On second lactations, they were 0·09, 0·24 and 0·42.

4. As a consequence of the low heritability of the second lactation yield, the average yield of the first four lactations proved to have no more value as a prediction of a cow's breeding merit for yield than did her heifer yield.

5. In agreement with other workers, we found that 70-days yield was an excellent guide to the total lactation (r ~ 0·80), and that it could be used as a guide to early selection.

6. There was some indication that the correlation between yield and fat content in the same lactation was more strongly negative in heifers and in the Channel Island breeds. The overall genetic correlation on first lactations was found to be − 0·66 ± 0·20, rather more strongly negative than has been found previously.

The main objective of the experiments described was to compare the effects of milling straw and/or soaking or spraying it with sodium hydroxide on its digestibility and acceptability to sheep. Some preliminary trials were made in the laboratory to compare different alkali treatments with respect to losses of organic matter, chemical composition and digestibility in vitro.

In a feeding trial of Latin-square design, involving six sheep, the following treatments of barley straw were compared: C, chopped; M, coarsely-milled; OIL, chopped and soaked in 1·5% NaOH (9 g NaOH/100 g straw); CIH, chopped and soaked in 3·0% NaOH (18 g/100 g straw); CS, chopped and sprayed with 16 % NaOH (8 g/100 g straw); MS, milled and sprayed with 16 % NaOH. After treatments OIL and CIH the straw was washed; this caused losses of organic matter of 28 and 32%, respectively. For CS and CM the excess NaOH was neutralized by addition of 7·4 ml propionic acid/100 g straw.

The straws were given with supplements of purified soya protein, minerals and vitamins. The digestibility of energy for the straw was (%): C, 40·4; M, 39·1; CIL, 65·0; CIH, 64·4; CS, 57·3; MS, 60·2. Dry-matter intake (g/kg W0·75 per day) was: C, 26·7; M, 36·2; CIL, 37·1; CIH, 44·2; CS, 48·4; MS 53·6.