bluuebunny/crossref_metadata_2025 huggingface dataset:
The influence of sward characteristics on the herbage intake of grazing calves
Authors: Hodgson J. , Capriles J. M. Rodriguez , Fenlon J. S.
Published: March 2009

Experiments were carried out at the Grassland Research Institute, U.K. (Expt 1) and the Universidad Central de Venezuela, Maracay (Expt 2), to study the influence of sward characteristics upon the herbage intake of young grazing cattle. In both studies the animals were strip-grazed in small groups on a series of plots, at a generous herbage allowance.

The digestibility of the herbage ingested exerted a dominant influence on herbage organic matter (OM) intake, which increased at a constant rate as organic matter digestibility (OMD) increased throughout the range observed, 55–81% in Expt 1 and 53–63% in Expt 2. Intakes were similar in the two experiments at 60–65% OMD, but the rate of decline with decreasing digestibility was much greater in Expt 2 than in Expt 1.

Intake was affected to a small extent in Expt 2 by the weight of herbage, the proportion of green material, and the extended height of the sward. In Expt 1 the intake from plots of primary growth was approximately 10% greater than that from secondary growths at equivalent digestibility and crop weight.

The implications of these observations to techniques of grazing management are discussed.
The growth and activity of winter wheat roots in the field: nutrient uptakes of high-yielding crops
Authors: Barraclough P. B.
Published: March 2009

Root and shoot growth and nutrient uptake have been monitored for several winter wheat crops which gave a mean grain yield of 9·5 t/ha (85% D.M.) when grown on three soil types in 1980 and 1981. Averaged over all crops, maximum growth rates were 170 kg/ha/day for shoots and 14 kg/ha/day for roots; maximum nutrient uptake rates for N, P, K, Ca and Mg were 2·75, 0·47, 341, 0·60 and 0·18 kg/ha/day respectively. Maximum uptake of K and Ca occurred at anthesis with values of 239 and 38 kg/ha respectively, whilst for the other nutrients maximum uptake was at final harvest with values of 200, 39 and 14 kg/ha for N, P and Mg respectively. The grain contained 141 kg N, 27 kg P, 41 kg K, 3·2 kg Ca and 7·1 kg Mg/ha.

The quantity of nutrients arriving at root surfaces by mass flow was calculated for one of the crops from measurements of soil solution concentration and potential evapotranspiration data. The potential supply of nutrients by mass flow, as a percentage of that actually taken up between 19 March and 29 June, was 25% for N, 4% for K, 800% for Ca and 32% for Mg.
Further studies on the response of maize to K fertilizer in the tropics
Authors: Kayode G. O.
Published: March 2009

A study designed to investigate the effect of K nutrition on the yield, components of yield and on macro- and micronutrient concentration of maize showed no significant effect of K on yield in forest alfisols derived from basement complex rocks and in savannah alfisols derived from sandstones in the tropics. Potassium addition significantly decreased lodging, but had little influence on cob length, ear weight, shelling percentage or moisture content.

Ear-leaf N and K were significantly increased, while Ca and Mg were decreased by K application. All the micronutrient concentrations (Zn, Fe, Mn, Cu) were significantly increased by K application in the forest and savannah zones. Yield was positively correlated with ear-leaf N on both soils.
A model of lysine deposition in cereal grains
Authors: Draper S. R.
Published: March 2009

A general model of lysine deposition in cereal grains is presented. By inserting into the model values for the lysine contents of various individual protein fractions, equations have been derived which relate total lysine content to total nitrogen. The equation for barley has been used to predict the likely variation in lysine content for this species and the results are compared with published data.
The ‘teat order’ of suckling pigs: 3. Relation to competition within litters
Authors: Fraser D. , Thompson B. K. , Ferguson D. K. , Darroch R. L.
Published: March 2009

Piglets in litters, paired according to farrowing date, were redistributed during the first day after birth according to two schemes. In scheme AC–BD, one sow of the pair received the heaviest and the third heaviest quarters of the combined litters (based on weight post partum), while the other sow received the second heaviest and the lightest quarters. In scheme AB–CD, one sow received the heavier half, and the other the lighter half of the piglets. After 3 weeks under scheme AB–CD, the weight difference between the second and third quarters had become reversed, while under scheme AC–BD the difference was preserved. There was no evidence of a corresponding interaction in the selection of anterior or posterior teats. The rank correlation of the piglets' initial weight and suckling position was low for most sows. No marked differences were observed between fostered and unfostered piglets in the weight measures or suckling position. It is concluded that the growth of the piglets was influenced by the relative size of their litter-mates after redistribution, but that little of the effect could be explained by competition for the anterior teats.
Gluconeogenesis in foetal, suckling and weaned lambs: the effect of glucagon
Authors: Savan P. M. J. , Jeacock Marjorie K. , Shepherd D. A. L.
Published: March 2009

The effect of glucagon on the rate of glucose production in the presence of alanine, of lactate and of propionate has been studied in isolated perfused livers obtained from foetal, suckling and weaned lambs.

Glucose utilization occurred in foetal livers in the absence of glucagon whereas addition of glucagon resulted in a net production of glucose from the three substrates. In livers from suckling and weaned lambs addition of glucagon was not essential for glucose production to occur and the stimulation of gluconeogenesis by added glucagon was less evident in the older lambs. The effect of glucagon was not dependent on changes in the rate of substrate uptake.

It is concluded that gluconeogenesis will be induced by glucagon in foetal lambs when their mothers are severely undernourished, and that placentally derived lactate could contribute up to 90% of the glucose synthesized.
The physiological basis for mixing varieties and seed ‘ages’ in potato crops
Authors: Burstall Lindsay , Harris P. M.
Published: March 2009

Three techniques designed to increase radiation interception, and thus yield, in potato crops by extending the duration of the crop canopy were investigated over a period of 2 years. These were: mixing contrasting varieties; mixing seed tubers of contrasting physiological ages of the same variety, and early planting with protection from frost.

The first technique was partially successful; increases in total tuber fresh weight of the mixture over either of its components grown alone were recorded but the mixtures generally did not have any advantage in terms of ware yield (40–80 mm tubers) and total yield advantages were found in only 1 year. The second technique was unsuccessful in both years with all seven varieties tested. The third technique was successful with the long-lived variety Cara; large advantages both in ware yield and total tuber dry weight yield were obtained under two irrigation regimes. No advantages from early planting were obtained with the shorter-lived variety King Edward.

Radiation interception was estimated for all treatments by means of relationships established between intercepted radiation and percentage ground cover. None of the three techniques increased radiation interception; the yield advantages obtained could be ascribed either to an increase in the proportion of assimilates allocated to tubers or possibly to improvements in the efficiency of use of intercepted radiation.
Protein studies on maize silage as a basal ration for dairy cows
Authors: Phipps R. H. , Weller R. F. , Smith T. , Fulford Rosemary J.
Published: March 2009

In Expt 1 40 lactating British Friesians, 20 cows and 20 heifers, were used to study the effect of crude protein (CP) content of the whole ration on milk yield, milk composition and live-weight change when maize silage was fed as the basal ration. There were four treatments with five cows and five heifers on each. During lactation weeks 4–12 the cows on treatments 1, 2, 3 and 4 all received 7 kg maize silage dry matter (D.m.) plus 8 kg D.m./day of a concentrate containing either 14, 18, 22 or 24% CP, respectively; heifers received 1 kg/day less of both silage and concentrate. This produced whole-ration CP contents of 11·7, 13·9, 16.·0 and 17·1%. In the subsequent lactation weeks 13–20 silage feeding was increased to 9 kg D.m./cow/day and concentrate feeding decreased to 5 kg D.m./cow/day. Heifers again received 1 kg/day less of both silage and concentrate. This decreased whole-ration CP contents to 10·5, 11·7, 12·9 and 13·4%.

During lactation weeks 4–12 and 13–20, with the exception of milk fat content in weeks 13–20, there were significant linear effects of whole-ration CP content on milk yield, milk fat, protein, lactose and total solids. There were no significant curvilinear relationships. Thus, despite the fact that the highest numerical values were generally recorded for the animals on treatment 3, the results indicate that a whole-ration CP content of at least 17·1 and 13·4% are required in early and mid-lactation respectively.

In Expt 2 the loss of D.m., acid-detergent fibre and nitrogen from maize silage suspended in nylon bags in the rumen was measured. Compared with feeding either a low or high protein supplement, losses were greater for silage fed alone. If it is accepted that nitrogen loss can be approximated to protein degradability, then the value for maize silage was between 0·6 and 0·7. Using the same technique in Expt 3, comparable nitrogen losses for fish meal, decorticated groundnut meal and soya-bean meal were 0·3, 0·9 and 0·9, respectively, after 24 h incubation.
Evaluating selected forage legumes for livestock and crop production in the subhumid zone of Nigeria
Authors: Tarawali S. A.
Published: March 2009

A programme of forage legume evaluation was developed at the International Livestock Centre for Africa's (ILCA) subhumid research site in Nigeria from 1985 onwards. Evaluation included monitoring herbage and seed yields, incidence of diseases/pests, regeneration ability and persistence for three growing seasons. This was followed by an in situ bioassay to determine the direct effect of the sown legumes on maize (Zea mays L.) production in the absence of added nitrogen.

The results for selected accessions from introductions received in 1987 and 1988 are presented. Stylosanthes guianensis CIAT184 (ILCA164) and ILCA15557 and Aeschynomene histrix ILCA 12463 were promising both in terms of biomass production (up to 9·4, 3·4 and 9·6 t/ha respectively) and quality (all had crude protein values of 11% or more), and in terms of beneficial effects for maize production (all plots gave significantly more grain than those with no legume, reaching over 3 t/ha for maize grown on plots after S. guianensis ILCA15557). The use of such appropriate forage legumes to enhance both livestock and crop production in a sustainable farming system is recommended.
Effects of various hand-weeding programmes on yield and components of yield of sweet potato (Ipomoea batatas) grown in the tropical lowlands of Papua New Guinea
Authors: Levett M. P.
Published: March 2009

The effects of weed competition, harvest date and cultivar on sweet potato (Ipomoea batatas(L.) Lam.) yield and components of yield were investigated in three factorial experiments planted during the wet seasons of 1984 (Expt 1) and 1986 (Expts 2 and 3) in the tropical lowlands In Expts 1 and 2, the commencement of regular hand-weeding (every 14 days) was delayed for varying lengths of time following planting. In Expt 3, the duration of hand-weeding from planting onwards was varied. The main competing weed species following planting were Cyperus rotundus, C. brevifolius, Euphorbia geniculata and Portulaca oleracea. After canopy closure, E. hirta, Imperata cylindrica, Eleusine indica, Sida rhombifolia, Mollugo pentaphylla and Mimosa invisa were the predominant weeds to emerge and persist. Cultivars differed in their sensitivity to weed competition. In L431 both mean marketable root tuber weight and number of tubers/plant were severely reduced. However, in L44, tuber number was more sensitive than tuber weight: marketable tuber weight was significantly reduced only by prolonged weed competition (no weeding until 56 days after planting (DAP)). In Expts 1 and 2, delaying the commencement of weeding beyond 14 DAP significantly decreased vine weight, total yield and mean number of tubers/plant. In Expt 3, prolonging regular weeding until 14 DAP and longer significantly increased total and marketable tuber yield and mean number of tubers/plant.

Effects of weed competition in the early part of the season during the first 28–42 DAP substantially reduced crop production in the later part of the growth cycle (after 110 DAP). This was probably due to a partial suppression of vine growth early on, which reduced tuberous root initiation and thus limited the number of root tubers that could develop in the later stages of crop growth. Hand-weeding during the period 28–42 DAP also appeared to have a detrimental effect on tuber initiation as a result of mechanical root disturbance at this sensitive period of root differentiation. There was also a trend towards lower yields when the crop was regularly hand-weeded after 56 DAP, probably due to disturbance of the vine canopy.

The critical period for weed competition commenced at or before 14 DAP, possibly as early as 7 DAP, and did not continue beyond 56 DAP. In order to avoid weed competition and the detrimental mechanical effects of hand-weeding, an optimum hand-weeding programme for sweet potato in the tropical lowlands of will probably involve (i) keeping the crop weedfree for the first 14–21 DAP; (ii) no crop disturbance during the period of maximum tuberous root initiation (from c. 21–28 DAP until 42–56 DAP); (iii) clean weeding at c. 56 DAP; and (iv) minimal or no weeding after 56 DAP. Weeding during the period 7–14 DAP is particularly important.
Rate of production of protozoa in the rumen and the flow of protozoal nitrogen to the duodenum in sheep and cattle given a pelleted diet of lucerne hay and barley
Authors: Punia B. S. , Leibholz J. , Faichney G. J.
Published: March 2009

Two crossbred wethers (c. 45 kg) and two Hereford heifers (c. 215 kg) were fitted with permanent cannulas in the rumen and abomasum and given a diet of lucerne hay and barley (60:40). Organic matter (OM) intakes were 0·67 kg/day for sheep and 3·14 kg/day for cattle.

The mean numbers of protozoa in the rumen fluid were 9·3 × 105/ml for sheep and 7·4 × 105/ml for cattle. 14C-labelled protozoa were prepared by incubating rumen fluid in vitro with [14C]methyl choline and then isolating them by sedimentation and differential centrifugation. The labelled protozoa were returned to the rumen of each of the donor animals in a single injection. The specific radioactivity in mixed protozoa isolated from the rumen was measured for 3 days. The protozoal pool size was 10 and 12 g N in the sheep and 64 and 44 g N in the cattle. Protozoal N contributed, on average, 48% of the total N in the rumen.

Production of protozoal N in the rumen was 9·5 and 11·2 g/day for the sheep and 49·5 and 38·6 g/day for the cattle. The flow of protozoal N from the abomasum was calculated to be 1·6 and 2·9 g/day for sheep and 17·3 and 13·3 g/day for cattle. Thus, on average, 79% of the protozoal N was recycled within the rumen of the sheep and 65% within the rumen of the cattle. Protozoal N made up 11–20% of total N flow from the abomasum. The turnover times of 14C-labelled protozoa injected into the rumen of the sheep and the cattle were similar (26·2 and 26·8 h for sheep; 30·8 and 27·5 h for cattle) and were similar to those for protozoa isolated from the rumen of sheep after direct intraruminal injection of [14C]methyl choline (28 and 36 h).
Intravaginal oestradiol-progestagen treatments in the induction of early breeding in sheep
Authors: Gordon I.
Published: March 2009

Six hundred and sixty-two sheep in twenty-two farm flocks were treated in June/July (period of late anoestrus) with intravaginal sponges impregnated with 30 mg ‘Cronolone’ (9α-fluoro-11β-hydroxy-17α-acetoxy-progesterone; G. D. Searle) or ‘Cronolone’ plus 400 mg progesterone and incorporating doses of 0-800 μg oestradiol-17β. Treatment was for 12 days; a single dose of 500 i.u. PMS (Burrough's Wellcome) was injected at pessary withdrawal. Seventy rams were joined to breed the ewes at first and second heats.

Oestradiol treatment resulted in a significantly higher incidence of sponge loss, a lower mating response, a lower conception rate and a lower number of lambs/conception. There was also a tendency for onset of oestrus to be delayed. Such effects were confined to first services and were much less evident in sheep receiving doses of 50 μg oestradiol or below. Data indicate that an intravaginal treatment for the induction of early breeding should consist of progestagen alone rather than progestagen in combination with oestradiol. The addition of 400 mg progesterone to the ‘Cronolone’ sponges appeared to reduce the adverse oestrogenic effects. Sheep treated with ‘Cronolone’/progesterone pessaries in the absence of oestradiol showed a mating response of 97%, a conception rate of 64% and 1·7 lambs/conception at the controlled oestrus.
Behaviour of ewes during parturition
Authors: Sharafeldin M. A. , Ragab M. T. , Kandeel A. A.
Published: March 2009

A number of 237 Barki ewes of 2, 3, 4 and 6 years of age and weighing 25–45 kg were put under close observation so as to study the subjective and objective aspects of their behaviour during parturition.

During the choice and preparation of the parturition site ingestive behaviour ceased and an investigatory behaviour took place using the visual and olfactory senses. Ewes showed preference for the less illuminated and less disturbed places. They pawed the chosen spots with their hooves so as to prepare them for parturition. The parturient behaviour was characterized by signs of uneasiness and of pain, which increased gradually until the lamb's expulsion.

The overall average pre-partum time of labour was 46·1 plusmn; 1·6 min. The 2-year-old ewes took longer to give birth than older ones. The pre-partum labour was not significantly affected by body weights of ewes. The overall average duration of the post-partum labour was 143·27 min. Age and weight of ewes had no significant effect on the duration of the post-partum labour. Births were not evenly distributed over the period of observation.
The effect of Water Loading on urea metablism in Cattle
Authors: Vercoe J. E.
Published: March 2009

Steers fed low nitrogen diets were infused intraruininally with water.

Increasing the water load increased the urine volume and urinary urea excretion and depressed the plasma urea level.

The effect of intraruminal water loading was studied in association with intravenous urea loading of 25 and 65 g N/day. When 25 g N/day as urea was infused intravenously, water loading did not significantly increase the urinary urea excretion but the plasma urea level was depressed. At 65 g N/day water loading increased the urinary urea excretion and decreased the plasma urea level.

Significantly different relations between plasma urea and urea load existed for the ad lib. water and the water-loaded treatments but the relation between rumen ammonia level and plasma urea level was not affected by the water loading.

The results are discussed with reference to the recycling of urea.
Dry matter production of oilseed rape (Brassica napus) with special reference to the root system
Authors: Kjellström C. G. , Kirchmann H.
Published: March 2009

At the research farm of the Swedish University of Agricultural Sciences, Uppsala, above- and belowground production and changes with time in root length, mean root radius and root surface area of spring oilseed rape were studied during the growing seasons 1987 and 1990. In both years, the highest root growth rate was recorded during the stem elongation phase, and the highest shoot growth rate during flowering. The root: shoot ratio decreased throughout the whole period of root sampling, from 0·64 to 0·16, during the cool and wet first year. In the warmer and drier second year, the ratio increased to a maximum of 0·72 when flowering started, and thereafter decreased. More than 80% of the root dry matter was found in the topsoil. Roots were longer and thinner in the dry and warm 1990 than in the wet and cool 1987. Maximum root length was c. 4·9 km/m2 in 1990, and mean root radius varied between 01 and 0·7 mm. Increases in root surface area during periods of root growth were due to increased root length rather than to increased mean root radius.
Effects of date of planting, date of harvesting and seed rate on yield of seed potato crops
Authors: O'Brien P. J. , Allen E. J.
Published: March 2009

Fourteen experiments which studied effects of date of planting in July, date of harvesting and seed rate on seed tuber yields (10–51 mm) of several potato varieties were carried out in four seasons in East Anglia. Seed tuber yields of c. 30 t/ha in Estima, Wilja and Maris Piper and 20 t/ha in Record were produced from the early planting and in all varieties c. 20 t/ha were produced from planting in late July. For maximum seed yield in all varieties, seed rates of 1·5–2 t/ha were sufficient for most harvests from both dates of planting but for the earliest harvest of the late-July planting, seed rates of only 1–1·5 t/ha were required. The value of seed crops was assessed as the number of ware hectares that could be replanted from the seed yield of one hectare graded 10–51 mm. In all varieties, the number of seed-size tubers and replantable hectares increased with increasing seed rate over most of the range, but numbers were close to the maximum at the early harvests. With delay in harvesting, the number of seed tubers and replantable hectares decreased in many experiments, especially from low seed rates, as more tubers exceeded the upper seed size limit. Maximum numbers of replantable hectares of 15, 15, 20 and 25 were found in Record, Estima, Wilja and Maris Piper, respectively.

The monetary value of seed crops of Record and Maris Piper was calculated using (i) a fixed price per tonne of seed and (ii) cost of seed per replantable ware hectare. Sale values from the latter were substantially higher than from the former at early harvests in Record and at all harvests in Maris Piper. In Record, differences in sale value between the two pricing methods decreased with delay in harvesting as yields increased while number of replantable hectares varied little. The results showed that high multiplication rates and monetary returns can be obtained from short-season seed potato crops which may follow crops harvested earlier in the same season. The implications for potato production in the UK are discussed.
Modification of the analytical procedures for the determination of herbage and faecal n-alkanes used in the estimation of herbage intake
Authors: Vulich S. A. , Hanrahan J. P. , Crowley B. A.
Published: March 2009

The evaluation of n-alkane concentrations in herbage and faeces is the basis of a methodology that yields precise estimates of herbage intake. Established chemical analysis procedures for the determination of n-alkane concentrations in herbage and faecal samples involve an elaborate sequence of steps utilizing n-hexane as solvent for both the liquid-liquid extraction of n-alkanes from the sample and the solid-phase separation of n-alkanes in the extract. Composites of herbage and faecal samples from studies with sheep provided the experimental material used to evaluate a series of modifications which would simplify and reduce the workload involved in the chemical analysis. The results show that a less hazardous chemical, n-heptane, can replace n-hexane at all stages of the analytical procedure. They also show that evaporation of the sample extract and redissolving it prior to the separation of the n-alkanes, using a silica gel column, is unnecessary and that the volume of solvent used can be reduced. Procedures for saponification of samples prior to extraction can also be simplified as the process can be run overnight involving a slow build-up of temperature to 90 °C. The gain in precision from processing samples in duplicate was negligible and it would be more appropriate to invest extra efforts on an increased number of experimental animals. The results snowed that the workload and cost of using the n-alkane technique to estimate herbage intake can be reduced substantially.
Residual effects of N, P and K applied to cotton on following crops of sorghum, dolichos and wheat in the Sudan Gezira
Authors: Burhan H. O. , Said M. B.
Published: March 2009

Residual effects of N, P and K applied to cotton on the following crops of dura (Sorghum vulgare), lubia (Dolichos lablab) and wheat (Triticum vulgare) were investigated using data obtained over a 30-year period from a factorial field experiment including various levels of the three nutrients. The three crops differed in their response to residual N, P and K. Dura and wheat, being nitrogen depleters highly responsive to fertilizer nitrogen, were consistently affected by residual N. The residual effects of N on grain and straw yields of both dura and wheat were significant in all seasons and the effects were proportional to the amount of N applied to the preceding cotton. There were indications, however, that a much greater part of the N applied in the preceding year was not available to the succeeding crop. Residual P did not have a significant effect on dura but it varied in its effect on the different components of wheat in different seasons. Residual K did not have any effect on dura or wheat. Data on nutrient uptake and composition of wheat tended to support the yield responses. Contrary to the response of the two cereal crops lubia, being a nitrogen fixing legume, did not respond to the effect of residual N and was consistently affected by residual P. Residual K had a slight effect on lubia in only a few seasons.
The presence of indigenous glauconite in soils and its effect on soil fertility:II. Soils developed on Gault Clay (Denchworth series)
Authors: McRae S. G.
Published: March 2009

Twelve stagnogley soils of the Denchworth series from East Kent were studied to determine the effect of indigenous glauconite on their fertility. The presence or absence of glauconite was not the major factor controlling the potassium or magnesium status which was largely determined by the nature of the < 2 μm clay. Glauconitic soils had much higher levels of available phosphate than corresponding non-glauconitic soils due to calcium phosphate associated with the glauconite in the parent material. Weathering has partially converted this to aluminium and iron phosphates which were the main forms of phosphate present, especially in the A (0–15 cm) horizons.
Blood biochemical polymorphic traits in relation to wool production efficiency in Indian sheep
Authors: Kalla S. D. , Ghosh P. K.
Published: March 2009

Seven hundred and twenty-five adult ewes of six breeds, namely Marwari, Chokla, Magra, Pugal, Jaisalmeri and Russian Merino x Marwari (F1) were typed for blood potassium, haemoglobin and erythrocyte-reduced glutathione (GSH) types. The nature of the association between each polymorphic trait and wool production efficiency (wool yield per kg body weight) in these breeds has been examined.

GSHh animals were predominant in all the breeds. A negative correlation was observed between wool production per kg body weight and erythrocyte glutathione level. In general, mean wool production per kg body weight was found to be more in animals of Hb type A than in other Hb type animals. No significant correlation between blood potassium level and wool production per kg body weight was found in any of these breeds.
Effect of supplementary irrigation during reproductive growth on winter and spring chickpea (Cicer arietinum) in a Mediterranean environment
Authors: Saxena M. C. , Silim S. N. , Singh K. B.
Published: March 2009

Inadequate soil moisture is one of the main constraints on the productivity of chickpea in the rainfed farming systems of the dry areas in West Asia and North Africa. The response to irrigation at flowering and pod filling of winter- and spring-sown kabuli chickpea was studied in 1983–86 at ICARDA's main research station at Tel Hadya in northern Syria. In 1983/84 when the cultivar ILC3279 was sown in winter, irrigation increased yield by 105% over a crop receiving 229 mm of precipitation. In 1984/85, ILC3279 was sown in winter and spring. Advancing the date of sowing to winter increased yield by 65% and irrigation increased seed yield by 73% in winter and 143% in spring sowings compared with crops grown receiving 373 mm rainfall.

In 1985/86, six cultivars (ILC482, ILC3279, FLIP81–57W, FLIP81–293C, FLIP84–19C and FLIP84–80C) were compared, but differences in their response to irrigation were negligible. Advancing sowing from spring to winter increased seed yield by an average of 66%. Irrigation increased seed yield in winter and spring sowings by 56% and 72%, respectively, over those receiving 316 mm annual precipitation. Irrigation is, therefore, a way of increasing the productivity and yield stability of chickpea in northern Syria but the improvement in yield depends on the total rainfall and its distribution over the growing season.
The role of tolerant genotypes and plant nutrients in the management of iron toxicity in lowland rice
Authors: Sahrawat K. L. , Mulbah C. K. , Diatta S. , Delaune R. D. , Patrick W. H. , Singh B. N. , Jones M. P.
Published: March 2009

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 effects of soil sodicity on emergence, growth, development and yield of oilseed rape (Brassica napus)
Authors: Gutiérrez Boem F. H. , Lavado R. S.
Published: March 2009

The effects of exchangeable sodium on emergence, growth, development and yield composition of oilseed rape were investigated at Buenos Aires, Argentina in 1992. A pot experiment was performed using five exchangeable sodium levels, expressed as Sodium Adsorption Ratio (SAR: 12, 20, 27, 34 and 44). Soil with nine different exchangeable sodium contents (SAR from 0·5 to 50) and seven different particle size distributions (from sandy loam to clay) were used in a parallel trial to study the effect of soil crusting on oilseed rape emergence. Soil crusts were made using a rainfall simulator after seeds were sown. Both experiments showed that the direct effect of sodium on emergence occurred with SAR values higher than those which caused clay dispersion (SAR > 20). Oilseed rape seedlings could penetrate crusts having a resistance of < 230 kPa. At SAR values > 20, main stem growth and yield decreased significantly (P< 0·05). These reductions were counterbalanced by an increase in the number of secondary stems. At SAR levels > 34, stem number, grain number per pod on the main stem, as well as pod number on both main stem and secondary stems, were reduced, leading to a marked reduction in total yield. The most important agronomic effect of soil sodium on oilseed rape would be at emergence stage, due to soil crusting.
The phosphorus requirements of growing cattle consuming forage diets
Authors: Ternouth J. H. , Bortolussi G. , Coates D. B. , Hendricksen R. E. , McLean R. W.
Published: March 2009

The results of six experiments on growing cattle weighing 140–480 kg, and with liveweight gains of —0·46 to 1·11 kg/day, were reanalysed to provide estimates of their phosphorus (P) requirements. The 158 data sets were from individually penned cattle offered barley straw-based diets ad libitum with dry matter digestibilities of 0·53–O·65, or from cattle grazing tropical pastures with in vitro dry matter digestibilities ranging from 0·50 to 0·62. Various concentrations of dietary energy, nitrogen (N), calcium (Ca) and P were imposed during the course of the experiments with the penned cattle and various rates of application of P fertilizer changed the botanic and nutrient composition of the forages available to the grazing cattle. The P balances and P kinetics of the cattle were studied using 32P as a tracer.

Over the range of P intakes normally observed in cattle consuming forage diets (10–60 mg/kg LW), the coefficient of P absorption was high and not affected by age or liveweight. The regression coefficient relating P intake to P absorption was 0·77 for unsupplemented grazing cattle and 0·82 for penned supplemented cattle. When the plasma inorganic P concentrations were < 50 mg/1, urinary P excretion of the penned cattle was low, as were the endogenous faecal P losses of both the penned and grazing cattle. These losses were concluded to represent obligatory losses and were related to dry matter intake (r = 0·73) in the range 9–17 mg P/kg LW.

The total P requirements of growing cattle were estimated as g/day and g/kg DM intake from this data. The requirements of cattle consuming forage diets were 40–50% lower than those published by the Agricultural and Food Research Council (AFRC 1991), even though the same equation for the net requirements for growth was utilized.
Herbage production and tiller density in five related grasses, their hybrids and mixtures
Authors: Wilman D. , Gao Y.
Published: March 2009

Four grass species, three hybrids and three mixtures were grown in field swards near Aberystwyth. All swards were amply supplied with nutrients and were cut at 5-week intervals during the year of sowing (1989) and during the following 4 years. The order of the grasses in rate of establishment was: Westerwolds ryegrass > Italian ryegrass (Lolium multiflorum) > Italian ryegrass × perennial ryegrass, Italian ryegrass × meadow fescue, perennial ryegrass (Lolium perenne) > perennial ryegrass × meadow fescue, meadow fescue (Festuca pratensis) > tall fescue (Festuca arundinacea). During the sowing year as a whole, Italian ryegrass was the highest yielding grass, followed by Westerwolds ryegrass. During the remaining period (1990–93), as a whole, the highest yields were obtained from perennial ryegrass sown alone or in a mixture with tall fescue. Tall fescue sown alone was one of the lowest yielding grasses in the year of sowing, but developed to be the highest yielding in 1992 and 1993. Westerwolds ryegrass persisted least well, although some plants did survive until 1992. Italian ryegrass persisted better than Westerwolds and Italian ryegrass × meadow fescue persisted better than Italian ryegrass. Hybrid ryegrass and perennial ryegrass × meadow fescue persisted satisfactorily but with fewer tillers/m2 than perennial ryegrass or tall fescue. The yield of tall fescue in March was as high as that of Italian ryegrass in 1990 and 1991 and higher than that of any of the other grasses in 1992 and 1993; the tiller density of tall fescue was particularly high in March. The yield of mixtures (Italian ryegrass with perennial ryegrass, Italian ryegrass with tall fescue and perennial ryegrass with tall fescue) was, on average, 2·5% more than the mean of the component species when sown alone. When grown with ryegrass, tall fescue was not prominent initially but its proportion in the sward gradually increased.
pH and buffer component dynamics in the surface layers of animal slurries
Authors: Sommer S. G. , Sherlock R. R.
Published: March 2009

The changes in the buffer components and pH in the surface layer of a pig and a cattle slurry were studied in the laboratory of the Department of Soil Science, Lincoln University in 1994. The slurries were spread to a depth of 7 mm in Petri dishes open to the atmosphere. Slurry pH, total inorganic carbon (TIC = CO2+ HCO-+ H2CO3), total ammoniacal nitrogen (TAN = NH3+ NH4+) and volatile fatty acids (VFA = C2-C5acids) were determined at 8–10 intervals after 1–96 h of incubation at 10, 16 and 22 °C. A great increase in pH over the first 8 h was due to the release of CO2. If the initial TIC > TAN, pH then increased steadily but slowly from 8 to 96 h. When the initial TIC < TAN, the pH declined or did not change after 20 h incubation. The initial pH elevation rate increased with temperature and initial concentration of TIC. Calculation indicated that the NH3partial pressure (PNH3) in equilibrium with the slurry increased and pH decreased at increasing temperature if gases could not exchange between the slurry and the atmosphere. From the open slurry system PNH3increased with temperature during the first 1–20 h. At 16 and 22 °C the PNH3declined to low values after 20 h, whereas at 10 °C the PNH3remained appreciable after 20 h. This explains why high accumulated NH3losses may occur when slurry is applied to the field at low temperatures.
The effect of honeycomb selection for grain yield on a maize population
Authors: Sotiriou A. , Koutsika-Sotiriou M. , Gouli-Vavdinoudi E.
Published: March 2009

Starting with the F2generation of a single-cross hybrid, a maize population was improved from cycle 0 (= F2) to cycle 4 by mass honeycomb selection and from cycle 5 to cycle 8 by pedigree honeycomb selection. Seven half-sib families were derived from cycle 8. The grain yield of these, their corresponding S1lines, testcrosses with B73 and diallel crosses were studied. The results showed (i) that the seven half-sib families contained half the percentage of the load of deleterious genes present in the F2generation, (ii) that four of them outyielded their corresponding single-cross hybrids, (iii) that they could constitute an open-pollinated variety, which could be used as a source population and (iv) that they revealed different patterns for general and specific combining ability. Honeycomb selection for grain yield was successful in favouring the existing additive genetic variation in the derived families.
Nitrate leaching from a sandy soil: the effect of previous crop and post-harvest soil management in an arable rotation
Authors: Shepherd M. A. , Lord E. I.
Published: March 2009

Agronomic practices can be modified to decrease autumn soil nitrate and nitrate leaching. This experiment aimed to measure the effectiveness of such practices when integrated into a farming system under UK conditions. The experiment started in autumn 1988 on a sandy soil in Nottinghamshire, UK, and comprised a four-course rotation of potatoes–cereal–sugarbeet–cereal. Three husbandry systems were superimposed, ranging from current commercial practice to most nitrate retentive. Plots were split further to receive either half or full recommended rates of nitrogen (N) fertilizer. Soil mineral N (Nmin) and nitrate leaching (using porous ceramic cups) were measured on selected treatments; this paper presents the findings after five winters.

Autumn Nmin and N leached were strongly influenced by the previous crop, consistently following the order potatoes > cereal > sugarbeet. Pre-harvest management (chiefly N fertilizer input) affected Nmin, and post-harvest management also modified N loss. Cover crops (winter rye or forage rape) after cereals removed 10–40 kg/ha N, depending on previous N management, time and method of establishment. They decreased leaching and were particularly effective if they were able to establish fully before significant drainage occurred. Nmin following sugarbeet, which had received 125 kg/ha N, was less after November lifting than after October lifting (16 and 28 kg/ha N, respectively, as amean of autumns 1989–92). Potatoes left most Nmin (a mean of 60 kg/ha for autumns 1989–92, receiving 220 kg/ha fertilizer N), and their late harvest gave little scope for decreasing leaching losses by establishing green cover before the start of winter. After late harvested root crops (both beet and potatoes), it was often preferable to leave the land fallow over winter, rather than ploughing and drilling a winter cereal.

We show that nitrate leaching can be decreased by simple and inexpensive modifications to an existing crop rotation. Averaged over five winters, adopting such practices decreased the mean N concentration in drainage from 22·3 to 14·5 mg/1.
Effects of plant population density on determinate and indeterminate forms of winter field beans (Vicia faba) 1. Yield and yield components
Authors: Pilbeam C. J. , Hebblethwaite P. D. , Ricketts H. E. , Nyongesa T. E.
Published: March 2009

Using an indeterminate cultivar, Bourdon, and a determinate selection, 858 (provided by Plant Breeding International, Cambridge), of winter field bean, the effect of plant population density on yield was investigated in field trials at the University of Nottingham at Sutton Bonington in three consecutive seasons beginning in 1985/86.

Plant morphology had no effect on the optimum plant density, which for both entries lay between 10 and 20 plants/m2. Bourdon yielded significantly more (2 t/ha, on average) than 858 and this was attributable to more pods/pod-bearing stem, more seeds/pod and heavier seeds. Selection 858 was also less winter hardy.

Yield was most closely correlated with number of seeds/plant, but other components were almost as important, highlighting the plasticity of yield in Vicia faba and the difficulties in attempting to increase yield by selecting for particular components of yield.

In contrast to spring beans, the indeterminate cultivar of winter field bean produced as many branches as the determinate entry and both produced fewer branches at higher densities. There was no difference between the two growth habits in the relative contribution of each stem class to the yield of the whole plant. Higher-order branches contributed less than the main stem to final yield.
Influence of rates and methods of manganese application on yield and nutrition of wheat in a reclaimed sodic soil
Authors: Soni M. L. , Swarup A. , Singh M.
Published: March 2009

A field experiment was conducted at the experimental farm of the Central Soil Salinity Research Institute, Karnal, India during 1992/93 to evaluate the effects of rates and methods of manganese application on the yield and nutrition of wheat on a reclaimed and intensively cropped Mn-deficient sodic soil (pH = 8·7, exchangeable sodium percentage = 18 and DTPA-extractable Mn = 2·7 mg kg-1). There were eight treatments which consisted of a control (no Mn application), three rates of 25, 50 and 100 kg MnSO4. H2O ha-1 each either as a basal or a top-dressing at first irrigation or a foliar spray of 1·0% MnSO4.H2O at crown root initiation (CRI), tillering and jointing stages. Grain and straw yield of wheat increased significantly with increasing rates of Mn application. A foliar spray of Mn produced a significantly higher yield than 25 and 50 kg MnSO4. H2O ha-1 applied either as a basal or a top-dressing but similar to that from 100 kg MnSO4.H2O ha-1. Efficiency of Mn was higher with a foliar spray (82·6 kg grain kg-1 Mn) than with soil application (4·4–6·4 kg grain kg-1 Mn). Application of Mn increased its concentration in the crop but decreased Fe and Cu crop concentrations. Grain yield had a significant positive correlation with the Mn content of the grain (r = 0·72) and straw (r = 0·78). Grain yield was positively correlated with 1000-grain weight (r = 0·90). Recovery of applied Mn ranged from 28·1 to 33·0%.
Voluntary intake and gastric digestion of two hays by llamas and sheep: influence of concentrate supplementation
Authors: Lemosquet S. , Dardillat C. , Jailler M. , Dulphy J. P.
Published: March 2009

The efficiency with which llamas and sheep digest various roughages was compared in France in 1993. Six llamas (three of which were rumen-cannulated) and six rumen-cannulated sheep were simultaneously given three different diets: (i) a grass hay low in N content (HLN), (ii) the same hay with barley, representing 25% of the total dry matter (HLN+B) and (iii) a cocksfoot grass hay, rich i n nitrogen (HRN). Daily forage dry matter intake was slightly, but not significantly, lower in llamas (55·9 g/kg W0·75 ν. 60·3 g/kg W0·75 in sheep). Intake behaviour was similar for the two species except that the number of rumination periods was lower with llamas (P < 0·05). With all diets, the digestibility of both organic matter and cell walls (estimated from neutral detergent fibre) was higher in llamas (Animal Nutrition, 9700 Angra do Heroismo, Azores, Portugal 5+6 and +6+5 units respectively, P < 0·001). The higher digestibility in llamas may be related to the slightly lower level of intake and to the lower dry matter turnover rate in the forestomachs compared to sheep (3·9%/h ν. 5·3%/h, P < 0·01). However, in sacco degradation of both hays were higher in llamas' forestomachs after 24 h of incubation (+6+5%, P < 0·01) and 48 h (+4+3%, P < 0·05) than in sheep. The high microbial efficiency of the llamas can be ascribed to the physical and chemical characteristics of their forestomach contents, which had a higher liquid turnover rate (+1+4%/h, P < 0·05), a lower volatile fatty acid concentration (P < 0·01), a higher and more constant pH (P < 0·01) than in sheep and a greater buffering capacity when pH was close to neutral. These results suggest the greater ability of llamas to control the physicochemical conditions of their forestomach contents to digest cell walls efficiently and to minimize the negative effects of concentrate supplementation.
Some factors affecting the expression of the physiological age of potato seed tubers
Authors: Gillison T. C. , Jenkins P. D. , Hayes J. D.
Published: March 2009

Two experiments, each involving five potato cultivars, investigated the effects of date of planting and harvesting of the seed crop, and of two seed storage temperature sequences, on date of dormancy break, sprout growth and subsequent field growth. The seed storage sequences in each case involved early or late accumulation of temperature to produce a physiological age of 600 day-degrees > 4 °C.

The effects of seed crop husbandry on most variables were small, with the exception of date of dormancy break, which occurred earliest when the seed crop was planted and harvested early. Effects of temperature sequence were more pronounced, although cultivars differed significantly in degree of response. Late temperature accumulation gave a larger number of sprouts per tuber, the length of the longest sprout was increased, as was the total sprout length per tuber. Emergence was more rapid, ground cover was initially greater and the number of mainstems per plant was greater with late temperature accumulation. Secondary stem production was more prolific and the total number of stems per plant greater when temperature accumulation was early. The number of tubers per plant reflected the total number of stems, and individual tuber size generally decreased as numbers increased, with the result that storage temperature treatment affected graded yields in some varieties.

The field growth of the crops from the late temperature accumulation treatment was in many ways suggestive of greater physiological age than the early temperature accumulation treatment, although the number of day-degrees accumulated was the same in each case. It is possible that the number of day-degrees underestimates physiological age as the period of accumulation is delayed.