bluuebunny/crossref_metadata_2025_split huggingface dataset:
Potassium reserves in British soils. I. The Rothamsted Classical Experiments
Authors: Talibudeen O. , Dey S. K. 
Published: March 2009

SummaryThirty-four soils from the Rothamsted Experiments were exhaustively cropped with ryegrass in the glasshouse. The concentration and yield of potassium in ryegrass tops and the potassium intensity in the soil were measured every 4 weeks, after harvesting the grass.The change in K-intensity of soils, rich in potassium, with exhaustion differed from that of ‘poor’ soils. This change was related to the rate of change of the cumulative K-yield. The rate of change of soil K-intensity demarcated periods of intense and limited exhaustion and partial recovery of the soil during cropping.The cumulative K-yield of ryegrass was very significantly related to the K-intensity of the uncropped soil; the ‘16-week’ yield was slightly better related than the ‘60-week’ yield. For Park Grass soils, the relationship was improved by allowing for variations in soil pH.The K-intensity of all soils, with or without manuring, decreased to nearly 10-3(M)½in (AR)0units after 16 weeks cropping, although large differences in K-yield persisted until much later.K-buffer capacityper unit clay contentof the soil, measured by a laboratory method, was inversely related to the K-intensity of the uncropped soil. The K-buffer capacities of soils rich in potassium, measured in laboratory and glasshouse experiments, were significantly related, but were unrelated for ‘poor’ soils. The K-buffer capacity (laboratory method) of Rothamsted soils with different manurial treatments was only very approximately related to the cumulative K-yield.Less K was taken up from all Rothamsted soils given nitrogen fertilizer in the field and their K intensities were also smaller than the corresponding soils without ‘N’. Field liming of acid soils decreased their K-intensity and increased their K-buffer capacity, presumably because more potassium was removed by the field crop.A rapid method is suggested for measuring potassium intensities of soils.
Variation between tetraploid red clover plants in corolla tube length and height of nectar
Authors: Bond D. A. 
Published: March 2009

SummaryCrosses between eelworm-resistant tetraploid red clover plants varied significantly in corolla tube length and in the distance between the top of the nectar and mouth of the corolla tube. Variability between plants in height of nectar above the base of the corolla was positively correlated with corolla tube length but a significant residual variance in nectar height was independent of corolla tube length.Tetraploids had higher nectar but longer corolla tubes and greater distances for bees to reach than those in related diploids which were previously reported.The implications of the findings are discussed in relation to the improvement by breeding of the attractiveness of tetraploid red clover to honey-bees.
A comparison of the yield of three grass species at various levels of nitrogenous fertilizer sown alone or in a mixture
Authors: Cowling D. W. , Lockyer D. R. 
Published: March 2009

SummaryThe production of herbage dry matter harvested from a mixture of S. 24 perennial ryegrass, S. 37 cocksfoot and S. 48 timothy is compared with the yields of the same species sown alone. Various levels of fertilizer nitrogen were applied to the grasses which were harvested by cutting fourteen times over a 3-year period.The possibility that the mixture produced a greater yield than swards of pure species (after taking into account that the three species are not present in equal proportions in herbage harvested from the mixture) was examined using the concept of ‘the sum of the relative yields’. There was no evidence of a beneficial or antagonistic effect of one species on another; rather, the species seemed to be ‘mutually exclusive’ (de Wit & van den Bergh, 1965).The botanical composition of the mixture changed through the course of the experiment, e.g. cocksfoot became increasingly dominant, particularly at the highest level of nitrogen. Changes in composition accounted for any tendency for the yield of the mixture to deviate from the mean of the pure-sown swards.Some of the advantages and disadvantages of using mixtures are discussed and it is concluded that a rational approach to grassland husbandry should be based on swards sown to a single grass variety.
Prediction of leaf area indices and yields of wheat
Authors: Benbi D. K. 
Published: March 2009

SUMMARYChanges in leaf area index (LAI) of wheat are predicted by using information on daily heat units, atmospheric evaporative demand, water supply and nitrogen. The results of experiments on two different soils at Punjab Agricultural University Farm, Ludhiana, India from 1987 to 1990 showed that the rate and extent of leaf area development and its decline were dependent on the amount and pattern of water supply. Maximum leaf area index (LAImax) during the three years was found to depend on a combined effect of NO3-N in the 180 cm soil profile at sowing plus fertilizer N added. A relative growth factor (RGF) to scale cumulative water supply commensurate with crop growth was computed, which takes into account the combined effect of crop demand and supply of water and nitrogen from the soil. For adequately irrigated wheat, leaf area senescence could be predicted from cumulative potential evapotranspiration (PET). However, under droughted conditions, water supply, along with PET, also affected leaf area senescence. The dependence of wheat grain yield on LAImaxin conjunction with water supply subsequent to attainment of LAImaxwas almost linear. It is concluded that, for adequately irrigated wheat, N availability at sowing and cumulative PET determines LAImaxand the pattern of leaf development. Wheat grain yield is determined by LAImaxand cumulative water supply from LAImax to maturity.
The effect of bacterial inoculants on kikuyu silage quality
Authors: Figueiredo M. De , Marais J. P. 
Published: March 2009

SUMMARYTwo commercial bacterial inoculants (Lacto-flora and Ecosyl) were added to kikuyu grass (Pennisetum clandestinum) at ensiling, in 1985 and 1988 respectively, at Cedara, South Africa, using laboratory silos. In 1985 (Expt 1), Lacto-flora was added on its own and in combination with the enzymes Celluclast or SP249. In 1988 (Expt 2), Ecosyl was added on its own and in combination with molasses, at two levels of addition.The addition of Lacto-flora alone did not significantly increase the lactic acid bacteria or the lactic acid content of the treated silage. However, treated silage contained 53·6% less iso-butyric acid and 53·7% less ammonia than the control silage. Kikuyu silage supplemented with a combination of Lacto-flora and Celluclast or SP249 had higher numbers of lactic acid bacteria at ensiling (0·231 × 108/ml) than the control silage or silage receiving Lacto-flora alone. However, only silage supplemented with the combination of Lacto-flora and Celluclast had a significantly higher lactic acid content (2·23 compared with 0·04, 0·18 and 0·13% DM for the control silage, silages with Lactoflora and with a combination of Lacto-flora +SP249, respectively). Nevertheless, this silage contained 19·78% more acetic than lactic acid.Silage supplemented with Ecosyl on its own did not differ significantly in digestibility, loss of dry matter, ammonia, total non-structural carbohydrates, lactic acid and crude protein, from the untreated silage. A significant decrease in silage pH (from 5·08 to 4·70) was observed when Ecosyl was added together with molasses at the higher level of addition only. However, no other benefit was obtained by the addition of Ecosyl in combination with molasses.
Effect of green manuring on the physical properties of soil under a rice–wheat cropping system
Authors: Joshi R. C. , Haokip D. D. , Singh K. N. 
Published: March 2009

SUMMARYThe effects of green manuring withSesbania aculeata, or withLeucaena leucocephalaleaves and of weed incorporation on the physical properties of a clay loam soil under a rice–wheat rotation were compared at New Delhi, India, in 1986–87. Under puddled conditions, the volumetric moisture content of the saturated topsoils varied from 0·400 cm3/cm3in theSesbania-treated plots to 0·425 cm3/cm3in plots receiving no green manure, but in the unsaturated soils at rice harvest the corresponding values were 0·317 and 0·271 cm3/cm3. The effects of the green manures on the water content of the soils were still evident after a subsequent wheat crop. Other soil physical properties affected by the treatments were the following (data refer to topsoils measured after the rice harvest): settling index (cm/cm), an estimate of structural instability, which ranged from 25·5% (Sesbania-treated plots), to 28·6% (weed incorporation), 29·7% (Leucaena-treated plots) and to 33·5% (NPK-fertilizer only). Soil dispersion increased from 6·0 to 10·0 g/100g through the same treatment sequence. Hydraulic conductivity in the NPK-fertilizer only plots was 31 cm/day, but increased to 4·8 cm/day in theSesbania-trealed plots.Sesbaniawas superior to the other green manures for improving soil physical properties after its incorporation.
Intake and digestibility of low quality roughages when supplemented with leguminous browse
Authors: Goodchild A. V. , McMeniman N. P. 
Published: March 2009

SUMMARYIn the first two of four experiments, sheep were fed,ad libitum, sorghum stover supplemented with graded levels of foliage of the shrub leucaena (Leucaena leucocephald) or mulga (Acacia aneura), which provided between 0 and 0·34 or between 0 and 0·43 of the dietary dry matter (DM) respectively. A second treatment (with or without urea) was superimposed in a factorial design. The effect of treatments on liveweight (LW) was explainable by their effects on voluntary intake of apparently digestible organic matter (DOMI). D0M1 was increased by mulga, largely due to an increase in the total voluntary intake of organic matter (OM). Leucaena increased DOMI by increasing the ration OM digestibility and, at low levels of inclusion, intake of the basal diet. Roughage intake was greatest when leucaena provided 0·15–0·20 of the dietary DM. Leucaena increased rumen ammonia, and whenever roughage intake was increased by urea, leucaena also increased it.In the third experiment, when diets were made isonitrogenous with urea, roughage intake was slightly greater when leucaena, rather than its ash or a mineral mixture, was supplemented. Total OM intake and DOMI were greatest when leucaena was fed.In the final experiment, sheep were fed one of ten treatments: three basal diets (two of sorghum stover and the third of native pasture hay) each supplemented with legumes (leucaena to the hay and one stover diet and cowpea straw to the second stover diet), ash of the respective legume and formaldehyde-treated casein. The tenth treatment was sorghum stover plus urea. For sorghum stover diets with leucaena-based or cowpea straw-based supplements, DOMI responded linearly to the nonurea nitrogen concentration of the diet. On the other hand, for native hay with leucaena-based supplements, the response of DOMI to non-urea N was negligible. It was noted that the native hay (predominantly Flinders grass,Iseilema vaginiflorum), contained lower concentrations of polyphenols than sorghum stover.It was concluded that browse foliage can increase the voluntary DOMI of sheep consuming low quality roughages by providing nitrogen and sometimes minerals and OM of greater digestibility. The slowly-degradable proteins in leucaena, cowpea straw or formaldehyde-treated casein are more effective with polyphenol-rich sorghum stover than with native hay of otherwise similar composition.
Nutritional evaluation of kale (Brassica oleracea) diets:1. Growth of grazing lambs as affected by time after introduction to the crop, feed allowance and intraperitoneal amino acid supplementation
Authors: Barry T. N. , McDonald R. C. , Reid T. C. 
Published: March 2009

SUMMARYThree successive sowings of marrow-stemmed kale (cv. Maris Kestrel) were grazed with lambs (initial weight 22·5 kg) for two consecutive 6-week periods, so that crop yield at the time of grazing was kept relatively constant at 6·5 t D.M./ha. Three crop allowances, 3·9 (H), 2·6 (M) and 1·3 (L) kg D.M./animal/day were imposed in a replicated design. Halfof the 32 lambs grazing each allowance received intraperitoneal injections of L-methionine + L-threonine three times per week. Twelve lambs were slaughtered at the start of the experiment and 48 at the end of each period.Leaf tissue, the diet of the H groups, contained 0·5% D.M. as S-methylcysteine sulphoxide (SMCO) and 0·7–1·5% total N as nitrate. Whole plants, the diet of the L groups, contained 0·75% D.M. as SMCO and 4·0–7·5% total N asnitrate. The diet of the M groups was intermediate.Rates of live-weight gain (LWG), empty-body weight gain (EBWG) and carcassweight gain (CWG) were lower in period 1 than in period 2 for animals grazing at all three allowances. A Heinz-Ehrlich body anaemia developed that was more severe in the first period, but did not differ between groups receiving the different allowances. Methaemoglobin was only detected in significant quantities at the time of peak Heinz body formation in period 1. CWG/EBWG was increased by the amino acid supplementation during period 1 but not period 2, showing that there was a temporary amino acid deficiency corresponding to the time when tho anaemia was most severe and body growth most depressed.In both periods animals grazing at L allowance had lower rates of LWG, EBWG and CWG than M and H animals, who performed similarly. Most of the differences in EBWG between feed allowance treatments and between periods could be explained by changes in estimated intake. Wool growth rates increased with increasing feed allowance and were slightly stimulated by amino acid supplementation.Copper true availability was calculated to be 1·6–2·7% with the lowest values for leaf tissue due to its high sulphur content. Truly available Cu/kg plant D.M. was below the minimum requirement for lamb growth, thus leading to a reduction in total liver Cu as the experiment progressed. Some indication was obtained that this could have been depressing LWG in the second period, especially in H lambs. Slight increases in thyroid gland weight were observed as the experiment progressed, but these were considered unlikely to have depressed body growth. It was concluded that the major factor limiting the feeding value of B. oleracea was its high content of nonprotein sulphur compounds, especially SMCO.
Genotype-environment interactions in tea (Camellia sinensis L.) and their implications in tea breeding and selection
Authors: Wickramaratne M. Rupa T. 
Published: March 2009

SUMMARYAn analysis of yield data from 31 tea clones grown in replicated trials at four locations revealed the presence of significant genotype-environment interactions. Joint regression analysisshowed that a significant proportion of these interactions could be attributed to differences in the linear response of each genotype (clone) to the range of environments. However, estimates of the deviations from regression were also significant, indicating the presence of some unpredictable variation.The response of each individual clone was estimated by computing the regression coefficient of individual yield on environmental mean yield at each location. The clones used in this study had regression values ranging from 0·19 to 2·08, indicating considerable genotypic difference in response to environmental change. Genetic variation in adaptation was also found to be present. Clones of the Assam type were found to possess general adaptation whereas the one clone of Indo-Chinese origin was specifically adapted to low-yielding environments.Some known features of several tea clones are explained on the basis of the linear regression model and a more scientific basis is provided for the recommendations of clones for differentdistricts. The implications of genotype-environment interactions in practical tea breeding and selection are also discussed.
Performance of different Scottish Blackface stocks and their crosses
Authors: Al-Nakib F. M. S. , Findlay R. H. , Smith C. 
Published: March 2009

SUMMARYThe performance of different stocks of Scottish Blackface sheep and their crosses was compared on a harsh Scottish hill experimental farm. The strains were the Stanhope farm stock (a control flock, closed for 30 years), stock from local Breeders, and first crosses and back-crosses of Stanhope stock with stocks represented by rams purchased at Lanark market. Some 3892 ewe records were available with 1837 lamb performance records. Estimated effects for the three types of stock and of heterosis in the Stanhope and Lanark cross were derived statistically. The local Breeders' stock had the heaviest lambs at weaning and the Stanhope stock the lightest. The local Breeders' stock also had the heaviest ewes and higher litter size but had lower fertility and lower lamb survival. Output expressed relative to ewe weight was highest for the cross-bred stock. Heterosis was positive for all traits studied except survival but was statistically significant only for ewe weight and lamb birth weight. If the Stanhope stock was representative of Scottish Blackface sheep of 30 years ago, breeding by Scottish Blackface breeders has led to an estimated improvement of 9% in the output per ewe exposed, and 5% in efficiency of production.
Trends in herbage yields over the last century on the Rothamsted Long-term Continuous Hay Experiment
Authors: Jenkinson D. S. , Potts J. M. , Perry J. N. , Barnett V. , Coleman K. , Johnston A. E. 
Published: March 2009

SUMMARYYields from five of the plots on the Park Grass Continuous Hay experiment at Rothamsted, started in 1856, were examined to see if any long-term trends could be detected over the last 100 years. Three of the plots examined are unfertilized; two receive inorganic nutrients every year; all are harvested twice a year. In 1959 the harvesting procedure was changed: yields for the periods before and after this change were examined separately and together. On none of the three unfertilized plots was the slope of the regression of total yield (i.e. first and second cutscombined) on time significantly (P< 0·05) different from zero in either the 1891–1958 or 1960–1992 periods. On both the fertilized plots, there were significant declines in yield with time over the 1960–92 period, assuming that the effects of autocorrelation are sufficiently small to be ignored; there were no consistent changes between 1891 and 1958. There were some significant trends on the five plots when the two cuts were considered separately.A linear regression model was fitted to the data in an attempt to separate the effects of meteorological variables (rainfall and sunshine hours over selected parts of the year) on total yield from possible long-term effects brought about, for example, by the increasing concentration of CO2in the atmosphere. On four of the five plots this model accounted for between 12 and 21% of the yield variance in the pre-1959 period and between 45 and 63% after 1960. On the fifth plot, which received the highest level of N, the model accounted for 29% of the variance in the first period but only for 16% in the second period. When a linear trend with time was included in the model, this was not significant on any of the plots over the entire 1891–1992 period, although some significant trends appeared when the two periods were considered separately. The model was also fitted with the atmospheric CO2concentration in place of the linear trend with time: again there were no consistent trends.Neither changes in the concentration of CO2in the atmosphere over the last century nor increasing inputs of combined N in rainfall or in dry deposition have had any detectable effects on yield in these plots.
Morphology and position of the shoot apex in some temperate grasses
Authors: Wilman D. , Gao Y. , Michaud P. J. 
Published: March 2009

SUMMARYThe morphology and position of the shoot apex in field swards was studied in 12 grasses for 12 months, in eight related grasses in 2 years, and in seedlings, young tillers and older tillers of Lolium perenne.Lolium multiflorum had relatively large numbers of primordia, long apices, which were above ground or near ground level, and a small length of apex per primordium. Festuca arundinacea had few primordia, a large length of apex per primordium, and apices which were well below ground or near ground level. Lolium perenne, Festuca pratensis and Lolium × Festuca hybrids were intermediate between Lolium multiflorum and Festuca arundinacea in numbers of primordia and length of apex per primordium. Festuca rubra and Dactylis glomerata had rather small numbers of primordia, whereas Phleum pratense had relatively large numbers of primordia and of unemerged and emerged leaves.The numbers of leaf primordia in Lolium perenne increased as the seedling main shoots or the tillers grew older, while the numbers of unemerged leaves per shoot remained more constant.The morphology, position and protection of shoot apices are discussed in relation to differences between species in rate of establishment and persistence.
Effects of number and siting of single-space feeders on performance and feeding behaviour of growing pigs
Authors: Morrow A. T. S. , Walker N. 
Published: March 2009

SUMMARYTwo experiments of randomized block design were carried out at the Agricultural Research Institute of Northern Ireland in 1991/92 involving groups of 20 pigs fed ad libitum from single-space feeders with built-in water supply from 37 kg to slaughter at 91 kg liveweight.Treatments were replicated 16 and 6 times respectively in Experiments 1 and 2. In the first experiment, one feeder perpen was compared with two feeders per pen positioned side by side. Two feeders increased feed intake (P < 0·05) but had no significant effects on growth rate or feed conversion. With two feeders, the total time that feeders were occupied and the number of visits to feeders were both increased, while the number of enforced withdrawals from feeders and the amount of queuing were both decreased compared with the single feeder. In the second experiment, placing two feeders 2 m or more apart instead of side by side had no significant effects on feed intake or growth rate but improved feed conversion efficiency by 4%. This improvement was associated with fewer and longer visits to feeders but no difference in enforced withdrawals or queuing. In both experiments all treatments showed broadly similar patterns of diurnal feeding behaviour with two peaks of activity daily, a smaller peak pre-midday and a larger one in the afternoon. This pattern was influenced more by number of visits to feeders than by the mean duration of each visit. It is recommended that two single-space feeders are used in pens of 20 finishing pigs when non-pelleted diets are offered ad libitum and that feeders are sited some distance apart, not side by side.