Effect of fertilizers on the yield and chemical composition of pure sown white clover and on soil nutrient status

The effects of three levels of potash, phosphate and lime fertilizers on the yield and mineral content of white clover ( Trifolium repens ) and on soil nutrient levels were studied in a field experiment over 7 years. The aim of the experiment was to define an optimum fertilizer programme for breeding nurseries and experimental fields.
Potash was the main factor limiting production: clover yield was negligible after 2 years where no potassium was applied. Phosphate increased yields after the third year, while liming had no significant effect on clover yield.
The soil potassium status improved with the repeated application of potash over the 7–year period, but no consistent pattern was discernible for the phosphate treatments. There was a slight increase in soil pH with liming.
Application of phosphate increased the phosphorous content of herbage, but had no effect on other plant constituents for the first 2 years. Subsequent applications increased the calcium and sodium contents. Potash reduced the content of all constituents other than potassium as the treatment levels increased. Lime had little effect on plant constituents other than calcium.     

Reseeding in the Falkland Islands. Herbage production of a range of grass species and cultivars

The productivity of 20 cultivars from a range of 13 grass species was compared by harvesting four times during each of three successive growing seasons. In the experiment, 120 kg N ha⁻¹, 42 kg P₂O₅ ha⁻¹ and 42 kg K₂O ha⁻¹ were applied annually.
Mean annual yield was 3229 kg DM ha⁻¹ and 2147 kg DOM ha⁻¹. Cultivars were arranged in seven groups for comparison. Three of the groups, Lolium, Phleum and 'others' (the latter consisted of Festuca arundinacea cv. Dovey and Poa pratensis cv. Bensun A.34) appeared significantly lower yielding than the Dactylis, Festuca (fine-leaved), Agrostis and Holcus groups.
In the Lolium group, cv. Gremie outyielded cv. Melle every year. No cultivar of Dactylis was significantly better than any other in its group. Phleum CVS Motim and Eskimo were similar and superior to cv. S.50. Festuca ovina cv. Novina and Agrostis canina cv. Kingstown were marginally the best in their respective groups. The two cultivars of Holcus performed virtually identically. Festuca arundinacea cv. Dovey was a good producer of early spring grass. Poa pratensis cv. Bensun A.34 was generally low yielding and subject to fungal rust attack in autumn. The pattern of seasonal DM production was 16% in early spring (cut in October/November), 39% in mid-season (cut in December), 40% in late summer (cut in February/March) and 5% in autumn (cut in April/May). Quality of the herbage was superior to the main indigenous grass Cortaderia pilosa.
It was concluded that although the experiment was conducted under a cutting regime it provided useful guidance for seeds mixture formulation and stock carrying capacity calculations.     

Adonis microcarpa (pheasant''s eye) toxicity in pigs fed field pea screenings

Seed of Adonis microcarpa (pheasant's eye) fed at 5.6 g/kg of the diet induced virtually total feed refusal within 3 d in growing and finishing pigs. It also caused vomiting, rapid and shallow breathing and death in a minority. These effects were probably caused by cardiac glycosides whose structure and effects closely resemble those of digoxin. Feed intake and growth recovered within 2 weeks of removal of the seed.     

Variation in spring temperatures, grass production and response to nitrogen over twenty years in the uplands

Large between-year variation was observed in spring air and soil temperatures at Pant-y-dwr Hill Centre (305 m altitude) from 1967 to 1984 and at Bronydd Mawr Research Centre (330 m) from 1985 to 1986 in Powys. The mean date of attaining T-sum 200°C accumulated air temperature was 13 March (range 9 February to 23 April) and that of soil temperature at 100 mm depth permanently above 5 5°C was 9 April (range 7 March to 4 May). Net herbage accumulation and response to applied N from Aberystwyth S23 perennial ryegrass (Lolium perenne L.) swards during April were also highly variable and were correlated with the date of reaching target soil temperatures of above 5 5°C for 5 consecutive days ( r =−0·68, P < 0·001 for net herbage accumulation and r =−0·70, P < 0·001 for response to N).
The use of early flowering varieties of perennial ryegrass gave a significant increase of herbage growth in spring compared with late varieties. From 1979 to 1980 net herbage accumulation during April from the early variety Frances was 94% more than from Perma (late) and 55% more than from Talbot (intermediate) varieties. Under conservation management more winter hardy and persistent varieties of Italian and hybrid ryegrasses ( L. multiflorum L. and L. multiflorum X L. perenne ) gave higher quantities of firstcut silage crops in early June than RvP Italian ryegrass.
After the severe winters of 1978–79 and 1985–86, subsequent spring production from a wide range of ryegrasses was shown to be affected by sward survival, highlighting the value of winter hardy varieties when resowing in the uplands     

Assessment of contrasting perennial ryegrasses, with and without white clover, under continuous sheep stocking in the uplands

Comparative sheep production from Aurora (very early-flowering), Meltra (late-flowering tetraploid) and Aberystwyth S23 (late-flowering) perennial ryegrass ( Lolium perenne L.) varieties was assessed as both grass-only (200 kg N ha⁻¹) and grass-white clover ( Trifolium repens L.) (75 kg N ha⁻¹) swards under continuous stocking management. Beulah Speckled Face ewes and their Suffolk cross lambs were used from late April to mid-July. From late July to early November only lambs grazed the pastures.
Mean (1985–87) total annual lamb production per hectare from Aurora and Meltra was 16% and 13% more than that from S23. The magnitude of the differences between these varieties and S23 declined from the first to the third year. Aurora gave 29% more lamb output per hectare than S23 in 1985 but only 10% more in 1987, while the advantage of Meltra over S23 fell from 19% in 1985 to 6% in 1987. Seasonal lamb production per hectare varied between the grasses, especially during spring when lamb output from Aurora was 43% and 22% more than that from S23 and Meltra respectively, with that from the tetraploid being 17% higher than that from S23.
It is concluded that the superior spring output from Aurora offers the farmer the opportunity to reduce his dependence on bought-in feedstuffs, hence improving the efficiency and profitability of lamb production from grassland.     

Effects of some herbicides on soil enzyme activities

Effects of glyphosate, paraquat, trifluralin and atrazine on activities of dehydrogenase, phosphatase and urease in one soil were measured. Only glyphosate at 21.6 kg/ha was found to inhibit the enzyme activities and generally the results were not statistically significant. Enzyme activity associated with micro-organisms proliferating in soil supplemented with lucerne meal was similarly not affected by the herbicides. Interpretation of results from enzyme activity measurements in soils treated with herbicides is discussed. It is proposed that effects of natural stress can be used to judge the relative importance of herbicide induced change.     

The effect of herbicides on respiration and transformation of nitrogen in two soils II. Dalapon, pyrazone and trifluralin

The effects of dalapon, pyrazone and trifluralin at 100 ppm on carbon dioxide evolution and nitrogen transformation in two soils have been investigated in the laboratory. None of the herbicides had any adverse effects on carbon dioxide evolution or mineralisation of nitrogen. In Triangle soil (organic carbon 3.9%, pH 5.4) dalapon and pyrazone inhibited nitrification for at least 3 weeks. In Boddington Barn soil (organiccarbon 1.5%, pH 6.6) this effect was not observed. Dalapon degraded rapidly during the first 6 weeks, but pyrazone and trifluralin were more persistent.     

Utilization of (3S,3'S)-astaxanthin acyl esters in pigmentation of rainbow trout (Oncorhynchus mykiss)

The deposition of natural, optically active, astaxanthin fatty acid esters in rainbow trout ( Oncorhynchus mykiss ) was studied. Mono-esterified and di-esterified (3 S ,3' S ) astaxanthin were purified from the green microalga Haematococcus pluvialis and incorporated into extruded diets and compared with diets containing synthetic racemic astaxanthin (Carophyll Pink) and a total carotenoid extract from the alga. All sources of astaxanthin achieved >4 mg kg⁻¹ in the white muscle after 6 weeks feeding. No significant difference ( P  > 0.05) between the deposition of astaxanthin or total carotenoid for the different diets was observed. Other xanthophylls, namely lutein, zeaxanthin and idoxanthin were found in the white muscle of rainbow trout fed all diets and together accounted for 10–14% of total carotenoid. Astaxanthin was deposited in the white muscle in the stereochemical form administered in the diet, i.e. racemic astaxanthin for Carophyll Pink and ˜100% (3 S ,3' S )-astaxanthin for the algal sources. In contrast, epimerization of (3 S ,3' S ) astaxanthin from the alga was observed for the astaxanthin esters deposited in the skin of rainbow trout, with a ratio close to 1.0:2.0:1.0 (3 S ,3' S :3 R ,3' S :3 R ,3' R ).     

The pattern of growth in swards of two contrasting varieties of white clover in winter and spring

In a study of growth rates and developmental morphology of simulated swards of two contrasting white clover varieties, Katrina and Kent, it was found that both varieties continued to produce dry matter throughout the winter at Aberystwyth. The gross crop growth rate in the coldest periods was about 7 kg ha^-1 d^-1. The rates of formation and loss of new leaves were approximately equal so that there was no net increase in weight until the latter part of March. This initial net weight increase in both varieties was observed in the same harvest interval, the most important factor being the difference in weight between the new leaf plus petiole unit and the weight of the unit which it replaced. The weight of laminae and petioles throughout the experiment was somewhat higher in Katrina which has come to be regarded as the 'earlier' variety.
The prospects for improving spring production in white clover by variety improvement are discussed.