Caucasian clover

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Caucasian clover/ryegrass produced more legume than white clover/ryegrass pastures in a grazed comparison

Caucasian clover/ryegrass produced more legume than white clover/ryegrass pastures in a grazed comparison

The potential of caucasian clover to improve the legume content of lowland New Zealand pastures should result in enhanced animal performance. Liveweight gains from eight flocks of ewe lambs rotationally grazing irrigated ryegrass pasture with caucasian or white clover at two levels of soil fertility (Olsen P values 10 or 22) were compared during years 2 (1998/1999) and 3 (1999/2000) of an ongoing grazing experiment in a lowland environment. Clovers were sown in December 1996 and ryegrass in March 1997 into the pure clover swards. Lamb liveweight gains were similar in year 2 (1130 kg/ha/yr), but in year 3, gains were greater on pastures sown with caucasian than on those sown with white clover (1290 vs. 1110 kg/ ha/yr). Spring liveweight gains per head per day averaged 170 g/hd/d in year 2, and in year 3 were greater from caucasian than white clover pasture (180 vs. 160 g/hd/d). Caucasian clover pastures had more legume on offer than pastures sown with white clover in year 2 (26% vs. 17%) and year 3 (19% vs. 12%). In year 3, 39% of the total legume on offer in caucasian clover pastures was volunteer white clover. Soil fertility had little influence on results. Early years of this grazing experiment showed that caucasian clover can establish as well as white clover if sown alone, and that sowing caucasian clover can result in lowland pastures with an increased total legume content which may improve liveweight gains.

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Caucasian clover responses to fertiliser, lime and rhizobia inoculation at Lake Heron Station, Canterbury

Caucasian clover responses to fertiliser, lime and rhizobia inoculation at Lake Heron Station, Canterbury

Caucasian clover (Trifolium ambiguum M. Bieb) is a persistent legume option for high country grasslands in New Zealand (Allan & Keoghan 1994; Scott 1998; Strachan et al. 1994; Woodman et al. 1992). As with most pasture legumes, its establishment and persistence is dependent on its ability to fix atmospheric nitrogen (N) via symbiotic bacteria (“rhizobia”) in root nodules. This ability can help the plant compete against non- legume plants under low soil N conditions. However, the rhizobia suitable for Caucasian clover must be inoculated on to the seed before sowing, which can be difficult in practice (Pryor et al. 1998), and little N may be fixed in the first year (Seguin et al. 2001). Establishment of Caucasian clover in tussock grasslands is improved when inoculated seed is direct drilled with fertilisers that contain phosphorus (P)

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Dry matter yield of dryland and irrigated mixtures of Caucasian clover, white clover and perennial ryegrass over 5 years at Lincoln University

Dry matter yield of dryland and irrigated mixtures of Caucasian clover, white clover and perennial ryegrass over 5 years at Lincoln University

The advantage of Caucasian clover (Trifolium ambiguum; CC) over traditional legumes has been illustrated in a number of animal and pasture production studies (Taylor & Smith 1998). For example, at an irrigated lowland site in Canterbury, Black et al. (2007) reported greater liveweight gain for lambs grazing mixed CC-ryegrass (Lolium perenne; RG) pastures than white clover (T. repens; WC)-RG pastures. Similarly, in Wisconsin, USA, Mouriño et al. (2003) showed that the liveweight gain of steers on CC-grass pastures was 20% greater than on red clover (T. pratense)-grass pastures. These greater animal liveweight gains have been attributed to the higher legume content in the CC pastures.

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Constraints and opportunities for lucerne (Medicago sativa L.), Caucasian clover (Trifolium ambiguum M. Bieb), and Russell lupin (Lupinus polyphyllus L.) in the high country of New Zealand

Constraints and opportunities for lucerne (Medicago sativa L.), Caucasian clover (Trifolium ambiguum M. Bieb), and Russell lupin (Lupinus polyphyllus L.) in the high country of New Zealand

Results showed high specificity of Caucasian clover for rhizobia symbiont to nodulate the roots. Genotype AC (commercial strain ICC148) was the only Rhizobium leguminosarum genotype that recovered from Caucasian clover nodules irrespective of sites. This indicates lack of strain diversity for Rhizobium leguminosarum bv. trifolii in soils of the experimental sites in this study, which agrees with Patrick and Lowther (1995) who reported the absence of rhizobia capable of forming effective nodules on Caucasian clover in New Zealand soils. Seguin et al. (2001) also reported the lack of genetic diversity of R. leguminosarum genotypes occupying Caucasian clover nodules among the North American isolates. Therefore, inoculation was required, as few soils outside its centre of origin in the Caucasus contain effective indigenous rhizobia (Elliot et al., 1998). The commercial peat inoculants with two different isolate names were used to inoculate Caucasian clover seeds, in this study. Strain CC283b was applied in Pot Experiment 1 (Section 7.2.2), and strain ICC148 for other pot and field experiments. Strain CC283b was recommended for hexaploid cultivars of Caucasian clover (e.g., Monaro) in Australia (Zorin et al., 1976). Strain ICC148 was isolated in 1993 from a nodule off a Caucasian clover collected at the Mt. John Research Station, Tekapo (Scott and Mason, 1992). Seed had inoculated at sowing in 1975 and further rhizobia applied in 1983, but details of strains used are not available (Pryor et al., 1998). These two commercial strains revealed very similar ERIC fingerprints with one band approximately at 400 bp (Genotype code AC, Figures 7.4 and 7.6b). Therefore, both isolated strains (CC283b and ICC148) were identical according to their ERIC banding patterns.

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Caucasian clover was more productive than white clover in grass mixtures under drought conditions

Caucasian clover was more productive than white clover in grass mixtures under drought conditions

species. However, the most important specific result was the dramatic difference in legume content between clover treatments in pastures sown with cocksfoot. Cocksfoot has a reputation as a very aggressive grass species in fertile lowland environments, where the suppression of high quality companion grasses and clovers has resulted in poor grass productivity and palatability (Moloney 1995). After more than 5 years of association, the total legume content of cocksfoot/ caucasian clover pastures in February 2000 (46%) was superior to that based on white clover (2%). If caucasian clover can be established it is likely to improve the nutritive value of pastures in many dryland environ- ments where cocksfoot is the most persistent grass species.

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Caucasian clover (Trifolium ambiguum) rhizobia persists in New  Zealand soils for over 42 years

Caucasian clover (Trifolium ambiguum) rhizobia persists in New Zealand soils for over 42 years

leguminosarum biovar trifolii. Thus, this confirms that the rhizobia of the Caucasian clover have persisted at the Mesopotamia sites for 42 years. There was a 100% similarity between Rhizobium leguminosarum bv. trifolii locus KU517956 (Trifolium hybridum, 616bp), KU517958 (Trifolium repens, 649bp), KU517954 (Trifolium repens, 649bp), and Ku517943 (Trifolium pratense, 617bp) all from Illinois, USA (Gordon et al., 2016). The Mesopotamia station T. ambiguum strain was not significantly different to this group. The difference between these groups may be the reason that Caucasian clover plants cannot fix nitrogen with strains of Rhizobium leguminosarum bv. trifolii from sites that do not originate from the Caucasus region. Miller et al. (2007) stated that this difference was due to an insertion of 111bp in the nifH/fixA intergenic region only being found in Caucasian clover rhizobia, thus causing its specificity. This needs to be verified by further testing.

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Early development characteristics of different clover species during establishment

Early development characteristics of different clover species during establishment

2 It is important to select legume species which will be high producing and persist well in a pasture and in the dry climate. Subterranean clover has been used widely in Australia, and has shown to have adaptive mechanisms to avoid drought, and to maximize dry matter production in pastures in the dry areas. Many annual species such as balansa and gland clover and subterranean clover have drought avoidance mechanisms. These species set seed in spring and remain as a dormant seed over summer, the reestablishment of these species occurs in autumn once the hard seed has been overcome. Other species such as red clover, lucerne are considered as drought tolerant species because they have deep taproots (Brown, et al., 2003). Caucasian clover has a persistent and deep taproot which allows it to extract water from deep in the soil profile (Black et al., 2000). There are many new legume cultivars becoming available in New Zealand, among these there may be potential for these to be high producing in New Zealand dryland conditions. For successful production of these legume species in dryland pasture swards it is important to maximize the seedling survival at establishment. Direct drilling is the best way to establish legume pastures in a dryland area because it conserves moisture which remains available for germination and seedling growth. Legumes species which have rapid emergence, leaf appearance and rapid seedling growth after emergence will generally have greater survival in pasture mixes during establishment because it improves their ability to compete for essential resources.

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Effect of ploidy on interspecific hybridisation between Trifolium repens L  and related species : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Seed Technology in the Plant Science Department of Mas

Effect of ploidy on interspecific hybridisation between Trifolium repens L and related species : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Seed Technology in the Plant Science Department of Massey University, Palmerston North, New Zealand

Evans and Jones (1966) confirmed Hely's work by recording consistent differences in the response to inoculation of diploid, tetraploid and hexaploid forms of T. ambiguum, the diploids being the slowest to nodulate. Zorin et al. (1976a) indicated that the rlllzobial strain CC 2836 isolated from the roots of hexaploid T. ambiguum line CPI 53179, was a highly effective inoculant with a hexaploid caucasian clover. Subsequently commercial inoculants have been developed and are readily available (Speer and Allinson, 1985). Dear and Zorin ( 1985) found that by using superior inoculants, identified by Zorin et al (1976b, c), they were able to overcome the problem of poor nodulation so that the T. ambiguum remained well nodulated in the field and had acceptable herbage nitrogen contents (2.3-3.4% N). Rumbaugh et al. (1991) released ARS-2678 T. ambiguum germplasm which was selected for drought tolerance and high temperature, and for increased nodulation and N2 fixation activity when inoculated with Rhizobium leguminos arum biovar trifolii.

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"Dark Ages" in Comparative Studies and Ethnogenesis of Georgians in the Framework of the History of Comparative Studies

"Dark Ages" in Comparative Studies and Ethnogenesis of Georgians in the Framework of the History of Comparative Studies

Abstract The paper discusses the history of the issue of the ethnogenesis of Georgians. The comparative method of linguistics is universal and applicable to any language family. Like the methods of natural sciences the method is exact and verifiable. At some stages of contemporary linguistics, a crisis arose not because a method has some drawbacks, but because the method was considered to be useless to prove extralinguistic hypotheses by some linguists. As far as such extra-linguistic hypotheses cannot be proven by the comparative method, their authors tend to purposefully discredit comparative studies: I. They devalue the strictness of the method - language families are deliberately grouped into phyla; for instance, Noetic, Nostratic, Boreic, Dene-Caucasian... Hence, members of the Iberian-Caucasian family appeared in different phyla: Kartvelian languages – in Nostratic, Abkhaz-Adyghe and Daghestanian ones – in Dene-Caucasian. II. They ignore the method, linguistic items are qualified as languages and dialects by means of non-immanent marking. III. The comparative method is considered to be a non-universal one for the Iberian-Caucasian languages. IV. They consider the method to be unilateral, it was assumed that the method explained diverging process, however, it could not explain outcomes of convergence. V. The strength and credibility of sound correspondences was questioned; on the other hand, the establishment of secondary sound correspondences was considered possible. By way of a priori acknowledging the above-said, the allogenetic hypothesis was posited to be parallel with the theory of linguistic affinity. The paper analyzes the stages, having preceded the final proving of the Iberian-Caucasian affinity: it presents the research outcomes of the empirical data of the Iberian-Caucasian languages, the hologram principle of the reflection (resp. occurrence) of synchronic sound correspondences in diachrony, theoretical postulates determining the present-day level of the comparative study of the Iberian-Caucasian languages, research achievements and challenges. The detection of regular sound correspondences in the establishment of

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Management matters: testing a mitigation strategy for nitrous oxide emissions using legumes on intensively managed grassland

Management matters: testing a mitigation strategy for nitrous oxide emissions using legumes on intensively managed grassland

the clover parcel in the months April and June and slightly lower clover proportion in August compared to the control parcel. In 2016, clover proportions increased and stabilised in the clover parcel, while they decreased in the control par- cel with the progress of the growing season (Fig. 5c). Leaf area index (LAI) ranged between 0.4 and 5.9, with a maxi- mum at the first harvest each year (Fig. 5d). Average C con- centrations in the biomass of all harvests were similar across parcels and plant functional types (legumes 42.9 %–45.6 %, non-legumes 43.0 %–45.2 % C in biomass across parcels and years; Table 2, Fig. 5e). Average N concentrations in the biomass were always higher in legumes (3.3 ± 0.2 %) com- pared to non-legumes (2.1 ± 0.2 %) (Fig. 5f). The C / N ratios (data not shown) of total annual yields were slightly higher in the control (19.2 ± 1.7 and 19.8 ± 2.8) than in the clover parcel (17.1 ± 1.0 and 16.7 ± 2.1) for both years. Vegetation height reflected the vegetation dynamics and reached similar maxima on the control parcel (41 and 59 cm) and the clover parcel (44 and 60 cm) in 2015 and 2016 (Fig. 5g). C in annual yields at the control parcel was higher (5.8 ± 0.2 t ha −1 ) com- pared to the clover parcel (4.7 ± 0.3 t ha −1 ) in 2015, while C in biomass was similar for the control parcel (5.1 ± 0.3 t ha −1 ) and the clover parcel (4.8±0.2 t ha −1 yr −1 ) in 2016 (Table 2). The N exported was similar across parcels in the second year (control: 238±13 kg ha −1 yr −1 ; clover: 262±8 kg ha −1 yr −1 ; Table 2). Biological nitrogen fixation via rhizobia associated with clover (N derived from the atmosphere – N dfa ) resulted

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Clovers in Canterbury pastures

Clovers in Canterbury pastures

The first requirement is to sow the seed. This may appear to be an unnecessary statement, but it refers to white clover. Many pastures are sown without white clover, not because farmers do not appreciate the value of white clover, but because they have sown white clover and it has not established, or they have observed white clover coming into their pastures in the third or fourth years. They are content to rely on the so-called natural white clover in the land or that brought in by sheep. There is no doubt that there are areas where the land contains white-clover seed and this seed is likely to establish in a pasture, but there are thousands of acres on the plains where reliance on such natural clover results in a clover-deficient pasture. value of establishing clover in the first year has been mentioned, and one can have a reasonable chance of achieving this object only by sowing the seed. This, in itself, however, is not sufficient, and the other factors which influence the growth of clovers must be considered also.

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Nitrogen dynamics in temporary multi species grasslands

Nitrogen dynamics in temporary multi species grasslands

The functional difference between the ryegrass and forbs in their abilities to absorb N transferred from the red clover was likely associated with legume root exudation of the N compounds taking place mainly in the uppermost soil layer, where the grasses have a large fibrous root network and develop a close inter-connection with the legume roots (Pirhofer-Walzl et al. 2012; Frankow- Lindberg and Dahlin 2013;). This was supported by larger proportions, 65 to 100%, of red clover N rhizodeposition in the upper 0-10 cm soil layer and transfer of red clover N predominantly to the ryegrass component (Figs. 5 and 6; Paper II). On the other hand, such facilitative interaction might have been less in forbs due to their deep and thick tap or adventitious root system. It appears that forbs may have relied substantially on the N from soil pools due to their ability to assimilate N from the deeper soil layer (Thorup-Kristensen 2006; Pirhofer-Walzl et al. 2013). This was supported by the fact that the strong growth of chicory and plantain was not generally affected either by variations in amount of red clover BNF or by fertilization, whereas ryegrass biomass proportions and N uptake was greatly increased with fertilization (Fig. 2 and Table 5; Paper I). Despite the functional differences between the ryegrass and forbs in the ability to assimilate N transferred from the red clover, ryegrass did not show a growth advantage compared to chicory and plantain. It seems that the chicory and plantain either competed strongly with the ryegrass for uptake of soil N in all soil layers or that the ryegrass growth was limited by the utilization of above- and below-ground resources other than N.

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Using legume based mixtures to enhance the nitrogen use efficiency and economic viability of cropping systems   Final report (LK09106/HGCA3447)

Using legume based mixtures to enhance the nitrogen use efficiency and economic viability of cropping systems Final report (LK09106/HGCA3447)

The trials showed that there is a large degree of functional complementarity among the legume species. No single species scored high on all evaluation criteria. In particular, the currently most frequently used species, white clover, is outscored by other legume species on a number of parameters such as early development and resistance to decomposition. Further complementarity emerged from the different responses of legume species to environmental variables, with soil pH and grazing or cutting regime being among the more important factors. For example, while large birdsfoot trefoil showed better performance on more acidic soils, the opposite was true for sainfoin, lucerne and black medic. In comparison with the monocultures, the ASM showed increased ground cover, increased above-ground biomass and reduced weed biomass. Benefits of mixing species with regard to productivity increased over time. In addition, the stability of biomass production across sites was greater in the ASM than in the legume monocultures. Within the on-farm trials, we further found that on soils low in organic matter the biomass advantage of the ASM over the

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The influence of below-ground herbivory and defoliation of a legume on nitrogen transfer to neighbouring plants

The influence of below-ground herbivory and defoliation of a legume on nitrogen transfer to neighbouring plants

Roots from each species were carefully separated from the soil. Nodules were clearly visible on clover roots, indicating that they had successfully formed an asso- ciation with Rhizobium . Shoot and root biomass for each species was determined by drying and weighing plant material (70 ° C). A subsample of shoot and root material was ground for stable isotope analysis, which was conducted on a Carlo Erba elemental analyser (CE Elantech, Lakewood, USA) coupled to a isotope ratio mass spectrometer (Denis Leigh Technologies, Manchester, UK). Separate clover and grass-root subsamples, taken from block 1 pots only, were analysed for root infestation by H. trifolii : only a single measure- ment of clover and grass-root infestation was made for each treatment. Roots were cleared, mixed with distilled water (25 ml) and acid fuchsin stain solution (1 ml), and boiled for 30 s (Byrd, Kirkpatrick & Barker 1983), then stained nematodes within the roots were counted using a stereomicroscope. In addition, H. trifolii cysts were extracted from 100 g (FW) soil from each microcosm by elutriation for 90 s at 4·5 l min − 1 ,

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Formononetin content in selected red clover strains and its effects on reproduction in ewes : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University

Formononetin content in selected red clover strains and its effects on reproduction in ewes : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University

Zealand in 1 974 (Anonymous, 1 982). Pawera red clover, which was derived largely from seed of Turoa origin but included some material of Swedish origin ( Anderson, 1 973a), had a greater persistence and production than the diploid red clovers Hamua and Turoa (Anderson, 1 973b). Hay and Ryan ( 1 989) also showed that Pawera was more productive and persistent than other red clover cultivars, and that its strong summer growth met the need for heavy-weight lamb feed and high quality forage for conservation in intensive sheep farming systems in Southland. But this cultivar was also shown to contain high levds of formononetin, and to be highly oestrogenic to sheep (Kelly et aI. , 1 979). Pastures dominant in Pawera red clover were found to be unsuitable for grazing by ewes at or about mating as the grazing of Pawera pasture for 8 days before and during the first cycle of mating resulted in a reduction in the incidence of oestrus, low ovulation rate and high returns to service (Kelly et ai., 1980). Furthermore, as the formononetin concentration in Pawera red clover was found to be high throughout the year (0.64- 1 .38%), it was suggested that even a 30% red clover dilution in non-oestrogenic pasture might not be 'safe' for sheep fertility in the long term (Kelly et ai., 1979). Under typical New Zealand pastoral conditions, permanent clover infertility is unlikely to occur but Shackell et ai. , ( 1 993) showed permanent infertility could be induced in ewes after prolonged grazing on Pawera red clover.

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Susceptibility of ten red clover (Trifolium pratense) cultivars to six viruses after artificial inoculation

Susceptibility of ten red clover (Trifolium pratense) cultivars to six viruses after artificial inoculation

Inoculum was prepared by homogenising symp- tomatic leaves of host plants in 0.1 mol/l of phos- phate buffer (0.1 mol/l solution of Na 2 HPO 4 .12H 2 O, and 0.1 mol/l solution of NaH 2 PO 4 .2H 2 O), pH 7.0, with carborundum powder (silicon carbide, SiC) as abrasive. 1 g of fresh leaves was homogenised with 5 ml of buffer. Once the inoculum was prepared, the three first true leaves of clover seedlings were gently rubbed with sap using glass pestle on July 14, 2011. Each leaf of all three tiny leaves was rubbed all over the surface of the blades. About 60 plants of each examined cultivar were inoculated with a given virus and 10 plants of each cultivar were in- oculated solely with the buffer and carborundum served as negative (healthy) controls. The seedlings were washed 2 h after inoculation and maintained outside under roof protected against rainfall. The average monthly temperature, rainfall, and hours of light per day were 17.3°C, 144.5 mm, and 162 h in July; 19.1°C, 71.8 mm, and 247 h in August; 15.3°C, 14.7 mm, and 218 h in September; 8.68°C, 29.8 mm, and 110 h in October; 2.47°C, 0.3 mm, and 121 h in November, respectively.

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Cows fed vitamin rich feed produce vitamin rich milk

Cows fed vitamin rich feed produce vitamin rich milk

Table 1 shows the composition of the crops included in the different types of silage registered at field level before harvest. The vitamin E content in roughage was analysed in a sample taken from the silo just after it had been filled and 3-4 times during the period when the silage was fed to cattle, here shown as the average. In the grass-clover silage the average vitamin E content was 30 mg per kg dry matter (DM) during the feeding period, which was the same as the average content of the freshly harvested silage in the silo. The potential loss of vitamin E from the fresh crop during the drying period was not measured in this investigation. On farm 206 the vitamin E content in the grass-clover silage was 22 mg/kg DM and 34 mg/kg DM on farm 609.

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Annual and seasonal changes in mineral contents (Ca, Mg, P, K and Na) of grazed clover grass mixtures in organic farming

Annual and seasonal changes in mineral contents (Ca, Mg, P, K and Na) of grazed clover grass mixtures in organic farming

A grazed field experiment was established in 1995 to evaluate alsike clover (Trifoliun hybridum L.), red clover (Trifolium pratense L.) and white clover (Trifolium repens L.) in clover-grass mixtures under or- ganic farming practices. In this study the effect of seed mixture (alsike clover, red clover, white clover, white and alsike clover or grass mixture), year (1997, 1998) and grazing period (5 per grazing season) on the herbage calcium (Ca), magnesium (Mg), potassium (K) phosphorous (P) and sodium (Na) contents was assessed and the relationships between botanical proportions and herbage mineral contents were studied. Herbage Ca and Na contents varied between the seed mixtures, Ca, Mg, P and Na contents between the years and all measured minerals, except Na, between the grazing periods. The white clover mixture re- sulted in higher Ca and Na contents. The contents of Ca and Mg were positively related with the proportions of clovers and weeds and were higher in 1997. The contents of P and K were higher in the rainy summer of 1998. The seed mixtures resulted in similar mean K/(Ca + Mg) equivalent ratios, but the Ca/P ratio was higher for the white clover mixture. Mineral rations varied between and within grazing seasons. Under or- ganic practices the supply of minerals in the pasture herbage varied temporally and according to the bo- tanical contents and was unable to meet fully the requirements of dairy cows. Additional mineral feeding is recommended for organic farming systems to balance the dietary mineral contents for grazing cows.

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Annual and seasonal changes in production and composition of grazed clover grass mixtures in organic farming

Annual and seasonal changes in production and composition of grazed clover grass mixtures in organic farming

Within organic farming systems herbage produc- tion is dependent on biological N fixation, soil mineralisation and nutrient recycling (Lampkin 1994). The major factor is related to the estab- lishment and maintenance of N-fixing legumes in the sward (Weller and Cooper 2001). Unferti- lised white clover rich swards have been esti- mated to achieve DM yields in excess of pro- portionally 0.80 of those attained with conven- tionally managed N fertilised grass swards (Bax and Thomas 1992). In New Zealand and Aus- tralia, white clover and other pasture legumes are the primary source of N for many conven- tional pastures (Lane et al. 2000). According Ledgard and Steele (1992) the level of biologi- cal N fixation should match N losses from the pastoral system. On pasture fixed N is mainly transferred to grasses by animal excreta and by decomposition of legume roots and plant mate- rials (Ledgard 1991). Environmental stress, for instance compromised water supply or grazing intensity, increases clover turnover, decomposi- tion and N availability to other plants (Ledgard and Steele 1992). In the present study, the bene- ficial role of clovers was shown during sward establishment, when the CP of grasses was mark- edly lower for GM than clover based mixtures. Overall, WM appeared to have the most positive effect on soil N status based on measurements of botanical composition and CP content of PRE HM (Table 3, Kristensen et al. 1995).

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Pest and Disease Control in Grass and Forage Crops

Pest and Disease Control in Grass and Forage Crops

In a survey in England and Wales (Lewis and Thomas, 1991) the mean number of leaves damaged by sitona weevils ranged from 3% to 62%. There appear to be no reliable estimates in cash terms of the losses caused but damage impacts yield, sward quality and nitrogen fixation capacity, resulting in the need for more regular reseeding. In New Zealand, Harris (1995) calculated that when the clover content was reduced from 20% to 10% the relative pasture yield must increase by 15% to give the

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