One of the major environmental issues currently facing New Zealand is that of the sustainability of pastoral farming on North Island hill country. To be sustainable, a system must be resource conserving, environmentally compatible, socially supportive and commer-cially competitive. The Resource Management Act defines sustainable management as managing the use, development and protection of natural and physical resources in a way, or at a rate, which enables people and community to meet their needs without unduly compromising the ability of future generations to meet their needs. Evidence shows that at present this is not so for some hill country, for reasons of on-site land degradation and soil loss, and off-site sediment loading. Socioeconomic sustainability is also in doubt through deterioration in rural infrastructure and social services and steadily decreasing average returns for produce. In the long term there is no conflict between environmental and economic sustainability. The major conflict arises in the short term when the environmental needs of the community can conflict severely with the economic survival of the individual land holder. Adoption of sustainable management will require a much greater understanding of the dynamic interaction between land resources and land use practices and improved matching of land uses with inherent soil and climatic properties. A quantitative understanding of the relationship between biophysical stability of our land resources and their productive capability is required. This paper attempts to: (i) examine how biophysical indicators could be used to quantify the impact of current land use on the productive capability of our hill land resource, and in so doing identify several critical issues facing hill country farmers, and (ii) discuss some of the possible solutions to what we see are currently unsustainable farming practices. It is our contention that the adoption of sustainable management practices will ensure the long-term viability of this sector of the pasture industry and not, as many suggest, its demise. Keywords: biophysical indicators, hill land, offsite effects, on-site effects, sustainability
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The soils of North Canterbury occur mainly on steep land (31%), hilly land (28%), rolling downs and downlands (11%) and terraces and floodplains (30%). Most soils are predominantly formed from greywacke and tertiary sediments and some 85% comprise yellow-grey earth, yellow-grey earth to yellow-brown earth intergrade, yellow-brown earth and recent soil groups. In terms of the relationship between pasture production and fertiliser nutrient use these major soil groups are considered as a single entity, namely “sedimentary” soils (a reference to their derivation from sedimentary rocks). The relationships (production functions) between pasture production and soil test level for sulphur (S), phosphorus (P) and potassium (K) are shown to be of the “diminishing returns” type for the sedimentary soils and the point at which near-maximum production (97%) occurs is defined as the “biological optimum” soil test level. Biological optimum sulphate-S and organic-S levels-are-l.0 and 15 respectively, for O-l.s-en- P. -is _ 20 and quick-test K is 6. Once the biologrcal optimum soil test levels have been attained then maintenance fertiliser nutrient rates are appropriate. In order to correct S deficiency sedimentary soils require an average of 35 kg S/ha. To move up the pasture production curve an average of 5 kg P/ha above maintenance will increase Olsen P by 1 unit. Potassium requirements depend on soil group within the sedimentary soils. -Keywords:~biological~optimum, North Canterbury, nutrient requirements, phosphorus, potassium, sedimentary soils, Sulphur
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High rates of nitrogen (N) fertiliser (217 and 324 kg N/ha/y) applied during a farrnlet study at No. 2 Dairy, DRC, Hamilton increased annual net herbage accumulation by 23% and 27% respectively. Increases in feed conservation and milk production reflected the extra pasture growth. On low stocked (3.2 cows/ha) farmlets where 219 and 330 kgN/ba/yr were used, clover contents declined to 12.5% and 3.4% respectively compared with 22.8% where no N was used. Decreased clover content was probably a result of competition from increased growth of ryegrass. At the high stocking rate (4.5 cows/ha), N application resulted in clover contents of 19.6% and 7.9% respectively, compared with 23.8% where no nitrogen was used. Pasture utilisation was better on these fannlets than under the lower stocking rate, suggesting the improved utilisation of additional feed, particularly during spring, was responsible for the higher clover content. Nitrogen fixation activity was lower in pastures which received N fertiliser due to both the decreased clover content and a reduction in activity per clover plant. Keywords: conservation, dairying, milk production, nitrogen fertiliser, pasture production, Trifolium repens
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(152 KB)Natural inputs of sulphur in North Canterbury are restricted to l-2 kg of sulphur(S)/ha/year in rainfall. On the limited area of irrigated land a further 7 kg of S may be added in irrigation water. These inputs are inadequate to replace losses which occur through leaching, removal in animal products, and excretal transfer, so fertiliser S is essential to maintain farming systems. The choice of form of fertiliser varies from sulphate, to mixtures of sulphate and elemental S, to elemental S forms. Focus in this paper is on the forms which will be effective in North Canterbury, other factors which influence choice of fertilisers, and recommended fertilisers for different farming situations. Keywords: elemental sulphur, fertiliser recommendations, rate constant, sulphur oxidation, sulphur superphosphate
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(142 KB)Results from the first two years of a farmlet trial carried out on a dryland Lismore soil near Ashburton, Mid Canterbury are reported. Farmlet treatments were 0, 25 (25 N) and 50 (50 N) kg N/ha applied as urea in mid-April of 1992 and 1993. Stocking rates for each farmlet were 9.5, 10.5 and 11.5 (Year l), and 11, 12 and 13/ha Borderdale ewes/ha (Year 2). For both years of the trial, there were small increases in mean pasture cover from N use despite the higher stocking rates on the N farmlets. Both mean clover content (14%) and N fixation rates (36 kg N/ha/year) were low but only declined slightly with N use. Average lamb carcass weight was lower on the 25 N and 50 N farmlet than the nil N farmlet (16.9 cf 18.3 kg). Despite this decrease, lamb carcass production per ha was significantly higher on the 50 N farmlet (216 kg/ha) compared with the nil N farmlet (199 kg/ha), Similar wool weights per ewe between farmlets resulted in an increase in wool production per ha from both N farmlets (25 N - 34.9 kg/ha, 50 N - 38 kg/ha) compared to nil N (30.8 kg/ha). Keywords: clover content, lamb production, nitrogen fertiliser, nitrogen fixation, stocking rate, wool production
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(94 KB)Clover-based pastures frequently require both sulphur (S) and phosphorus (P) fertilisers for nearmaximum growth. Fertilisers with a wide range of S:P ratios are commercially available. Selection of fertilisers to provide well-balanced pasture nutrition requires criteria to judge nutritional balance. In the work described in this paper, the effects of various combinations of S and P fertilisers on clover growth and herbage chemical composition were investigated in a field trial. There were large clover dry matter responses to both nutrients and a large positive interaction between them, emphasising that balanced nutrition is essential for efficient use of both nutrients. The ratio of S:P in clover herbage appeared to be a useful indicator of nutritional balance. For data combined over the experimental period (16 months), treatments more deficient in S than in P had clover S:P ratios less than 0.72 and vice versa. However, because S fertiliser costs much less than P fertiliser, a higher S:P ratio in clover, approximately 0.76, corresponded to an -economically optimal balance of S:P in fertiliser. - Keywords: clover, fertiliser, nutrient ratios, pasture, plant analysis, phosphorus, sulphur
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In this paper we review the research findings research to date indicate that S. sclerotiorum has published to date on the development of a plant pathogenic fungus, Sclerotinia sclerotiorum, as a mycoherbicide for Californian thistle, Cirsium arvense, and other weeds of pastures. A strain of the fungus isolated from Californian thistle was virulent also on Scotch thistle (Cirsium vu&are), nodding thistle (Cur&us nutans) and ragwort (Senecio jacobaea) when applied as a myceliumon- wheat formulation to the foliage of these weeds under glasshouse conditions. In field trials in which this formulation of the mycoherbicide was applied to the new spring foliage of Californian thistle in Canterbury sheep pastures, the thistle was controlled, to a high level both in the season of application and during the following growing season. Debilitation of root systems of the thistle occurs through reductions in photosynthetic capacity through death of treated shoots, and by invasion and rotting of roots by the pathogen. The strain of the fungus used in the field trials did note infect either grasses or clovers. The results of research to date indicate that S, sclerotiorum has considerable potential as a mycoherbicide for use in pastures against Californian thistle and some other species of weeds. Keywords: biological weed control, Carduus nutans, Cirsium arvense, Cirsium vulgare, mycoherbicide, Sclerotinia sclerotiorum, Senecio jacobaea
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(134 KB)Although the role of the endophytic fungus Acremonium lolii in protecting the host plant from attack by insect pests, particularly Argentine stem weevil (Listronotus bonariensis), is often described in terms of plant resistance, it is a case of classical biological control. Endophytes in commercially available perennial ryegrass cultivars are acting as biological control agents against at least four pest species in New Zealand. Generally, endophyte adversely affects insect stages that feed on the above-ground parts of the plant, particularly those stages that feed near the base of the plant. It is apparent from insect feeding tests that there is no one universal anti-insect metabolite that will adversely affect all pest populations. It is therefore likely that an endophytelgrass combination that produces a cocktail of metabolites at low concentrations may be more useful than a combination that produces a very narrow suite of metabolites. Keywords: Acremonium spp., Listronotus bonariensis, Heteronychus arator, Costelytra zealandica, Wiseana spp., biological control, endophyte
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(160 KB)Between 1988 and 1990 three visits were made to South America to search for and collect the Argentine stem weevil parasitoid Microctonus hyperodue. ‘Ibis resulted in the importation of 240 parthenogenetic parasitoid lines collected from seven very different ecoclimatic zones. Each zone was assumed to have resulted in a corresponding ‘ecotype’. Throughout the winter of 1991,100 000 parasitised weevils were liberated at selected sites in the northern North Island, northern South Island and Otago/Southland. During this work, care was taken to rear and release the parasitoid ecotypes in equal numbers. In this way establishment patterns of the different ecotypes in different climate zones should eventually be able to be established thereby giving new insights into the importance of parasitoid preadaptation in achieving biological control. Since its release, detailed research has been conducted into the spread and build up of Microctonus hyperodue. In most places, especially in the north, the parasitoid has established and built up to high levels of parasitism (80%) with unexpected rapidity, although its rate of spread has been modest at around l-3 km p.a. Preliminary results from both Canterbury and the northern North Island indicate that the pest potential of Argentine stem weevil population has already been substantially reduced in its release areas.
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Concern at the effect of winter pasture residuals on pasture productivity led to the comparison of different wintering systems at the DRC No. 3 Dairy from May-December 1993. Three farmlets were designed to have 2000 kg DM/ha average farm cover at calving, but with pastures grazed to either 900, 1400 or 1800 kg DM/ha at least once during the winter. A fourth farmlet was spelled from grazing from 25 May-4 July to give an average farm cover at calving of 2900 kg DM/ha. Pasture regrowth, composition and structure, milk yield, liveweight and reproductive performance were measured. A simulation model UDDER was used to generalise from the specific experimental results. Pasture regrowth in July-August was greater on the wintering-off treatment than those grazed during winter, but treatment differences in late spring were inconsistent. Wintering-off decreased ryegrass tiller and white clover growing point densities in August but differences had disappeared by November. Winter grazing treatment had no effect on any component of milk production from calving to late October. From late October until m&December-milk-protein-and.milksolids y i e l d were less on the wintering-off treatment than the mean of the other three treatments (0.62 vs 0.68 kg/cow/day) and (1.49 vs 1.59 kg/cow/day), respectively. Grazing to different winter pasture residuals had no consistent effects on subsequent pasture productivity, composition or milk yield. Simulation showed that wintering-off can lead to increased milksolids production when average farm cover in September is predicted to fall below 1750 kg DM/ha. Timing and amount of conservation become c&i&i1 slfterwintering;off if pasture quality and hence milk production are to be maintained in late spring. Keywords: dairy cow, milksolids, milk yield, pasture regrowth, pasture residual, pasture structure
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(105 KB)Special-purpose finishing areas must achieve the maximum output of carcass gain to ensure their cost effectiveness. Liveweight and carcass weight gain were measured from lambs finished on Puna chicory (Cichorium inrybus)/Hakari upland brome (Bromus sitchensis)lPawera red (Trifolium prutense) and Huia white clover (Trifolium repens) pasture for periods of 3 to 18 weeks after grazing medium or low quality pastures over two summers at the Gore Research Station. The relationship between growth of lambs and time on finishing pasture was quadratic in year 1 when chicory comprised 37% of the pasture on offer. Highest live and carcass weight gains were achieved by finishing for between 9 and 18 weeks. In year 2 with a chicory content of 7% all finishing periods produced similar live weight and carcass weight gains. Carcass gain on low quality pasture (year 2) averaged only 3.5 g/100 g liveweight gain compared with of 42 g/l00 g liveweight gain and 47 g/100 g liveweight gain for medium quality and finishing pastures, respectively, averaged over two years. A finishing period of 9 weeks is recommended when chicory levels are high. Increased lamb performance was still evident when chicory content d65lined. No detrimental fat deu. osition was found in faster growing lambs. Skin and wool weights were significantly (P ~0.05) improved through high quality diets. Keywords: carcass weight gains, Cichorium intybus, fat deposition, finishing time, liveweight gain
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(124 KB)A study was undertaken to compare the reduction in th elength of grass tillers in two temperate mixed pastures grazed by cattle, sheep and goats alonein spring. One hundred identified tillers in each of 24 plots (2 reps per pasture type) were measured daily during grazing periods of 3 (GD3) or 6 (GD6) days and disappearance rate of grass was determined. Initial pasture mass was similar for all treatments (mean = 3 500 kg dry matter/ha). Paddock area for CD6 was twice that for CD3 so that the nominal daily DM allowance/kg live weight0.9 was the same for each animal group at
the start of the trial. Cattle ate taller than average
tillers while sheep and goats ate tillers of a length
closer to that of the mean tiller length (P A method has been developed which enabled 100
white clover cultivars to be screened and ranked
for improved nutritive value. Our objective was to
identify cultivars having protein which was
relatively insoluble and resistant to rumen
degradation. The methods were developed for fresh
forages, so that the results were applicable to the
grazing animal. The clover was harvested and
minced to give a particle size distribution similar
to material chewed by ruminants during eating.
Crude protein solubility was estimated by
measuring nitrogen (N) loss from minced clover
incubated in nylon bags in the rumen of a cow.
This required the optimal amount of dry matter
(DM) and incubation times to be determined,
variation between animals to be defined and
repeatability of measurements established. Crude
protein degradation was measured by incubating
minced clover with buffered rumen bacteria in
vitro and determining net conversion of plant N to
ammonia N. Nitrogen loss to degradation and cultivars w&e identified as having low solubility
_ ability-for-the-1.OO-cultivar-were-positively
and slow degradation and five cultivars having
high solubility and rapid degradation. Mean values
correlated (r=+O.29; P Download
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Screening white clover cultivars- for improved nutritive value - development
of a method
G.C. WAGHORN and J.R. CARADUSview more
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Grasslands Gala grazing brome, the first cultivar bred from Bromus stamineus (B. stamineus Desv.), was selected from plant material collected in central Chile. Small-plot evaluations have indicated Gala has agronomic characteristics appropriate to dryland grazing systems. This trial was designed primarily to evaluate the seasonal production, persistence and animal performance obtainable from Gala under dryland conditions. Gala was compared with cultivars from three different Bromus species, Grasslands Matua (B. willdenowii Ku&r.), Grasslands Hakari (B. sitchensis Trin.) and Grasslands Tiki (B. inermis Leyss.) and an endophyte ryegrass Grasslands Pacific (Lolium perenne L.). Gala established rapidly, and under a long rotation lax grazing management, had seasonal yields similar to Grasslands Pacific, Matua and Hakari. Hogget liveweight trials indicated Gala produced quality forage in all seasons with weight gains similar to those on Matua and surpassing those on Pacific during summer and autumn. Under a short rotation hard grazed management Gala was more competitive and yielded at a similar level to Pacific and Matua, and showed the least sign of tiller depletion. Hakari became severely depleted under this management and along with Tiki was eliminated from this evaluation at the end of the first year. These initial results (3 years’ data) indicate that Gala compares favourably with existing cultivars, and its broad range of tolerances should make it a desirable option as a perennial in South Island dryland pastoral systems.
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(95 KB)Successful establishment of drought-tolerant pastures through direct drilling on erosion prone dry East Coast downlands can be guaranteed if some simple management practices are put in place. Pasture mixtures containing mainly Grasslands Wana cocksfoot, Grasslands Maru phalaris Grasslands Roa tall fescue and Grassland Tahora white clover were direct drilled into 450 ha on 60 paddocks in North Otago. Establishment of new pastures on paddocks that had been double herbicide treated prior to sowing (spray-fallow technique), were significantly superior to those treatments that only had a single spray prior to drilling. Correct sowing depth was made possible with the use of the Massey University bioblade direct drill. Its inverted ‘T’ coulter creates an underground cavort with sufficient tilth to provide an ideal microclimate for seedling establishment. The success of the programme is reflected in the fact that 50% of farmers involved have established new pasture by direct drilling since the programme was implemented, 93% intend establishing pastures by direct drilling in the future and 98% hive sown, or intend to sow, pastures using alternative species to perennial ryegrass. Keywords: direct drilling, drought-tolerant species, erosion, pasture establishment, spray-fallow technique, summer fallow
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(59 KB)This paper examines how the spring management options of making silage or planting brassicas can change hogget performance. Research by Gore Research Station staff compared winter hogget growth on various winter forages including brassicas, Italian ryegrass, perennial pasture and silage from several pasture types over 5 years. Liveweight gains varied from 0 to 160 g/day for silage made from various pasture options. Specific brassicas or brassica plus Italian ryegrass combinations provided average gains of up to 146 g/day. The yields of forage turnips for summer and autumn use were also compared. An initial harvest of 90 days with two subsequent cuts of 30- day intervals maximised yields from the treatments examined. The combining of these spring forage management options is discussed and used to outline options which will help farmers to maximise hogget performance. Keywords: Brussica, Cichorium intybus, hoggets, liveweight gain, L&urn multiflorum, perennial pasture, sheep, silage, summer, winter
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(151 KB)Changes in dryland pasture composition were monitored over 5 years in pastures that were managed under a normal sheep farm management system. Grass grub population built up with time and appeared to be the main reason for plant loss and the resultant changes in pasture composition. Grass grub densities in ryegrass mixtures increased to a high level (220/m* ) by year three, with subsequent ioss of ryegrass plants. Grub densities increased more slowly in cocksfoot-, tall fescueand phalaris-based pastures, with no apparent loss of plants. Cocksfoot dominated pasture composition by year three, even when sown at only 25% of total seed mix. Phalaris did not increase its contribution and at no stage made a significant contribution to production when sown in mixtures with other grasses. As grass grub numbers declined there appeared to be some regeneration of the ryegrass component. The more persistent cocksfoot and tall fescue pastures increased their herbage yield advantage over ryegrass pastures with time. Autumn animal performance was directly related to the amount of green herbage on offer. Keywords: Costelytra zealandica, Dactylis glomerata,dryland pastures, Festuca arundinacea, Lolium perenne, Phalaris aquatica, pasture composition
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trial to measure the effects of establishment techniques and fertiliser application on seedling establishment and early root and rhizome development of Caucasian clover (Trifolium ambiguum) was sown in early October 1992, on a low-fertility, depleted short tussock grassland site at Mesopotamia Station, South Canterbury. Three sowing techniques, broadcasting, sod seeding and strip seeding, each with, two rates of fertiliser, 150 or 300 kg/ha molybdic sulphur superphosphate, were used. By mid December, 48 and 38% establishment had occurred in the strip and sod seeding respectively, but only 9% inthe broadcast. Strip seeding was the most successful technique. resulting in earlier rhizome and tap: root development and wider lateral spread of rhizomes. However, both strip seeding and sod seeding resulted in all plants developing rhizomes 9 months after sowing. Plants from broadcasting were small with few rhizomes in the,first season. The higher fertiliser rate improved establishmenttrial to measure the effects of establishment techniques and fertiliser application on seedling establishment and early root and rhizome development of Caucasian clover (Trifolium ambiguum) was sown in early October 1992, on a low-fertility, depleted short tussock grassland site at Mesopotamia Station, South Canterbury. Three sowing techniques, broadcasting, sod seeding and strip seeding, each with, two rates of fertiliser, 150 or 300 kg/ha molybdic sulphur superphosphate, were used. By mid December, 48 and 38% establishment had occurred in the strip and sod seeding respectively, but only 9% inthe broadcast. Strip seeding was the most successful technique. resulting in earlier rhizome and tap: root development and wider lateral spread of rhizomes. However, both strip seeding and sod seeding resulted in all plants developing rhizomes 9 months after sowing. Plants from broadcasting were small with few rhizomes in the,first season. The higher fertiliser rate improved establishmenttrial to measure the effects of establishment techniques and fertiliser application on seedling establishment and early root and rhizome development of Caucasian clover (Trifolium ambiguum) was sown in early October 1992, on a low-fertility, depleted short tussock grassland site at Mesopotamia Station, South Canterbury. Three sowing techniques, broadcasting, sod seeding and strip seeding, each with, two rates of fertiliser, 150 or 300 kg/ha molybdic sulphur superphosphate, were used. By mid December, 48 and 38% establishment had occurred in the strip and sod seeding respectively, but only 9% inthe broadcast. Strip seeding was the most successful technique. resulting in earlier rhizome and tap: root development and wider lateral spread of rhizomes. However, both strip seeding and sod seeding resulted in all plants developing rhizomes 9 months after sowing. Plants from broadcasting were small with few rhizomes in the,first season. The higher fertiliser rate improved establishment and growth, particularly in the strip seeding-treatment; By using a strip-seeding technique Caucasian clover was established ai rapidly as white clover and plants of both species were similar in size after 5 months. Keywords: broadcast seeding, establishment, fertiliser, rhizomes, sod seeding, sowing methods, Trifolium ambiguum, Trifolium repens, tussock grasslands
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(98 KB)Results from oversowing trials in the tussock grasslands have shown that nodulation problems can limit the establishment of Caucasian clover (Trifolium ambiguum). They also strongly suggest that previously reported difficulties with establishment of Caucasian clover, in areas where white clover (T. repens) had established sucessfully, were likely to be due to inoculation failures due to low numbers of rhizobia on the seed, or in the case of tetraploid cultivars, to the use of an unsatisfactory strain. With the tetraploid cultivar Treeline, inoculation with the recommended strain ICMP4074b resulted in low levels of effective seedling nodulation even with very high levels of rhizobia/seed at sowing (149 000). Treeline seedling nodulation was increased when inoculated with strain ICMP4073b, the approved strain for hexaploid cultivars, and the strain was effective at symbiotic nitrogen fixation. Effective seedling nodulation of both tetraploid Treeline and hexaploid Monaro cultivars inoculated with ICMP4073b increased as the number of rhizobia on the seed at sowing was increased. Low levels of seedling nodulation occurred when populations of rhizobia on the seed were in the range likely to be present when seed is slurry inoculated, or inoculated and pelleted and stored for several days before oversowing. To maximise effective nodulation, seed should be inoculated at least 5 times the recommended rate, with the incorporation of gum arabic in the slurry or pellet and oversown within one day. Keywords: Caucasian clover, establishment, inoculation, nodulation, rhizobia, Trifolium ambiguum
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(120 KB)Hexaploid Trifolium ambiguum M. Bieb. (Caucasian clover cv. Prairie) persisted and dominated in high country plots which received more than 100 kg P/ha at establishment. After 13 years the biomass of coarse roots (rhizomes and tap-roots) amounted to 20 t/ha. The contents of nutrients in the root fractions were approximately five times that in the herbage. This ability to retain nutrients in coarse roots may be a strategy that contributes to the dominance of Caucasian clover on this acid soil. Keywords: nutrients, phosphorus, roots, Trifolium ambiguum
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(82 KB)
Seasonal and annual dry matter production of ryegrass was compared with drought- and grass grub-tolerant species Grasslands Roa tall fescue (Festuca arundinacea Schreb.), Grasslands Maru phalaris (Phalaris aquatica L.) and Grasslands Kara cocksfoot (Dactylis glomerata L.) as both single species and different combinations of mixes in two trials from 1982 to 1991. In trial 1, Nui ryegrass (damaged by Argentine stem weevil) produced significantly less than cocksfoot, phalaris and mixtures of the drought-tolerant grasses. Yatsyn-1 ryegrass in trial 2 was not subjected to stem weevil attack and the annual dry matter production was significantly higher than that of tall fescue and, although not significantly, higher than that of phalaris and cocksfoot. In both trials the highest producing mixture was the phalaris/ cocksfoot mix with the exception of the triple mix of phalaris/cocksfoot/tall fescue in trial 2. The phalaris/cocksfoot mix produced significantly more than phalaris as a single species and although not significant, 14% more than cocksfoot suggesting these species are complementary in a mix. The triple mix in trial 2 produced significantly more than all single species except ryegrass. Mixes of srgnificant. tall fescue/phalaris and tall fescue/cocksfoot had no advantage in DM production over single-species sowings of phalaris or cocksfoot, but improved yields over tall fescue. These results show possible complementary effects to sowing phalaris and cocksfoot. The addition of tall fescue to the mix had small and non-significant benefits. Keywords: Dactylis glomerata, Festuca arundinacea, Loliumperenne, Phalaris aquatica. grass grub, pasture mixes, pasture production, single species, summer dry spells
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(163 KB)Tall oat grass has a long history in New Zealand agriculture. Reference was made to it in the 1880s as a useful grass and it was included in many trials such as those of Macpherson, Cockayne, Calder, Dunbar, Sievwright, Moore and others. While the survival and performance of tall oat grass was generally reported as being good, observations on palatability were mixed. The growth pattern was typically noted as being one of early spring growth, rapidly changing to reproductive form thereafter with a consequent decrease in acceptability to stock. In 1988, new accessions of tall oat grass originating from diverse countries were introduced to New Zealand from the US Department of Agriculture. This paper describes the physical characteristics of tall oat grass and field performance at Galloway Station, a site badly affected by hawkweed, and on other farms. This grass appears best suited to moderate-low rainfall areas (400-700 mm p.a.) which are not too exposed or too cold and it shows good potential for survival and spread in the drier soil conditions which result from hawkweed invasion in mid-altitude grassland areas. Two accessions, one from Chile and the other from Switzerland, have been identified which have superior winter performance, rust resistance and are less prone to bolting into a reproductive phase in the spring. These, along with a preliminary selection containing a wider genetic base, are being commercially evaluated at present. Keywords: Arrhenatherum elatius, tall oat grass, hawkweeds, plant selection, vegetation
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(158 KB)A breeding programme to improve. the herbage yields and persistence of alsike clover (Trifolium hybniium L.)’ for the South Island high country was initiated in 1984. A screening trial with gennplasm from the Baltic region of Russia, local types collected in the Mackenzie Basin, selected plants from high. country trials and overseas cultivars was established under grazing at Mt John, Tekapo. Material was assessed over 3 years for seasonal herbage yields, shoot density, growth habit and plant survival. Principal Component Analysis was used to order the agronomic performance of the.alsike lines. A set of superior alsike lines from the Russian and local New Zealand groups was identified. These lines were not significantly better than commercial alsike but showed a consistent pattern of higher yields in all seasons and years. Overseas cultivars had average to poor yields and many had low shoot densities. Elite plants were selected from the superior lines and combined in a polycross in 1988. A progeny test was sown to determine the lines with high breeding value to make up a cultivar. Similar parameters to the screenings, including seedling establishment, were assessed in the progeny test. Seventeen elite progeny were identified in 1991 and the best four plants removed from each progeny and isolated to form the ‘G50’ alsike clover selection. The selection is currently in comparative grazing trials in the high country. Keywords: high country, progeny test, screening, selection, Trifolium hybridum
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(157 KB)The area of luceme (Medicago sativa L.), regarded as the best adapted legume for dry areas of New Zealand, has declined by 67% over the last 2 decades. The major reason for the decline has been the effect of pests, diseases and poor grazing management on productivity and persistence. The development of disease- and pest-resistant cultivars has allowed plant breeders to investigate methods for developing grazing-tolerant lucernes. It has been suggested that frequent cutting is harder on plants than grazing and that it could be used to rapidly identify the survival characteristic of breeding lines. Lines surviving cutting every 4 m weeks for 2 seasons have been selected at Lincoln. To evaluate the breeding method these selected lines were compared with their parents, under 4- weekly cutting (frequent), 8-weekly cutting (infrequent) and frequent grazing. Frequent grazing was less severe on plants than frequent cutting and evaluation by this treatment was discontinued after 3 years. There was a trend towards increased production through selection under both frequent and infrequent cutting and there appeared io be line differences in response to selection. Persistence of lines after 7 years of frequent and infrequent cutting was significantly improved by selection for most lines. The different degrees of improvement between lines indicate that lines responded differently to selection. Cutting frequency had little effect on the final plant numbers of lines. The differences between cultivars and lines can be attributed to disease and pest resistance and adaptability of lines. The trial showed that selecting plants tolerant of frequent cutting can improve production and persistence. Keywords: frequent cutting, grazing, Medicago sativa, persistence, production, selection
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(89 KB)Tall fescue (Festuca urundinacea Schreb.) pastures in New Zealand have been considered to have slow establishment (Grasslands Roa) or lower summer quality (the faster establishing AU Triumph). Three experiments were conducted to study the establishment vigour, herbage production and animal growth rates of a new tall fescue cultivar, Grasslands Advance. Establishment vigour of Advance was similar to that of Au Triumph and 30% greater than that of Roa. Advance and AU Triumph were 17 and 8% higher in annual grass production than Roa, with Advance significantly out yielding the other two cultivars in the warm season. Animal performance per head of young sheep on Roa was significantly higher than on AU Triumph in spring, both Advance and Roa having a significant advantage over AU Triumph in the warm season. Keywords: animal performance, Festuca arundinacae, herbage production, pasture establishment, seedling vigour
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(72 KB)Fifteen accessions and 3 cultivars of subterranean exnected for this site. It is concluded that lateclover (Trifolium subterranean L.) were sown in autumn in shallow stony soil south of Christchurch, New Zealand. The following growing season was atypical, with drought occurring briefly but one month earlier than usual, the rest of the season being wetter than usual. Contrary to previous results highest seed yields were given by mid- to lateseason flowering lines. Early flowering lines were severely disadvantaged by the early drought, resulting in seed yields of only 20-25 kg/ha. High seed yields were linked with the ability of lines to recommence flowering after drought and continue this for a prolonged period. Two late flowering accessions, 014454B and 014205B, yielded more than 200 kg/ha seed, outyielding the late flowering cv. Tallarook in spite of this cultivar having the same ability as the other two to reflower. Six highseed yielding lines gave naturally regenerated seedling numbers near to or exceeding 1000/m2. Apparent hardseededness at the time of autumn germination averaged 49% which was lower than expected for this site. It is concluded that late fldwering lines of subterranean clover should always be included in mixtures of this species for pasture to ensure adequate regeneration in wetter than normal seasons. Keywords: accessions, cultivars, flowering, hardseededness, regeneration, seed production, Trifolium subterraneum
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(113 KB)
Grazing trials were established at Dashwood, Marlborough and at Winchmore Research Station, Mid Canterbury, to determine persistence, production patterns and changes in composition of various dryland pasture species. Plots were individually fenced and grazed to optimise individual species performance. At Dashwood (Dashwood shallow silt loam and stony loam, 600 mm rainfall), nine species were established: ryegrasses (Grasslands Supernui, Grasslands Nui, and a local ecotype), cocksfoot (Grasslands Wana), phalaris (Grasslands Maru), bromes (Grasslands Tiki and Grasslands Hakari), wheatgrass (Grasslands Luna), and a luceme/phalaris mix (Grasslands Otaio Maru). All species were sown with white clover (Grasslands Tahora) and red clover (Grasslands Pawera). Interim results of the first 3 years show ryegrass species Supernui, Nui and the local ecotype established well in the first year but are gradually being surpassed by the slower establishing species such as Mar-u, Wana and Otaio lucerne. The Winchmore project (Lismore stony silt-loam 739mm rainfall) included 11 species: lucerne (Grasslands Otaio), sheep’s burnet, birdsfoot trefoil (Grasslands Goldie), red clover (Grasslands Colenso), browntop (Grasslands Muster), chicory (Grasslands Puna), wheatgrass (Grasslands Luna), ryegrass (Grasslands Pacific), smooth brome (Grasslands Tiki), upland brome (Grasslands Hakari) and grazing brome (Grasslands Gala). Over the first three years Otaio has remained as one of the best producers, but Colenso and Tiki, while producing well in the first year havedropped considerably by year three. Results demonstrate that there is potential for some species tested to enhance the production on the light east coast soils in the South Island but in the long-term persistence must be monitored. Keywords: dryland, pasture species, pasture composition, pasture yield
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(132 KB)A grazing trial on oversown tussock country at Tara Hills Research Station, started in 1978 and still continuing, has highlighted short comings of clovers and grasses traditionally used for improvement. In 1984 a wide range of legume and grass germplasm was planted into each of the nine stocking rate/management treatments to identify plant material more persistent than that traditionally used, and investigate specific responses under Extreme (high stocking rate), Optimal (moderate stocking rate and management giving optimum liveweight gain/ha) and Las (low stocking rate) grazing management. After 6 years none of the 12 white clover, 7 alsike and 9 lotus lines tested persisted significantly better than Grasslands Huia white clover (Trifolium repens). Plant survival and spread of Caucasian clover (Trifolium ambiguum) was exceptional. In terms of persistence and spread this legume ranked first out of the 56 germplasm lines under examination. The 15 ryegrasses examined did not persist better than Grasslands Nui ryegrass (Lolium perenne). However, for Optimal management, many ryegrasses performed better than Nui. Cocksfoot(Dactylis glomerata) also performed very well, with Grasslands Wana showing greater persistence under Extreme management than other cocksfoots and ryegrasses. Tall oat grass (Arrhenatherum elatius) was very persistent and like Caucasian clover performed well under all managements. Other grasses tested showed poor persistence, as did the herb sheep’s burnet (Sanguisorba minor). Keywords: Arrhenatherum elatius, Dactylis glomerata, grazing management, high country persistence, sustainable improvement, Trifolium ambiguum, tussock grasslands
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(139 KB)Young Merino wethers set stocked from November to April, over 5 years, on developed high country legume pastures, at Lake Tekapo at 50 kglhafyr superphosphate, showed daily liveweight gain on perennial lupin and alsike clover that were 53% and 70%; respectively, of that on Pawera red clover (110 g/day). Keywords: high country, Lupinus polyphyllus, Trifolium hybridum, T. pratense, sheep weight gains
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(63 KB)Birdsfoot trefoil (Lotus comiculatus L.) is a species with considerable potential for hill and high country of the South Island; however, difficulties in maintaining satisfactory stands due to problems with persistence have been reported. Plant recruitment through natural reseeding is considered a necessary tool for the maintenance and improvement of birdsfoot trefoil stands in the USA, but research which investigates the role of soil seedbanks, seedling recruitment and stand management for improving the persistence of birdsfoot trefoil in the drier hill and high country of the South Island of New Zealand is limited. Two field experiments in the dry hill and high country of Otago monitored changes in stand populations and seedling emergence of birdsfoot trefoil under differing grazing management. At Ardlui Station on the Coastal Otago Plateau, seedling emergence was greatest in autumn rather than spring after spelling over the flowering period. Despite considerable numbers of autumn seedlings (128 seedlings/m2), less than 1 seedling/m2 survived to contribute to the stand after 12 months. Plant populations did,however increase in 199l/92 following adequate rainfall in the previous autumn. Spring emerged seedlings did not survive through summer. At Omarama Station in the southern Mackenzie Basin, plant populations of birdsfoot trefoil continued to decline despite the presence of seedlings in spring and autumn. Results imply that natural reseeding cannot be relied upon to improve birdsfoot trefoil plant populations unless favourable climatic conditions prevail during spring or autumn. Keywords: establishment, Lotus corniculatus, management, natural reseeding, persistence, seedling recruitment, soil seedbanks, survival
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(75 KB)
Various fertiliser and trace element products were applied to small plots (10 m2) dominated by Hieracium species (predominantly Hieracium pilosella) in Central Otago. The object of this study was to assess whether any fertiliser product had any “direct control” effect on Hieracium. Originally, 30 treatments were applied to a series of replicated small plots. At the sites studied, the boron compound Fertiliser Borate FB48 was the only treatment to display directly control on Hieracium. Further research has since concentrated on using boron as a control method. Twenty-three sites in total have developed along this theme covering a large range of climate zones (mainly Otago) and soil types, Boron-containing compounds can selectively control Hieracium (especially H. pilosella) without adversely affecting other plant species present. The timing of treatments and evenness of application is critical. New pasture species can be introduced successfully by traditional methods such as direct drilling and oversowing. Keywords: boron, direct control, fertilisers, Hieracium, seasonal variation, selective control
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(182 KB)Forage production from a newly established pinepasture system at 1000 trees per ha and pasture alone was compared. Pastures of ryegrass/clover, cocksfoot/clover, phalaris/clover and lucerne were used. Overall, forage production varied little between the grass/clover pastures and was little affected by the pine trees except for the 14% reduction in pasture area in the trees because of herbicide-treated planting strips. Lucerne production between the trees was similar to that of the grass/clover pastures but in the open pasture, lucerne yielded a total of 29.5 t DM/ha compared with 22 t DM/ha from grass/clover treatments. Pasture growth within 1 m of the trees in the third summer was reduced by as much as 40%, indicating that competitive dominance was shifting in favour of the pines. Keywords: agroforestry, competition, pasture-tree interaction, radiata pine, temperate pasture
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(169 KB)Hawkweeds (Hierucium species) presently dominate 500 000 ha of the South Island high country. Their spread threatens the ecology of the tussock grasslands and the livelihood of runholders. Management practices have been partially ‘i successful at controlling hawkweed spread, but increasingly runholders are cultivating suitable areas. Crops planted into this environment are usually poor with negligible yield. Over 2 seasons 5 trials investigated the role of nitrogen, lime and molybdenum, boron superphosphate in the growth of soft turnips (Brassica campestris ssp. rapifera Green Globe) and Italian ryegrass (Lolium multiflorum). The results showed the importance of nitrogen. The nitrogen response of total yield was curvilinear or linear in every trial. Up to 48 kg DIWkg N was grown when 80 kg N/ha was applied, There was no significant reponse to molybdenum, boron, superphosphate or lime. Vegetation and soils dominated by hawkweeds are low in nitrogen, therefore little nitrogen is released after cultivation. Keywords: crop-yields, dryland, Hieracium pilosella, nitrogen, toe slopes, Brassica campestris ssp. rapifera, tussock grasslands, Lolium multiflorum
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(96 KB)Major findings from 13 pasture irrigation experiments conducted in Canterbury are discussed. Yields and response curves on 8 of the experimental sites were very similar to those of the long-term trial (34 years) site at the Winchmore Research Station. Irrigating when soil moisture dried to 50% asm (available soil moisture), increased annual pasture DM yields by an average of 5.2 t/ha DM (80% increase over the non-irrigated yield). Response per irrigation and yield variation between years decreased as the number of irrigations increased. During water restrictions, irrigators often choose to either keep watering their whole farm with a longer irrigation return period, or drop out paddocks and fully irrigate the remainder. The irrigation response data are used to discuss these and other possible strategies. Keywords: irrigation, pasture yields, response curves, water restrictions
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(79 KB)Pasture production and irrigation water-use efficiencies were measured for 3 irrigation regimes on a Mackenzie shallow, stony soil in the Mackenzie Basin near Omarama. Irrigating at 25% was the most efficient of three irrigation frequencies maintained over the 198 1-1986 period (irrigated at O%, 25%, and 50% plant-available water capacity). Less frequent irrigation resulted in lower pasture yields due to increased water stress, while more frequent watering resulted in a 55% drainage loss of irrigation water below the root zone. At 1.16 t DIvUha per irrigation, the increase in pasture yield with irrigation at 25% was higher than most increases achieved in existing irrigation schemes in Central Otago and mid Canterbury. Over 6 years, this treatment required 4-7 irrigations annually and, on average, produced 6.0 t DM/ha more than did dryland pasture. The water-use efficiencies achieved in the border-strip irrigation system used were generally greater than expected for highly permeable stony soils where large drainage losses of irrigation water below the root zone are common. This was the result of reduced soil water transmission rates after compaction by heavy machinery during border strip* preparation. That effect of compaction was persistent, and had not diminished 9 years after initial pasture and irrigation development, as structural improvement of this soil is slow, even under irrigation. Keywords: high country pasture, irrigation, Mackenzie Basin
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(150 KB)
The effect of reproductive stem removal on the growth and development of Grasslands Puna chicory (Cichorium intybus L.) was studied on the Deer Research Unit (DRU) and the Pasture and Crop Research Unit (PCRU) at Massey University in 1993-1994. The chicory was in its second and fourth years on the DRU and PCRU respectively. A medium grazing intensity with deer was used on the DRU and four grazing intensities were applied with sheep on the PCRU. Chicory accumulated 10 007 kg DM/ha herbage mass over 6 months from November to May on the DRU and it accumulated 4904 kg DIWha herbage mass on the PCRU over the same period. The growth of primary reproductive stems was suppressed by grazing intensities that left less than 100 mm of stem stubble. None of the grazing intensities prevented the growth of secondary and axillary reproductive stems. Leaf mass accumulation over the season was greatest under very hard grazing (O-50 mm), whereas the total herbage (leaf and stem) mass was greatest under lax grazing (150-200 mm). The primary stems produced in spring were The effect of reproductive stem removal on the growth and development of Grasslands Puna chicory (Cichorium intybus L.) was studied on the Deer Research Unit (DRU) and the Pasture and Crop Research Unit (PCRU) at Massey University in 1993-1994. The chicory was in its second and fourth years on the DRU and PCRU respectively. A medium grazing intensity with deer was used on the DRU and four grazing intensities were applied with sheep on the PCRU. Chicory accumulated 10 007 kg DM/ha herbage mass over 6 months from November to May on the DRU and it accumulated 4904 kg DIWha herbage mass on the PCRU over the same period. The growth of primary reproductive stems was suppressed by grazing intensities that left less than 100 mm of stem stubble. None of the grazing intensities prevented the growth of secondary and axillary reproductive stems. Leaf mass accumulation over the season was greatest under very hard grazing (O-50 mm), whereas the total herbage (leaf and stem) mass was greatest under lax grazing (150-200 mm).
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(146 KB)A 4-year trial on marginal Pukaki high country soil showed adequate (5 t DMIha) pre-winter yields were obtained only following several years of a development legume phase, N fertilizer, early sowing, some irrigation or favourable autumn growing conditions. The highest yields were from swedes, rape, annual lupin and some cereals. Keywords: brassicas, cereals, high country, winter feed
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(57 KB)A 2 ha 6-year trial on pure stands of irrigated Grasslands Roa tall fescue compared the effect of high (600-300 kg N/ba/yr as urea) and moderate (300-150) nitrogen rates split over either 2- or 4- weekly application, on hay production, some summer grazing and autumn regrowth prior to winter and fed to pregnant ewes on the same plots. Annual yields averaged 13.8 t DM/ba with a 24% advantage to high N. Pregnant ewes break fed a mixed allowance of hay and grass regrowth lost c. 2.4% body weight over a g-week winter period. There was thinning of the stands under high N and long summer regrowth period. It was considered better to forego some of the winter feed potential for some summer grazing, or a further hay cut, to maintain stand density. Keywords: Festuca arundinacea, high country, irrigation, winter feed
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(89 KB)An experiment was conducted on a fertile Walcanui silt loam in 1991/92 to examine the productivity of 4 perennial pasture grass species, Grasslands Roa tall fescue (Festuca arundinacea), Grasslands Marsden hybrid tyegrass (Lolium perenne x Lolium hybridum), Grasslands Maru phalaris (Phalaris aquatica), Grasslands Wana cocksfoot (Dactylis glomerata), and 2 binary mixtures, tall fescue plus cocksfoot and phalaris plus cocksfoot. Between July 1991 and September 1992 the highest production came from phalaris plus cocksfoot at 19.05 t DM/ha. Hybrid ryegrass, phalaris, tall fescue plus cocksfoot, cocksfoot, and tall fescue produced 17.44, 17.13, 16.96, 14.17, and 13.13t DM/ha respectively. The botanical composition of both mixtures averaged equal proportions of the sown species. The proportion of cocksfoot increased over the summer period then declined for the following autumn/winter period. The experiment shows that simple pasture grass mixtures may be highly productive. These findings support the increasing farmer practice of sowmg some pasture grasses in simple mixtures. Keywords: binary mixture, botanical composition, Dactylis glomerata, dry matter production, Festuca arundinuceu, Lolium perenne x Lolium hybridum, pasture mixtures, Phalaris aquatica, seasonal production
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(130 KB)There is a conflict in British grassland farming between management for agricultural purposes, centring on profit maximisation, and that of nature conservation and the enhancement of biological diversity. Within the European Union’s Common Agricultural Policy there is a growing emphasis on reducing output from the community’s livestock sector and this is achieved through allocation of quotas (sheep and milk) whilst maintaining alongterm agricultural base. This could result in the widespread adoption of more extensive grazing regimes. An experiment was set up in upland Wales in 1991 to study the effect of reducing inputs and defoliation on species balance and animal production in a Lolium/Agrostis dominant pasture. Spectacular changes in species balance took place in the first grazing season. Elimination of CaPK and N applications encouraged Agrostis capillaris at the expense of Lolium perenne and Poa spp. and led to a 43% reduction in stock carrying capacity by the 3rd year. Where no defoliation took place important pasture species such as Lolium perenne and Trifolium repens were lost from the swards-by-theZ&year:However;-an-annu&midsummer cut maintained these potentially highly productive species within the sward. Keywords: extensive grazing, low inputs, ryegrass, sheep, species balance, Trifolium repens, upland Britain
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(139 KB)A 0.5 ha 6-year trial compared 6 grass species x 4 N fertiliser rates x 2 times of closing for summersaved standing winter feed. The pre-winter yields averaged 3.4 t DM/ha from November, closing with a high browntoplsweet vernal component, as compared with 1.7 t DM/ha from December closings with a low browntop/sweet vernal component. Grasslands Kara cocksfoot was the highest yielding cultivar, followed by Grasslands Apanui cocksfoot, Grasslands Wana cocksfoot, Grasslands Roa tall fescue, Grasslands Nui perennial ryegrass and Grasslands Maru phalaris, with decreasing proportions of sown grass. Nitrogen fertiliser had a limited effect on prewinter yields but did have a carry-over effect into spring yields. Keywords: Dactylis glomerata, fertiliser, Festuca arundinacea, high country, Lolium perenne, nitrogen, Phalaris aquatica, winter feed
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(103 KB)Wind erosion can have severe long-term consequences on the soils of Canterbury. Pasture production was measured, in the 1992193 year, 47 years after a severe wind erosion event in the Hurunui gorge, North Canterbury. The topsoil was removed from this Tasman/Ashwick intergrade soil, exposing the underlying gravel. Herbage yields from the severely eroded site were very low and only 29% of those from an area which had retained 480 mm of topsoil. Both areas had been under the same management both before and since the erosion event. Where fertiliser had been applied to the area with retained topsoil, herbage yield was greater than where it had not been applied. Keywords: erosion, herbage production, wind
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(66 KB)Field observations indicate that conditions at the stolen/soil surface interface are important for the survival of white clover (Trifolium repens) during drought. Mini-swards of clonal material of two contrasting white clover cultivars (Grasslands Tahora, small-leaved, densely branched; Dusi, large-leaved, tap-rooted) were established in boxes (300 x 420 x 290 mm deep) for 6 months, then subjected to a 6-week drought. Stolen/soil surface conditions were modified to have stolons either, 1) fully exposed, 2) shaded, or 3) buried. Numbers and, characteristics of surviving plants were measured. The major effect was on the number of plants surviving. More plants survived under shading (55%) than burial (25%) and full exposure (17%). Numbers of plants surviving drought was related to pre-drought plant density, hence Tahora had higher plant survival than Dusi, particularly when fully exposed. Although initially Dusi plants were 25 times heavier, with 5 times the number of stolons and roots of Tahora, surviving plants of both cultivars were small and similar in dry weight, although Tahora had higher numbers of growing points and roots thanDusi. The tap-rooted character of Dusi did not. confer any advantage during drought. It was concluded that the main factor influencing drought survival of white clover appears to be grazing management. Systems that can produce dense white clover populations and maintain high pasture density (grass) capable of providing shelter from direct solar radiation during drought stress, are superior. Keywords: drought survival, plant density, plant morphology, stolon burial, stolon shading, Trifolium repens
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(105 KB)The physical and financial outcome from the tactical application of nitrogen fertiliser in pastoral farming is always uncertain. A management policy is therefore required to minimise uncertainty. Listing the sources of production, price and financial risk for nitrogen fertiliser inputs and identifying management actions that mitigate these creates awareness of risk and indicates where management effort can be focused. Data obtained from traditional pasture response research trials are not well suited to decision-making at the farm level. However, results obtained using an expert knowledge approach demonstrated that response relationships for nitrogen can be generated in a form which is more applicable to decision-making situations faced on farms. These data can be adapted to a decision tree framework which allows the likelihood of uncertain events to be formally incorporated in the estimation of financial returns for alternative application decisions for nitrogen fertiliser. A bull beef example showed that highest returns for different weather scenarios were consistently obtained for the application of 50 kgN/ha (as urea); rather than O or 25 kgN/ha. Keywords: economics, fertiliser, nitrogen, pastures, risk
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(93 KB)
The economics of the development transition from an average high country enterprise dependent to various extents on hay, to an all-grass wintering enterprise (involving further development of hill country) such as that at Tara Hills, was investigated with the assistance of the dynamic economic model RANGEPACK HerdEcon. Transitional options ranged from ‘do nothing’ through 18 development scenarios that included factorial combinations of the following variables: three different levels of hay-making costs ($30 000, $60 000 and $90 000 per year) for the average enterprise; failures in oversowing establishment (0, 1 or 2 years out of 5); and either maintaining or increasing by 13% stock numbers subsequent to development. Each transitional option was evaluated over a 20-year period involving real climate effects. Shifting from the $90 000 hay enterprise, and incurring zero establishment failures, allowed an economic position better than ‘do nothing’ to be achieved in 8-9 years. Where the average high country enterprise was less dependent on hay ($60 000 and $30 000 hay operations) the period required to achieve a cash posltlon htterthan-‘do-nothing’- took longer (12 to 20 years respectively). The economic leverage gained from the original enterprise with high hay costs compared to those with lower hay costs was far more influential than the other variables tested establishment failures, climate and stocking rate). Keywords: climate variability, dynamic modelling, economics, high country, pasture systems, transition
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(78 KB)There are four main options for controlling Hieracium: agricultural development, herbicides, biological control and grazing management. Grazing management appears one of the most feasible current strategies for limiting Hierucium spread on low-input land. Exclosure studies in Canterbury and.Otago show grazing can reduce Hierucium flower density 40-fold, limiting expansion by seed. Autumn recruitment from seed varied from 46 to 95 seedlings /m* , suggesting this may be an important dispersal mechanism in wet summers. Low-intensity spring-summer grazing significantly reduced plant number and ground cover of upright Hieracium species, but not prostrate species. Conversely, high-intensity grazing may assist establishment. In a 16-year grazing trial in Otago, Hierucium cover, an4 that of similar flatweeds, was greatest at high stocking rates. Farming with Hierczcium in the future will require development of grazing strategies integrating the requirements for the optimal management of different Hieracium species. Keywords: Hieracium, hawkweed, high country, grazing management
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(156 KB)This paper discusses the successional changes that have occurred during 13 years of a designed experiment in short tussock grassland. The ‘experiment site is at Mt. Possession Station, Canterbury and was established in 1979. Nine species of legume were overdrilled and 9 phosphate rates (O-800 kg P/ha) broadcast at sowing. A vegetation survey of all plots was carried out in November 199 1 and soil sampled in the following year. Legumes were dominant during the early years of the experiment but the responses to P rates differed. Some of the differences in the present vegetation could be explained by earlier treatment effects. Exotic grasses invaded the plots which received higher levels of fertiliser with the exception of plots sown with Lupinus species where grass growth was independent of the applied P rate. The initial treatments have strongly affected present vegetation. Had an attempt been made at the beginning to predict the current composition, or even half way through the experiment, the conclusions are unlikely to have been realistic. It is suggested that the dynamics and composition of the responses are inter-related and complex and as such, they require long-term monitoring before any predictions can be made. Kewords: long-term experiment, phosphate gradient, sown legumes, species composition, tussock grasslands
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(93 KB)This paper reports on chemical changes that have occurred since 1978 in topsoils (O-7.5 cm depth) of upland and high country farms at 3 sites: Longslip and Glencaim Stations near Omarama, north Otago, and the east Otago uplands between Middlemarch and Alexandra. Between 1978 and 1992 on Longslip, on fertilised and oversown hilly and steep slopes, mean soil organic C increased by 67%, total N value changed little, and pH declined by 0.41 units. Associated with the soil changes were declines in the amount of bare ground and snow tussock cover, and increases in legume and hieracium cover. The organic C change was equivalent to an increase of about 11 t C/ha between 1978 and 1992. Over the same time period no topsoil changes on lower landscape positions were apparent. On Glencairn, under grazing but no topdressing, mean organic C declined by lo%, total N declined by 25% and pH declined by 0.43 units between 1978 and 1993). The organic C and N changes were equivalent to a decline of about 1.7 t C/ha and 0.4 t N/ha between 1978 and 1993. In contrast, within unfertilised and fertilised plots of exclosures that had not been mown or grazed for 9 years, organic C rose by 40-55%, total N rose by 21-36%, and there was no significant change of pH. Vegetation changes outside the exclosures included an increase of hieracium and briar cover. On the east Otago uplands under light grazing and little or no fertiliser application no significant changes of pH, organic C or total N were~recorded between 1978 and 1994. The results show that soil monitoring can give useful information about the changes associated with pastoral use and the options available to maintain or enhance soil organic matter and pH levels. Keywords: high country, monitoring, organic C, pH, sustainability, total N
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(112 KB)
Endophytes in perennial ryegrass protect their hosts against attack by Argentine stem weevil but cause adverse affects, including heat stress, in grazing animals. Ten lambs were grazed on Grasslands Nui ryegrass without endophyte or with its wildtype or a high ergovaline-producing endophyte (196). Five lambs from the 196 treatment were swapped for 5 on the endophyte-free treatment after 20 days. Rectal temperatures and respiration rates were measured daily; on one day they were measured every 2-4 hours. There was a significant difference in respiration rate and body temperature between lambs grazing endophyte and endophytefree treatments but not between the two endophyte treatments. There was no interaction with ambient temperature within the range 12-30°C. When lambs where transferred from toxic to non-toxic treatments there was no significant decrease in body temperature or respiration rate witbin 14 days. Ergovaline, even at low concentrations, affects thermo-regulation in lambs and is undesirable in perennial ryegrasslendophyte associationsEndophytes in perennial ryegrass protect their hosts against attack by Argentine stem weevil but cause adverse affects, including heat stress, in grazing animals. Ten lambs were grazed on Grasslands Nui ryegrass without endophyte or with its wildtype or a high ergovaline-producing endophyte (196). Five lambs from the 196 treatment were swapped for 5 on the endophyte-free treatment after 20 days. Rectal temperatures and respiration rates were measured daily; on one day they were measured every 2-4 hours. There was a significant difference in respiration rate and body temperature between lambs grazing endophyte and endophytefree treatments but not between the two endophyte treatments. There was no interaction with ambient temperature within the range 12-30°C. When lambs where transferred from toxic to non-toxic treatments there was no significant decrease in body temperature or respiration rate witbin 14 days. Ergovaline, even at low concentrations, affects thermo-regulation in lambs and is undesirable in perennial ryegrass endophyte associations. Keywords: body temperature, endophyte,ergovaline, heat stress, Lolium perenne, respiration rate
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(145 KB)The requirement for ‘cobalt (Co) of ruminants grazing pastures on the pumice soils of the Central Plateau was established in the late 1930s and Co topdressing to increase the Co intake of animals became commonplace from the mid-1950s. An on-farm survey in 1978-79 indicated that Co inputs could be halved because of adequate reserves of soil Co accumulated since the 1950s. However, the economic downturn in agriculture of the 1980s led to marked reductions in Co use. Follow-up surveys between 1991-93 indicated a general decline in soil and pasture Co levels. This decline was much more pronounced in areas with a poor history of Co topdressing. The 1991-93 survey results indicated a relationship between soil Co and pasture Co, Using probability analysis it was possible to indicate the soil Co level required to maintain a particular pasture Co concentration. Keywords: EDTA soil cobalt, fertiliser practice, pasture cobalt, stock health
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(170 KB)The influence of perennial tyegrass endophyte on sheep reproduction and early lamb growth was studied in a 3-year grazing experiment at the AgResearch regional station at Gore (46”07’S, 168”54’E). The trial consisted of 8 paddocks sown in endophyte-infected (+E) or endophyte-free (-E) Grasslands Nui perennial ryegrass, with (+C) or without Grasslands Huia white clover. Endophyteinfected ryegrass delayed the lamb drop and reduced lamb weight gains during the lactation period. Lamb drop was delayed by an average of 3-5 days especially in the presence of clover. This may be due to an extended gestation period or delayed mating. There was no effect of endophyte on lamb birth weight, ewe conception rate and liveweight changes over autumn, winter and spring. Keywords: Acremonium l&i, lambing time, liveweight change, Lolium perenne, sheep reproduction, Southland
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(109 KB)Four 2.5 ha farmlets based on endophyte-infected (H) and endophyte-free (L) ryegrass were established with or without white clover (kc) in March 1993. Fifteen cows were allocated to each farmlet before 3-week test periods in spring, summer and autumn. Milk yield and composition (fat, protein, lactose), cow rectal temperature, liveweight, condition score and incidence of ryegrass staggers were measured. Pasture sampling included assessments of yield, botanical composition, alkaloid, and endophyte content. H and L endophyte ryegrass treatments contained 94 and 26% endophyte, respectively, in March 1994. Herbage accumulation on all treatments was similar over the season (20 May 1993 - 19 April 1994). Treatments did not affect milk production in the October test period. Interaction between endophyte and clover in the January/February period showed cows on the L + C treatment produced more milk than all others (10.3 vs 9.0 l/cow/day). However, in the March test period a different interaction was apparent as cows on the H+C treatment produced produced less milk than all others (4.7 vs 6.3 l/cow/day), and all cows on H endophyte showed clinical ryegrass staggers. Milk production responses were not directly related to the endophyte status of the pastures in any test period. Treatment trends for green herbage consumed in March were similar to those for milk production. Keywords: Acremonium lolii, dairy cows, grazing, lolitrem B, Lolium perenne, milk production, ryegrass staggers
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(160 KB)
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