Mob Stocking Research Articles

Grazing intensity effects on sward responses of UF Riata Bahiagrass

AbstractBahiagrass (Paspalum notatum Flüggé) is a rhizomatous, perennial, warm‐season forage widely grown in the southeastern United States "UF Riata" bahiagrass is more upright growing with greater herbage production when days are shorter compared with most other cultivars. Lesser daylength sensitivity extends the grazing season, but in combination with more upright growth may negatively affect persistence under grazing, especially if out‐of‐season herbage production interferes with normal reserve storage. This 3‐year study investigated above and belowground sward responses of UF Riata bahiagrass to three levels of post‐grazing herbage mass (HM) (500 [heavy grazing, HG], 1500 [moderate grazing], or 2500 [light grazing, LG] kg DM ha−1, where DM is dry matter) imposed by mob stocking every 14 days. Total herbage accumulation (HA) and HA rate were not affected by treatment. Crude protein (CP) was affected by treatment × grazing cycle × year, whereas in vitro digestible organic matter concentrations were affected by treatment × year and grazing cycle × year. Root–rhizome biomass (12,940–9230 kg OM ha−1, where OM is organic matter) and soil cover percentage (97%–93%) decreased linearly as grazing intensity increased from LG to HG. Proportion of non‐planted grasses was 34% and 17% in HG and LG swards, respectively. Proportion of non‐grass weeds increased across treatments from 2% to 22% over the years. Moderate grazing could maintain similar CP to HG, and similar root–rhizome biomass to LG. Thus, considering both sward persistence and forage nutritive value, a target post‐grazing HM of ≈1500 kg DM ha−1 is recommended when UF Riata pastures are grazed every 2 weeks.

109 Invited Talk: Grazing Management and Stocking Strategy Decisions for Pasture-Beef Systems: Experimental Confirmation vs Testimonials and Perceptions

Abstract The primary objectives of forage-based livestock grazing systems are to enhance sustainability of pastures and cattle production, and to maintain economic stability in the presence of changes in input costs and returns. Grazing management strategies and implementation vary for adapted forages according to vegetational-hardiness zones, livestock production objectives, and manager preferences for grazing systems, stocking rates, and stocking methods. Stocking methods are strategies or techniques to manipulate grazing animals in space and time and may be considered as variations of continuous or rotational stocking. In many stocking method discussions, the debates are often focused on experimental confirmational data vs testimonials and perceptions. Acceptable methodology and statistical analyses of grazing experimentation on continuous vs rotational stocking provides repeated measures of forage nutritive value, forage mass, grazing intensity, and stocking rate on gain per animal, gain per unit land area. Additional measurements may include effects on forage stand maintenance and soil nutrient analyses-status. Recent adaptations of mob stocking and intensive rotational grazing via popular press and consultants have received acclaims for methods to enhance ecosystem services, soil health, and other non-experimentally documented attributes. Managers may adopt these testimonials of stocking methods of 60 days or more deferment based on their perception of protecting and enhancing the environment rather than logic of seeking experimental evidence. However, when given a choice of forage available for consumption, cattle select more than 80% of their diet as leaves. Thus, with respect to average daily gain per animal (ADG), only a small percentage of pasture studies have shown an advantage for rotational stocking. The lack of ADG was attributed to reduced nutritive value of forage available for selection during the residence time. Selecting management and stocking strategies for optimum utilization for forage produced, individual animal performance, and overall gain per unit land area has led to flexible grazing systems. These grazing systems may not be “hardcore rotationally, time-scheduled stocked,” but they do involve multiple pastures with strategies to incorporate movement of cattle based on current paddock forage status and forage mass estimates for desired animal performance. Grazing management strategies control the degree of intensity of beef cattle production based on level of economic risk and desired-expected environmental stewardship goals. Of all the strategies that management may adopt for grazing, the primary factor that controls resultant sustainability of pastures is that of grazing intensity as measured by stocking rate or forage height-density. Implementing revised or new management strategies requires attention to detail and the use of data-results-recommendations from comparative experiments conducted by a recognized source without conflict of interest in the method promoted.

111 Forage Mass and Nutritive Value of Cool-Season Grass-Legume Mixtures Overseeded into Bahiagrass Pastures

Abstract Warm-season perennial pastures are the base of livestock production systems in lower Alabama. To overcome the shortage in forage production during the late fall and winter months, during bahiagrass dormancy, overseeding pastures with cool-season annuals can be used as an option for providing forage during this period. Diverse forage mixtures of multiple species and functional groups have gained popularity in use among forage-livestock producers, but few evaluations have been conducted in overseeded sods. The objective of the study was to evaluate forage mass and nutritive value of cool-season forage mixtures overseeded into bahiagrass pastures. Six, 0.40-ha paddocks of ‘Pensacola’ bahiagrass were overseeded with one of three cool-season forage mixtures (n = 2 paddocks/treatment) on November2, 2021: 1) oat (Avena sativa), wheat (Triticum aestivum), and balansa (Trifolium michelianum), red (Trifolium pratense), and white clover (Trifolium repens; ‘clovers’); 2) oat, cereal rye (Secale cereale), and clovers; and 3) cereal rye, annual ryegrass (Lolium multiflorum), and clovers. When forage mixtures reached a target grazing height of 20 cm, paddocks were managed using flash mob stocking with beef cow-calf pairs to graze to a target height of0 cm. Herbage mass, nutritive value, botanical composition and height samples were collected pre- and post-grazing events. There was no treatment (P = 0.240) or treatment × harvest (P = 0.4239) effect on forage mass. Harvest date affected (P = 0.029) forage mass, with greater forage mass at late harvest (1,903.33 kg DM·ha-1) than at early (1,253.33 kg DM·ha-1) in the growing season. There were no treatment effects observed for species components (P > 0.05), although grasses dominated the forage mixtures with an average of 80% grass presence. Legume establishment was poor (less than%) and the remaining species composition consisted of weed species (19%). There was a treatment effect (P = 0.003) on CP, where oat-rye-clovers had the greatest CP and rye-ryegrass-clover had the least CP. Oat-wheat-clover mixtures had greater TDN (79.2%), less NDF (39.8%), and ADF (18.7%) than cereal rye-ryegrass-clover (75.4%, 46.1%, and 22.2% for TDN, NDF, and ADF, respectively), but did not differ from oat-cereal rye-clover mixtures (76.6%, 45.7%, 21.0% for TDN, NDF, and ADF, respectively). In year of this study, overseeding bahiagrass supported forage production over a 2-month period and can be a management tool used to reduce the need for supplementing in the dormancy periods of warm season perennial grasses.

Mob grazing: A nature-based solution for British farms producing pasture-fed livestock

Mob grazing is a nature-based solution to boost sustainable livestock productivity by optimising pasture management. It is already used widely in North America, and is now also receiving increased attention in the United Kingdom. In spite of this, its implementation by British farmers has so far remained largely unexplored. To close this gap, we studied how and why mob grazing is being adopted by British pasture-fed beef farmers. Field-level grazing management information was collected on 15 farms and analysed using cluster analysis and ordination analysis, showing the diversity of practices and establishing a gradient of mob grazing implementation. Farmer interviews explored general farming context, and rationale and motivations underpinning each farmer's grazing approach. Four main rotational approaches were identified at the field level: (1) conventional non-mob stocking by farmers still in the initial stages of discovering mob grazing; (2) mob stocking, involving reduced grazing duration at increased stocking densities, with pasture rest periods similar to those used in rotational non-mob stocking; (3) mob grazing, involving similar stocking densities as in mob stocking, but allowing for longer rest periods; and based on one early adopter of mob grazing practices in our sample (4) intensive mob grazing using very high stocking densities and frequent cattle movement, allowing for even longer rest periods. Interviews revealed the shift to mob grazing as a gradual process of farmer adaptation, involving the need to overcome constraints such as fencing and water access. Some early adopters amongst our sample of farmers observed various benefits to sustainability of livestock production, soil and ecosystem health, and animal health. We found much variation across farms, partly due to farmers adopting mob grazing gradually. Also, many farmers in our sample, in varying degree, were influenced by holistic grazing approaches. The ‘systems’ basis underlying such approaches, and variation in mob grazing implementation, mean that interdisciplinary and longer-term investigations may be most appropriate for exploring mob grazing effects. This is also illustrated by a case study involving long-term data from one intensively mob grazed farm.

Grazing management and stocking strategy decisions for pasture-based beef systems: experimental confirmation vs. testimonials and perceptions

Abstract Grazing management and stocking strategy decisions involve the manipulation of grazing intensity, grazing frequency, and timing of grazing to meet specific objectives for pasture sustainability and economic livestock production. Although there are numerous stocking systems used by stakeholders, these methods may be broadly categorized as either continuous or some form of rotational stocking. In approximately 30 published experiments comparing continuous vs. rotational stocking, there was no difference in liveweight gain per animal between stocking methods in 66% of studies. There was no difference in gain per hectare between methods in 69% of studies, although for gain per hectare the choice of fixed or variable stocking rate methodology affected the proportion (92% for fixed; 50% for variable). Despite these experimental results showing limited instances of difference between rotational and continuous stocking, rotational strategies (e.g., “mob stocking” or “regenerative grazing”) have received what appears to be unmerited acclaim for use for livestock production. Many proposed “mob stocking” or “regenerative grazing” systems are based on philosophies similar to high intensity-low frequency stocking, including provision for >60 d of rest period from grazing. In addition, grazing management practitioners and stakeholders have voiced and proposed major positive benefits from rotational stocking, “mob stocking”, or “regenerative grazing” for soil health attributes, carbon sequestration, and ecosystem services, without experimental evidence. The perceptions and testimonials supporting undefined stocking systems and methods have potential to mislead practitioners and result in economic disservices. Thus, we suggest that scientists, extension-industry professionals, and producers seek replicated experimental data as the basis for predicting outcomes of grazing decisions.

Regenerative Agriculture: farmer motivation, environment and climate improvement

Regenerative agriculture has become a social movement in farming. It embraces the environmental basis of farming. Land, water and nutrients are viewed as an ecological whole. This includes bacteria and mycorrhiza as essential to soil health and plant diversity, and mob stocking and no-till farming above ground. Regen ag, as regenerative agriculture is often called, is a paradigm shift for farmers, who are often perceived as resistant. There is a mismatch between academic and policy interest focusing on the scientific need for and value of regenerative agriculture, and the social and human motivating benefits of regenerative agriculture. This crucial willingness, not simply the turn away from denialism, is the signal significance of this new form of farming. In New Zealand and globally, climate change and environmental degradation can be addressed much more quickly, more thoroughly and less contentiously if regenerative agriculture is supported and extended, even as science documentation is achieved over time.

Yield and nutritive value of grazed complex legume–grass mixtures under increasing nitrogen application rates

Complex pasture mixtures are advantageous, but little information exists on the best forage species and nitrogen (N) management in eastern Canada. We compared under mob stocking four complex mixtures of one of two legume species [alfalfa (Medicago sativa L.) and birdsfoot trefoil (Lotus corniculatus L.)] plus one of two grass mixes [No. 1 — timothy (Phleum pratense L.), meadow fescue (Schedonorus pratensis (Huds.) P. Beauv.), reed canarygrass (Phalaris arundinacea L.), and Kentucky bluegrass (Poa pratensis L.); No. 2 — tall fescue (Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.), meadow bromegrass (Bromus biebersteinii Roem. and Schult.), reed canarygrass, and Kentucky bluegrass] under three N application rates at three sites over the first three post-seeding years. Legume species had little effect on most forage attributes mainly because of their low contribution to forage dry matter (DM) yield (<30%) in second and third years. The grass mix with tall fescue and meadow bromegrass (No. 2) yielded similar or slightly better than the one with timothy and meadow fescue (No. 1) but tended to have a greater neutral detergent fibre concentration, and lower N and total digestible nutrient concentrations. Nitrogen fertilization increased forage DM yield only in second and third years when the legume contribution to forage DM yield was <30%, and it increased N concentration and decreased nonstructural carbohydrate concentration. These results highlight the challenge of maintaining legume species in rotationally grazed pastures of eastern Canada and confirm recommendations of applying no or little N fertilizer on grazed legume–grass mixtures when the legume contribution to forage DM yield is >30%.

Registration of ‘Kenhy’ and ‘Gibtuck’ Limpograss Hybrids

‘Kenhy’ (Reg. No. CV‐283, PI 682663) and ‘Gibtuck’ (Reg. No. CV‐284, PI 682664) hybrid limpograss [Hemarthria altissima (Poir.) Stapf & C.E. Hubbard] cultivars were produced by the University of Florida Agronomy Department, a unit of the Florida Agricultural Experiment Station, and released in 2014. These two hybrids were selected from 51 hybrid seedlings produced by greenhouse hand crosses of ‘Floralta’ × ‘Bigalta’. Floralta is estimated to constitute >95% of the limpograss grown in Florida, raising concerns about genetic vulnerability. Bigalta, although less persistent than Floralta, has been shown to have slightly greater in vitro organic matter digestion. Evaluations of these hybrids were conducted at the Range Cattle Research and Education Center, Ona, FL, at two locations near Gainesville, FL, and at the North Florida Research and Education Center, Marianna, FL. Evaluations included greenhouse pot studies, small plot clipping experiments, two different mob stocking grazing experiments, and an experiment to evaluate herbage accumulation and nutritive value under stockpiling management. Kenhy and Gibtuck were selected for superior herbage accumulation, persistence under grazing defoliation, improved nutritive value compared with Floralta, and utility as stockpiled forage. Vegetative planting material was first distributed in summer 2014 to a group of growers selected by the Florida Cattlemen's Research Committee, and further public distribution will be coordinated by this committee.

The future of grazing research

The future of grazing research

How the Intercropping between Corn and Palisade Grass Cultivars Affects Forage Production and Pastures Characteristics under Grazing

Crop-livestock integrated systems have been identified as an excellent option to use land efficiently. This study investigates how the intercropping between corn and three palisade grass cultivars affects the species productivity and the physiological and structural characteristics of swards grazed under 95% light interception under mob stocking. Evaluations were performed before corn harvest and during three grazing cycles. Similarity between the cultivars on the proportion of corn morphological components has shown that none of the studied forage plants had influence on the growth of corn. The crop-livestock integrated system with corn modified the proportion of palisade grass cultivars’ morphological components, promoting the development of Xaraes cultivar. In the pre-grazing in the grazing cycles, considering 95% of light interception the Xaraes cultivar showed higher height (0.47 m) compared with Marandu (0.37 m) and similar to Piata (0.42 m). Forage density was higher in the second grazing cycle only when the forage mass was also greater with greater contribution of both leaves and stems compared to the other cycles. Mass of leaves, stems and dead material was similar between the cultivars both pre- and post-grazing. The corn and forage intercropping did not affect the growth and development of palisade grass pastures and it is a viable alternative for the crop-livestock integrated system. Corn production is not affected by the palisade grass cultivars but production can be affected by environmental conditions mainly rainfall. The Marandu, Xaraes and Piata cultivars can be recommended for integration farming system in crop-livestock integrated system and are recommended for sward managed under 95% light interception and 15 cm high residue.

Direct seeding of indigenous tree and shrub species into New Zealand hill country pasture

Summary Our study aimed to examine the applicability of a native plant restoration technique involving close grazing, blanket herbicide spraying and mob stocking (to trample the seed into the soil) for establishing New Zealand native tree and shrub species into exotic hill country pasture. This approach represents an alternative to the usual spaced‐planting of seedlings in the context of an indigenous vegetation restoration programme. Field‐collected seed of Cabbage Tree (Cordyline australis), Kahikatea (Dacrycarpus dacrydioides), Kanuka (Kunzea ericoides), Karamu (Coprosma robusta), Kohuhu (Pittosporum tenuifolium), Koromiko (Hebe stricta), and Manuka (Leptospermum scoparium) were germination tested in the laboratory, and broadcast sown in two field experiments in spring 2001 and autumn 2002. The spring‐sown experiment tested the effect of mob stocking and the autumn‐sown experiment tested the effect of mob stocking and sowing rate. Laboratory germination varied widely among species (0–88%). In the field, the two shrubs, Koromiko and Karamu, established densities of up to 5 and 1.2 plants/m2, respectively, after 2.5 years. Autumn emergence for these two species strongly related to sowing rate. Three tree species, Cabbage Tree, Kahikatea and Manuka, emerged in the field but did not survive beyond 6 months. Mob stocking was effective in spring but not autumn sowing, implicating soil moisture content as an important factor in germination success. The study demonstrated that the direct seeding technique was successful for two shrub species, highlighting the potential for development of a cost‐effective native plant restoration approach.

The distribution of urine deposited on a pasture from grazing animals

Intensive agricultural production practices are known to cause far-reaching effects on water quality. The current paper addresses and quantifies these effects caused by high stocking rates.A set of stochastic difference equations describing the development of the proportion of a grazed field either unaffected by urine deposition, or affected by multiple (1, 2, …) urine depositions is described. A solution to this set of equations is found for the expected value of multiple (0, 1, 2, …) urine depositions, and the variances of these depositions. It is assumed that an animal voids urine with a Poisson probability distribution, and that each urine deposition covers a random area with a Gaussian probability density. Given these reasonable assumptions, the probability distributions for each multiplicity of patch distribution can be found numerically.The utility of the results obtained is illustrated for a problem in assessing the nitrogen (N) pollution of ground water from different grazing strategies. It is demonstrated quantitatively that mob stocking (typical of winter management regimes in New Zealand) is often caused by rotational grazing. The latter is often used to optimize grass growth and intake, especially in winter. This increases (more than linearly) the level of N pollution in ground water. This is because of the increased frequency of multiple urine depositions, i.e. more than one urine deposition on the same patch of land in a short time.

Sustainability of New Zealand high‐country pastures under contrasting development inputs. 3. Sheep carrying capacity

Annual sheep‐grazing‐days over 14 years is reported for two grazed, mixed‐species pasture trials on a Pukaki/Tekapo high‐country soil. One compared 30 combinations of 5 superphosphate rates (0–500 kg ha‐1 yr‐1) × 3 stocking rates × 2 stocking methods; the other compared 27 combinations of P and S fertiliser (0–100 kg element ha‐1 yr‐1). Carrying capacity increased with both S and P fertiliser from 2.3 grazing‐days/365 ha‐1 yr‐1with zero fertiliser, to 20.9 under high fertiliser and irrigation. Carrying capacity was 11–27% less under sustained or set‐stocking than under mob stocking, the difference increasing with mean carrying capacity. There were several time trends in carrying capacity: a year to year fluctuation related to positive effects of Sep‐Dec rainfall and negative effect with March temperature; the difference between treatments increasing in good years; an increase or decrease to asymptote carrying capacity dependent on P fertiliser rate; and an increasing positive effect of S fertiliser.

Effects of grazing management on phalaris herbage mass and persistence in summer-dry environments

Grazing management strategies that included resting or intensely utilising pasture on a seasonal basis were compared for their effects on phalaris production and plant frequency (persistence). Experiments were established at 4 on-farm sites (Cootamundra ‘old’, Cootamundra ‘new’, Springhurst and Cavendish) in southern New South Wales and Victoria that had previously been sown to phalaris and were grazed by sheep. At each site, 8 core treatments and extra locally determined treatments were initially imposed in 1993–94 on 2 spatial replicates. In order to determine and describe any year of start effects, treatments were applied again in 1994–95 to plots that had been maintained as controls. The phalaris component of the pastures varied from a minor component to the dominant component depending on site (11–54%). Measurements of botanical composition, available herbage and plant frequency were made between September 1993 and September 1996. Of the core treatments, autumn closure (Cootamundra old and new), winter closure and grazing between defined levels of available herbage (mob stocking) during autumn–winter (Cootamundra old and new, Springhurst), were the most effective in either maintaining or increasing phalaris herbage mass compared to the continually grazed control treatment. In addition, the frequency of phalaris was higher than the control at each of these sites for the autumn–winter mob stocking treatment. These treatments had no effect at the Cavendish site where phalaris was a minor component of the pasture. Rotational grazing, imposed at 2 of the sites (Cavendish and Cootamundra new), led to an increase in phalaris herbage mass compared to continual grazing. A further treatment aimed at encouraging phalaris seedling recruitment by using an extended spring rest until seed fall in summer followed by a rest after the autumn break was imposed at the Cootamundra old site. This treatment increased phalaris herbage mass but did not result in seedling recruitment. The results emphasise the need for periods of rest when buds are regenerating and tillers developing over the autumn–winter period for phalaris pastures in summer-dry environments.

Effects of grazing management on botanical composition of native grass-based pastures in temperate south-east Australia

Grazing management strategies to alter botanical composition of native pastures were investigated at 4 locations in the high rainfall zone of south-east Australia, including Tasmania. These studies were conducted as part of the Temperate Pasture Sustainability Key Program, which evaluated the effects of grazing management on a wide range of pasture types between 1993 and 1996. Pastures in this study were based on Aristida ramosa/Bothriochloa macra, Microlaena stipoides–Austrodanthonia spp. or Themeda triandra–Austrodanthonia spp. Seasonal rests, increased grazing pressure in spring, mob stocking and cutting for hay were compared to continuous grazing at all sites. In addition, specific local treatments were tested at individual sites. Changes in composition resulting from the treatments were minimal at most sites. This may have been due to a combination of the inherent stability of the pastures, the relatively short duration of the experiments, and the drought conditions experienced, which minimised differences between treatments. Some strategies to alter composition of natural pastures are suggested. In the Aristida–Bothriochloa pasture there was a general decrease in Aristida and an increase in Bothriochloa, which was largely unaffected by the type of grazing management applied. The combination of drought conditions and increasing grazing pressure was sufficient to alter composition without specific management strategies being necessary. In the Themeda–Austrodanthonia pasture, resting in spring, 12-month rests or cutting for hay (which involved a spring rest) allowed Themeda to increase in the pasture. The Microlaena–Austrodanthonia pastures were very stable, especially where annual grass content was low. However, certain treatments allowed Microlaena to increase, a result which is regarded as being favourable. The major effects in these latter pastures were on undesirable species. Vulpia spp. were reduced by resting in autumn and increased spring grazing pressure, while Holcus lanatus was increased dramatically by resting in spring and was also increased by resting in autumn or winter, but only when conditions were suitable for growth of this species. In many cases, treatment differences were only expressed following recovery from drought, showing that timing of grazing management to achieve change is critical.

Preliminary trials using a white clover (Trifolium repens L.) understorey to supply the nitrogen requirements of a cereal crop

AbstractA method of growing cereals with no input of N fertilizer was tested. Two experiments are reported in which white clover (Trifolium repens L.) was used to supply the nitrogen requirements of the cereal. Spring barley, spring oats and winter barley were direct drilled into an established clover crop and grown with the legume as an understorey. The yield of whole crop cereal, for ensilage, and yield of cereal grain were similar to those grown by traditional methods. In the first experiment, clover survived adequately to be used again, but in the second experiment it was killed by a very high slug population. A method of slug control by mob stocking with sheep is discussed. Where clover survived, no weed, insect or disease problems were encountered. The technique offers a possible method of reducing the environmental problems arising from the use of nitrogen fertilizers.

Evaluation of mob stocking for control of grass grub

Evaluation of mob stocking for control of grass grub

The effects of pasture management on population density and diseases of porina (Lepidoptera: Hepialidae).

Abstract In a field trial carried out at three sites over 2 years at Owaka, South Otago, mob stocking of pasture by sheep in February caused up to 75% mortality of porina (Wiseana spp.) larvae. Mob stocking in March had less effect, suggesting that small larvae, living on or near the soil surface and forming a high proportion of the populations until late February, were most affected. There was no evidence that mob stocking affected the prevalence of virus diseases in porina populations, but microsporidial infections and parasites were higher in mob stocked compared with untreated or haymaking treatments. Haymaking did not effect porina density in the first year; it did, however, effect both porina density in the second year and virus prevalence in each year, the effects varying between sites. The reasons for this were not understood.

Seasonal variation in the vertical distribution of white clover stolons in grazed swards

Abstract Swards under mob stocking or rotational grazing by sheep at Kaikohe, Taupo, Ballantrae, Wairarapa, Palmerston North, Lincoln, and Gore were sampled every three months for three years. The white clover stolon material was dissected into three vertical classes: aerial, surface, and buried. Length and dry weight of stolon in each class were measured. The mean total weight of stolon and the distribution by weight of stolon in the three vertical classes varied among sites (P<0.001). In addition, each year there was a highly significant (P<0.001) seasonal change in the vertical distribution of stolon at each site, with mean levels of approximately 80070 of stolon buried in winter and 40% in summer and autumn. At two sites, Wairarapa and Lincoln, exceptions to the seasonal. pattern of distribution of stolon were observed when low rainfall periods occurred. A significant negative correlation between threemonthly effective rainfall (rainfall minus Penman potential evapotranspiration) and weight per unit l...

OBSERVATIONS ON THE DISTRIBUTION OF WHITE CLOYER STOLONS IN HILL SWARDS

Hill swards under mob stocking by sheep at Taupo, Ballantrae and Wairarapa were sampled every three months for one year and white clover stolon dissected into three vertical classes: aerial, surface and buried. In 198081 swards at Ballantrae under three different grazing managements, rotationally grazed by cattle IRGC) and by sheep (RGS) and set stocked by sheep (SSS), were sampled six times over one year and white clover stolon dissected out. The distribution of stolon among the three vertical classes varied with season. Buried stolon ranged from a minimum of 42% in autumn to a maximum of 86% in early spring. The proportion of stolon in the aerial and surface classes peaked in summer at 14% and 48% respectively and was at a minimum in early spring (l%and 13%). Distribution of stolon among the vertical classes differed among sites. The Taupo site had respectively 12% and 17% less stolen buried than the Ballantrae and Wairarapa sites. Environmental conditions such as overgrazing during drought reduced the amount of white clover stolon by up to 70% and modified distribution in favour of the buried class. Grazing management had a large effect both on the amount of stolon in the swerds and on the morphology of stolons. Under RGC there was greater total stolon weight (570 kg/ha) than under RGS (310 kg/ha) and SSS (225 kg/ha). Stolons under RGC were heavier per unit length by 32% and 53% respectively than the stolons under RGS and SSS managements. Keywords: white clover, hill swards,stolons,grazing management, vertical distribution, stolon morphology.