Soil Science Commons^™

Integrating Forage Maize With Pasture Legumes For Efficient Dairy Production In South Eastern Australia, K E. Pritchard, W K. Mason, C R. Stockdale, J B. Moran

IGC Proceedings (1977-2023)

In south eastern Australia, the mild climate permits year­round grazing for 1.5 million dairy cows which results in a low production cost for milk. More than 1 million hectares of annual and perennial pastures are irrigated to supplement rain­fall of 300-500 mm/ annum, for dairy, beef and sheep pro­duction. Animal production from the present system of grazing pasture is limited by the inefficient conversion of solar radiation achieved by temperate pasture species ; seasonal variation in quantity and quality of pasture forage ; by poor utilization of pasture ; and by the low quality of grass-dominant pasture. The Kyabram Research …

Valeur Alimentaire Des Associations Graminees- Trefle Blanc Au Stade Du Paturage, R Giovanni

IGC Proceedings (1977-2023)

Cette etude a eu pour objectif de comparer la composition et la digestibilite du trefle blanc a celles des deux principales gra-. minees fourrageres, le ray-grass anglais (RG) et le dactyle (D), utilisees dans l'Ouest de la France. En effet, ii est apparu interessant de preciser !'influence du trefle blanc (TB) sur la valeur alimentaire de son association avec ces graminees. Cette etude a ete effectuee simultanement sur des fourrages coupes distribues a des moutons en cage de digestibilite et sur des echantillons preleves a chaque cycle du paturage de jeunes bovins.

Factors Affecting The Productivity Of Elephant Grass, G.E D. Tiley

IGC Proceedings (1977-2023)

Elephant grass (Pennisetum purpureum Schumach) is a highly productive and palatable fodder which is widely grown in the tropics (Bogdan, 1977). Optimum utilisation of its production potential is, however, limited by management factors which are associated with plant form and growth habit (Horrell and Tiley, 1970). These factors were studied in a series of trials at Kawanda Research Station, Kampala, Uganda (0°27'N, 32°30'E). A summary of the princi­ pal results is given.

The Efficacy Of A High Magnesium Italian Ryegrass Cultivar In Alleviating Hypomagnesamia, G Moseley, D M. Baker, D H. Hides

IGC Proceedings (1977-2023)

Hypomagnesaemia continues to cause serious economic losses in grazing livestock and recent evidence suggests that its incidence may be increasing. The disease is characterised by a drop in the concentration of magnesium in extracellular fluid and occurs in two forms, chronic and acute. Both forms give rise to classical clinical symptoms which may either result in death or drastically reduced levels of production. The body does not contain a major source of labile magnesium nor does it have a homeostatic mechanism for controlling the level of magnesium in extracellular fluid. The maintainance of normal levels therefore depends almost entirely on …

Ammonia Volatilisation And Loss From Grassland Systems, S C. Jarvis, B F. Pain, D J. Hatch, R B. Thompson

IGC Proceedings (1977-2023)

There is considerable interest in monitoring flows of nitrogen (N) through various parts of grassland systems. Until recent developments in methodology it had been particularly difficult to assess the contribution of NH3 volatilisation to N cycling. Emission rates for NH3 over Europe are thought to have increased by 50 % over the past 30-40 years and to arise largely from livestock excreta. This occurs after the hydrolysis of excreted urea and, with cattle, takes place directly from grazed swards, animal houses (during overwintering) and stored or applied slurry. As well as the economic losses, NH3 fluxes have important environmental consequences …

The Effects Of Fertilizer/Urine Interactions On Nh3 -N Losses From Grassland Soils, R D. Meyer, S C. Jarvis

IGC Proceedings (1977-2023)

Recent studies (Black et al., 1984) have indicated that the vol­atilisation of ammonia (NH3) from urea granules broadcast on to pastures at application rates of 50-100 kgN/ha often exceeds 20 % of the N applied. The extent of this loss becomes an import­ant consideration when manipulating management systems to maximise N efficiency and minimise losses to the environment. This will become especially important as the use of urea fertiliser increases because of relative cheapness and as technological advances in production and in farm handling are made (Gould et al., 1986). The factors influencing the volatilisation of urea in simple systems …

Evaluation Of Wild Nut-Producing Arachis Species For Forage, A E. Kretschmer Jr, C E. Simpson, T C. Wilson, W D. Pitman

IGC Proceedings (1977-2023)

Fourteen nut-producing wild peanut (Arachis spp,) accessions were evaluated in single-plant plots and in ranchers' fields under grazing. Transplants were used for initial and some secondary planting, Agronomic characteristics and persistence were measured. The cv. Amarillo (4222) and a selection previously evaluated (2273) were used as controls. Plant yield, leaf and stem weights, nut production and other attributes varied among the accessions. Accession 2273 was one of the earliest and most prolific flowering and nut producers, while 4222 was the most persistent under initial grazing evaluation,

Conservation Of Biodiveristy In Managed Rangelands, With Special Emphasis On The Ecological Effects Of Large Grazing Ungulates, Domestic And Wild, Patrick Duncan, Peter J. Jarman

IGC Proceedings (1977-2023)

Biodiversily with its different components (genes, species and ecosystems) is defined in relation to rangelands, whose Importance in its conservation is described. At the fine scale grasslands are much more diverse than tropical rain forest, and are comparably diverse at a regional scale, at least in Africa. Rangelands are crucially important world wide for 1he conservation of plants, and also for birds and large mammalian herbivores. Large ungulates (and other large herbivores) ace "keystone" species in these·ecosystems, playing a crucial role in the maintenance of diverse communities of plants, birds and invertebrates associated with such grasslands. Modification of the natural …

Fire And Grazing Interact To Manipulate Pasture Composition In Heteropogon Contortus (Black Speargrass) Pastures, D M. Orr, C J. Paton

IGC Proceedings (1977-2023)

Aristida spp, (wiregrasses) are invading areas of Heteropogon contortus (black speargrass) pastures in southern Queensland. Interim results from 2 field experiments indicate that increasing the frequency' of annual spring burning over 3 years, with and without grazing, results in a progressive reduction in the yield of Aristida spp. H. contortus yields also increased with increasing frequency of burning under non-grazing but not when grazed, H. contortus yields have increased after burning when grazing has been deferred or where the stocking rate has been halved after the fire. The results suggest that botanical composition in these pastures can be manipulated readily …

Persistence Of Roundleaf Cassia In Grazed Pastures - A Conceptual Model, R M. Jones, C K. Mcdonald, G A. Bunch

IGC Proceedings (1977-2023)

Roundleaf cassia (Cassia rotudifolla) cv. Wynn is a short-lived perennial that relies on seedling recruitment for long-term persistence. Its persistence is considered in terms of survival of plants from the initial sowing, seed set, seedling recruitment, run-down of reserves of soil seed, and survival of seedlings. The major factor controlling all these stages is soil moisture stress; grazing management 'is less important. A conceptual model of Wynn persistence is presented and progress in mathematical modeiling is reported.·

Integration Of Pastoral And Non-Pastoral Uses On Temperate Rangelands With Cold Winters In Developed Countries, T J. Maxwell, W A. Laycock

IGC Proceedings (1977-2023)

The demands of the relatively wealthy and sophisticated societies of developed countries, with their substantial amounts of leisure time and discretionary income, are having an increasing impact on temperate rangelands in a variety of ways. Some parts of these societies are concerned to protect the landscapes, habitats, wildlife and solitude that can be found there, and wish to constrain any further development within these ecosystems; others also wish .to gain ready access to these resources for hunting, recreation and sport and believe that this requires the exclusion of domesticated livestock. Temperate rangelands are frequently used as water catchments and some …

Effects Of Burning And Grazing On Stability Of Upland Snow Tussock (Chionochloa Spp.) Rangeland In South Island, New Zealand, A F. Mark

IGC Proceedings (1977-2023)

A brief history of the origin and I SO years of pastoral use is given for the rangelands of New Zealand's South Island rain-shadow mountains. Deterioration of the upland snow tussock (Chionochloa spp,) rangelands is outlined and the explanations emerging from detailed ecological research, especially over the last 3 decades, are presented. Modifications to the burning and grazing, as traditionally practised, will be the basis for sustaining the rangeland resource and are now required by legislation.

Natural Revegetation And No Grazing, Department Of Primary Industries And Regional Development, Western Australia

Natural resources factsheets

The department recommends that any dryland salinity management is part of a whole farm, and preferably a whole catchment, water management plan.

Natural revegetation and no grazing are only recommended for sites that are too saline, waterlogged and/or inundated for other treatments to succeed in the south-west of Western Australia. It is also the preferred option for the lowest possible cost.

Rangeland Through Time: A Photographic Documentation Of Range Changes In Northern New Mexico, Usa, Christopher D. Allison

IGC Proceedings (1977-2023)

Publlc rangelands and their condition have recently come under close scrutiny by the general public and professionals alike. In an attempt to document rangeland changes during the past SO years or more, old photographs were obtained from USDA Forest Service. Photo-journalistic trips were conducted in 1988 and 1990 in the Santa Fe National Forest for the purpose of locating, retaking and comparing recent photographs with the old landscape pictures. Changes in fire regimes and grazing pressures have drastically changed the productivity and condition of these areas with an obvious increase in woody vegetation.

Animal Keeping By Grazing, I Vinczeffy, M Kota

IGC Proceedings (1977-2023)

This study calls attention to some important parameters and effects of the pasture and grazing, on the basis of our experiments carried out during the last 45 years.

Trends In Intensive Temperate Grassland Systems, J D. Leaver, F Weissbach

IGC Proceedings (1977-2023)

Intensification of grassland in temperate zones has been successful in substantially increasing output of animal products per unit area of land. This trend is unlikely to continue, however, where intensification has been supported by large subsidies, as in EC countries. The high costs of both subsidising the production systems and the export of surplus products is not sustainable. The distortion in world trade caused by such policies combined with concerns over the environmental implications of intensification has already led to CAP reforms in Europe to de-intensify ruminant. livestock systems. Liberalisation of world trade through GA TT could lend to further …

An Overview Of The New Zealand Experience In Establishing, Maintaining, And Utilizing White Clover Based Pastures, M B. O'Connor, A M. Bryant, R A. Prestidge

IGC Proceedings (1977-2023)

Establishment of white clover (Trifolium repens L.) involves the provision of all major and minor elements necessary for clover growth and N fixation (particularly P, S, K, Mo). Nitrogen fertiliser is not necessary. Inoculation of seed with rhizobium is required where white clover has not been grown previously and in difficult environments. Pest control where necessary is enhanced by insecticidal and nematicidal seed coatings on the white clover seed, Barty management is critical and involves regulnr close grazing during the first 6 months. Maintenance of white clover pastures involves annual inputs of fertiliser (P, S, K) with lime at …

Dynamics And Interactions Of Carbon, Nitrogen, Phosphorus And Sulphur Cycling In Grazed Pasture, A K. Metherell, C V. Cole, W J. Parton

IGC Proceedings (1977-2023)

There are close links between the carbon (C), nitrogen (N), phosphorus {P) and sulphur (S) cycles. This is especially evident in legume-based pasture in which ahe application of P and S fertilisers are required to achieve saaisfactory levels of N2 fixation and pasture production The dynamics of the nutrient cycles are controlled largely by the rates of pasture production and consumption, and by the rate of decomposition of organic matter. The CENTURY soil organic matter model integrates climate, soil and management driving variables to predict C, N, P and S dynamics. Simulated effecls of P and S fertiliser on nutrient …

Development Of Intensive Grassland Systems: From Science To Practice, D G. Mccall, G W. Sheath

IGC Proceedings (1977-2023)

Level of nnimal production from grassland is determined by the amount of pasture grown, pasture utilisation and animal conversion efficiency. The key components affecting production are pasture growth and animal conversion efficiency. These arc mainly influenced by environment, genetics and through inputs to maintain soil fertility or animal health. Systems development aims to link pasture growth and animal conversion through efficient strategies for pasture utilisation. The means of influencing pasture utilisation is through adjustments to animal feed demand, feed supply or grazing management. Stock policies that adjust the pattern and level of feed demand are of greatest significance in developing …

Use Of Brassica Forage Crops To Extend The Grazing Season In The North-East Usa, G A. Jung, H W. Harpster, M G. Lambert, K T. Leath, R A. Byers

IGC Proceedings (1977-2023)

Forage turnip (Brassica rapa L,) can be made available for animal utilisation in late summer or In late autumn-early winter, when cool­season grass pastures have a low animal carrying capacity. field trials were conducted to identify and quantify factors that influence turnip yield in December or January and to determine whether these factors affect turnip cultivars similarly. Different levels of production in late autumn-winter were attributed to summer drought, foliar diseases, freezing temperatures and rate of leaf senescence. In all instances, the effects of these factors varied with turnip cultivar. However, cultivar ranking generally was the same whether mean …

Effects Of Increasing Stocking Rate And Feeding Maize Silage On Live-Weight Gain And Pasture Utilization By Beef Cattle In Southern Australia, W J. Wales, J B. Moran

IGC Proceedings (1977-2023)

Two systems of grazing management were compared in 3 trials conducted on annual or irrigated perennial pastures over different seasons in northern Victoria, Steers grazed either at low stocking rates or at high stocking rates together with maize silage feeding, The more intensely grazed steers grew faster on autumn perennial pastures but at similar rates to steers at low stocking rates on winter­spring annual and on spring perennial pastures, Higher stocking rates increased live-weight gain per ha by 90% on winter-spring annual pastures, 101% on autumn perennial pastures and 53% on spring perennial pastures. This was associated with improvements in …

Grazing Management Effects On Diverse White Clover Cultivars, G E. Brink, G A. Pederson

IGC Proceedings (1977-2023)

Tall fescue (Festuca arundinacea Schreb.) was oversewn with Grasslands Huia, Louisiana S-1, and Regal white clover (Trifolimn repens L.) and stocked the following year continuously or rotationally with cattle to detennine cultivar response to grazing method. When precipitation was 59% above normal, mean leaf area, forage and stolon dry weight, and stolon growing point density in June and August were unaffected by grazing method. These parameters were reduced under continuous stocking when precipitation was 32% below normal. Cultivar ranking for mean leaf area and petiole length was the same as that for leaf size: Grasslands Huin

Acquisition And Allocation Of Phosphorus In A Population Of White Clover Plants In A Rotationally Grazed Pasture, M.J M. Hay, D F. Chapman

IGC Proceedings (1977-2023)

This paper quantifies the processes of acquisition, allocation and retranslocation of phosphorus (P) within a white clover (Trifolium repens L.) population in a mixed grass-clover pasture during a regrowth period in early winter (13 May-8 July 1991). The work described is part of a broader study examining seasonal variation in these processes. The data allows an analysis of the changing P economy of plants and of whole populations. White clover plants were grouped by !heir hierarchy of branching. Within plants, stolons were grouped by order of branching, dissected into leaf, stolon and root, oven-dried, weighed and analysed for P …

Nitrous Oxide Emissions From Grassland In Manawatu, New Zealand, R A. Carran, J P. Evans

IGC Proceedings (1977-2023)

Nitrous oxide (Np) is a minor component of the atmosphere which acts as a potent greenhouse gas and also causes ozone depletion. Soil bacteria are the most important agents of N2O production, but both the New Zealand and the international data on N2O emission rates from soils are very poor at present. In order to help define the possible range of emission ranges from pasture soils· we selected sites with characteristics that would make then "high" or "low" emitters of N2O. The "high" emission site was a fine-textured, fertile but poorly drained flood plain soil. The "low" emission site was …

Climate, Land Use And Plant Life Form Distribution In A Semi-Arid Savanna, Christina Skarpe

IGC Proceedings (1977-2023)

Number of plant species, total vegetation cover and the abundance of different life forms are compared over a rainfall gradient between savanna woodland and semi-desert. The effects of different land use intensities are superimposed on the differences in rainfall regimes. The outcome is discussed in the light of present global change scenarios,

Climate Change And Grasslands: A Life-Zone And Biota Perspective, Steven Archer

IGC Proceedings (1977-2023)

Grasslands experiencing climatic and atmospheric change may be altered with respect to: (1) geographic extent and location of local/ regional boundaries; (2) productivity, organic matter dynamics and nutrient cycling; and (3) the relative abundance of constituent life forms (woody v. herbaceous), growth forms (tall vs. shorl-statured grasses), and/or photosynthetic physiologies (C3 v. C4). Classification models based on vegetation-climate correlations predict an increase in the global acreage of grassland and savanna at the expense of boceal forest and dry tropical forest. However, extrapolation of these relationships to climates with atmospheric CO2 concentrations without present-day analogues is suspect. Dynamic models of plant …

An Ecological Approach To Forage Management, J L. Brock, R.J M. Hay

IGC Proceedings (1977-2023)

The principles of defoliation management for maximum production of quality herbage are well researched, namely the manipulation of frequency and severity of defoliation, but their impact on the various levels of ecological organisation in pastures is nol fully understood or their interpretation appreciated. Using grazed ryegrass-white clover pasture as; example, detailed sward studies have suggested the following model. Defoliation frequency and severity interact lo produce varying levels of physiological stress and morphological adaptation which affecl the survival rate and size of individual growth units, the lowest level of organisation. Increasing frequency of defoliation reduces organ size but increases survival rate …

Use Of Pasture As A Receivers For Swine Lagoon Effluent, J P. Mueller, J C. Barker, J P. Zublena, M H. Poore, R W. Harvey, J T. Green

IGC Proceedings (1977-2023)

Swine waste management-cattle grazing systems were monitored on 2 North Carolina farms from 1990-1992, Farmers co-operated directly in the project by furnishing land, labour, equipment and cattle and by maintaining records of grazing and waste applications. Local county agricultural extension agents helped with management decisions, record­keeping and co-ordinating activities among project participants. On a fann where waste was applied to pastures for 5 years, soil N in the upper l m averaged from 230-500 kg/ha, NO3 -N in the forage remained above 10 g/kg for the grazing season and 2 of 4 test wells recorded NO3 levels above 10 mg/I. …

Foraging Strategies Of Ruminant Livestock On Intensively Managed Grasslands: Potential And Constraints, I J. Gordon, C Lascano

IGC Proceedings (1977-2023)

All grazed swards exhibit heterogeneity in the spatial (horizontal and vertical) dispersion of species/biomass. A herbivore foraging at random within such a heterogeneous environment would ingest less nutrients than wou Id one which exploited the heterogeneity on offer through selective grazing. The suite of decision-making processes involved in the selective grazing we observe is termed the animal's foraging strategy. On first observation, intensively managed sown swards appear to offer little opportunity for a herbivore to exhibit a foraging strategy; however, opporlunities do exist and there is empirical evidence that herbivores foraging on sown swards tend to have a diet higher …

Field Test Of Optimal Foraging With Cattle: The Marginal Value Theorem Predicts Patch Selection And Utilization, Emilio A. Laca, R A. Distel, T C. Griggs, G Deo, M W. Demment

IGC Proceedings (1977-2023)

Grazers selectively forage within heterogeneous vegetation. Prediction of intake rate necessitates theoretical developments to understand site selection. We tested III optimal foraging model to predict patch selection by cattle in the field, Nine "grazing environments" (GB) consisting of 16 0.36 m2 patches each were created by mowing. Treatments were a factorial of 3 distances between patches and 3 sets of patch heights. Patch residence time (T,) was accurately predicted (r2=0.89), and increased linearly whh patch distance (P