Digital Commons Network^™

Modelling As Tool For Grassland Science Progress, N G. Seligman

IGC Proceedings (1977-2023)

Simulation modeling in grassland science has a history of more than 20 years. To dnle it has been distinguished more by its continuing and expanding development than by its success in advancing grassland science and practice. This possibly reflects the phenomenal increase in computer technology compared with the much more modest progress in grassland science. Models have nevertheless been the vehicle for identifiable contributions to grassland theory and there are an increasing number of successful applications in management and policy situations. Expectations for future contributions are more realistic today than in the heady early years, but despite much disillusion, the …

Decision Support System In The Transfer Of Grassland Technology, J W. Stuth, W T. Hamilton, J C. Conner, D P. Sheehy

IGC Proceedings (1977-2023)

A world-wide demand for sustainable development of our grazinglands has placed an unprecedented urgency to determine mechanisms to develop and transfer technology that meets the needs of individual landholders and overarching values of society. Unfortunately, advances in science and technology have outstripped our ability lo organise information into a usable form using traditional institutions. The emergence of computer technology with high power/ cost ratios has accelerated interest in computerised decision support systems (DSS) over the past 10 years. These systems assist resource managers in dealing with complex planning problems by allowing exploration of alternatives and selection of appropriate technology. If …

Software For Grassland Management For The Supply Of Fresh Feed For Stall-Feeding And/Or Grazing And For Conservation In Combination With Feed Production On Arable Land, A Chudy

IGC Proceedings (1977-2023)

Tasks, fundamentals and methodics (algorithms) of software for the projection of feed production (FUPRO) as part of an integrated software program (the package Futterplanung), are described. It covers total feed-economic relations, starting from the use of agricultural acreage up to specific animal requirement.

Sward Production Estimated By Spectral Reflectance, G Nagy, V Zilinyi

IGC Proceedings (1977-2023)

A non-destructive spectral reflectance method was used for the measurement of aerial biomass yields of different grasslands. Vegetation indices {VI) were calculated from the green, red and near-infrared light reflectance. These indices were compared with actual grass yields cut just after the reflectance measurement. The correlation coefficient between actual yields and VI was significant (r=0.969,n=24). This non-destructive technique is therefore a reliable tool for the estimation of standing biomass of grasslands.

Inference Space Choices In Combined Mixed Model Analyses Of Discrete Grazing Trials, H A. Fribourg, R W. Thompson, J C. Waller, W L. Sanders

IGC Proceedings (1977-2023)

Grazing trials are limited by financial and logistical constraints that restrict duration and number of treatments to be investigated. Combining data from independent trials may be a feasible way to circumvent these constraints and provide a more meaningful body of information. Datasets were pooled from 12 independent trials conducted during the last 13 springs at 9 locations in 7 USA eastern states (a total of 37 location/ years) to provide combined estimates of steer (Bos taurus) performance on Festuca arundinacea pastures free of or infested with the endophytic fungus Acrenoium coenophialium, and to demonstrate the effectiveness and …

An Expert System To Advise Tasmanian Farmers On Pasture Mixtures And Fodder Crops, Peter Gillard

IGC Proceedings (1977-2023)

In Tasmania, the Department of Primary Industry and Fisheries needed to find a more effective method of informing farmers obout the best pasture and forage species. PASTURBPAK, an expert system, was designed to meet this need. The program offers advice on mixtures of species and lists cultivars that are adapted to the environment, and the need of the farmer and livestock type. Seed merchants have installed the software to make the information available when farmers buy seed. Sales starf can now instantly access the corporate expertise of DPIF, and offer customers printed advice specific to their need. The relevance of …

Comparison Of Two Calibration Procedures For Predicting Leaf Percentages From Forage Sorghums And Pearlmillets Using Near-Infrared Reflectance Spectroscopy, T P. Karnezos, A G. Matches, J W. Keeling

IGC Proceedings (1977-2023)

A rapid method for determining leaf percentage (LP) from forage sorghums (Sorglium bicolor (L.) Moench) and pearlmillets (Pennisetum americaum (L.) Leeke) is reported. Our objective was to develop and compare two near-infrared reflectance spectroscopy (NIRS) calibration methods for predicting LP. Calibration methods developed were: I) leaves assigned a value of 99.99% leaf and 0.01 % stem, and stems a value of 99.99% stem and 0.01% leaf; and 2) ground leaf and stem samples mixed by weight to obtain a range of LP. Samples were scanned using NIRS and calibration equations developed. Equations had coefficients of multiple determination (R2) …

Computer Simulation To Aid The Development, Transfer An Adoption Of Alternative Forage Conservation Systems, C A. Rotz, D R. Buckmaster

IGC Proceedings (1977-2023)

A computer simulation model of forage production, conservation and use was developed to evaluate forage technologies. The model simulates forage losses and quality changes along with the use and costs of machines, structures, labour, fuel, chemicals, etc. Alfalfa and corn produced on the farm arc supplemented with purchased feeds to feed a dairy herd or they are sold. Simulation over many years of weather conditions provides a long-term evaluation of the performance and economics of alternative forage systems. Simulation results provide manufacturers with design-performance constraints which aid the development of new products. Adoption of available forage technology is aided by …

Developing Long-Term Weather Records For Use With Rangeland Management Modelsc, Clayton L. Hanson, J Ross Wight

IGC Proceedings (1977-2023)

The use of natural resource models for research and management of rangeland ecosystems is limited by the unavailability of long-term weather records. This paper identifies sources of weather information for the United States; suggests methods for estimating missing records; and illustrates the use of double-mass curve procedures for evaluating the quality of data sets. Where weather data are limited in ducat ion or unavailable, stochastic weather generation is an option to simulate daily weather records.

Making Models Easy To Use, J Ross Wight, Clayton L. Hanson

IGC Proceedings (1977-2023)

A major limitation to the application of natural resource models to resource management problems is the unavailability of input information and complexity of model operation and output interpretation. These problems can be moderated by using synthetic weather data, algorithms and expert systems to calculate model parameters and input variables and computer programs to simplify development of input data files and interpretation of output results. This paper summarises some of the procedures and techniques that can be used to make models easier to use and more useful as management tools.

Simulation Models As Decision Aids For Management Of Rangeland Ecosystems, J Ross Wight, Clayton L. Hanson

IGC Proceedings (1977-2023)

Rangeland simulation models have been used primarily as research tools to synthesise and organise information and to conceptualise and describe the interacting components of the ecosystem. Their application as decision aids for range management has not been developed. This paper discusses ways simulation models, such as SPUR· (Simulation of Production and Utilisation of Rangelands), can be used to forecast herbage p1oduction and the occurrence of biological windows, enhance monitoring, and predict the impacts of management and climate change on the soil, water, and plant resources including species composition.

Models Of Pasture Production To Aid On-Farm Decision Making In New Zealand, J A. Baars, M D. Rollo

IGC Proceedings (1977-2023)

Two microcomputer-based predictive pasture models, for use in decision making by agricultural consultants and industry, are described. The first model (GRASS) was developed to understand the interactions between environment and management. The second model supplies pasture growth rates for current or predicted weather conditions by adjustment of stored actual average fortnightly pasture growth rates for a wide range of measurement sites. Ways are described in which the models are being used in transfer of technology.

Production Of Dryland Lucerne In The Western And Southern Cape Regions Of South Africa, J M. Van Heerden

IGC Proceedings (1977-2023)

Cutting trials were conducted with lucerne (Medicago sativa) cv. S A Standard under dryland conditions over a period of 8 (1982 to 1989) years at 2 sites, one each in the western (Elsenburg) and southern (Tygerhoek) Cape. The sites differed in soil type and rainfall distribution. Replicated plots were harvested at 3 set frequencies (4·, 6- and 8- weekly). Production was lowest during summer and highest in late spring and increased with decreased harvesting frequency at both sites. These data were used to derive equations for the extrapolation of the seasonal yield. Inputs into the model 11cc average …

Graze Model: Importance Of Simulating Conceptual Grazing Areas Within A Paddock, Otto J. Loewer, L D. Parsch, H D. Scott, C P. West, A L. Goetsch

IGC Proceedings (1977-2023)

The selective grazing logic within the computer simulation model GRAZE was tested to determine if predicted ·results differed appreciably from situations ·where non-selective grazing logic· was used. Results indicated that predictions would_ differ somewhat." The main cause of the differences was determined to be the simulated levels of plant dry matter availability, which were considerably higher when non-selective· grazing was used.

Development Of An Expert System For New Zealand Seasonal-Supply Dairy Farmers, D I. Gray, G A. Lynch, E G. Todd, J C. Lockhart, W J. Parker

IGC Proceedings (1977-2023)

The mechod for developing an expert system for the drying-off decision on seasonal-supply dairy farms is described. The decision-making process ' of 4 expert seasonal-supply dairy farmers and the consultancy process used by 2 New Zealand Dairy Board Consulting Officers were identified in a series e>f interviews. This information ,was used to develop 2 models; one of expertise and the other of user requirements. These models form the basis of an expert system to improve the decision-making ability of. New Zealand seasonal-supply dairy farmers.

Rehabilitation On Public Rangelands In Idaho, Usa: A Change In Emphasis From Grass Monocultures, Mike Pellant, Stephen B. Monsen

IGC Proceedings (1977-2023)

Since the 1940s the Bureau of Land Management has reseeded 485 830 ha of public rangelands in southern Idaho. Introduced wheatgrasses were seeded on most rehabilitation projects, often resulting in monoculture plant communities. Introduced wheatgrasses were relatively inexpensive to seed, established well, excluded weedy annuals and provided additional livestock forage. Concern about extensive shrubland losses after wildfires prompted BLM managers to begin reseeding native shrubs in the early 1980s. Use of different herbaceous plants on rehabilitation projects is increasing. Seed mixtures now include up to 10 species (grass, forb and shrubs) that, when established, meet multiple use resource objectives.

Micro-Computer Version Of The Database On Feed Commodities Derived From Pastures And Green Crops, H T. Ostrowski-Meissner

IGC Proceedings (1977-2023)

The subunit of the national feed database devoted specifically to feeds derived from grasslands and green crops is presented. This collection of chemical and nutritional data is the result of 20 years of data collection from analyses conducted from 62 laboratories Australia-wide, The data entries are classified according to each Australian state and laboratory which provided the analytical and nutritional characteristics of fodder. Each entry is classified according to the International Feed Numbering (IFN) system as maintained by the International Network of Feed Information Centres (INFIC), The data in the collection as presented in the paper are an integral part …

A Computer Model For Determining When To Start Spring Grazing, Dennis R. Buckmaster, Warren J. Parker

IGC Proceedings (1977-2023)

A simple computer model is presented for determining the earliest grazing date after winter freezing. The model also illustrates principles of rotational grazing management and projects when forage should be conserved during the spring. Inputs to the model include initial herbage cover, herbage growth rate, herbage quality, a post•grazing residual dry matter target, a harvest set•aside threshold, and a description of the grazing animals.

Comparison Of Methods For Assessing Productivity Of Native Pastures In Queensland, K A. Day, G M. Mckeon, D M. Orr

IGC Proceedings (1977-2023)

The relationship between seasonal climatic conditions and observed seasonal pasture growth was examined for 3 native pasture sites in south-east Queensland for periods of up to 5 years. Nine indices of seasonal climatic conditions were considered. Across sites, between year differences in observed growth were best accounted for by the average daily ratio of calculated transpiration and vapour pressure deficit, This index accounted for 83% of the between year variation in observed growl h.

Application Of Neural Networks To The Extraction Of Various Types Of Grasslands In Japan Using Landsat Thematic Mapper Data, Mikinori Tsuiki, Shigeo Takahashi, Toshiki Oku

IGC Proceedings (1977-2023)

A neural network was applied to the extraction of various types of grasslands using Landsat Thematic Mapper (TM) data. Training fields contained 12 classes (water, paddy field, farmland, sands and rocks, urban area, coniferous forest, deciduous forest, golf course, Sasa­type grassland, Miscanthus type grassland, meadow before culling and meadow after cutting). Classification performance using the neural network was 99.4%, which was 2.4% higher than that obtained using the maximum likelihood method. For all types of grasslands, classification performance was 99.8%. The results of the classification area obtained using the neural network and the maximum likelihood method resembled each other. …

Use Of A Simple Model Of Continuous And Rotational Grazing To Compare Herbage Consumption, Simon J.R Woodward, G `C Wake, D G. Mccall, A B. Pleasants

IGC Proceedings (1977-2023)

A simple mathematical model (a linear dynamical system) was constructed to predict herbage consumption by grazing animals. This model was used to compare 3 grazing methods over a range of stocking rates at low pasture mass. The grazing methods compared were: continuous grazing (CTS), rotational grazing with equal time intervals (BQ), and rotational grazing where the time of shift was optimal for maximising intake (OPT). The rotational methods were the simplest possible, the land being subdivided into 2 fields, each of which was grazed once. The order of grazing the fields was also considered. The model predicts (I) that at …

Pasture Plant Identification In The Western Queensland Arid Zone, J A. Milson, I F. Beale, J A. Reynolds, J J. Bushwell, D Phelps

IGC Proceedings (1977-2023)

Since plant species composition is an important indicator of the health or condition of pastures and therefore the land, a first step for graziers interested in conserving the total range resource is to understand vegetation species and thus be able to identify them and to recognise species changes. This project is aimed at producing and distributing colour leaflets of the major native and problem plant species (including woody weeds) in the four major community types in western Queensland. The number of colour leaflels for the series totals 60. The number of species represented is about 230. These leaflets are dislributed …

Farm Monitoring, A Way To Improve Performance On Sheep And Beef Farms, R W. Webby, G W. Sheath

IGC Proceedings (1977-2023)

A programme that centres on monitoring the performance of sheep and beef farms is being used to encourage farmers to make decisions based on objective measurements, Monitor farmers are supported by their farming peers in groups that include extension and science personnel. Key biological performance indicators such as animal numbers, weights; weight gains, pasture production; and financial returns from meat and wool are monitored. Farmers are encouraged to be in a position to use this information and identify opportunities. Processors of sheep and beef products are demanding the production of livestock to tighter specifications. Close monitoring by farmers will be …

Use Of A Model To Investigate The Profitability Of Fertilizer Application, T.J M. Johnston, D G. Mccall, P R. Marshall

IGC Proceedings (1977-2023)

Use of a model to investigate the payback to alternative phosphate (P) fertiliser programmes is described. Input for the model is fertiliser history (kg P/ho/year) over 5-15 years. A site fertility index is established by summing discounted P applications. The index is related to relative pasture yield (annual yield/non P limited yield) for a soil type. The economics of P use are evaluated by scaling current gross margin/ha for changes in relative pasture yield and subtracting fertiliser costs. The model provides the decision maker with yearly cashflow information and a I 0-year net present value (NPV) analysis of the relative …

What Is The Best Fit For Electric Weed Control In Australia?, Miranda J. Slaven, Catherine Borger

Experimental Summaries - Plant Research

Electric weed control is a non-chemical weed management alternative that will apply to a range of agricultural systems. The current project assessed electric weed control via the continuous electrode-plant contact method (using a Zasso™ XPower).

A wide range of field trials in 2022 and 2023 investigated weed control efficiency, suitability of electric weed control for fence line control of glyphosate-resistant annual ryegrass (Lolium rigidum Gaud.), use for crop topping, fire risk, damage to the soil biota, or use for inter-row weed control in vineyards or lupin crops. Broadleaf weeds were controlled more effectively than grass weeds with electric weed …

Effect Of Chemical And Mechanical Weed Control On Weed Seed Banks In Rice Field, Uum Umiyati, Dedi Widayat, Yani Maharani

Jurnal Kultivasi

Weed control is essential for ensuring the diversity of weeds on agricultural land. A study was conducted in rice fields in Subang and Cianjur districts, where 24 fields were observed to have varying weed management approaches. The research employed descriptive methods, including surveys to identify weed types and destructive methods to analyze weed seed banks at different depths. The descriptive methods included surveys to identify weed types and destructive methods to analyze weed seed banks at different depths. Each district contained twelve rice fields that reflected diverse environmental conditions and weed control techniques, yet shared a similar age range of …

Effects Of Cutting Management On Herbage Production And Tiller Population In Smooth Bromegrass (Bromus Inermis Leyss), J X. Xia, J Hodgson, A.C P. Chu, P Wang, F Y. Liu

IGC Proceedings (1977-2023)

This paper reports the results of an experiment with smooth bromegrass (Bromus inermis Leyss) under cutting management at Beijing Agricultural University, China from June-October 1989. The main treatments were cutting intervals (l month v. 2 months) and cutting height (10 cm v. 30 cm) with 2 additional treatments (uncut control, and delayed first cut) and 4 replications. Frequent cutting decreased tiller population density, herbage accumulation and underground biomass. Tiller populations were greater under lax than hard cutting, though closer cutting resulted in greater green herbage accumulation. Delaying cutting until flowering was completed resulted in a subsequent depression in herbage …

Relative Productivity And Persistense Of White Clover Cultivars Under Cutting Or Continuous Stocking By Sheep, D A. Davies, M Fothergill

IGC Proceedings (1977-2023)

Perennial ryegrass-white clover (Lolium perenne-Trlfollium repens) swards of 3 clover cultivars were studied at a lowland (30 m) and upland (340 m) site in mid Wales over 3 years (1989-91). Lamb production from small-leaved Aberystwyth S 184 at 1021 kg/ha was 25% and 1191, more than from small-leaved Ac3351 and medium-leaved Grasslands Huia respectively. The relative lamb output from Huia was poorer at the upland location. Clover production, survival and morphology under a number of cutting heights and frequencies were different from those in the continuously stocked pastures. Cutting every 10 days at 2-3 cm resulted in poor clover and …

Morphological Changes In Three Clover (Trifolium Repens L.) Cultivars Under Continuous Stocking, M Fothergill, D A. Davies

IGC Proceedings (1977-2023)

Individual plant morphology of 3 white clover (Trifolium repens L.) cultivars was studied during 1990 and 1991. Seasonal shifts were demonstrated by all cultivars towards a higher proportion of less complex plants from winter to mid summer. Over the latter half of the year the population tended lo return towards its original distribution. Seasonal fluctuations in stolon dry weight/plant and root number/plant were also identified, with the small-leaved Ac3351 maintaining a greater stolon OW/plant than Aberystwyth S184 and Grasslands Huia during 1990. Ac3351 and S184 also maintained a larger root number/plant over this period. However, no significant differences were detected …

Response To Defoliation Of Tall Fescue, H Tavakoli, J Hodgson, P D. Kemp

IGC Proceedings (1977-2023)

An experiment studying the behaviour of toll fescue (Fesutca anrundinacea Schreb,) was conducted under steady stale grazing on a sward dominated by this plant. The swards were grazed lo maintain a surface height of 30-40 mm (H), 50-60 mm (M) and 90-100 mm (L). These treatments were applied on swards with and without white clover (Trifolium repens L.) from November 1990 to April 1991. Results showed that leaf growth decreased as the severity of grazing increased. Tiller number was less under H grazing than under M or L grazing, but tiller size remained constant over time in this …