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Articles 5371 - 5400 of 59520
Full-Text Articles in Earth Sciences
Pillar Wall Angles Of Karst Collapse Pillars In The Xishan Coalfield: Characteristics And Implications, Zhao Jingui, Wang Jiangwei, Yang Gaofeng, Guo Mintai
Pillar Wall Angles Of Karst Collapse Pillars In The Xishan Coalfield: Characteristics And Implications, Zhao Jingui, Wang Jiangwei, Yang Gaofeng, Guo Mintai
Coal Geology & Exploration
Significance As coal mining expands into deep parts, karst collapse pillars have become one of the most concealed disaster-causing geological factors in coal mining from mines in North China. The pillar wall angle of a collapse pillar serves as an important index used to describe the morphology of the collapse pillar. Methods and Results With 265 karst collapse pillars cut by the fully mechanized mining of the upper and lower coal seams in the Xishan coalfield as the data source, this study extracted the geological information contained in the pillar wall angles of karst collapse pillars in the Xishan coalfield …
R&D And Application Of An Experimental System For Coal Permeability Enhancement Through Resonance Under The Excitation Of Low-Frequency Vibration, Wen Zhihui, Guo Shuqian, Wei Jianping, Zhang Tiegang, Wang Jianwei, Zhang Libo, Ren Yongjie
R&D And Application Of An Experimental System For Coal Permeability Enhancement Through Resonance Under The Excitation Of Low-Frequency Vibration, Wen Zhihui, Guo Shuqian, Wei Jianping, Zhang Tiegang, Wang Jianwei, Zhang Libo, Ren Yongjie
Coal Geology & Exploration
Objective As an emerging green, efficient method for enhancing coal permeability, coal resonance under the excitation of vibration waves works by stimulating the development of pores and fractures in coals using the stress waves generated by low-frequency vibration. To investigate the impacts of excitation frequency, stress field, and resonance effect on permeability enhancement, as well as exploring the mechanisms behind coal permeability enhancement using the method, this study independently designed and developed an experimental system. Methods The system, consisting of a mainframe control unit, a coal-sample clamping unit, a vibrational excitation unit, and a coal vibration parameter monitoring unit, allows …
A Tin-Gtp Algorithm-Based Technique For 3d Geological Modeling Of Coal Mines, Wang Xiaohui, Liu Zaibin, Zhang Dongliang, Ma Liang, Chen Baohui, Lei Xiaorong, Bai Baojun, Yan Junsheng
A Tin-Gtp Algorithm-Based Technique For 3d Geological Modeling Of Coal Mines, Wang Xiaohui, Liu Zaibin, Zhang Dongliang, Ma Liang, Chen Baohui, Lei Xiaorong, Bai Baojun, Yan Junsheng
Coal Geology & Exploration
Background A 3D geological model of a coal mine serves as an essential prerequisite to guiding the safe and efficient production of coal mines, holding great significance for precise coal mining and geological guarantee. Especially in complex geologic conditions, the failure of geological models to accurately describe the relationship between structures and strata will affect the mining area planning, mining processes, and production efficiency during the production of coal mines. Methods With the Qipanjing Coal Mine in the Zhuozishan Coalfield, Inner Mongolia, as an example, this study investigated the technology for high-accuracy 3D geological modeling of coal mines based on …
Accumulation Mechanisms And Resource Potential Of Helium In Coal Measures: A Case Study Of The Eastern Margin Of The Ordos Basin, Liu Xiangbai, Tao Shizhen, Yang Xiuchun, Zhao Qun, Chen Yanyan, Liu Ziyang, Pei Xiangbing, Wang Longfei, Yi Wei, Feng Jianqiu, Zhang Tan, Gao Jianrong, Tao Xiaowan, Liu Zhuangxiaoxue, Li Chaozheng, Yang Yiqing, Chen Yue
Accumulation Mechanisms And Resource Potential Of Helium In Coal Measures: A Case Study Of The Eastern Margin Of The Ordos Basin, Liu Xiangbai, Tao Shizhen, Yang Xiuchun, Zhao Qun, Chen Yanyan, Liu Ziyang, Pei Xiangbing, Wang Longfei, Yi Wei, Feng Jianqiu, Zhang Tan, Gao Jianrong, Tao Xiaowan, Liu Zhuangxiaoxue, Li Chaozheng, Yang Yiqing, Chen Yue
Coal Geology & Exploration
Background Helium, with advantages such as stable chemical properties and high thermal conductivity, has been extensively applied in high-tech sectors like national defense, military, aviation, and aerospace, playing an irreplaceable role. Presently, helium in China is primarily imported from other countries, manifesting a high degree of dependence on foreign trade, suggesting a prominent issue concerning helium resource security. Previous studies on helium principally focus on conventional natural gas, rendering helium in coal measures relatively under-studied. Objective and Methods To determine the distribution and potential of helium resources in coal measures, this study analyzed the coal-measure gas sampled from the eastern …
Coal Permeability Enhancement Via Cyclic Percussion Using Low-Temperature Liquid Co2 And High-Temperature Water Vapor And Simulations Of Resultant Gas Drainage Performance, Qin Lei, Wang Ping, School Of Civil And Resource Engineering, University Of Science And Technology Beijing, Beijing 100083, China Shugang, Wang Hui, Liu Pengfei, Li Jiawei, Lin Haifei
Coal Permeability Enhancement Via Cyclic Percussion Using Low-Temperature Liquid Co2 And High-Temperature Water Vapor And Simulations Of Resultant Gas Drainage Performance, Qin Lei, Wang Ping, School Of Civil And Resource Engineering, University Of Science And Technology Beijing, Beijing 100083, China Shugang, Wang Hui, Liu Pengfei, Li Jiawei, Lin Haifei
Coal Geology & Exploration
Objective In the application of the coal seam permeability enhancement technique based on liquid CO2, pore water in coal seams freezes due to low temperatures, blocking pathways for gas migration. Hence, this study developed a technique for coal permeability enhancement through cyclic percussion using low-temperature liquid CO2 and high-temperature water vapor (also referred to as the cyclic cold and hot percussion). Methods This study delved into the permeability evolutionary patterns of coals under cyclic cold and hot percussion using a low-field nuclear magnetic resonance (NMR) spectrometer, an automatic coal permeability tester, a contact angle tester, and 3D …
Deep Beam Theory-Based Mechanical Analysis Of Water-Resisting Key Strata Of Coal Seam Floors In A Deep Mining Environment, Wang Bingwen, Zha Wenhua, Lu Haifeng
Deep Beam Theory-Based Mechanical Analysis Of Water-Resisting Key Strata Of Coal Seam Floors In A Deep Mining Environment, Wang Bingwen, Zha Wenhua, Lu Haifeng
Coal Geology & Exploration
Objective An increase in the mining depth of mines poses a more serious threat from highly confined karst water, resulting in water hazards like water inflow and inrushes on the mining faces of coal seams. The key content used to address this issue is to analyze the water pressure resistance of the water-resisting key stratum of the coal seam floor in a deep mining environment. Methods This study simplified a water-resisting key stratum into a rock beam model and then dealt with this model using the deep beam theory in the prediction of water inrushes in deep mining. Specifically, by …
Fracture Mechanical Criteria And Simulation Of Floors With Y-Shaped Branches Of Major Faults In Coal Mines, Li Ang, Sun Jingxin, Zhang Wenzhong, Zhang Zhuang, Yang Yuxuan, Wang Weidong, Lyu Wei, Fan Liuyi
Fracture Mechanical Criteria And Simulation Of Floors With Y-Shaped Branches Of Major Faults In Coal Mines, Li Ang, Sun Jingxin, Zhang Wenzhong, Zhang Zhuang, Yang Yuxuan, Wang Weidong, Lyu Wei, Fan Liuyi
Coal Geology & Exploration
Objective Despite wide distribution, the branches of major faults (also referred to as the fault branches) tend to be overlooked. However, they represent one of the primary causes of water inrush. Methods Under the engineering geological background of the Liuzhuang coal mine in Anhui Province, this study established a fracture mechanical disaster model for fault branches under the impacts of both seepage and stress based on the criteria for compression-shear fracture of rock masses considering the Mohr-Coulomb criterion. Using this model, this study obtained the critical water pressure and the minimum safe distance between the fault branch and the floor's …
Elastoplastic Stress Analysis Of Multi-Refrigerant Combined Heterogeneous Artificial Frozen Wall, Wang Bin, Liang Xiuling, Zhang Zihao, Cai Haibing, Rong Chuanxin
Elastoplastic Stress Analysis Of Multi-Refrigerant Combined Heterogeneous Artificial Frozen Wall, Wang Bin, Liang Xiuling, Zhang Zihao, Cai Haibing, Rong Chuanxin
Coal Geology & Exploration
Objective Affected by the temperature difference of the refrigerant and the distance difference between the frozen formation and the freezing pipes, the heterogeneity of the multi-refrigerant combined double-row-pipe frozen wall is more significant. In order to evaluate the safety of such frozen wall reasonably, the elastic plastic stress analysis should be carried out for the artificial frozen wall with multi-refrigerant considering the heterogeneity. Methods The frozen wall at 1/4 pipe distance was selected as the characteristic section. Then, the temperature distribution curve on this section was equivalently converted to three linear functions, and the frozen wall was regarded as a …
Analytical Model For Reactive Solute Transport In A Channel-Matrix System, Wei Nana, Li Xu, Xu Guangquan, Zhang Haitao, Shao Zefan
Analytical Model For Reactive Solute Transport In A Channel-Matrix System, Wei Nana, Li Xu, Xu Guangquan, Zhang Haitao, Shao Zefan
Coal Geology & Exploration
Objective The accurate quantitative characterization of fractured media and the theoretical research on solute transport in fractured media have become the key to the prevention and control of groundwater contamination in fractured aquifers. Currently, fractured aquifers are generalized to horizontal fractures, ignoring the geometric characteristics of the open parts of fractures, called channels, and the impacts of matrix diffusion on solute transport. Methods A model for solute transport in a single channel-matrix system was established, obtaining the semi-analytical solutions using Laplace and numerical inverse transforms. The COMSOL Multiphysics software was employed to construct a numerical model for verification. Furthermore, the …
Landslide Sensitivity Assessment Of Coal Mining Subsidence Areas Based On Information Value - Machine Learning Coupling Models, Niu Chenhao, Jiao Runcheng, Han Jianfeng, Wang Shengyu, Guo Xuefei, Liu Chang, Han Yucheng, Song Guofeng
Landslide Sensitivity Assessment Of Coal Mining Subsidence Areas Based On Information Value - Machine Learning Coupling Models, Niu Chenhao, Jiao Runcheng, Han Jianfeng, Wang Shengyu, Guo Xuefei, Liu Chang, Han Yucheng, Song Guofeng
Coal Geology & Exploration
Objective Due to their special geological conditions and coal mining background, coal mining subsidence areas are prone to suffer from ground cracks and subsidence, which tend to further induce geological disasters such as landslides. This makes it extremely necessary to conduct landslide sensitivity assessment of these areas using appropriate influencing factors and training models. Methods This study investigated the Xishan coal mine area in Beijing as an example to conduct landslide sensitivity assessment of coal mining subsidence areas by coupling slope units with mathematical statistical and machine learning models. With 10 influencing factors, including topographic and geomorphic factors such as …
Research And Application Of The Seismic Exploration Technique Using Reflected In-Seam Waves In Identifying Folds And Faults In Coal Seams, Wu Guoqing
Coal Geology & Exploration
Background Accurately identifying subsurface anomalies is crucial to building a geological transparency system in the transformation to intelligent coal mines. The precise exploration of fold anomalies is a challenge of underground geophysical exploration technology, holding great significance for reducing excavation costs, mining difficulties, and safety risks. Objective and Methods Previous in-seam seismic explorations reveal that folds pose significant impacts on the propagation characteristics of in-seam waves. However, conventional inversion techniques of in-seam waves are difficult to distinguish folds from faults. This study constructed numerical models for faults and folds with similar geometric shapes and equal exploration distances. Specifically, the differences …
A Method For Reconstructing Consecutively Missing Seismic Data Based On Recurrent Feature Reasoning, Li Zijuan, Chang Guangyao, Jia Yongna
A Method For Reconstructing Consecutively Missing Seismic Data Based On Recurrent Feature Reasoning, Li Zijuan, Chang Guangyao, Jia Yongna
Coal Geology & Exploration
Objective Due to the constraints of natural environments like rapids, rifts, and high mountains, the acquired seismic data are often challenged by consecutive missing, affecting subsequent seismic data processing and geologic analysis. Hence, it is necessary to reconstruct the missing data through interpolation. Methods This study proposed a method for reconstructing consecutively missing seismic data based on recurrent feature reasoning. First, the missing seismic data undergo partial convolution operations, in which the weight of the convolution results is adaptively adjusted based on the proportion of valid feature map data in the receptive field, avoiding invalid convolution operations on consecutively missing …
A Neural Network-Based Method For Analyzing Diffracted Wave Velocity, Tao Junhong, Zhao Jingtao, Sheng Tongjie
A Neural Network-Based Method For Analyzing Diffracted Wave Velocity, Tao Junhong, Zhao Jingtao, Sheng Tongjie
Coal Geology & Exploration
Background In seismic imaging, accurate velocity models are crucial for characterizing subsurface structures in a fine-scale manner. Notably, in coal mining, small-scale geological structures like faults and collapse columns are closely associated with mining accidents. These structures typically occur as diffracted waves in seismograms.Objective and Methods To effectively image these small-scale geological bodies, fine-scale velocity modeling using diffracted wave information is particularly important. Hence, this study proposed a neural network-based method for analyzing diffracted-wave velocity. First, diffracted-wave velocity spectra were generated using the gathers of diffracted waves that were separated in the common virtual source domain. Second, a gamma-ray …
Key Technology And Practice Of Deep Borehole Pneumatic Directional Drilling In Broken-Soft Coal Seam In Yangquan Mining Area, Liu Fei, Li Quanxin, Fang Jun, Liu Jianlin, Yang Weifeng, Chu Zhiwei, Zhao Jianguo, Wang Siyi
Key Technology And Practice Of Deep Borehole Pneumatic Directional Drilling In Broken-Soft Coal Seam In Yangquan Mining Area, Liu Fei, Li Quanxin, Fang Jun, Liu Jianlin, Yang Weifeng, Chu Zhiwei, Zhao Jianguo, Wang Siyi
Coal Geology & Exploration
Objective In response to the need for precise, proactive, and regional management of gas in the broken-soft coal seam of the Yangquan Mining Area, a technical scheme utilizing pneumatic directional drilling for pre-drainage boreholes was proposed. Methods Based on the analysis of the technical challenges in pneumatic directional drilling, a series of technologies suitable for the broken-soft coal seam in the Yangquan Mining Area were developed. These include stable operation technology for pneumatic downhole motors, precise control technology for drilling boreholes, efficient deep-hole slag discharge technology, and pneumatic milling and salvage technology. The pneumatic directional drilling equipment was optimized, and …
Emergency Response And Critical Technologies For Large-Diameter Boreholes In Mine Rescue Through Surface Drilling, Ma Tan, Zhuge Lei, Zhao Weidong
Emergency Response And Critical Technologies For Large-Diameter Boreholes In Mine Rescue Through Surface Drilling, Ma Tan, Zhuge Lei, Zhao Weidong
Coal Geology & Exploration
Objective Large-diameter lifesaving holes have been successfully applied multiple times in mine rescue through surface drilling. However, they show limitations in emergency response like quick dispatch and cross-regional rescue, and their technological adaptability is insufficient to cope with complex strata. Methods From the perspective of overall emergency rescue, with rescue timeliness as an indicator, this study summarized the critical technologies like response capability enhancement and borehole-forming technology for complex strata. It constructed an emergency handling process for mine rescue through surface drilling, specified the improvements in contingency plan activation, response actions, and response speeds, and established the hierarchical cross-regional rescue …
Accumulation Patterns And Exploitation And Utilization Targets Of Geothermal Resources In The Coal-Bearing Area In North China, Pang Zhonghe, Duan Zhongfeng
Accumulation Patterns And Exploitation And Utilization Targets Of Geothermal Resources In The Coal-Bearing Area In North China, Pang Zhonghe, Duan Zhongfeng
Coal Geology & Exploration
Objective China is a major producer and consumer of coal resources in the world. The urgent need for the transition of the coal industry necessitates the investigation of both the origin and distribution patterns of geothermal resources in the coal-bearing areas of the country. The coal-bearing area in North China, with geothermal reserves accounting for 74.7% of the whole country, stands out as one of the areas with the most abundant geothermal resources nationally. This area encompasses four major coal-bearing basins: the Bohai Bay, Ordos, Qinshui, and Southern North China, with the lithospheric thermal state gradually weakening from east to …
Convection - Heat Transfer Coupling Mechanism For Closed-Loop Heat Extraction From Hydrothermal Resources Using Horizontal Wells, Gu Feng, Li Youwu, Zhang Yue, Gao Ying, Yang Peng, Wang Anran, Cui Jingyun
Convection - Heat Transfer Coupling Mechanism For Closed-Loop Heat Extraction From Hydrothermal Resources Using Horizontal Wells, Gu Feng, Li Youwu, Zhang Yue, Gao Ying, Yang Peng, Wang Anran, Cui Jingyun
Coal Geology & Exploration
Objective Closed-loop heat extraction technology, which extracts geothermal energy without draining geothermal water, has emerged as a research focus in geothermal energy exploitation. However, there is a lack of studies on the impacts of convection in reservoirs on heat transfer. Methods To improve single-well heat extraction, this study proposed a technology of closed-loop heat extraction from hydrothermal reservoirs using horizontal wells. This technology aims to increase the contact area between wellbores and reservoirs while fully leveraging the convection in reservoirs. A flow and heat transfer model characterized by the coupling of horizontal wells, circulating water and reservoirs was established to …
Development Of Intensive Grassland Systems: From Science To Practice, D G. Mccall, G W. Sheath
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 …
The Ecology Of Grazing Management, R K. Heitschmidt
The Ecology Of Grazing Management, R K. Heitschmidt
IGC Proceedings (1977-2023)
The broad objective of this paper is to review the fundamental principles of grazing management as a means of assessing the inherent value of intensive and extensive grazing systems. Conceptual analyses of intensive and extensive grazing systems reveal that the fundamental differences between intensive and extensive grazing systems are related to differences in non-grazing rather than grazing tactics. Intensive grazing systems employ a wide array of non-grazing tactics in an attempt to overcome the inherent ecological constraints that limit secondary (i.e., livestock) productivity in extensively grazed systems. Moreover, analyses of the ecological or true efficiency of various agricultural production systems …
An Analysis Of The Dry Matter Intake And Rate Of Live-Weight Gain Of Growing Cattle Fed Forage Diets, J G. Buchanan-Smith
An Analysis Of The Dry Matter Intake And Rate Of Live-Weight Gain Of Growing Cattle Fed Forage Diets, J G. Buchanan-Smith
IGC Proceedings (1977-2023)
The intake and rate of live-weight gain of 500 growing steer calves fed experimental forage diets in 7 trials were compared with corresponding values predicted using the Na1ional Research Council (NRC) model (1984). The cattle were predominantly weaned calves and most of the experimental diets were alfalfa-grass silage, either unsupplemented or supplemented with various protein sources, but some diets were based on maize silage or maize grain. The feeding period evaluated in this study ranged between the first 84 and 147 days when protein accretion rate in the cattle would be relatively high. Dry matter intakes were overpredicted by the …
Management Of Extensive Pastures For Dairy Youngstock, G.E J. Fisher, D J. Roberts
Management Of Extensive Pastures For Dairy Youngstock, G.E J. Fisher, D J. Roberts
IGC Proceedings (1977-2023)
The effects of low input systems on the ground cover of species and yield and chemical composition of herbage cul from extensive lowland swards was studied over 3 years. The live-weight gain of dairy heifer replacements offered grazed or conserved forage from these pastures was also assessed, The swards were sown with a mixture of grasses, wildflowers and herbs and received no inorganic fertilizers, Applications of slurry in January and February increased herbage yield by 43%, but reduced the cover of flowers and herbs. Using a 2- cut conservation system improved yield of metabolisable energy/ha in herbage by 33%, and …
Intensive Grazing Of Alfalfa By Beef Steers, M Rasnake, W R. Burris, G D. Lacefield, J Randolph, N Gay, L Davis
Intensive Grazing Of Alfalfa By Beef Steers, M Rasnake, W R. Burris, G D. Lacefield, J Randolph, N Gay, L Davis
IGC Proceedings (1977-2023)
In the temperate region of North America, high temperature and moisture deficit cause low forage growth during the summer of most years, making it difficult to grow beef (Bos taurus), calves through summer grazing. Alfalfa (Medicago sativa), offers some potential to provide high dry matter production during summer if an effective system of grazing can be developed. The objective of this study was to test a system of intensive grazing of beef steers on alfalfa to maximise live-weight gains/ha and maintain plant population. Alfalfa was no-till seeded into a 6.5 ha field in autumn 1988 after …
Variance Across Years In Growth Of Cattle On Annual Pastures In A Mediterranean Climate, K D. Greathead, J Zorrilla Rios
Variance Across Years In Growth Of Cattle On Annual Pastures In A Mediterranean Climate, K D. Greathead, J Zorrilla Rios
IGC Proceedings (1977-2023)
Annual pastures were continuously grazed by new drafts of yearling cattle each year for 4 years at 2 sites. The variability of weight gained across years at any date was not different between sites. The level of rainfall in April, but strongly influenced weight gained by the cattle in any year. Variances in weight change were small up to April, they increased rapidly from April to late July and were not different after July (P<0.05).
Modification Of The Botanical Composition Of Perennial And Annual Temperate Pastures By Strategic Grazing Practices, D R. Kemp, P M. Dowling
Modification Of The Botanical Composition Of Perennial And Annual Temperate Pastures By Strategic Grazing Practices, D R. Kemp, P M. Dowling
IGC Proceedings (1977-2023)
Where livestock production depends upon pastures, management is more difficult in environments where rainfall varies considerably from season to season and year to year. Flexible grazing practices are needed to optimise species composition and pasture productivity. Results presented in this paper show that pasture composition can be improved within climatic constraints, by grazing practices within seasons, In temperate annual pastures, long rests in winter (similar to a long rotation during that season) increased annual legume content in early spring from 20 to 50%. Annual grass content was unchanged. In perennial (phalaris) pastures, the dominant legume can change over years from …
Development Of Grass-Clover Pasture Systems For Autumn-Calving Beef Cows. I. Forage Production, G D. Mooso, D G. Morrison, J I. Feazel, D R. Morris
Development Of Grass-Clover Pasture Systems For Autumn-Calving Beef Cows. I. Forage Production, G D. Mooso, D G. Morrison, J I. Feazel, D R. Morris
IGC Proceedings (1977-2023)
Four 8-ha areas of bermudagrass-based (Cynodon dactylon (L.) Pers.) grazing systems were sodseeded and received annual N fertiliser as follows: I) clover (Trifolium sp.)+81 kg Nnm, 2) annual ryegrass (Lolium multiflorum Lam)+clover +81 kg N/ha, 3) ryegrass+clover+l39 kg N/ ha, and 4) ryegrass+139 kg N/ha. Monthly forage accumulation was estimated for 3 years by clipping samples from 2 exclosures/pasture. Environmental conditions had a significant effect on total annual forage dry matter (DM) production. Systems 3 and 4 produced more (P<0.05) forage DM than Systems 1 and 2 (11.0 v. 10,3 Mg/ha). System I produced more (P<0.l) forage DM than 2 (10.6 ll, 9.8 Mg/ha). Systems 3 and 4 were similar, producing I 1.0 Mg/ha. Monthly forage accumulation was lowest in winter (December to February) and highest in spring and summer (March to August). The results of this study demonstrate that at a low N level, there was no benefii from including ryegrass in the system and al a moderate N level, there was no benefit from including clover.
Development Of Grass-Clover Grazing Systems For Autumn-Calving Beef Cows. Ii. Cow-Calf Production And Economic Analysis, D G. Morrison, J I. Feazel, G D. Mooso
Development Of Grass-Clover Grazing Systems For Autumn-Calving Beef Cows. Ii. Cow-Calf Production And Economic Analysis, D G. Morrison, J I. Feazel, G D. Mooso
IGC Proceedings (1977-2023)
Four 8-ha areas of bermudagrass-based (Cynodon dactylon (L.) Pers.) grazing systems were sod seeded and received annual N fertiliser as follows: I) clover (Trifolium sp.)+81 kg/ha, 2) annual rye grass (Lolium multiflorum Lsm.)+clover +81 kg/ha, 3) ryegrass+clover+139 kg/ha, and 4) ryegrass+l39 kg/ha. Each system was stocked year-round with 20 (2,5/lla) cows each with crossbred suckling calf. Cow and calf performance data for 3 of 4 years are included. Year affected (P<0.01) cow and calf live weight, Cows in System 2 were 25-50 kg lower in live weight in autumn and winter than cows in other systems. From February to July, cow daily live-weight gains were 0.11 kg higher (P<0.01) for Systems 2 and 3, Cow live weight in July was affected by N level (Systems 1,2<3,4; P<0,01), Year by system interactions (P<0.05) occurred for cow live weight in February, April and July because of live weight increasing over years in Systems 3 and 4 but not in Systems 1 and 2. Calf daily live-weight gain February to weaning (July) was higher (P<0.01) for System 2 v. 1 (0.06 kg), Syuem 3 v. 4 (0.07 kg), and Systems 3, 4 v. 1, 2 (0.07 kg), Estimated net returns favoured Systems 3 and 4 over Systems 1 and 2.
Improved Grazing Systems For Lamb Production On Appalachian Hill Farms, R L. Reid, J R. Puoli, G A. Jung, D P. Belesky
Improved Grazing Systems For Lamb Production On Appalachian Hill Farms, R L. Reid, J R. Puoli, G A. Jung, D P. Belesky
IGC Proceedings (1977-2023)
Improved grazing methods were tested to increase lamb outputs per ha from Appalachian hill farms. Components of a grazing system were cool-season grass [tall fescue (Festuca arundinacea Schreb.), Grasslands Matua prairie grass (Brom us willdenowii Kunth)J or grasslegume [Kentucky bluegrass (Poa pratensis L.)•red clover (Trifolium pralense L.)] pastures in spring and early autumn, warm-season grass [switchgrass (Panicum virgatum L.)] in summer, and brassicas in late autumn and early winter. Matua was highly productive in cool weather but was subject to fungal infection and grazing ewes had low Mg status in spring. Rotationally grazed switchgrass maintained high numbers …
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
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 …
Interactions Of Rotational And Continuous Grazing With Stocking Rate On Warm And Cool-Season Pastures, David I. Bransby
Interactions Of Rotational And Continuous Grazing With Stocking Rate On Warm And Cool-Season Pastures, David I. Bransby
IGC Proceedings (1977-2023)
With more intense commercialisation of electric fencing many production and economic advantages have been claimed for rotational grazing compared with continuous grazing. However, very little research data are available from the south-eastern USA to verify these claims, Therefore, the objective of this study was to evaluate animal performance under conditions of continuous and IO-paddock rotational grazing on cool- and warm-season pastures commonly used in this region. Three 2-year grazing experiments were conducted, one each on a mixed rye-annual ryegrass (Secale cereale-Lolium multiflorum) pasture, Coastal bermudagrass ( Cynodon hybrid) and Pensacola bahiagrass (Paspalum notatum). In each experiment continuous …
Integrating Pasture Technology Research With Farm Management, R T. Cowan, T M. Davison, K F. Lowe, G K. Reason, G D. Chopping
Integrating Pasture Technology Research With Farm Management, R T. Cowan, T M. Davison, K F. Lowe, G K. Reason, G D. Chopping
IGC Proceedings (1977-2023)
An applied research programme which involved farmers in a continuum of trials measuring pasture, soil and milk responses to the application of nitrogen fertiliser to tropical grasses is described. Pasture responses were consistent across farms, grass species and, within limits, rainfall zones and soil types. Soil pH declined by 0.03 lo 0.2 units each year. Additional milk production ranged from 4 to 14 I/kg nitrogen, the response being greater at lower levels of application. Results from farm and research station experiments were consistent. The high adoption rate, reaching 68% in 6 years, was ' attributed to the integration of farm …