Earth Sciences Commons^™

Evolutionary Characteristics Of Microcracks In Rocks Under Weak Dynamic Disturbance And Disaster Prevention And Control, Jiang Mingwei, Liang Yuntao, Feng Wenbin, Li Haitao, Zhou Rui, Guo Baolong, Liu Yang, Ma Ju

Coal Geology & Exploration

Objective High stress with superimposed weak dynamic disturbance serves as a critical factor including rock bursts. However, the microcrack propagation characteristics and energy dissipation pattern of rocks under different disturbance amplitude, frequencies, and unloading ranges remain unclear, leading to a lack of technical support for rock burst prevention and control.Methods Based on the true triaxial unloading dynamic disturbance tests, this study analyzed the instability failure patterns of deep surrounding rocks under different disturbance amplitude (5, 10 MPa), frequencies (4, 10 Hz), and triaxial stress unloading (0, 12 MPa). Moreover, this study examined the characteristics of microcracks in rocks using …

Table Of Contents, The Editors

Coal Geology & Exploration

No abstract provided.

Rock Bursts Induced By Thick-Hard Roof With Compound Key Strata: Mechanisms And Technical Modes For Prevention, Zheng Kaige, Yuan Liang, Zhang Pingsong, Wang Lintao

Coal Geology & Exploration

Objective Thick-hard roofs serve as the key factor inducing disasters such as rock bursts and mining-induced earthquakes in coal mines. These disasters are especially serious in the case of coal seam roofs with compound key strata. Hence, there is an urgent need to reveal the mechanisms behind the rock bursts induced by thick-hard roofs with compound key strata and to develop technical modes for the prevention and control of these rock bursts. Methods Using methods including physical simulation experiments on similar materials and mechanical analysis, this study developed methods for identifying roofs with compound key strata and for non-synergistic breaking …

Mechanisms Behind Mine Earthquake-Induced Dynamic Instability Of Thick Top Coals In High-Stresses Roadways, Zhou Kunyou, Dou Linming, Cao Anye, Ma Yankun, Kan Jiliang, Li Jiazhuo, Ma Xiaotao

Coal Geology & Exploration

Objective Thick top coals are common in roadways excavated along the bottom of thick coal seams. Mine earthquakes along the mining face can exert dynamic loading on thick top coals in roadways, prone to induce the dynamic instability of thick top coals and even roof fall-rock burst compound disasters. Therefore, there is an urgent need to explore the mechanisms behind the dynamic instability of thick top coals in roadways under dynamic loading induced by mine earthquakes. Methods This study investigated a roadway of deep thick top coals in the Binchang mining area, Shaanxi. Specifically, this study analyzed the dynamic instability …

Fracturing Characteristics Of Significantly Thick Overburden Inducing Mine Earthquakes And The Stress-Triggering Mechanisms Of The Mine Earthquakes, Dou Linming, Cao Anye, Yang Yao, He Hu, Yang Yaoxin, Bai Xianxi, Gu Qianyue, Li Songhui, Fu Xiangchao, Gu Yingshi, Wu Zhen, Zhang Di

Coal Geology & Exploration

Objective Frequent mine earthquakes that cause surface seismaesthesia, induced by the fracturing of significantly thick overburden in deep coal mining, are identified as the most severe challenge to the efficient production of mining areas. There is an urgent need to overcome the current difficulty caused by mine earthquakes induced by significantly thick overburden, which feature high frequency and challenging prevention and control. Methods Using such mine earthquakes occurring in a certain fully mechanized mining face adjacent to goaves in the Khujirt mining area in Ordos, Inner Mongolia Autonomous Region, as an example, this study (1) analyzed the evolutionary patterns of …

Mechanism Of Thrust Fault Slip Under The Disturbance Of Stress Waves Induced By Coal Mining, Zhang Ningbo, Xu Qianhai, Ouyang Zhenhua, Li Yizhe, Shi Qingwen, Qin Hongyan, Yi Haiyang

Coal Geology & Exploration

Objective The seismic sources, such as roof collapse and artificial blasting, in coal mining may induce stress waves, which will cause the surrounding faults lose its stability and thus cause the dynamic disasters such as rockbursts etc. Methods The propagation law of stress waves in the fracture structure and the evolution characteristics of friction energy under the action of stress waves were studied through dynamic photoelastic experiment, numerical simulation and theoretical analysis based on the thrust fault F16 in Henan Yima mining area. Meanwhile, the disturbance law of the location of seismic source and energy to the slip of thrust …

Influencing Analysis Of Bedding Plane Location On The Dynamic Failure Characteristics Of Coal-Rock Combinations, Zheng Jianwei, Zhang Xiufeng, Ju Wenjun, Wang Cunwen, Han Yueyong, Li Guoying, Chen Yang, Li Haitao, Hao Jinwei, Liu Biao

Coal Geology & Exploration

Objective The bedding plane location significantly impacts the dynamic failure processes and mechanical properties of coal-rock composites, but the specific influence patterns remain unclear. Methods Dynamic mechanical tests were conducted on coal-rock composite specimens with bedding planes located at the top, middle, and bottom using the split Hopkinson pressure bar (SHPB). The investigation focused on the dynamic stress-strain behavior, failure process, energy distribution, and fragmentation characteristics under impact loading conditions. Results and Conclusions The findings indicate that: (1) The dynamic stress-strain behavior of coal-rock composites can be segmented into five distinct stages: near-linear stage, nonlinear dynamic stress-strain stage, elastic modulus …

Exploring The Evolutionary Patterns Of Stress Field In Coal Seams During Water Drainage In Overburden Confined Aquifers Based On Charge Monitoring, Wang Gang, Yu Xiaojie, Wang Aiwen, Xiao Xiaochun, Wang Yong, Ding Xin, Wang Weibin, Xu Zengjun, Du Lulu

Coal Geology & Exploration

Objective Deep coal mining areas in regions such as Inner Mongolia, Shaanxi, Shandong, and Gansu in China feature intricate hydrogeological conditions, which lead to substantial water drainage from roofs and increasingly prominent rock bursts induced by water drainage in overburden confined aquifers. This study investigated the evolutionary patterns of the stress field in coal seams during the water drainage of overburden confined aquifers. Methods By combining the laboratory charge induction experiments of coals under graded loading with charge monitoring pre- and post-water drainage from a roof in a coal mine, this study systematically examined the variations of induced charge in …

Spatiotemporal Evolutionary Characteristics Of Asymmetric Stress Transfer In Overburden Of Steeply Dipping Coal Seams, Zhu Kaipeng, Li Zhilin, Luo Shenghu, Xie Panshi, Fan Juan, Wang Tong, Tian Chengyang, Yan Zhuangzhuang

Coal Geology & Exploration

Objective The key to the safe and efficient mining of steeply dipping coal seams is the effective control of the stability of surrounding rocks, while the effective control is underpinned by identifying and revealing the spatiotemporal evolutionary characteristics of the stress transfer path of the overburden. Methods This study investigated mining face 25221 of a coal mine in Xinjiang through field measurement, physical simulations using similar materials, and numerical computation. This study determined the rock pressure behavior of the mining face, along with the deformation and failure patterns of the overburden, through a comprehensive analysis. Accordingly, it established stress characteristic …

Evolutionary Pattern And Control Technology Of Mine Pressure When Mining Face For Coal Pillars In Main Roadways Passing Through Abandoned Roadways, Li Zhenhua, Ren Ziyuan, Du Feng, Ren Hao, Wang Wenqiang

Coal Geology & Exploration

Objective With the adjustment of the mining face layout in mines, the overburden roof of the mining face for coal pillar recovery is frequently difficult to control when the mining face passes through abandoned roadways. Methods To address this challenge, this study investigated the coal pillar mining face outside the No.2 panel in the Zhaogu No.2 Coal Mine in Henan Province, which passes through abandoned roadways. Using methods like theoretical analysis, numerical simulation, and in-situ tests, this study examined the composite structure of the mining face and the broken overburden of abandoned roadways, followed by simulation of the full-cycle evolutionary …

Spatial Surveying Characteristics And Reconstruction Method Of Millimetre Wave Radar In Complex Environment Of Coal Mine Roadway, Xue Xusheng, Yang Xingyun, Yue Jianing, Wang Chuanwei, Mao Qinghua, Ma Hongwei, Wang Rongquan

Coal Geology & Exploration

Objective Underground spatial surveying of coal mine is an important part of transparent geological modelling for coal mine. However, the complex environment of coal mine roadway, incomplete information acquisition, insufficient accuracy of sensed data and other difficulties need to be urgently solved. Methods First, the signal characteristics of millimeter wave radar under the complex environmental factors such as dust, water mist, surrounding rock structure, etc. were studied in depth, the millimeter wave signal attenuation model was established for the surrounding rock of coal mine roadway, and the influence mechanism of complex environmental factors for millimeter wave radar was comparatively analyzed. …

Advances In Research On Stratigraphic Characteristic Parameter Modeling And Safety Early Warning For Deep Geological Drilling Processes, Yang Yulong, Cao Weihua, Gan Chao, Li Yupeng, Wu Min

Coal Geology & Exploration

Significance As the new round of national exploration & development planning continues, resource exploration is advancing toward the deep Earth. However, deep strata exhibit diverse rock types, which complicate the measurement of rock mechanical parameters. Furthermore, the harsh environments of these strata, characterized by high temperatures, high pressures, and high in-situ stress, are prone to induce downhole accidents like drilling tool failure, wellbore collapse, loss of circulation, and well kicks, posing challenges to geological drilling. Advances Aiming at the perception and modeling of complex geological environments, this study reviews the existing studies on the modeling of stratigraphic characteristic parameters from …

Subsoil Testing Required To Detect The Rundown Of Soil Potassium To Deficient Levels For Wheat Production On Loam-Textured Soils, Craig Scanlan, Richard Bell, Miaomiao Cheng, Tim Boyes

Grain and Other Field Crops Research Articles

Context

Long-term negative potassium (K) balances in crop production have depleted soil K levels in Western Australia (WA). Previous research has focussed on sand-textured soils, but recently, monitoring of crops grown on loam-textured soils has shown deficient or marginal shoot K concentrations where Colwell K 0–10 cm is above current critical levels.

Aims

The aims were to examine whether grain yield responses to fertiliser K can be detected on loam-textured soils and if soil test calibration curves can be identified for these soils.

Methods

Eight field trials were conducted with wheat on loam-textured soils. The same experimental design was used …

Effect Of Crop Age On Seed Yield Of Arachis Pintoi At Two Sites In Costa Rica, Pedro J. Argel, Alfredo Valerio

IGC Proceedings (1977-2023)

Arachis pintoi is a forage legume well adapted to the humid tropics of Costa Rica. Seed production studies were carried out at two contrasting localities within the country, Gulipiles (very humid tropics) and San Isidro (seasonal evergreen tropical forest). The accessions CIAT 18748, 18744 and 17434 cv. Amarillo of A. pinloi were vegetatively planted at both sites. Seed yields were measured at 8, 12, 16 and 20 months post- planting inGulipiles, and at·8, 16 and 20 months in San Isidro. Mean seed yields among accessions were similar in San Isidro but significantly different in Gulipiles; however, the contrary occurred in …

Efficient Nitrogen Fertilization In Grass Seed Crops With Regard To Soil Mineral Nitrogen Content And Analyzing Grass Tillers In Spring, W Schoberlein, H J. Wahl

IGC Proceedings (1977-2023)

When applying the Nmln method in grass seed crops analogously lo that in cereal crops we proceed from the experience that for a mean level of mineralisation, the sum total of soil-borne Nm1n available to plants at the beginning of the growth period and Nd Input in the form of fertiliser will provide sufficient N to the crop. The total quantity of mineral soil-borne N and fertiliser N is considered as the nominal value. The required N input can be derived from the difference between nominal value and mineral soil-borne N (Nd = nominal value• Nrnin>· For Dactylis glomerata …

Effects Of Aneuploidy On Seed Production In Autopolyploid Forage Crops, A Elgersma

IGC Proceedings (1977-2023)

Between the selection of a population and its commercial use, several generations of multiplication are necessary. The essential feature in variety maintenance is that no genetic changes occur during multiplication. In seed-propagated species, however, during each multiplication cycle natural selection takes place at ihe gamete, zygote, seed and plant level. In induced autopolyploids high frequencies of aneuploids can occur. Aneuploidy not only affects the seed yield level, but also the selection processes that occur during multiplication. It may cause genetic shift and affect variety stability. Species differ in their tolerance to aneuploids. It is not possible to eliminate aneuploidy by …

Effects Of Ratooning And Protection From Diseases And Birds On Seed Production In Guinea Grass, Okoro Oji, F N. Madubuike, F.O C. Ezedinma

IGC Proceedings (1977-2023)

Effects of ratooning and protection from diseases and birds on seed production in guinea grass (Pannicum maximum L.) were assessed in a study from October 1986 to April 1987. Treatments included ratooning and mancozeb application with or without protection from birds (netting). Highest yield occurred with combined netting and mancozeb application. Mancozeb sp,aying without netting gave lower seed yield than netting without fungicide spraying. Seed yield, which generally decreased with ratooning, was lowest among unnetted and unsprayed crops. Prom anthesis to seed maturation lasted, on average, 9 days, and seeds borne on the upper part of the panicle matured …

Potential For Improved Honey Bee Pollination Efficiency From Easy-To-Trip Lucerne, L R. Teuber, E E. Knapp

IGC Proceedings (1977-2023)

The principal pollinator of lucerne (Medicago sativa L.) in California, USA is the honey bee (Apis mellifera L.). However, honey bees are notoriously inefficient pollinators of lucerne because they learn to avoid tripping the floret. Easy-to-trip lucerne florets could reduce this problem. These studies were designed to determine the inheritance of ease of tripping and assess the effect of ease of tripping on the rate of outcrossing. Both additive and digenic variance for ease of tripping were significant, resulting in a heritability of 34.0:1:16.2%. Ease of tripping had no influence on outcrossing rate, which was estimated to average …

Effect Of Final Cutting For Fodder On Seed Yield And Seed Quality In Berseem, S L. Saini, R K. Chowdhury

IGC Proceedings (1977-2023)

The study was conducted to determine the appropriate time of final culling (closing) for fodder to optimise the seed yield and seed quality in berseem (Trifolium alexandrinum L.). Based on 2 years' experimentation, the maximum seed yield was obtained when the final cut for fodder was taken in mid•March and the crop was then closed for seed. Seed yield was reduced drastically when the final cut was delayed to late March•April. The seed quality parameters of standard germination, seed weight and vigour index were also reduced when the final cut for fodder was delayed to late March•early April. Based …

Effect Of Post-Harvest Management Practices On Seed Yields On Fine-Leaf Fescue, Gale A. Gingrich, William C. Young Iii, Thomas B. Silberstein

IGC Proceedings (1977-2023)

Public opposition and legislative actions have restricted the practice of open-field burning of grass seed fields in Western Oregon's Willamette Valley. Finding economically acceptable alternatives to straw residue removal has become a priority for valley grass seed growers. Trials using 4 residue management practices were established on 2 commercial fine fescue (Festuca rubra) seed fields. Seed yields varied significantly between residue management practices. Seed yields from thermal-treated plots were equal or significantly greater than yields from the non-thermal treatments. Fertile tiller number was also greater with thermal treatments. Most fine fescue fields produce 4-6 seed crops before replanting, …

Floret Site Utilization Of White Clover, A H. Marshall, D H. Hides

IGC Proceedings (1977-2023)

Plants of white clover (Trifolium repensL.) cv. Olwen were grown in an open glasshouse at 20°C and ovule growth and development measured. Differences in the rate of growth of ovules within ovaries were observed as early as 2 days after pollination. Ovules reached a maximum size after 8 days, with the smallest only half the size of the largest. After 8 days the smallest ovules became flaccid and shrivelled. Ovule position within the ovary had no effect on the frequency of seed set. Inflorescence position and floret position on the inflorescence had a significant effect on the number …

Influence Of Harvest Date On The Yield And Quality Of Seed Of Phalaris, K Reddy, W R. Scott, R J. Lucas

IGC Proceedings (1977-2023)

Grasslands Maru phalaris (Phalaris aquatica L,) was harvested every third day commencing 12 days after mid-anthesis (DAA) to define the optimum time of harvest for seed yield and quality. Harvesting earlier than 21-24 DAA reduced 1000-seed weight and viability. Delaying harvest until 24 days reduced seed yield due to shattering but had no detrimental effect on seed weight and viability. Heavy seed losses occurred 24 DAA when seed moisture fell below 40%. The results of this experiment suggest that Maru phalaris should be harvested 21-24 DAA when the seed moisture is in the range of 40-42% to reduce the …

Annual Bluegrass And Rat's Tail Fescue Control In Perennial Ryegrass, M E. Mellbye, William C. Young Iii, George W. Mueller-Warrant

IGC Proceedings (1977-2023)

Annual bh1egrass (Poa annua L.) and rat's-tail fescue (Vulpia myruros (L.) C.C. Omel.) are common weed contaminants in seed from perennial ryegrass fields Lolium perenne L. grown in Oregon. A trial was conducted to evaluate post-harvest residue removal methods and herbicides to reduce the level of these impurities. The best weed control was obtained from herbicides following crew-cut management, a comparatively thorough non-thermal nppronch to residue removal. Control was good with sequential herbicide treatments, especially when an effective pre-emergence herbicide such as pendimethalin was used, although no treatment completely eliminated annual bluegrass and rat's-tail fescue from threshed seed samples …

Flowering And Seed Production Of Centrosema Spp. In Relation To Day Length And Temperature, R.J M. Gonzalez, R J. Clements, L R. Humphreys

IGC Proceedings (1977-2023)

The effcc1s of variation in daylength and temperature on the flowering processes leading to seed production were studied in genotypes of 5 Centrosema spp. Short days (11 h) enhanced flowering in accessions of C. virginatum from low latitude but flowering of lines from high latitude was more prolific in 16-h days. A quantitative long-short day response was evident in 2 intermediate latitude accessions. The critical photoperiod for flowering·varied: C. virginianum cross 31 flowered in 13.5 h or less, C. pubescens, C. pascuorum and C. macrocarpum in 12 h or less, and C. schiediam Oowcred only in a 10.5 …

Herbicide Treatments For Non-Thermal Grass-Seed Production, George W. Mueller-Warrant, William C. Young Iii

IGC Proceedings (1977-2023)

Legislation phasing down open-field burning in the Willamette Valley of Oregon is forcing grass seed growers to alter crop production piactices. Adoption of new mechanical means for straw removal has increased reliance on herbicides. Volunteer seedling control and crop tolerance for 15 herbicide treatment sequences were evaluated in established tall fcscue (Festuca arundinacea) and perennial ryegrass (Lolimn perenne) stands during 2 growing seasons using 5 methods of residue removal. Pre-emergence pendimethalin was extremely safe yet fairly effective on volunteer seedlings in both crops. For perennial ryegrass subsequently treated with post-emergence herbicides, pre-emergence metolachlor was slightly more …

A Development Scale For Perennial Ryegrass, Miriam L. Martin, Roger J. Field

IGC Proceedings (1977-2023)

Vernalised plants of perennial ryeg ra ss (Lolium prenne L. cv. Orasslonds Nui) were grown under controlled conditions and apical development followed by regular excision of apices, which were examined by light and scanning electron microscopy. A 12-point scale describing apical development from the vegetative stage to ear emergence has been produced that is presented in 2 forms: a developmental sequence describing organogenesis events at specific stages, and a commentary on easily recognised features of each stage. The developmental scale provides a detailed analysis that is of value as a botanical description and as a practical aid to those involved …

Seed Yield Potential Of White Clover: Characteristics, Components And Compromise, P.T P. Clifford, I J. Baird

IGC Proceedings (1977-2023)

Nd relationship between leaf size and any of the measured variables was found for 63 agronomically superior white clover (Trifolium repens L.) plants of relatively diverse morphological and physiological characteristics, Predominantly crown-flowering plants gave more than double the seed yield of stolon-lip 'flowerers. High seed yields were also associated with delays in peak flowering, harvest date and increased harvest dry matter. Similar associations were evident for inflorescence density. Increased dry matter accumulation was associated with increases in both floret numbers and seeds/ inflorescence.

Studies In Germination And Thousand-Seed Weight In Chicory Cv. Grasslands Puna, W J. Archie, J S. Rowarth, B R. Guy

IGC Proceedings (1977-2023)

A strong, positive correlation was found between 1000-seed weight (TSW) and germination in chicory (Cichorium intybus L.) cv. Grasslands Puna. Low TSW tended to be associated with empty or immature seed; empty seed was associated with exclusion of bees. No significant differences in seed characteristics were found between seeds harvested from different positions (top, middle or bottom third) on the plant. Optimum harvest lime was 4 weeks after peak flowering.

Seed Production Of Plantain (Plantago Lanceolata L.), J S. Rowarth, M P. Rolston, W J. Archie

IGC Proceedings (1977-2023)

Seed development studies showed that seed maturity in plantain (Plantago lanceolata L,) occurred 6 weeks after anthesis; maximum seed yields were obtained 8 weeks after anthesis. This is consistent with the fact that seed heads take approximately 17 days to complete flowering. Fertiliser nitrogen increased plantain seed yield. Time of closing, timing of nitrogen application and different stand densities did not significantly affect seed yield, probably because plantain can adapt to and compensate for the treatments imposed.

Reproductive Initiation, Closing Dates, Nitrogen Requirements And Harvesting Of Smooth Brome Cv. Grasslands Tiki, J S. Rowarth, W J. Archie

IGC Proceedings (1977-2023)

Reproductive initiation, closing dates, nitrogen requirements and optimum harvest time were investigated for seed production of Grasslands Tiki smooth brome (Bromus inermis Leyss.) in the South Island of New Zealand. Reproductive initiation began in late June, spikelet initiation in mid-September and ear-emergence in mid­October. Seed yield was not affected detrimentally by mowing to 5 cm in mid-September but decreased 24% by mowing in mid-October. Seed yield tended to increase with increasing amounts of N. However, although the highest seed yields were achieved with 50 kg/ha of N in autumn plus I 00 or 150 kg/ha in spring, they did not …