Institute for Rural Engineering

This study deals with the influence of biochar use on sugarcane growth and nitrate-nitrogen percolation losses, as well as chemical and physical properties of Shimajiri maji soil. Two varieties of biochars, biosolids and bagasse (residues of sugarcane stalks after juice extraction), were mixed with Shimajiri maji soil. Changes in nitrate-nitrogen concentration in percolating water, specific gravity, and available soil moisture before sugarcane planting and after harvest were investigated. Indices of sugarcane growth (stem diameter and length), Brix, and yield of estimated available sugar in each plot were estimated. Results indicated that bagasse charcoal reduced soil dry density and increased available moisture of Shimajiri maji soil. Maintaining suitable soil water content increased yields and sugar content of sugarcane, while nitrate-nitrogen concentration in percolating water also decreased. Hence, bagasse charcoal use may reduce nitrogen loads in Shimajiri maji soil.

The U.S. hired farm work force presently is two-thirds foreign-born: mostly young Mexican men with low educational attainment who neither read nor write English. Sixty percent earn so little that they and their families live in poverty. Four of ten migrate to find work, 33% are not authorized to work in the U.S., and 25% work for a labor market intermediary, usually a labor contractor. Few hired farm workers have health insurance of any kind and, despite low incomes, relatively few seek or receive government benefits. Government regulation of the workplace exempts agricultural employers from numerous provisions that apply to other industries; for example, agriculture is exempt from portions of the Fair Labor Standards Act, allowing children as young as age 12 to work in the fields, and employers with 10 or fewer employees are exempt from OSHA regulation. Only 12 states require farm employers to carry workers' compensation insurance. While hired farm workers face significant safety and health risks, there are major gaps in existing research covering this occupational group. An ad hoc task force convened by NIOSH developed a prioritized agenda for occupational safety research in this population: musculoskeletal disorders, pesticide-related conditions, traumatic injuries, respiratory conditions, dermatitis, infectious diseases, cancer, eye conditions, and mental health.

East Asian regions in the North Pacific have recently experienced severe riverine flood disasters. State-of-the-art neural networks are currently utilized as a quick-response flood model. Neural networks typically require ample time in the training process because of the use of numerous datasets. To reduce the computational costs, we introduced a transfer-learning approach to a neural-network-based flood model. For a concept of transfer leaning, once the model is pretrained in a source domain with large datasets, it can be reused in other target domains. After retraining parts of the model with the target domain datasets, the training time can be reduced due to reuse. A convolutional neural network (CNN) was employed because the CNN with transfer learning has numerous successful applications in two-dimensional image classification. However, our flood model predicts time-series variables (e.g., water level). The CNN with transfer learning requires a conversion tool from time-series datasets to image datasets in preprocessing. First, the CNN time-series classification was verified in the source domain with less than 10% errors for the variation in water level. Second, the CNN with transfer learning in the target domain efficiently reduced the training time by 1/5 of and a mean error difference by 15% of those obtained by the CNN without transfer learning, respectively. Our method can provide another novel flood model in addition to physical-based models.

A subsurface dam is a facility that stores groundwater in the pores of strata and uses groundwater in a sustainable way. These dams have many merits that surface dams do not, e.g., land is not submerged to store water and there is no danger of breaching due to natural or manmade disasters. In addition, the surface area can be used in the same way before and after construction of the subsurface dam. Because of these merits, there are many underground dams in the world. This paper reviews the basics about underground dams, the construction of underground dams around the world, and the problems involved in the sustainable use of groundwater. According to a recent review of the construction of underground dams, the scale of underground dam projects has grown. Some problems with underground dams reported in the past, i.e., sedimentation, flooding, collapse, and salination, occurred because of human error, as well as the immaturity and complexity of geological features. In terms of water quality, long-term monitoring was carried out after construction of underground dams on Miyako Island, Japan. To deal with any problems, countries must exchange information gathered from their experiences in constructing underground dams.

This paper briefly introduces choice experiments using R, which is a language and environment for statistical computing. Choice experiments belong to the family of stated preference methods and are applied to numerous issues in research fields such as marketing science, transportation economics, environmental economics, agricultural economics, or health economics. We explain the process of creating choice sets using the AlgDesign package and the process of statistically analyzing responses using the survival package. Since R is free software, readers of this document may find it easy to apply choice experiments to their research projects.

This paper summarizes the seismic response of five large-scale retaining walls having a geocell facing. The walls were 2.8m high and the backfill and foundation soil were a fine sand compacted to 90% standard Proctor density (relative density of 55%). The first two walls were of the same geometry, with a tapered facing made of geocells each of height 20cm, one infilled with gravel and the other with sand. In Wall 3, a facing of depth 60cm was constructed while the backfill sand was reinforced with a polyester geogrid. Wall 4 was similar to Wall 3 except that the backfill was reinforced with several geocell layers. Wall 5 had thin geocell layers of 5cm height as reinforcements in order to improve the performance compared with Wall 4. The walls were subjected to the scaled horizontal and vertical motions as recorded during the 1995 Kobe earthquake, 4.5m∕s2(450gal) and 9.0m∕s2(900gal) maximum horizontal accelerations in the first and second excitations, respectively. In an attempt to induce failure, and therefore, to investigate the failure mechanism, Walls 3–5 were subjected to a third shaking in which the horizontal accelerations were scaled to 12.0m∕s2(1,200gal). The walls were fully instrumented with accelerometers, laser displacement transducers, force transducers, and strain gauges. All five walls performed satisfactorily under the simulated earthquake motions. An improved wall performance was seen with the geocells acting as reinforcement layers. The study showed that geocells can be used successfully to form gravity walls as well as reinforcement layers even when subjected to a very high seismic load beyond that of the Kobe earthquake.

Abstract The purpose of this study was to assess the hydrological roles of the Cambodian floodplain of the Mekong River, from Kompong Cham as far south as the Vietnam border. An intensive observation of water levels at 20 locations, discharge measurements by ADP and ADCP in the main/floodplain channels and analysis of satellite images (RADARSAT) to estimate inundated area and storage volume, were carried out during the flood and post flood season in 2002. A hydro‐hydraulic model was set up for the entire study area to establish a tool for assistance in understanding the dynamics of recurrent floods as well as the hydrological roles of the floodplain in Cambodia. The model system used was MIKE11, a generalized one‐dimensional model system for rivers and estuaries. The hydraulic modeling work enabled us to assess the hydrological roles of the study area. The flood reduction amount in the peak flood season and river flow augmentation in the dry season were determined as part of the study. The main findings are of importance to floodplain management, as future construction for example for improved road levees and higher agricultural dykes, may reduce the benefits presently derived from flows over the floodplains. The work was carried out under the MRC (Mekong River Commission) Project named Consolidation of hydro‐meteorological data and multi‐functional hydrological roles of Tonle Sap Lake and its vicinities.

Physicochemical properties of biochar, which are used as a soil amendment material in agricultural fields, are different depending on biomass feedstock and pyrolysis processes. In this study, we evaluated the influence of feedstock type and pyrolysis temperature on the water-retention related properties of biochar. Wood-chips [cedar (CE) and cypress (CY)]; moso bamboo (MB); rice husk (RH); sugarcane bagasse (SB); poultry manure (PM) and agricultural wastewater sludge (WS) were each pyrolysed at 400, 600 and 800 °C with a retention time of two hours. Scanning electron microscopy micrographs (SEM), hydrophobicity indices, pore-size distribution measured by mercury-intrusion porosimetry, water-retention curves (WRCs) and plant-available water capacities (AWCs) of the biochars were measured to evaluate their potentials as soil-amendment materials for improving soils' water-retention. As the pyrolysis temperature was increased, the hydrophobicity index decreased. On the other hand, pyrolysis temperature did not affect the distribution of micrometre-range pores, which are useful for plant-available water, of biochars. The AWCs of the biochars formed from CE, CY and SB were greater than those produced from other feedstocks, at 600 and 800 °C. Therefore, we can suggest that the biochars derived from wood-chips (CE and CY) and SB have greater potential for enhancing soils' water-retention.

Biochar (BC), charcoal produced through the pyrolysis of biomass, is reported to adsorb dissolved nitrate-nitrogen (NO3-N). The NO3-N adsorption properties of BC differ depending on the feedstock and the pyrolysis conditions, and the influences have not been systematically clarified. Therefore, we evaluated the dependence of feedstock and pyrolysis temperature on the NO3-N adsorption properties of BC. Wood chips [Japanese cedar [Cryptomeria japonica] (CE) and Japanese cypress [Chamaecyparis obtusa] (CY)], moso bamboo [Phyllostachys edulis] chips (MB), rice [Oryza sativa] husks (RH), sugarcane [Saccharum officinarum] bagasse (SB), poultry manure (PM) and domestic wastewater sludge (WS) were air-dried and heated in a batch-type carbonization furnace at pyrolysis temperatures of 400, 600 and 800°C, with a hold time of 2 h. Among the BC produced from each feedstock, the one produced at 800°C had the greatest NO3-N adsorption. The NO3-N adsorption by BC produced from wood-based biomass at 800°C was significantly higher than that of the BC produced from non-wood-based biomass at 800°C. Therefore, BC made from wood-based biomass at higher temperature can be adequate as soil amendment material for adsorption of NO3-N.

Abstract Four direct shear (DS) apparatuses having different sizes with the specimen lengths ranging from 40 to 800 mm were constructed in the study. The vertical and shear stresses acting on the shear zone were measured as accurately as possible confirming its importance. Noticeable effects of specimen shape were observed. The effects of specimen size were evaluated by performing constant pressure DS tests on a fine poorly graded sand (Toyoura sand) in the small, semimedium, medium and large DS apparatuses and a well-graded sandy gravel in the medium DS apparatus. The residual shear strength of Toyoura sand was independent of the specimen size and initial density. Due likely to specimen size effects on both progressive failure and boundary mechanical restraint, the peak strength decreased with an increase in the specimen size. As the specimen size increased with dense Toyoura sand and as the particle size increased in the medium DS tests, the shear displacement at the peak stress and the ultimate volume increase at the residual state consistently increased while the postpeak strain softening became slower. These specimen size effects can be attributed to the thickness of shear zone and the number of shear bands included in the shear zone.

In order to mitigate the damage due to sediment disasters, knowledge about how slopes fail due to rainfall is indispensable. The main objectives of this paper were to investigate experimentally the effects of surface sand layer density and rainfall intensity on the slop failures due to rainfalls. We conducted a series of experimental tests using 1g physical slope models constructed of Kasumigaura sand and a silt soil named DL clay for the permeable residual surface layer and the firm rock foundation, respectively. A total of nine cases with different combinations of surface sand layer densities and rainfall intensities was tested. Two types of failure: surface slide failure and retrogressive failure, were observed depending on the rainfall intensity and the surface sand layer density. The following mechanism of failure was accounted. At first some sands, which contained a lot of accumulated rainwater, flowed out (flowslide) at the slope toes. The flow slides may be due to the reductions of effective stresses as a result. When a surface slide failure occurred, most of the PWP (pore water pressure) values were still negative but the whole sand layers were almost at the saturation condition. In the case of retrogressive failures, seepage surfaces rose up to higher positions and excess PWPs appeared under the seepage surfaces. This difference of generation mechanism of PWP values may be the deciding factor in the difference in the type of failure.

Using the CFD model, a new ventilation system design will be found later taking into consideration the ventilation efficiency such as uniformity, stability, and suitability of environmental factors in a naturally ventilated broiler house. Because conducting a field experiment for the ventilation study presented so many difficulties, a reliable 3-dimentional computational fluid dynamics (CFD) model had to be developed to investigate the natural ventilation. Before investigating its accuracy, a wind tunnel and particle image velocimetry (PIV) test was initially conducted to find their best experimental conditions and improve the PIV accuracy13,15. A 1/20 scale model of a naturally ventilated broiler house was used to get qualitative and quantitative airflow distribution in the broiler house using the PIV and CFD. To improve the CFD accuracy, the PIV and CFD computed airflows in the broiler house were compared, particularly on the distribution, local air velocity, and turbulent intensity in the house. The quality of the mesh density and the design of the boundary condition, especially the wind velocity and turbulence profiles, were found to be very important for getting accurate results. Assuming the PIV results were accurate, the most accurate CFD results were obtained when using a RNG k-ε turbulence numerical model. The average error of the CFD computed air velocity when using the RNG k-ε models was -6.2%.

The gas diffusion coefficient in soil is affected by several soil physical parameters, including (1) air-filled porosity, (2) bulk density, (3) soil disturbance, (4) the kind of diffusion gases, and (5) soil texture. From the measurement of the relative gas diffusion coefficient (D/D0) of alluvial and volcanic soils, the effects of (2), (3), and (4) on D/D0 were evaluated. Gas diffusion coefficients of sieved, repacked and of undisturbed soil samples were measured in the laboratory. The gas diffusion coefficient of soil increased with bulk density at the same air-filled porosity in both soil types because the proportion of the effective pore space for gas diffusion relatively increased during the compaction procedure. In alluvial soil, the gas diffusion coefficients of undisturbed samples were higher than those of disturbed samples because of the presence of macropores and cracks in the undisturbed samples. The apparent D/D0 of CO2 gas was larger than for O2 and N2 because of differences in the solubilities of the gases.

In this paper, the effects of wind speed, side ventilators and span numbers on gothic type multi-span greenhouse natural ventilation were studied by numerical simulation using the Computational Fluid Dynamics (CFD) approach. The realizable k-ε model was used for the turbulence model in the simulations. The results showed that the maximum greenhouse ventilation rate was achieved when both side and roof vents were used for ventilation. Without the existence of buoyancy effect in the computations, it was found that the ventilation rate increased linearly with the external wind speed in all the cases studied. The ratio of the opening of the ventilator area to the greenhouse floor area, 9.6%, was found to be small compared to the recommended ratios of 15-25%. The results showed that a significant reduction in ventilation rate was determined as the number of spans was increased and an exponential decay explained the relationship between the ventilation rate and the number of spans.

Marine Isotope Stage (MIS) 19 is an important analogue for the present interglacial because of its similar orbital configuration, especially the phasing of the obliquity maximum to precession minimum. However, sedimentary records suitable for capturing both terrestrial and marine environmental changes are limited, and thus the climatic forcing mechanisms for MIS 19 are still largely unknown. The Chiba composite section, east-central Japanese archipelago, is a continuous and expanded marine sedimentary succession well suited to capture terrestrial and marine environmental changes through MIS 19. In this study, a detailed oxygen isotope chronology is established from late MIS 20 to early MIS 18, supported by a U-Pb zircon age and the presence of the Matuyama–Brunhes boundary. New pollen, marine microfossil, and planktonic foraminiferal δ18O and Mg/Ca paleotemperature records reveal the complex interplay of climatic influences. Our pollen data suggest that the duration of full interglacial conditions during MIS 19 extends from 785.0 to 775.1 ka (9.9 kyr), which offers an important natural baseline in predicting the duration of the present interglacial. A Younger Dryas-type cooling event is present during Termination IX, suggesting that such events are linked to this orbital configuration. Millennial- to multi-millennial-scale variations in our δ18O and Mg/Ca records imply that the Subarctic Front fluctuated in the northwestern Pacific Ocean during late MIS 19, probably in response to East Asian winter monsoon variability. The climatic setting at this time appears to be related to less severe summer insolation minima at 65˚N and/or high winter insolation at 50˚N. Our records do not support a recently hypothesized direct coupling between variations in the geomagnetic field intensity and global/regional climate change. Our highly resolved paleoclimatic and paleoceanographic records, coupled with a well-defined Matuyama–Brunhes boundary (772.9 ka; duration 1.9 kyr), establish the Chiba composite section as an exceptional climatic and chronological reference section for the Early–Middle Pleistocene boundary.

Abstract Calibration of global hydrological models (GHMs) has been attempted for over two decades; however, an effective and generic calibration method has not been explored. We present a novel framework for calibrating GHMs assuming that parameters can be regionalized by climate similarities. We calibrated four sensitive parameters of the H08 global hydrological model by aggregating the results of 5,000 simulations with randomly generated parameters into 11 Köppen climate classes and using an objective function Nash–Sutcliffe Efficiency (NSE) with random sampling from the proposed parameter distribution. From a 100‐fold split‐sampling test, we found that both the representativeness and robustness of the transferred parameter sets were guaranteed when the upper 5% of the samples were accepted and assign the median of each accepted parameter distribution for the climate class. The simulation with the climate‐based parameters yielded satisfactory (NSE > 0.0) and good (NSE > 0.5) performances at 480 and 234 stations (61.7% and 30.1% of 777 stations), respectively. The storage capacity ( SD ) and the conductive coefficient ( C D ) were sensitive to the climate classes and exhibited well‐constrained distributions of the accepted samples, whereas the recession parameters for the subsurface storage ( γ and τ ) showed little or no explanatory power to climate. The identified parameters for climate classes exhibited consistency with the physical interpretation of soil formation and efficiencies in vapor transfer. The consistency of the identified parameter values with physical underpinnings indicates that the appropriate parameters were determined, which ensured the robustness of parameters, especially when they are transferred to ungauged watersheds.

Abstract Lignin-based amphiphiles were prepared from the waste liquors of softwood and hardwood kraft pulpings (SKLliq and HKLliq, respectively) and their isolated lignins (SKL and HKL, respectively) by a reaction with several epoxylated polyethylene glycol analogues: polyethylene glycol diglycidylether (PEGDE), its monoglycidyl ether (EPEG), and dodecyloxypolyethylene glycol glycidyl ether (DAEO). The effect of these amphiphiles on cement dispersity was examined at 6°C and 20°C. Generally, only half the amount of EPEG- and PEGDE-series (e.g., 0.4%) was required to achieve the same cement dispersibility (e.g., Γp value of 2) compared to lignosulfonate (LS) (e.g., 0.8%). DAEO-lignin derivatives with the highest surface activity did not show cement dispersibility, suggesting no correlation between cement dispersibility and surface activity of the amphiphiles. Thus, together with the test of bending strength, it was found that the amphiphiles prepared from isolated lignins and EPEG were promising cement dispersants, which were available even in the wintertime without losing mechanical strength. Keywords: Technical ligninblack liquoramphiphilesurfactantcement dispersant Acknowledgments This study was supported by a grant from the Ministry of Agriculture, Forestry, and Fisheries of Japan (Rural Biomass Research Project).

Abstract The excessive use of chemical fertilizers and manure in intensive agriculture sometimes causes environmental problems, including water pollution. Although it is speculated that surplus nitrogen (N) from Japanese agriculture may have had a strong impact on the environment, few quantitative assessments are available. In this study N flow in agricultural production was estimated from1980 to 1997. During this period, application of chemical fertilizers per unit area of farmland peaked in 1985 and then decreased. This was largely due to a decrease in the input of chemical fertilizer on paddy rice, although the input for vegetables per unit area increased. Even though the input of chemicalfertilizers for industrial crops decreased, it was still higher than for any other crop category. The amount of livestock wastes per unit area of farmland increased during the period and that of non-utilized livestock wastes also increased. Residual N on farmland and non-utilized livestock wastes could cause environmental pollution. The amount of residual N on farmland, which is expressed as the difference between N inputs and N outputs, was lowest in 1997because of the low input of chemical fertilizers and manure, though the amount of non-utilized livestock wastes was highest. Therefore the sum of the amount of residual N on farmland and non-utilized livestock wastes was not the lowest during the period and the sum of both was 141, 163, 158, and 148 kg N ha-1 in 1980, 1985, 1990, and 1997, respectively. To decrease these levels as well as the environmental risk associated with agricultural production, reduced input of chemical fertilizers for vegetables and industrial crops and, effective and active use of livestock wastes are important. Key Words: chemical fertilizerenvironmental risklivestock wastesnitrogen flow

A series of consolidated drained triaxial compression tests were performed on recycled concrete aggregates to investigate the feasibility of their use as a backfill material for geotechnical engineering structures requiring a high stability while allowing a limited amount of deformation, such as embankments and conventional type and geosynthetic-reinforced soil retaining walls supporting highway and railway. The experimental results showed the following. The compressive strength qmax when well compacted at water content in the vicinity of the optimum water content wopt is similar to that of typical well graded gravelly soil that is categorized as the highest class backfill material. When well compacted at the same energy level, the peak strength and pre-peak stiffness of recycled concrete aggregate is insensitive to changes in the moulding water content relative to wopt. When well compacted around wopt, the effect of confining pressure on qmax is similar to the one of typical well graded gravelly soil, while confined saturation does not have any detrimental effects on the qmax and pre-peak stiffness. With a decrease in the compacted dry density from the maximum dry density at fixed water content around wopt for a given compaction energy level, the qmax and pre-peak stiffness decreases at a very high rate. The viscous property of the recycled concrete aggregate is similar to the one of ordinary type backfill materials. When well compacted around wopt, residual strains by sustained and cyclic loading are not significant.

by Yusuke Suganuma, Makoto Okada, Martin J. Head, Koji Kameo, Yuki Haneda, Hiroki Hayashi, Toshiaki Irizuki, Takuya Itaki, Kentaro Izumi, Yoshimi Kubota, Hiroomi Nakazato, Naohisa Nishida, Masaaki Okuda, Yasufumi Satoguchi, Quentin Simon, and Yoshihiro Takeshita. Episodes 2021;44:317-47. https://doi.org/10.18814/epiiugs/2020/020080