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Anan M.,Takasaki Sogo Consultant Co. | Yuge K.,Kyushu University | Oohira Y.,Kyushu Environmental Evaluation Association
Paddy and Water Environment | Year: 2012

The subject of this study is water management in low-lying paddy fields. The objective of this study is to quantify the water requirement, and estimate an appropriate volume and facilitate management of irrigation water in areas where it is difficult to estimate the flow rate continuously. A field observation was conducted at a 14-ha study site located in the Kuwabara area, Fukuoka City, southwest of Japan, to evaluate water management conditions in the command area of the reservoir. This site near the reservoir was selected, because it was impossible to understand the water supply situation in the entire command area. The farmers in this region have been unable to retain sufficient irrigation water. The observation results indicate that the water depth fluctuates widely in every irrigation canal. The canals are frequently empty because rotational irrigation is conducted by water managers; this makes quantifying the flow rate in the irrigation canal very difficult. To quantify the water requirement, an improved tank model was introduced. The accuracy of the model was examined by comparing the observed and calculated ponding depths at a paddy field. The simulation results agreed with the observed data. Using this model, water management for the reduction of water managers' labor was simulated. Simulation results indicated that rotational irrigation effectively reduces labor and saves irrigation water. © 2011 Springer-Verlag. Source


Yuge K.,Saga University | Anan M.,Takasaki Sogo Consultant Co. | Hamagami K.,Iwate University | Hamada K.,Kyushu University
Acta Horticulturae | Year: 2016

The objective of this study was to evaluate the effect of soil moisture condition on the bioelectric potential of a crop. The bioelectric potential of broccoli (Brassica oleracea var. italica) plants was measured under different soil moisture conditions and growth stages using pot experiments (Fukuoka, Japan in 2011). To more accurately clarify the relationship among the changes in bioelectric potential, soil moisture, and crop growth stage, a wavelet analysis was performed. The results showed that the bioelectric potential changed as a function of both soil moisture between pF 1.5 and 2.8 and crop growth stage. Further, the dominant frequency band under wet soil condition at the initial growth stage had a large wavelet coefficient compared with the results obtained under the dry soil condition. In the crop midgrowth stage, the wavelet conversion chart obtained using the data from the dry soil condition had the characteristic of the low frequency band compared with results obtained for the wet soil condition. The results showed that the growth stage and soil moisture condition both affect the crop bioelectric potential. Managing optimal soil moisture conditions by considering changes in crop bioelectric potential will likely facilitate the optimization of irrigation regimes in crop growth stages. Source


Yuge K.,Saga University | Hamagami K.,Iwate University | Anan M.,Takasaki Sogo Consultant Co. | Hamada K.,Kyushu University
Journal of Food, Agriculture and Environment | Year: 2015

The objective of this study was to evaluate the effect of soil moisture condition and irrigation regime on the bioelectric potential of crops with different growth stages. The bioelectric potential of broccoli (Brassica oleracea var. italica) plants at the initial and mid-growth stages was measured under different soil moisture conditions and irrigation regimes using pot experiments. The results indicated that the bioelectric potential varied as a function of the soil moisture, irrigation regime, and stage of crop growth. To more accurately clarify the relationship among the changes in bioelectric potential, soil moisture, and crop growth stage, a wavelet analysis was performed. The results showed that the bioelectric potential changed as a function of both soil moisture and crop growth stage. Further, the dominant frequency band under wet soil condition at the initial growth stage before irrigation had a large wavelet coefficient compared with the results obtained under the other soil moisture conditions. In the mid-growth stage, the dominant frequency bands under wet and intermediate soil conditions were similar before and after irrigation. However, the characteristics of the wavelet conversion chart under dry soil conditions changed after irrigation. The results showed that the growth stage and irrigation regime both affect the crop bioelectric potential. Although clarifying the relationship among the bioelectric potential, soil moisture and crop growth stage was difficult, the wavelet analysis was shown to be effective for evaluating the effect of soil moisture and crop growth stage on the bioelectric potential. The results of the analysis indicated the bioelectric potential could be an important indicator for managing soil moisture and for optimizing irrigation regimes. © 2015, World Food Ltd. and WFL Publishers. All rights reserved. Source


Yuge K.,Saga University | Anan M.,Takasaki Sogo Consultant Co. | Shinogi Y.,Kyushu University
Irrigation Science | Year: 2014

The objective of this study was to explore the soil water dynamics under micro-advective conditions. A numerical model was introduced to estimate the airflow turbulence generated by the crop canopy. The vapor pressure and air temperature in the vicinity of the soil surface were estimated from the wind velocity predicted by this model. The energy budget on the soil surface was estimated using wind velocity, vapor pressure, and air temperature simulated by numerical models. The soil water content and temperature were predicted using the simulation model describing the water and heat transfer in soil. Using the energy budget, the accuracy of this model was experimentally verified using a wind tunnel. Spatial changes of the soil water content simulated by this model were reproduced by the experiment. This indicated that the numerical model for estimating the soil water movement under micro-scale advection considering the crop body was satisfactory. © 2013 Springer-Verlag Berlin Heidelberg. Source


Yuge K.,Saga University | Anan M.,Takasaki Sogo Consultant Co. | Hamada K.,Kyushu University
Journal of Food, Agriculture and Environment | Year: 2015

The aim of this study was to quantify the drainage ability of a shallow subsurface drain in a rotational rice paddy field. A numerical method based on SWAP (Soil-Water-Atmosphere-Plant) model was developed to evaluate the soil water movement and the water balance under the shallow subsurface drain. The concept of macropore flow in the SWAP model was adopted to evaluate the effect of a mole drain as a supplement to the main subsurface drain. A field experiment was performed in a rotational rice paddy field during wheat cultivation to verify the accuracy of the model and to obtain input data for the numerical model. The soil moisture conditions, weather and groundwater levels were measured during the period of crop growth. The soil water retention curve and saturated hydraulic conductivity were evaluated in the field. The results of the experiment indicate that there are variable soil moisture characteristics that depend on the soil hydraulic properties. Using the numerical model and experimental data, the soil moisture and drainage flux were estimated. The simulated soil moisture conditions agreed well with the measured data and the model accuracy was verified. The daily change in drainage flux was quantified using this method. The results indicate that the drainage flux under a relatively dry soil condition was low. Following intense rainfall, the drainage flux greatly increased. The soil moisture decreased gradually after the drastic drainage, indicating that the downward bottom flux increased because of drastic subsurface drainage. This result indicates that a shallow subsurface drain is effective in promoting not only lateral drainage but also downward bottom flux. © 2015, World Food Ltd. and WFL Publishers. All rights reserved. Source

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