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poster - International Conference of Agricultural Engineering

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EVALUATION OF CROP CANOPY EFFECT ON THE MICRO-<br />

ADVECTIVE CONDITION AND SOIL WATER MOVEMENT IN MICRO-<br />

IRRIGATED FIELDS<br />

Kozue Yuge 1 *,Mitsumasa Anan 2 , Yoshiyuki Shinogi 1<br />

1 Faculty <strong>of</strong> Kyushu University, 6-10-1 Hakozaki Higashi-ku,Fukuoka, 812-8581, Japan<br />

2 Takasaki Sogo Consultant, Co. Ltd., 3-7-5 Higashiaikawa, Kurume, 839-0809, Japan<br />

*Corresponding author. E-mail: yuge@bpes.kyushu-u.ac.jp<br />

Abstrat<br />

The objective <strong>of</strong> this study was to evaluate the soil water content under micro-advective<br />

conditions considering the airflow turbulence generated by the crop canopy. A numerical<br />

model was developed to quantify the soil water movement under micro-scale advection,<br />

considering the spatial variation <strong>of</strong> the air moisture, heat, and flow generated by the crop<br />

body. In this study, the thermal and humidity environments <strong>of</strong> air and the air flow were<br />

simulated based on the assumptions that drip-irrigation is conducted in a crop field and wet<br />

portions appear partially on the soil surface. Using the thermal, humidity, and flow conditions<br />

<strong>of</strong> air, the soil moisture content and temperature were estimated using the soil surface<br />

boundary representing the energy budget. The accuracy <strong>of</strong> the model relative to the soil<br />

moisture content was verified in a wind tunnel experiment. Spatial changes <strong>of</strong> the soil<br />

moisture content, simulated by this model, were reproduced by the experiment. This<br />

indicates that the numerical model for estimating the soil moisture content under micro-scale<br />

advection considering the crop body is fairly satisfactory.<br />

Key words: 5 words or items at maximum must be included as key.<br />

1. Introduction<br />

Spatial distribution <strong>of</strong> the soil surface evaporation is observed in micro-irrigated fields<br />

because the water content on the soil surface is spatially varied. The wind effect, i.e.,<br />

advection, complicates the spatial variation <strong>of</strong> the soil surface evaporation in micro-irrigated<br />

fields. Micro-scale advection plays a significant role in the energy budget on the soil surface<br />

and soil surface evaporation. Quantification <strong>of</strong> the water consumption in the micro-irrigated<br />

field is very difficult because <strong>of</strong> these phenomena.<br />

Bonachela et al. (2001) evaluated the micro-scale advective effect on daily soil surface<br />

evaporation in olive orchards. The occurrence <strong>of</strong> micro-advection was illustrated using a<br />

micro-lysimeter filled with well-irrigated or dry soil and arranged in a grid-pattern (Daiz-<br />

Espejo et al., 2005). Yuge et al. (2005) introduced a numerical model to estimate the<br />

evaporation from the bare soil under micro-scale advection. These studies focused on<br />

quantifying the soil surface evaporation considering the energy budget variation and the<br />

difference between conditions in the wet and dry portions <strong>of</strong> the micro-irrigated field.<br />

Additionally, the wind conditions, which varied because <strong>of</strong> the crop canopy, influenced the<br />

micro-advective effect and soil surface evaporation. Wilson and Shaw (1977), Raupach and<br />

Shaw (1982), Yamada (1982), and Uno et al. (1989) developed numerical models to simulate<br />

the turbulent airflow around an isolated plant canopy. Ohashi (2004) evaluated the<br />

effectiveness and limitation <strong>of</strong> various plant canopy turbulence models. These studies could<br />

be useful in the evaluation <strong>of</strong> the air flow turbulence caused by the crop canopy. However,<br />

the air flow turbulence effect on the soil surface evaporation or soil water content was not<br />

mentioned in these studies.<br />

The objective <strong>of</strong> this study was to evaluate the soil water content under micro-advective<br />

conditions considering the airflow turbulence generated by the crop canopy. A numerical

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