Estimation of Short-wave Radiative Environment in Intercropping System Using Solar Radiation Transmission Model

抄録

The past studies have shown that productions in intercropping fields are affected by planting density of component crops. Because of the formation of short-wave radiative environment in an agricultural field is influenced by the spatial structure of vegetation, the water consumption may be affected by planting density. In this study, the solar radiative environment of the intercropping system is estimated using the solar radiation transmission model. The temporal change of the position of the sun is expressed with the change of altitude angle and azimuth angle of the sun. The profile of a canopy is assumed to be uniform in the direction of crop rows, and a whole crop community is expressed as the gathering of rectangular tubes of an infinite length. The amounts of two phases of solar radiation, one is intercepted by a tube and the other reaches to the ground passing through a tube, are calculated using a leaf area density and an extinction coefficient of the tube and the transmission length. The results of prediction of the solar radiative environments of the maize-mungbean intercropping systems, which are different in the planting density of maize, show the amount of solar radiation intercepted by mungbean comes to be larger with decreasing of planting density of maize.