Simulations of Light Interception and Soil Water Dynamics in Row Crops: a Two Dimensional Approach.

The architecture of row crops results in variable light interception by the crop and variable energy transmittance to the soil according to the orientation of the crop rows and direction of sunlight. One dimensional models assume average values of light interception for the canopy as a whole and partition energy to the canopy and soil based on fixed geometries. The two-dimensional soil model 2DSOIL has been incorporated into two mechanistic crop models (corn and potato). In the original formulation of the model, light and energy were distributed in the interrow zones as a function of row spacing and crop height. Dirunal effects of the changing sun path were not accounted for and only an average interrow light interception value was used. The objective of this study was to develop an improved model of two-dimensional radiation interception in interrow zones and test against field data. Field experiments were carried out over several years to quantify the spatial distribution of light interception, temperature and soil water dynamics in corn under different row spacing and canopy densities. Light interception was measured using light bars at 3 to 5 row positions depending on plant density. The results of the experiments showed that light interception at different distances between rows varied greatly over the daylit period.  The dynamics of light interception was also affected by position relative to the plant row. These results were used to evaluate the 2DSOIL model as linked with the corn model 2DMAIZSIM.