Plant density and leaf area index effects on the distribution of light transmittance to the soil surface in maize

The solar corridor concept examines approaches to better use light in row crops. To achieve this goal, an understanding of the diel patterns of light transmittance to the soil surface in the interrow zone in row crops is necessary. The objective of this study was to investigate the temporal and spatial distribution of light transmittance to the soil surface at different row positions. Light data and leaf area of maize (Zea mays L.) were collected over a period of 2 yr to quantify the spatial distribution of light transmittance to the soil surface under different plant and canopy densities. Leaf area index (LAI) was varied by using two different plant densities and a range of N applications. Photosynthetically active radiation (PAR) was measured using quantum line sensors at three to seven row positions depending on row spacing (0.78 and 0.36 m). Light transmittance to the soil surface varied by position within the row and time of day. The variation was greatest for low N and low plant density spacing treatments. On cloudy days with more diffuse light the variation in light transmittance between the within and row positions was less. Light extinction coefficients decreased as solar elevation increased toward midday. The wide variation in light transmittance to the soil surface in the interrow zone points out the need to manage plant and management properties such as leaf area, plant density, and row spacing to take best advantage of light in the solar corridor.