Measuring the rate of soil coverage to estimate the chief characteristics of a colza crop before plant emergence

Leaf area index (LAI), crop dry mailer (DM) and nitrogen amount in the cano py (N) are amongst the main parameters characterizing rapeseed crop before the onset of stem elongation. The correlations of these parameters with the ground cover ratio estimated from vertical-view-photographs taken at a hei ght of 1.5 m, allow a fairly good indirect estimate of LAI, and satisfactor y estimates of DM and N, when practical constraints make difficult their di rect measurement.