Plant roots are a major pool of total carbon in the planet and their dynamics
are directly relevant to greenhouse gas balance. Composted wastes are increasingly
used in agriculture for environmental and economic reasons and their role as a substitute for traditional fertilizers needs to be tested on all plant components. Here we
propose a regression quantile approach based on P-splines to assess, quantify and compare the root growth patterns in two treatment groups respectively undergoing compost and traditional fertilization
