Uptake of solutes by multiple root systems from soil

Summary The analog described in Part I is used to investigate quantitatively the the effects of pattern and density on the uptake and uptake rate of nutrients which move to plant roots by diffusion. The uptake by two roots is considered first, to illustrate the competitive effect. The results for multiple root systems are given for a variety of different soil and plant parameters at different times and demonstrate the importance of pattern and density in the uptake of different plant nutrients in both competitive and non competitive situations. Pattern can decrease the uptake by root systems by at least 75 per cent, depending on the value of the diffusion coefficient, time, and root density. Graphs of two indices of dispersion against uptake are given so that the effect of any pattern can be estimated. A procedure is outlined which enables the uptake after any time by a developing root system to be predicted and compared with a theoretical maximum. If the uptake is known, then the graphs show whether soil or plant parameters are limiting uptake.