s:766:"%T Mass flow and diffusion of nutrients to a root with constant or zero-sink uptake. 2. Zero-sink uptake. 
%A Willigen P D 
%A van Noordwijk, M. 
%X This paper deals with a model for zero-sink uptake of nutrients by a plant root. Transport to the root is by diffusion and mass flow. A solution for the transport equation is derived where the initial distribution of the concentration around the root is that of steady-rate as was obtained in the first of this set of papers. Also, relatively simple approximations of the analytical solutions obtained are derived. It is shown that a good approximation to the uptake rate is proportional to the average concentration. With the help of these approximations, macroscopic uptake by a root system can be calculated. 
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