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Root-induced spatial variation in soil water content



A project entitled “Root-induced spatial variation in soil water 
content and its effect on phosphorus uptake and growth of pearl 
millet Pennisetum americanum { L.} Leek under drought conditions” 
lead by Prof. Dr. Dr.h.c.H. Marschner, of Institut für 
Pflanzernerährung, Universtat Hohenheim, Deutschland, in 
partnership with other scientific institutions in France, Mali, 
Chad, Senegal, Burkina Fasso and Benin was carried out under the 
European Union (D.G.XII) STD2 scientific programme.

This project aimed at understanding the interrelationship between 
water availability and phosphorus uptake by the pearl millet 
(Pennisetum americanum L.) in order to be able to define the best 
strategy for phosphorus fertilization under drought conditions. 
Experiments were carried out under controlled conditions in growth 
chambers.

The researchers reached the conclusion that an increase in 
phosphorus supply, by promoting shoot growth in a larger extent 
than root growth, will result in increase water requirements. 
Therefore, unless satisfaction of water requirements is possible, 
one must be careful to the extent of phosphorus supply.

It was also concluded that soil water might be limiting well above 
the well known lower limit of soil water holding capacity (wilting 
point); as roots uptake water, regions of lower water content are 
created, originating a large variability in soil water content. 
Under these conditions, hydraulic lift can no longer assure 
nutrient uptake. 

The conclusions reinforce previous knowledge of interaction that 
exists among water use and nutrients uptake. They are particularly 
innovative in what concerns these crop with special interest in 
tropical regions. They also have added value of cautioning against 
the common practice of recommending as a general practice 
phosphorus fertilization as a measure to increase productivity. 
This is only true if water compensates for the increase 
transpiration that accompanies increased growth.

Within this project several publications have been issued.

For further information please contact:

Prof. Dr. Dr.h.c.H. Marschner
Institut für Pflanzernerährung
Universtat Hohenheim
P.O.Box 70056210,
700 Stuttgart 70,9470 Deutschland.
Phone +49-711-459 23 44
Fax     +49-711-459 32 95


CONTRACT TS2- A -068