The Relation of Temperature and Phosphate Placement to Growth of Clover
1959
Robinson, R. R. | Sprague, V. G. | Gross, C. F.
The effect of placement of mono-calcium phosphate on P availability to red clover seedlings was determined at 50°, 60°, 70°, and 80°F. in controlled temperature chambers. Band applications of phosphate, as compared with phosphate mixed with the soil, were much more effective at low temperatures than at higher temperatures. This is attributed to the effect of temperature on rate of P uptake by the plant. Where only small amounts of phosphate were mixed with the soil, the level of available phosphate was low and growth at low temperature was very poor. With increasing temperature, the rate of P uptake increased markedly and plant growth increased. It would appear that the more rapid uptake of P at higher temperature is associated with the temperature coefficient of absorption rather than with an increase in P concentration in the soil solution. Thus, as the temperature increases, plants apparently are able to absorb P more rapidly from soil solutions containing very small amounts of P. Band applications of phosphate greatly increase the concentration of phosphate in the root zone, and therefore the effects of temperature on rate of P uptake become less important.
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