Phosphorus fixation as affected by soil temperature
1942
Robinson, R.R.
Studies on a Dekalb soil showed that incubating the soil at optimum moisture content for 2 months with the temperature fluctuating between 15 degrees and 45 degrees C resulted in very poor plant growth as compared with incubation at a temperature of 3 degrees C, or with no incubation treatment. That the poor growth resulting from incubation at high temperature w as due to a decrease in available phosphorus was shown by the fact that where large amounts of phosphorus were applied at the conclusion of the incubation period, this poor growth was not obtained. These results suggest an explanation for the observation that in the southern states fall applications of phosphorus fertilizers are more effective than spring applications. Moreover, it would seem that the effect of fall as compared with spring applications of phosphorus to pastures should also be given serious consideration in some of the northern states where temperatures in the surface layer of soil may become high enough during the summer to reduce the availability of the phosphorus. It is also suggested that part of the discrepancies between the results of field and greenhouse studies on phosphate utilization may be attributed to differences in soil temperature which would influence the rate of phosphate fixation.
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