A Study of the Effect of Mineral Phosphates Upon the Organic Phosphorus Content of Organic Soil
1956
McCall, W. W. | Davis, J. F. | Lawton, K.
Laboratory studies were conducted to investigate the effect of mineral phosphates upon the organic phosphorus content of eight organic soils. Soil types represented were Carlisle muck, Everglades peat, Houghton muck, Istopoka peat, and Rifle peat. Six of the samples were obtained in Michigan and two from Florida. Monocalcium phosphate was applied to each soil at the following rates; 12.5, 25, 50, 100 and 200 ppm. of phosphorus. Unphosphated samples were left as controls. To determine if mineralization was as extensive as shown by analyses for organic phosphorus, available soil phosphorus was determined before and after a 4-month incubation period. The effect of sterilization, temperature and moisture upon the mineralization of organic phosphorus in Houghton muck was also determined. Samples were incubated for a period of 4 months and the amount of organic phosphorus determined, at the end of 2, 3, and 4 months. No “fixation” of mineral phosphate as organic phosphorus occurred, but mineralization of the original organic phosphorus did occur. In general, the trend was toward more complete mineralization of the soil organic phosphorus, with increasing rates of added monocalcium phosphate, over a period of 4 months. Generally, the rate of mineralization was rapid the first 2 months and somewhat slower during the last 2 months of the incubation period. The percentage increase in available phosphorus after 4 months incubation ranged from 31.1 to 292.0%. Temperature and moisture were shown to be two factors affecting mineralization of organic phosphorus.
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