THE EFFECT OF TIME OF FERTILISER-SOIL CONTACT, DISTANCE OF PHOSPHATE MOVEMENT AND FERTILISER SOLUBILITY ON PHOSPHATE AVAILABILITY TO EARLY GROWTH OF LOWLAND RICE

The importance of time of fertiliser-soil contact, distance of phosphate movement from fertiliser and phosphate fertiliser solubility in determining the availability of phosphate to the early growth of lowland rice was investigated. Phosphate availability was measured by phosphate uptake in a glassh...

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Bibliographic Details
Published in:Plant and soil 1977-02, Vol.46 (2), p.391-404
Main Authors: PORANANOND, KESORN, SEARLE, P. G. E.
Format: Article
Language:English
Subjects:
Acid soils
Agricultural soils
Fertilizers
Greenhouses
Lowlands
Phosphates
Rice
Rice soils
Solubility
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Summary:The importance of time of fertiliser-soil contact, distance of phosphate movement from fertiliser and phosphate fertiliser solubility in determining the availability of phosphate to the early growth of lowland rice was investigated. Phosphate availability was measured by phosphate uptake in a glasshouse experiment in which two week old rice seedlings were transferred to the surface of fertiliser-treated soils for three weeks before harvesting. The fertilisers used in the study were monoammonium phosphate (MAP), ammonium polyphospate (APP), superphosphate (SP) and rock phosphate (RP). Availability of all fertilisers was tested in this way after 2,4 and 8 weeks of fertilisersoil contact. In an associated laboratory experiment the distance of phosphate movement and fertiliser solubility (as measured by quantity of phosphate that had moved away from the fertilizer source) was determined at 2 and 4 weeks in glass tubes containing waterlogged soil. The results showed that at all times of measurement, the availability of the fertilisers could be ranked MAP > APP > SP > RP. Of the 6 possible correlations between phosphate uptake and phosphate movement, only one was significant for the fertiliser-soil contact period of 2 weeks and phosphate movement at 4 weeks, (r = 0.950, P < 0.05). Of the 6 possible correlations between phosphate uptake and fertiliser solubility, none were significant. However, of the 6 possible correlations between phosphate uptake and the product of the two laboratory parameters (referred to as the availability index) four were significant (P < 0.05 in all cases), and involved only the fertiliser-soil contact periods of 2 and 4 weeks. These results indicate that fertiliser solubility alone is not a satisfactory correlative determinant of availability of fertiliser phosphate to lowland rice. Phosphate movement alone is marginally better, but the best correlations are obtained when both parameters are taken into account. While their combined effects are evident only during the first four weeks after fertiliser application, this may still be important to the successful establishement of a rice crop.
ISSN:0032-079X
1573-5036
DOI:10.1007/BF00010095