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Movement of fertilizers in Carrington loam

Overseth, O.E.
Agronomy journal 1933 v.25 no.3 pp. 202-216
loam soils, irrigation, phosphorus, phosphorus fertilizers, potassium, NPK fertilizers, nitrogen fertilizers, nitrogen, potassium fertilizers
The results of these experiments with various fertilizers in Carrington loam permit of the following conclusions: 1. The movement of nitrogen out of the complete fertilizer tested, containing sulfate of ammonia as the source of nitrogen, was rapid. 2. The movement of phosphorus out of the complete fertilizer was rapid during the first 2 days in the soil and then the movement was noticeably retarded. 3. The movement of potassium out of the complete fertilizer was not quite as rapid as the movement of nitrogen. 4. Ammonium sulfate in the complete fertilizer apparently reduced the movement of phosphorus out of the phosphate. 5. The change in the phosphate in the complete fertilizer placed in the soil appeared to be rather sudden. Indications from the data presented are that monocalcium phosphate did not remain long in the complete fertilizer in that form. The first reaction that took place was the solution and outward movement of the readily soluble monocalcium phosphate. The remaining monocalcium phosphate then formed dicalcium phosphate, a reversion taking place within the fertilizer sample immediately after moisture from the surrounding soil had diffused into the fertilizer. 6. After a 21-day period, chemical analyses showed that about 80% of the phosphorus in the complete fertilizer was in the dicalcium phosphate form. A large part of the remaining phosphorus was present as tricalcium phosphate. 7. Sulfate of ammonia did not show any effect on the movement of potassium out of the complete fertilizer. Neither did muriate of potash appear to influence the movement of phosphorus or nitrogen. 8. The rate of movement of nitrogen in the soil was influenced by phosphorus as there was less movement and also a slower movement of nitrogen in the soil under fertilizers high in phosphorus content. The lateral movement was influenced to about the same extent. 9. The movement of phosphorus in the soil was increased by the greater amount of nitrogen present in the complete fertilizer as sulfate of ammonia. The presence of both sulfate of ammonia and muriate of potash apparently facilitated the movement of phosphorus in the soil. 10. The effect of the movement of soluble salts in the 4-16-4 fertilizer on the conductance of an electrical current was noticeable between the first pair of electrodes located 1 inch directly below the fertilizer. A significant decrease in resistance that continued throughout the experiment indicated constant salt movement in the soil between these electrodes. The diffusion of soluble salts in the immediate vicinity of the fertilizer zone was noted within the short time of 2 hours after the fertilizer was placed in the soil. At the 2- and 3-inch depth the soluble salt diffusion due to the movement of soil moisture was not significant even at the end of 150 hours.