fertilizer reaction in soil AND THEIR FATES IN SOIL

FERTILIZER IN SOIL

1. FERTILIZER REACTIONS IN SOIL

2. FERTILIZER Materials having definite chemical composition higher analytical value capable of supplying plant nutrients in available form

3. NITROGENOUS FERTILIZER Ammonical form ( Eg . Ammonium sulphate – 20% N) Nitrate form Eg : NaNO 3 – 16% N Both Ammonium- Nitrate Eg : CAN – 20% N Amideform Eg:Urea -46% N

4. Reaction of Ammonium sulphate in soil In Upland condition: Cation exchange - NH 4 + displaces some other cations .

5. 2. In calcareous soil: When (NH 4 ) 2 SO 4 applied as Broadcast – losses of Nitrogen is appreciable Drilled - losses of nitrogen is not appreciable

6. REACTION OF UREA IN SOIL Urea undergoes enzymatic hydrolysis to produce ammonium carbamate. NH 3 converted to NH 4 + Further reaction is similar to Ammoniacal form

7. High concentration of urea – combined toxic effect of NH 3 and NO 2 Higher concentration of NH 3 increases Due to low population of Nitrobacter inhibited

8. REACTION OF SLOW RELEASE NITROGENOUS FERTILIZER

9. PHOSPHATIC FERTILIZERS Water soluble Eg : SSP – 16% P 2 O 5 Citric acid soluble Eg : Dicalcium phosphate- 34 % P 2 O 5 Both insoluble Eg : Rock phosphate- 20-40% P 2 O 5

10. REACTION OF SUPERPHOSPHATE IN SOIL Superphosphate applied to moist soil Dissolved in soil moisture Within short time gets precipitated SSP not leached from soil by Rainfall

11. REACTION OF SSP IN ACID SOIL Combines with Fe and Al – forms insoluble phosphate - becomes unavailable

12. REACTION OF SSP IN NEUTRAL AND CALCAREOUS SOIL Monocalcium phosphate converted to Tricalcium phosphate Tricalcium phosphate converted to insoluble compounds like apatite REACTION OF SSP IN ALKALI SOIL SSP reacts with sodium and forms monosodium phosphate Monosodium phosphate – highly soluble and become available to plants

13. REACTION OF POTASSIC FERTILIZER IN SOIL Both KCl and K 2 SO 4 – soluble in water -on application in soil they ionize to K + , Cl - , SO 4 2- - available to plants

14. REACTION OF POLYPHOSPHATE FERTILIZER IN SOIL

15. LOSS AND GAIN OF NUTRIENTS

16. Fate of applied fertilizer Taken up by the crop Reacts with soil minerals and organic matter Can leach from the root zone with water lost to the atmosphere as a gas Can move from the field through soil erosion and water runoff

17. REFERENCE : W. L. Lindsay ,H. F. Stephenson. Nature of the Reactions of Monocalcium Phosphate Monohydrate in Soils: The Solution That Reacts with the Soil . Soil Science Society of America Journal . Vol. 23 No. 1, p. 12-18