Soil Fertility and Nutrient management (1+1)

Nutrient interactions in plants and soils

• Interaction can be defined as the influence of an element upon another in relation to growth and crop yield. There may be positive or negative interaction of nutrients occurs either in soil or plant. The positive interaction of nutrients gives higher crop yield and such interactions should be exploited in increasing the crop production. Conversely, all negative interactions will lead to decline in crop yield and should be avoided in formulating agronomic packages for a crop.
• The knowledge about interactions occurring in soils or plants or both is basic to help develop appropriate and efficient technologies. Further this will help to refine the existing ones to increase agricultural production.
• There are mainly two types of interactions effect viz. antagonistic and synergistic effects. Antagonistic effect means an increase in concentration of any nutrient element will decrease the activity of another nutrient (negative effect). While synergistic effects means an increase of concentration of any one nutrient element will influence the activity of another nutrient element (Positive effect). One must understand how the negative or positive interaction takes place within or outside the plant.

• The following antagonistic effects have been well established on the uptake of micronutrients by crops:

  1. Excess of P adversely affects utilization of Zn, Fe and Cu
  2. Excess of Fe adversely affects utilization of Zn and Mn
  3. Excess of Zn, Mn, and Cu induces Fe-deficiency in crops
  4. Excess of S and Cu induces Mo-deficiency in crops
  5. Excess of Lime induces deficiency of all micronutrients.
  6. Presence of carbonate and bicarbonate ions in soil due to sodicity or over liming reduces the availability of micronutrient cations to crops which suffer most iron deficiency.
  7. Lime X P, Lime X Mo, Mo X P, and Na X K are common negative interactions.
  8. Excess of Ca may induce P deficiency
  9. Excess of Ca and Mg may depress K uptake
  10. Excess of Ca may reduce Mg uptake, if ratio is wider than 7:1
  11. Excess of K and NH+ may reduce Mg uptake
  12. Excess of N, K and Ca may reduce B toxicity
  13. Excess of N,P,K may induces Cu deficiency
  14. Excess of NO3-N may cause Fe deficiency
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