Influence of Soil Characteristics on DTPA Extractable Micronutrient Cations in Some Soil Series of Punjab

Relationships of DTPA extractable Zn, Cu, Fe and Mn with pH, CaCO₃, organic matter, clay and silt have been examined in the samples collected from 23 soil series of Punjab. The correlation studies have indicated that pH, silt and organic matter influence the extraction of these micronutrients with DTPA. The dominant influence of pH on extractable Zn and Mn suggests that DTPA extracts largely the inorganic mineral forms of these nutrients. The extractable Fe is influenced by both pH and silt fraction of the soil indicating thereby that DTPA readily takes out the exchangeable ₃Fe held on silt particles as well as Fe-minerals. Judging from the effect of organic carbon and silt contents it becomes evident that DTPA extracts the organically complexed and easily exchangeable forms of copper held on the silt particles.