Effect OP PH, orgrnic matter and plant growth on the movement of iron in soils

Abstract

The aim of this work was to study the effect of soil pH value and organic matter decomposition products on the diffusion of Fe. A soil‐block technique was used to determine the magnitude of Fe diffusion added as FeSO₄ or FeEDDHA to alkaline and acid soil samples previously enriched with alfalfa residues (4%) and incubated for different periods.

Results indicated a remarkable increase in the DTPA‐extractable Fe in the layer of fertilizer application and in the successive two soil sections when the inorganic form of Fe was added to the natural acid soil having originally 2% organic matter. The increase in the extractable Fe fron FeSO₄, treatment to the alkaline soil was evident only when the soil was enriched with organic matter and incubated for 3 months. The FeEDDHA diffused in about the same magnitude in all soil samples.

A new technique of a combined sand culture and a soil‐block was also designed to study the effect of plant on the movement of Fe by diffusion and mass flow. Results showed a significant effect of plant on the movement of Fe as the extractable Fe increased in all soil sections as well as in the sand medium and plant tissues after 2 days of contact. Preliminary results obtained with such new technique suggests its possible use in evaluating the fertility status of soils.

Key words:

• FeEDDHA
• soil amino acids
• diffusion
• mass flow