Question

In which type of soils, copper deficiency is more ?

• A. Clay soils
• B. Sandy soils
• C. Mineral soils
• D. Organic soils

Hint:

Copper (Cu) has the highest affinity for organic matter among all micronutrients. Hence, Peat/Muck/Organic soils always show high Cu deficiency.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question asks which soil class exhibits the most pronounced Copper (Cu) deficiency in crop plants.

Step 2: Key Chemical Concepts of Soil Copper Availability:

• Copper ($Cu^{2+}$) Reactions in Soil: Copper forms stable insoluble complexes and chelate rings with organic matter ligands (humic and fulvic acids).

• Organic Soil Affinity: Organic soils (such as peat and muck soils containing $>20\%$ organic carbon) hold copper very tightly via complexation/chelation, making it uvailable for root uptake.

• Reclamation Disease: Copper deficiency in highly organic soils is historically termed "reclamation disease" (Urban-Krankheit).

Step 3: Detailed Explation:

• In organic soils (Peat/Muck soils), $Cu^{2+}$ ions are strongly bound to humic compounds by co-ordite covalent bonds, severely reducing concentration in soil solution.

• Although sandy soils can also be low in total micronutrients due to leaching, organic soils present the classic, most severe form of chemical Cu fixation/deficiency.

• Plants grown on peat soils frequently show typical Cu deficiency symptoms such as "dieback" in fruit trees and "reclamation disease" in cereals (bleached yellowing of leaf tips and poor grain formation).

Step 4: Fil Answer:
Organic soils are most prone to severe copper deficiency due to strong organic complexation. Therefore, option (D) is correct.