Micronutrient cation status of mandarin (Citrus reticulata Blanco) orchards of Sikkim.

Abstract

Soil samples of 0–20, 20–40 and 40–60 cm depths and leaf samples from the non-bearing twigs were collected from the 32 mandarin (Citrus retieulata Blanco) orchards of Sikkim to study the micronutrient cation status. The analysis of soils revealed that the orchard soils were sufficient in available Zn, Cu, Mn and Fe and leaf analysis indicated 1/3rd orchards to be low in Zn and Mn, sufficient in Cu and high to excess (80%) in Fe. The total micronutrient concentration was high in 20–40 cm depth excepting Fe and highly correlated to each other and clay content. Available micronutrient cation content decreased with increasing soil depths, and did not correlate to their concentration in the mandarin leaf. Soil pH had the negative correlation with available Fe and Mn and positive with Zn and Cu. Exchangeable Ca+ Mg and organic carbon almost showed the same relationship. The micronutrient concentration of leaf was significantly and negatively related to soil organic carbon content and weak and negative to other soil properties. However, the inclusion of properties viz clay, organic carbon, pH and exchangeable Ca+Mg with soil available micronutrient cations of the three soil depths to leaf concentration of micronutrients increased the predictability from 46 to 66 per cent, and indicated the usefulness of soil properties in assessing the micronutrient availability in mandarin orchards.