Micronutrient indexing in the apple orchards of Northern Punjab, Pakistan using geostatistics and GIS as diagnostic tools

Micronutrient deficiencies of soil are causing wide spread nutritional disorder in horticultural crops, grown in the calcareous soils. Keeping in view the limitations of classical statistics for explaining spatial heterogeneity a survey in the farmer grown apple orchards was conducted for indexing micronutrient using geo-statistics and GIS as a diagnostic tools. Geo-referenced soil samples were collected from 30 apple orchards. Recently matured leaves were sampled from associated apple trees. Widespread deficiency of Zn existed in the foliage of apple orchards followed by site specific Mn, Fe and Cu, respectively. Bioavailable Zn in soil was deficient in 30, 33 and 50%, and marginal in 10, 15 and 30% of total analyzed samples collected from the surface (0-15 cm), subsurface (15-30 cm) and lower soil depth (30-45 cm). Moderate to strong spatial dependence of studied micronutrients in three soil depths provided an opportunity to prepare contour maps for classifying the whole area in to various zones on the basis of having differential micronutrient content levels for regional scale information.