SPATIAL VARIABILITY OF MICRONUTRIENTS IN CITRUS ORCHARD OF NORTH WESTERN PAKISTAN

The spatial variability of micronutrients (Zn, Cu, Fe, Mn and B) in citrus orchards in Malakand Agency of Khyber Pakhtunkhwa Province during 2008 was assessed and mapped. Soil samples at 0-30 cm depth from 24 different spots at 6 m distance from one another were collected from a citrus orchard located in Warther area of Dargai Malakand Agency and were analysed for micronutrients. Geostatistical technique of semivariogram analysis was applied on data to determine spatial structure of micronutrients in soils. Soil test values at other locations were interpolated using geostatistical technique of kriging and detailed isarithmic maps. The results showed that Zn was low in none, marginal in 54.17 % and adequate in 45.83 % samples. Similarly, B was low in none, marginal in 83.33 % and adequate in 16.67 % samples. However, Cu, Fe and Mn were adequate in 100 % samples. Semivariogram analysis showed that Cu, Fe and B had strong, Zn had a moderate and Mn had a poor spatial structure described by linear model. Computer generated maps using kriging technique showed that almost all the maps had some spatial variation in different micronutrient contents in the field. These results suggested that the citrus orchard was not uniform in micronutrient contents and can be delineated into different categories for variable rate fertilizer management.