Quantification of Plant available Zinc, Copper, Iron, Manganese, Boron, and Visualization of their Spatial Distribution through GIS in District Mandi Bahauddin, Punjab, Pakistan

Micronutrients deficiency in alkaline-calcareous soils is a major constraint to get optimum crop yield.The possible solution could be the site-specific nutrient management after assessing the micronutrient status at a particular site.This study was conducted to quantify and visualize the spread of plant available micronutrients in district Mandi Bahauddin.Total 1194 georeferenced soil samples were collected at a depth of 0-15cm maintaining a sampling grid cell size of 10-acres (40469 m 2 ) throughout the sampling area.These samples were analyzed for plant available Zinc (Zn), Copper (Cu), Iron (Fe), Manganese (Mn) following Diethylenetriamine Penta-Acetate (DTPA) extraction methodology.Quantification was carried out by Flame Atomic Absorption Spectroscopy (AAS).Hot water-soluble (HWS) Boron (B) was determined spectrophotometrically.Additionally, soil samples were also analysed for electrical conductivity (EC), soil pH and soil organic matter (SOM) contents.These characteristics were correlated with plant available micronutrients.The DTPA-extractable Zn, Cu, Fe, and Mn ranged from 0.07-5.60,0.11-1.22,0.74-7.45and 0.02-3.39mg/Kg soil, respectively.Boron ranged from 0.06-0.69mg/Kg soil.Considering the critical limits set by National Agricultural Research Center (NARC), Islamabad, Pakistan, 92% soil samples were found deficient in B followed by 44% soil samples low in Fe.Whereas, Zn, Cu and Mn were deficient in 5, 1 and 12 % of soil samples, respectively.Soil EC and pH of analysed samples ranged from 0.10 to 3.74 dSm -1 and 6.70 to 8.40, respectively.Soil was free from salinity and sodicity menace.However, soil was deficient regarding SOM with mean value of 0.69%.The correlations between soil pH and plant available Zn, Fe, Mn, and B were significant and negative.The ordinary kriging technique was used to assess the micronutrient status at non-sampling sites and research area was classified into low, marginal, and adequate categories according to plant available micronutrient status.Digital maps thus developed using Quantum Geographic Information System (QGIS) would help to apply micronutrients more precisely and site-specifically.