Geographic Information System and Geostatistical Techniques to Characterize Spatial Variability of Soil Micronutrients Including Toxic Metals in an Agricultural Farm

ABSTRACT

Knowledge of spatial variability of soil properties is critical for precision farming and identification of pollution hot spots. This study examined the spatial dependence and variability of microelements to produce nutrient maps for site-specific nutrient management and for environmental modeling. A total of 94 grid samples (50 × 50 m²) were collected and analyzed for available zinc (Zn), copper (Cu), manganese (Mn), iron (Fe), nickel (Ni), cadmium (Cd), and lead (Pb) using an atomic absorption spectrometer. Coefficient of variation (CV) indicated that all the microelements were high in heterogeneity (CV > 35%). Available Zn was found deficient in 66.4% of soil samples and might be one of the limiting nutrients for crop growth, Cu and Ni were in medium, and Fe and Mn in very high range. Pb and Cd were lower than standard values, but careful management will avoid toxicity. Significant correlation was found between Zn with Fe (r = 0.377); Ni with Mn and Fe (r = 0.350 and 0.205, respectively); and Pb with Mn and Ni (r = 0.298 and 0.221, respectively). Spatial variability of soil microelements was mapped by ordinary kriging using exponential model for Fe, Mn, Ni, Cd, and Pb; Gaussian model for Cu, and spherical model for Zn. Semivariogram showed strong to weak degree of spatial dependence for all microelements. The study highlighted the importance for the creation of nutrient management zones for Zn availability. The spatial variability maps generated could be used as a guide for precise and site-specific micronutrient management in the study region.

KEYWORDS:

• Geostatistics
• lesser Himalayas
• micronutrients
• spatial variability
• toxic metals

Acknowledgments

The authors are grateful to Head of Department, Division of Soil science, SKUAST-K, Shalimar, for providing adequate laboratory and library facilities. We thank Dr Shaista Nazir for providing precious review comments on the manuscript. We extend our great appreciation to Mr Ali Mohammad, Mr Ismail Bhat, Mr Gulam Hassan, Mr Tariq Ahmad, Mr Fayaz Ahmad, and Mr Majeed for providing information on the histories of the sites and support during field and lab work. The present work is part of a thesis for the fulfillment of Doctor of Philosophy in Agriculture (Soil Science), to the Faculty of Post-Graduate Studies, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir.

Conflicts of interest

The authors declare that they have no competing interests.

Additional information

Notes on contributors

Mushtaq A. Wani

The authors Shazia Ramzan and Mushtaq A. Wani carried out the statistical and geostatistical analysis of the data generated after analysis of soil samples. The analysis of soil was carried mainly by Shazia Ramzan. The author Mushtaq A. Wani mainly contributed to the development of the methodological framework. All authors have read and approved the final manuscript.