Spatial distribution and quantification of plant-available nutrients and soil properties in Punjab, Pakistan

Abstract

The quantification and spatial distribution of nutrients are crucial for agriculture production and protection. However, locally quantifying these soil variables is challenging in areas where transitions change over short distances, making correct land-use management difficult. This research paper aimed to quantify and analyze the spatial distribution of micronutrients (zinc, copper, iron, manganese and boron), macronutrients (potassium and phosphorus), as well as soil characteristics (electrical conductivity, pH, organic matter, and soil saturation) in the agricultural districts of Sahiwal and Sargodha in Punjab, Pakistan. The mean available phosphorus (AP) concentrations ranged from 7.37 to 7.00 mg/kg in Sahiwal and Sargodha, respectively, falling below the permissible range in both regions. Conversely, potassium (K) levels were within the recommended range, with values ranging from 110 to 280 mg/kg in Sahiwal but lower in Sargodha. Zinc (Zn) concentrations ranged from 1.6 to 0.4 mg/kg in Sahiwal and 1.8 to 0.3 mg/kg in Sargodha, with acceptable levels in Sahiwal but not in Sargodha. Copper (Cu) concentrations in both regions met acceptable standards. Mean iron (Fe) values were 5.6 and 5.2 mg/kg in Sahiwal and Sargodha, respectively, exceeding the limit in Sahiwal but falling below in Sargodha. Manganese (Mn) concentrations were acceptable in Sargodha but low in Sahiwal while boron (B) levels were below acceptable thresholds in several Sargodha samples but within limits in Sahiwal. Some Sahiwal samples exhibited excessively high pH, unlike in Sargodha. Nevertheless, both areas adhered to permissible soil saturation levels, except for one Sahiwal sample with elevated electrical conductivity (EC). Soil organic matter (SOM) content ranged from 0.57% to 0.52% in Sahiwal and Sargodha, respectively, with the majority of samples from both regions falling below permissible SOM ranges. The results suggest that quantity and spatial distribution are affected by locality, and therefore, exciting land-use management protocols should be adopted for spatial distribution and changes, not just absolute quantities. This study provides practical recommendations for farmers, researchers, and policymakers to enhance agricultural production and sustainability in Sahiwal and Sargodha.