Evaluating the Primary Macronutrients and their Correlations with pH, Electrical conductivity, Organic Carbon and Soil Nutrient index in the Arid and Semi-Arid Climatic Zones of Anantapur District, Andhra Pradesh, India

Abstract

In the year 2022, the study was carried at Agricultural Research Station, Anantapur aimed to assess macronutrient levels and their correlation with soil physico chemical properties in the arid and semi-arid regions of Anantapur district, Andhra Pradesh. A total 42 samples were collected from farmers field under different land use. The soil analysis revealed a pH range of 6.53 to 8.94, with a mean pH of 7.89 and a majority of samples exhibiting alkaline properties. Soil electrical conductivity (EC) varied from 0.05 to 0.83 dS/m, with a mean EC of 0.22 dS/m, and most samples falling within the non-saline and very low salinity categories. Organic carbon content ranged from 0.07% to 1.15% with a mean of 0.38%, and a significant proportion of samples displayed low organic carbon levels. Available nitrogen content ranged from 50.4 to 264.6 kg/ha (mean: 139.44 kg/ha), mostly below the critical threshold. Phosphorus availability was medium (range: 16.1 to 44 kg/ha, mean: 29.97 kg/ha), while available potassium content varied widely (range: 15.68 to 311 kg/ha, mean: 129.65 kg/ha), with a substantial proportion of samples indicating low levels. The nutrient index categorized nitrogen and potassium as low in fertility and phosphorus as medium, reflecting values of 0.71, 1.37, and 1.09 (L, M, L) respectively. Correlations showed EC negatively related to pH (-0.056), while organic carbon positively correlated with EC (0.288*), and nitrogen displayed positive correlations with both organic carbon (0.283*) and pH (0.257). Phosphorus exhibited a positive correlation with organic carbon (0.224), and potassium displayed robust positive correlations with EC (0.592**) and moderate positive correlations with organic carbon (0.392**), nitrogen (0.311*), and a slight negative correlation with pH (-0.253). This result helps to understand nutrient status in the arid and semi-arid areas of Anantapur and recommended to incorporate compost, crop residues and green manure crops and use cover crops as live mulching helps to increase organic carbon, nitrogen and potassium and it also decrease nitrogen losses through volatilization.