Soil fertility dynamics in the Northeastern agroclimatic zone of Tamil Nadu: a targeted analysis of Tiruvannamalai district

Soil fertility degradation due to poor nutrient management is a growing concern in many farming areas. This study focuses on assessing the soil health of Tiruvannamalai district, Tamil Nadu, by examining key factors like pH, organic carbon (OC), electrical conductivity (EC) and the availability of essential nutrients (nitrogen, phosphorus, potassium) and micronutrients (zinc, iron, copper, manganese, boron). A systematic soil sampling method was employed, collecting 129 samples from 18 blocks using a 5 × 5 km grid at 0-15 cm depth. The results showed that the soils were primarily neutral to slightly alkaline, with pH values ranging from 7.15 to 7.41. Electrical conductivity was low (<0.26 dS/m), indicating minimal salinity. Organic carbon levels were also low, with more than half of the samples (53.06%) falling below optimal levels, ranging from 0.29% to 0.64%. The analysis revealed widespread nutrient deficiencies, with 65% of the soils low in nitrogen, 63.06% lacking phosphorus and 79.44% deficient in potassium. Additionally, significant micronutrient shortages were detected, with zinc (83.89%), iron (83.06%), copper (76.67%), manganese (88.89%) and boron (75.28%) all showing depletion. These results highlight the urgent need for improved soil management practices, including targeted fertilization and nutrient restoration efforts, to enhance soil fertility and ensure sustainable agricultural productivity in the region.