Nutrient indexing of benchmark sites of Erode district in Tamil Nadu

In order to forecast the emerging micro- and macro-nutrient deficiencies or toxicities in crops and soils resulting from intensive cropping, 15 benchmark sites have been identified in Gobichettipalayam taluk of Erode district in Tamil Nadu, based on the soil physico-chemical properties. The experimental soils were neutral in pH, free from salinity, low in organic carbon, medium in available P & K. The available micronutrient status has shown that the soil available Zn & Cu and Fe & Mn is in the range of deficiency and sufficiency levels, respectively. The soils belong to Irugur (red non-calcarcous), Chikkarasampalayam (black calcareous) and Sathyamangalam (black calcareous) series. Two intensive cropping systems such as Rice - Rice and Sugarcane - Sugarcane - Turmeric were chosen for the study. The soil data indicated that both intensive cropping systems have depleted the soil nutrient status heavily. However, as both cropping sequences have been supplied with sufficient quantities of fertilizer inputs carrying macronutrients, soils in the benchmark sites have maintained the inherent soil fertility status. On the other hand, non-addition of micronutrients has caused deficiencies of Zn, Cu and B as indicated by the available nutrient status in both cropping sequences. Plant samples showed sufficiency levels of both macro and micronutrients. The overall data indicated that there is an utmost necessity for application of micronutrients especially Zn, B and Cu to enable to maintain the crop yields in the intensive cropping systems in Erode district. Further, soil nutrient balance has to be maintained by proper substitution of organic and inorganic sources of macronutrients.