Indigenous soil nutrient supply and nutrient-use efficiency of rice (Oryza sativa) in Cauvery Delta Zone of Tamil Nadu

An experiment was conducted in both kuruvai (June to September) and thaldi (October to January) seasons of 2014–17 at Aduthurai, Tamil Nadu, using omission-plot technique, to study the indigenous soil nutrient supply and nutrient-use efficiency of rice (Oryza sativa L.) field. The experiment was laid out in a randomized block design with 4 replications and 6 treatments, viz. T₁, N₀PK; T₂, NP₀K; T₃, NP₀K; T₄, NPK; T₅, NPK + ZnSO₄; T₆,-F. The results showed that, indigenous soil nitrogen supply ranges from 51 to 55 kg/ha. The optimum values of recovery efficiency, physiological efficiency, agronomic efficiency, partial factor productivity and internal efficiency were obtained in both the seasons. To achieve the target yield of 7 t/ha in kuruvai, fertilizer rate was calculated as 118, 34.4 and 48 of N, P and K kg/ha and in thaladi it was 67, 23 and 30.9 of N, P and K kg/ha to attain the target of 5 t/ha. The data also indicated that application of recommended dose of NPK along with ZnSO₄ (T₅) in both the seasons’ recorded higher grain and straw yields and higher nutrient uptake (N, P and K).