RÉSUMÉ
Aim: To study the “Long Term Effect of Organic and Inorganic Manures on Rice Productivity and Major nutrient dynamics in 33 years old Rice- Rice Cropping System of Godavari Delta”.Place and Duration of Study: A field experiment was carried out during kharif 2022 at Regional Agricultural Research Station, Maruteru, West Godavari district in the ongoing All India Coordinated Rice Improvement Project (AICRIP) on Long term soil fertility management in low land rice soils of Godavari delta under rice-rice cropping system.Study Design and Methodology: Treatments imposed in this study were T1: Control, T2: 50 % NPK, T3: 50% NPK + 50 % N-FYM, T4: 50 % NPK + 50% N-Green Manure, T5: 50 % NPK + 50 % N-Azospirillum, T6: FYM @ 10t/ha, T7: 100 % NPK+Zn+S, T8: 100 % NPK +Zn+S+FYM @ 5 t ha-1. All together 8 treatments laid out in RBD with three Replications. The application of fertiliser was carried out in accordance with the treatments. The prescribed fertiliser dose (90:60:60) was administered in the following forms: urea (46% N), single superphosphate (16% P2O5), muriate of potash (60% K2O), and zinc sulphate (ZnSO4.7H2O) @ 50 kg ha-1. The total dosage of phosphorus, potassium, and zinc were applied as basal. Three equally divided applications of nitrogen were made: one at the basal, one at the tillering stage, and one at the panicle initiation stage. Well decomposed farmyard manure (FYM) manure and Pheltophorum (green leaf manure) were applied one week before transplanting. Popular cultivar of Kharif rice MTU 1064 (Amara) was used for the study.Results: Long-term application of organic and inorganic fertilizers and their combination didn’t show any marked difference on physico-chemical properties of soil (pH and EC). Bulk density was recorded lowest in FYM @ 10 t ha-1 and it was on par with (T8, T3, T4, T5). Organic carbon was observed highest in FYM @ 10 t ha-1 and it was on par with (T8 and T3). There was a significant impact of long-term application of organic and inorganic fertilizers and their combination on soil chemical properties, highest available N, P, K, S and Zn was observed highest in conjunctive treatment (T8) 100 % NPK + Zn + S + FYM @ 5 t ha-1 whereas, lowest was recorded in control. There was a significant impact on grain and straw yields. Highest grain and straw yields were recorded in (T8) 100 % NPK + Zn + S +FYM @ 5 t ha-1 and it was on par with (T7) 100 % NPK + Zn + S.Conclusions: After the investigation, present study concludes that conjunctive and combined application of organics with inorganics improve soil physical, physico-chemical and chemical properties of the soil.