INFLUENCE OF NUTRIENT MANAGEMENT PRACTICES AND MICROBIAL INOCULANTS ON PRODUCTIVITY AND SOIL QUALITY OF LOWLAND RICE IN EASTERN HIMALAYAS

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Date
2017
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DIVISION OF AGRONOMY ICAR-INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI-110012 सस्य िवज्ञान सभाग ं भारतीय कृिष अनसु धान ं सस्थान ं नई िदल्ली 11001
Abstract
A field study entitled “Influence of nutrient management practices and microbial inoculants on productivity and soil quality of lowland rice in eastern Himalayas’’ was conducted during Kharif 2016 at the research farm of ICAR Complex for NEH Region (Umiam) Barapani, Meghalaya. The soil of the experiment site was sandy clay loam in texture, acidic (5.0) in nature and having low available N (252.98 kg/ha) and P (8.19 kg/ha), but high available K content and soil organic carbon (2.51%) content. The experiment was laid out in a split plot design with three main plots and four sub-plot treatments with three replications. The popular rice variety ‘Shahsarang 1’ was taken. Main plot treatments included 3 nutrient management practices viz., organic, inorganic (mineral fertilizer at RDF of N80P40K40) and integrated nutrient management (INM) having 75% mineral + 25% organic. In sub plot 4 microbial inoculants viz., control, Azospirillum, Azospirillum+ Phosphate Solubilizing Bacteria (PSB) and Azospirillum+ PSB + Zinc Solubilizing Bacteria (ZnSB) were taken. Results showed that among the nutrient management practices, highest plant height, leaf area index and dry matter accumulation were observed in INM practice followed by inorganic and organic nutrient management. The similar trend was also observed in case of yield attributing characters viz., tillers/m2 , grains/panicle, panicle length and fertile grains/panicle. The highest grain yield (4.27 t/ha) was recorded in INM followed by inorganic (4.08 t/ha) and organic (3.65 t/ha) nutrient management and the difference between both INM and inorganic was statistically at par. This was the first year of organic farming in that field and there was a yield advantage of 12% and 17% in inorganic and INM over organic management, respectively. Among the three nutrient management practices, the highest cost of cultivation (₹ 28854/ha) was recorded under organic nutrient management followed by INM and inorganic treatment in reducing order. However, the highest gross return (₹ 74399/ ha) and net return (₹ 52508/ ha) were observed in INM practice with combined inoculation of Azospirillum+ PSB+ ZnSB. Benefit: cost (B: C) ratio also showed the same trend like gross and net return and it was ranging between 1.03 (organic- control) to 2.41 (INM with Azospirillum+ PSB + ZnSB). Higher enzymatic activity, root growth parameters and better grain quality of grains were observed in organic nutrient management practice followed by INM and inorganic nutrient management. Microbial inoculants significantly influenced the plant growth, yield attributes, yields and nutrient uptake of rice over the control treatment. The highest (4.25 t/ha) and lowest (3.72 t/ha) grain yields were obtained in Azospirillum+ PSB+ ZnSB and control treatments, respectively. There was a yield advantage of 5.9%, Whereas 10.2% and 14.2% due to the inoculation with Azospirillum alone, Azospirillum+ PSB and Azospirillum+ PSB+ ZnSB as compared to control treatment. Among the soil microbiological parameters, the highest value of soil FDA (11.80 µg fluorescein/g soil/hr), alkaline phosphatase activity (162.58 µg p-NP/g soil/ hr), soil microbial biomass carbon (MBC) (174.49 g/g dry soil) were higher in organic treatment compared to inorganic and INM. All the microbial activities were higher at 60 DAT as compared to crop harvest stage. The availability status of the N, P, K and Zn in soil at crop harvest was highest in INM practice followed by inorganic and organic management, the highest soil organic carbon (2.62%) was recorded in organic nutrient management followed by INM (2.55%) and inorganic (2.52%) treatment. Among microbial inoculation treatments, all the three inoculation treatments recorded significantly higher available N and P over the control. It was concluded that farmers may adopt INM including 75% mineral fertilizer with 25% organic input for higher crop productivity, profitability and grain quality of low land rice under eastern Himalayas.
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