Nitrogen Management in Sali Rice using Leaf Colour Chart

Conventional blanket application of nitrogen fertilizers in rice cultivation frequently leads to substantial nutrient losses, low nitrogen use efficiency, and increased costs for farmers. To address this inefficiency, there is a critical need to adopt real-time, crop-demand-driven nitrogen management strategies that optimize yields while reducing chemical dependency. A field trial was conducted during Kharif season, 2021 on transplanted Sali rice (var. Ranjit Sub-1) in the farmer's field of Nalbari district with a view to study the leaf colour chart (LCC) based nitrogen fertilizer management in Sali rice. The treatments comprised of T1: LCC4 with INM (Azospirillum + PSB @ 4kg/ha each + Rock Phosphate @ 10kg/ha + recommended dose of K @40kg/ha) and T2: Recommended dose of NPK @ 60:20:40 kg/ha. Under T1 treatment, 3 split doses of urea were applied @ 33.75kg/ha based on LCC after transplanting of rice with no basal application of N. The results reveled that LCC based N management practice was more beneficial in terms of improving the yield attributing characters (plant height, no. of effective tillers, length of panicle, no. of filled grain/panicle, no. of false grain/panicle and test weight of seed), yield of rice and total biological yield as compared to the recommended dose of chemical fertilizers. There was increase in NUE and AE of nitrogen by 47.17kg/kg N and 22.67 kg/kg N respectively and saving of 24.75 kg urea which was 11.25% in terms of chemical N and 10.16% increase in grain yield over the recommended dose of chemical fertilizers. Need based N fertilizer application through LCC4 with INM treatment was proved to be more profitable as indicated by the higher B: C ratio (2.5) than the RDF application B: C ratio (2.3) Thus, LCC based N application along with INM in rice cultivation proved to be a promising tool for reducing N losses with judicious application, obtaining better yield of rice and thereby increased the net return of the farmers.