Abstract

                                Nitrogen (N) fertility is an important component of rice cultivation systems, especially where rice growing under aerobic condition. This study examined the effects of silicon (Si) and leaf colour chart (LCC) based N management on yield and N use efficiency under aerobic rice. A field experiment was conducted in sandy loam soils at Bangalore-north with split plot design. The treatments consist of four main plots viz., control (No N), 60 kg Nha-1 (No basal + LCC-3), 90 kg Nha-1 (Urea at 30 kg Nha-1 as basal + LCC-3) and 100 kg Nha-1 as urea (RDF) and two sub plots viz., with (calcium silicate at 2 tha-1) and without Si treated plots. Periodical LCC readings were taken and N was applied if the LCC value falls below the prescribed critical value. The results revealed that the highest grain yield was noticed with the application calcium silicate at 2 t ha-1 and with 90 kg Nha-1 (Urea at 30 kg Nha-1 as basal + LCC-3) and it was on par with 60 kg Nha-1 (no basal + LCC-3) compared to recommended N (100 kg Nha-1) under aerobic rice. Higher fertilizer N-use efficiency was recorded with the application of Si and need-based N management using LCC-3 rather than recommended dose of fertilizer over control.

Key words : Nitrogen, LCC, NUE, Silicon and Aerobic rice.