Dates of Sowing and Residual Nitrogen Levels on Growth, Yield and Uptake in Sorghum under Zero-till Conditions in Coastal Belts of India

A field experiment was conducted during rabi seasons of 2017-18 and 2018-19 at College farm, Agricultural College, Bapatla, situated at 8 km away from the Bay of Bengal in the Krishna Agro-climatic Zone of Andhra Pradesh state of India to study the influence of dates of sowing and residue levels of nitrogen on growth, yield and uptake of sorghum under zero- till conditions in coastal rice fallows. The experiment was designed in RDB with factorial concept and replicated thrice. The treatments consisted of three dates of sowing (Factor-1): S1: 49 MW (5th December); S2: 50 MW (15th December); S3: 52 MW (25th December) and four residual nitrogen levels (Factor-2) applied to the previous rice crop: N1-60 kg, N2-80 kg, N3-100 kg and N4-120 kg N ha-1. Sorghum was grown as a residual crop under zero tillage in rice fallows. Significant higher improvement in drymatter (10395 and 10269 kg ha-1), length of spike (24.8 and 24.5 cm), grain (3839 and 3602 kg ha-1) and stover yields (7446 and 7298 kg ha-1) and nitrogen uptake by grain (51.9 and 42.9 kg N ha-1) and stover (42.0 and 39.9 kg N ha-1) was recorded in early date of sowing i.e. 49 MW in both the seasons 2017-18 and 2018-19, respectively, and among the residue nitrogen levels 120 kg N ha-1 showed highest drymatter (10661 and 10484 kg ha-1), length of spike (25.0 and 24.8 cm), grain (4078 and 3815 kg ha-1) and stover yields (7518 and 7443 kg ha-1) and nitrogen uptake by grain (54.6 and 46.6 kg N ha-1) and stover (44.3 and 42.1 kg N ha-1) compared to other nitrogen levels in both the seasons. Based on above results, early sowing of sorghum with high residue nitrogen levels could be recommended to small and marginal farmers in coastal belts of India for higher productivity.