Document Type: Research Paper
Scientist–Agronomy Regional Coffee Res. Station, Chundale, Wayanad, Kerala, India.
Scientist, Water Management (Agriculture) Division, CWRDM, Kerala, India.
Centre for Soil and Crop Management studies, Tamil Nadu Agricultural University Coimbatore–641 003.
Field experiment was conducted for 2 seasons to study the influence of drip
fertigation in combination with or without bio fertilizers on yield, plant uptake and
soil fertility of Bt cotton. The treatments comprised of four levels of drip
fertigation viz., 75, 100, 125 and 150 per cent of recommended dose of fertilizers
(RDF, NPK) combined with and without bio fertilizers, drip irrigation with soil
surface application of 100 per cent RDF and surface irrigation with soil surface
application of 100 per cent RDF as control. Biofertilizers used for fertigation is
azophosmet containing Azospirillum, phosphobacterium and pink pigmented
facultative methylotroph. Most of the yield attributes viz., number of sympodial
branches per plant, number of fruiting points, bolls per plant, plant uptake and
available soil N, P and K of Bt cotton were significantly increased by the drip
fertigation treatments. Application of 150 per cent RDF as drip fertigation
combined with biofertigation of liquid formulation of azophosmet @ 250 ml
(1012 cells ml-1) ha-1 registered the highest seed cotton yield of 3395 kg ha-1 and
was significantly superior over control. Biofertigation significantly increased seed
cotton yield and a progressive increase in seed yield was noticed with increasing
levels of NPK fertilizer application. Application of nutrients through drip
fertigation improved seed cotton yield by 43.0 per cent compared with
conventional surface irrigation with soil surface application of fertilizers. The
nutrient uptake pattern and post harvest soil fertility status also followed similar
trend and confirmed the significance of drip fertigation with biofertilizers.
Keywords: Available soil nutrients; Cotton; Plant uptake; Yield attributes and yield.