STUDY ON THE INFLUENCE OF IRRIGATION REGIMES AND FERTIGATION LEVELS ON SUGARCANE UNDER SUBSURFACE DRIP FERTIGATION SYSTEM

摘要

Field investigations were carried out at the central farm, Agricultural College and Research Institute, Madurai, Tamil Nadu during 2008-09 and 2009-2010, to elicit information on the influence of irrigation regimes and fertigation levels on sugarcane under subsurface drip fertigation system. The experiments were laid out in Split Plot Design with three replications. The main plots treatment consisted of three subsurface drip irrigation regimes viz., 75 per cent Etc (I_1), 100 per cent Etc (I_2) and 125 per cent Etc (I_3). The subplot treatment consisted of six fertigation levels viz., 75 per cent RDF as commercial fertilizers (F_1), 100 per cent RDF as commercial fertilizers (F_2), 75 per cent RDF – 50 per cent commercial and 50 per cent water soluble fertilizers (WSF) (F_3),. 100 per cent RDF – 50 per cent commercial and 50 per cent WSF (F_4), 75 per cent RDF as WSF (F_5) and 100 per cent RDF as WSF (F_6).The sugarcane variety CO 86032 was used for this study. Subsurface drip irrigation was given once in 3 days and fertigation was given once in 6 days. Tiller production and number of millable canes were higher in drip irrigation at 125 per cent Etc along with fertigation of 100 per cent RDF as WSF (I_3F_6) which was comparable with 125 per cent Etc along with 75 per cent RDF as WSF (I_3F_5) in both plant and ratoon crop. The combination of drip irrigation at 125 per cent Etc with 100 per cent RDF as WSF registered higher cane and sugar yield but it was comparable with 125 per cent Etc along with 75 per cent RDF as WSF in both crops. Surface irrigation with soil application of fertilizers recorded lower cane and sugar yield when compared to subsurface treatments. The subsurface drip irrigation regime of 125 per cent Etc registered higher total water use followed by 100 per cent Etc and 75 per cent Etc in plant and ratoon crops. The treatment combination of 75 per cent Etc along with 100 per cent RDF as WSF (I_1F_6) recorded higher WUE and water productivity. Higher net return was recorded in 125 per cent Etc with 75 per cent RDF as water soluble fertilizers in plant crop however in ratoon crop, higher net return was observed in 125 per cent Etc with 100 per cent RDF as WSF. Higher BC ratio was associated with drip irrigation at 125 per cent Etc in combination with 100 per cent RDF as commercial fertilizers followed by drip fertigation of 75 per cent RDF as commercial fertilizers at 125 per cent Etc in both crops.