IMPACT OF BIOFERTILIZERS ON SUGARCANE PRODUCTIVITY

摘要

Field experiments were conducted in Alfisols of Mandya (India) to study the influence of N levels, N_2 fixers, P levels, P sources and P solubilizing microorganisms (PSM) on plant and ratoon cane. Soil application of Azotobacter/ Azospirillum at 2.5 kg/ha was instrumental in increasing cane and sugar yield. Sett inoculation of Acetobacter had no significant effect on yield. Application of 50% as single super phosphate (SSP) + 50% as pressmud (PM) + B. megaterium improved yield significantly. A saving of 25% N (50 kg N/ha) and 25% P (25 kg P_2 O_5/ha) is assured due to the application of N_2 fixers and PSM, respectively. A pot and field study suggested that the N dose of 100-400 kg/ha to sugarcane pose no environmental threat. Soil application of N_2 fixers reduced leaching losses of NO_3-N, thus minimizingegating ground water pollution. Another field experiment was conducted in Entisols of KIAAR Sameerwadi to study the effect of single and dual inoculation of Azospirillum and PSM on sugarcane yield. Single or dual inoculation of bioagents were responsible for higher Rhizobial population of Azospirillum, enzyme activity, particularly dehydrogenase, nutrient status and nutrient availability which resulted in higher cane and sugar yield. The best treatment combination was Azospirillum ACD 20 + Burkholdena cepacia + 75% of recommended dose in maximizing cane and sugar yield. There is a saving of 25% fertilizer N and 25% fertilizer P due to the dual inoculation of N_2 fixers and PSM. This confirms the earlier findings. A study in the farmer's fields on sugarcane based Agro Forestry revealed that the inoculation of Frankia to Casuarina trees resulted in higher microflora in the rhizosphere. The synergism between N_2 fixers and P solubilisers should be gainfully exploited for enhancing the crop yield and environmental protection. Sure enough, these bioagents serve as the 'gate keepers' of sustainable crop production.